Archive for the ‘Male Genetics’ Category

Earthwork Portrait of Genghis Khan Christophe Boisvieux/Corbis

Since a 2003 study found evidence that Genghis Khans DNA was present in about 16 million men alive at the time, the Mongolian rulers genetic prowess has stood as an unparalleled accomplishment. But he isnt the only man whose reproductive activities still show a significant genetic impact centuries later. A 2015 study published in the European Journal of Human Genetics found that a handful of other men had prolific lineages, too.

To identify those lineages, the geneticists analyzed the Y chromosomes of more than 5,000 men from 127 populations spanning Asia, wrote Nature News Ewen Callaway in 2015. The Y chromosome is a part of the human genome handed down only from father to son. They found 11 Y-chromosome sequences that were each shared by more than 20 of the analyzed subjects. Chalk down one of those as Genghis Khans, and that leaves ten other men who initiated long-lived and widely spread family trees.

When he ruled during the 13th century, Genghis Khan presided over land that spanned from the Pacific coast of China to the Caspian Sea. Historians dont know exactly how many children Genghis Khan sired, but many agree his lineage is broad. In 1260, Persian historian Ata-Malik Juvaini wrote: Of the issue of the race and lineage of Chingiz [Genghis] Khan, there are now living in the comfort of wealth and affluence more than 20,000.

Mongol rulers such as Genghis Khan could have spread their genes widely, because of rapes during conquests and because the khans had access to many women in the areas they ruled, Oxford University geneticist Chris Tyler-Smith told Nicholas Wade of the New York Times in 2003.

Genghis Khans sons may have followed in their fathers footsteps and had large harems. Tushi, the emperors oldest son, had 40 sons himself, per the New York Times.

So, who were the other super-fertile fathers? One genetic sequence is attributed to Giocangga, the grandfather of the founder of the Qing dynasty. His Y chromosome was linked in a 2005 study to 1.5 million men in modern northern China. This large number likely resulted from his descendants taking many wives and concubines.

The other nine men are currently mysteries. Yet, by assuming they lived in the area where their genomes were most commonly found and by studying mutations in the genetic sequences, scientists suggest they originated throughout Asia between 2100 B.C.E. and 700 C.E., per Nature News.

According to Nature News, the founders who lived at the earlier end of this range, between 2100 B.C.E and 300 B.C.E., were part of both agricultural and nomadic cultures. They lived during the emergence of hierarchical, authoritarian societies in Asia. And the three lineages connected to more recent times, including those linked to Genghis Khan and Giocangga, were associated with nomadic peoples in Mongolia and northeast China.

Large genetic legacies are not confined to that part of the globe. According to a 2006 study in the American Journal of Human Genetics, 1 in 12 Irishmen worldwide can trace their heritage back to a single individual. That man may be a fifth-century Irish warlord dubbed Niall of the Nine Hostages, who could have as many as three million direct male descendants in modern times.

Genetic studies published in the last few years have continued to reveal more information about the heritage of peoples around the world. From uncovering the genetic history of the Viking age to confirming the origins of the Swahili people and pinpointing Neanderthal genes in modern populations, techniques analyzing ancient DNA have opened another window to understanding how genes flowed in the past.

As far as the nine unknown founders with impressive genetic lineages, more research is needed to discern their identities. But one thing is certain: Genghis Khan has never been the only big kid on the genetic block.

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Excerpt from:
Move Over, Genghis Khan. Many Other Men Left Huge Genetic Legacies - Smithsonian Magazine

image:

Photograph of a stick insect.

Credit: Filippo Castellucci.

Traits are often lost during evolution, either because they are no longer beneficial or because they are too costly to maintain. When this happens, it is generally believed that the genes underlying the trait will eventually degrade as well, making it difficult if not impossible for the trait to re-emerge. Yet, there are numerous examples in nature of once-lost traits reappearing in descendent lineages. According to Giobbe Forni, a Research Fellow at the University of Bologna, Mapping the presence and absence of traits onto a species tree suggests that some traits may have been lost in the lineages leading to extant species and then subsequently reinstated. Wings in stick insects are considered one of the more iconic instances of this evolutionary process. This implies that the genes underlying these traits may be preserved, in some cases for millions of years. Unfortunately, research on the molecular basis of such re-emergence is sparse, leaving the underlying mechanisms responsible for such preservation largely open to speculation until now. In anew study published in Genome Biology and Evolution, Forni and his colleagues shed light on another complex trait that has been lost in some stick insectsthe production of males. Loss of the ability to produce males results in populations of only females, which reproduce by parthenogenesis, a form of asexual reproduction. The study reveals that genes that are highly connected in regulatory networks and involved in multiple biological processes may be maintained long after a trait is lost, providing a potential avenue for trait re-emergence over long evolutionary time scales.

In the new study, Forni and his co-authors Barbara Mantovani, Alexander S. Mikheyev, and Andrea Luchetti performed a comparative analysis of three species of stick insects in the genusBacillus. WhileBacillus grandii marettimipopulations are composed of males and females that reproduce sexually,Bacillus atticuspopulations have lost the ability to produce males, comprising only females that reproduce by parthenogenesis. A third species,Bacillus rossius, includes both sexual populations and parthenogenetic populations that have lost the ability to produce males. By studying the fates of genes involved in male reproduction in these three species, the authors sought to investigate the extent to which genes are preserved after trait loss and the potential mechanisms driving this preservation.

The researchers first identified gene networks whose expression was correlated with either male or female reproduction in the sexual speciesB. marettimiand then evaluated the same genes inB. atticusandB. rossius. Surprisingly, male-related genes exhibited no signs of weakened selection or accelerated evolution compared with female-related genes in the parthenogenetic species. Furthermore, male-related patterns of gene expression were partially preserved across both parthenogenetic species.

Delving deeper, the researchers found that genes in female-related networks were primarily expressed in female reproductive tissues, while those in male-related networks were expressed in maleandfemale reproductive tissues, including both sexual and parthenogenetic females. This suggests that male-related genes may also play roles in female reproduction. The involvement of a gene in multiple biological processes is known as pleiotropy, and this phenomenon may explain the preservation of male-related genes in these parthenogenetic stick insects, as previously hypothesized.

Moreover, the authors found that genes that were highly connected to many other genes in the network were more likely to be expressed in the reproductive tissues of parthenogens, suggesting that a gene's network connectivity may also influence its gene preservation after trait loss. Taken together, these findings indicate that the molecular ground plan of the once-lost male reproductive process may persist due to pleiotropic effects on other traits, explains Forni. Different genes may undertake different trajectories of preservation and decay depending on the level of pleiotropy within the gene regulatory network.

This study not only sheds light on genetic architecture persistence after trait loss but also offers a potential glimpse into the emergence of rare males and cryptic sex (i.e. episodic generation of males and sexual reproduction), which have been observed in an increasing number of lineages that were thought to have lost the ability to produce males long ago. This opens up new potential avenues for research, with implications that may reach far beyond stick insects. Looking at how widespread genetic preservation after trait loss is on a larger scale remains fundamental. Although theBacillusspecies complex offers a nice framework to address these issues, it would be useful to analyze a larger species complex where multiple transitions between reproductive strategies has occurred, notes Forni. While it is often necessary to rely on model species to discover and dissect biological processes, it is even more important to test our hypotheses in a wider context. This will be possible only if we dedicate more effort to observing and analyzing the amazing diversity of organisms and their intricate adaptations.

Genome Biology and Evolution

Observational study

Animals

Parthenogenetic stick insects exhibit signatures of preservation in the molecular architecture of male reproduction

21-May-2024

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

Excerpt from:
Maintenance of male-related genes after loss of males in stick insects - EurekAlert

Silverback gorillas are famous for their impressive, bulging physiques and their rather modest genitalia. Now, scientists have uncovered a potential genetic link between these apes' small members and infertility problems in male humans.

Coming in at just 1.1 inches (3 centimeters) long, on average, the penis of the adult male gorilla (Gorilla) is the smallest phallus of all apes. The gorilla's genital size comes with other deficits in its reproductive capacity, such as low sperm count compared to other primates, and sperm with poor motility and a diminished ability to bind to eggs.

Given that these are reproductive issues that can also affect humans, it may seem surprising that all male gorillas share these traits. However, this can be explained by gorillas' mating system, said Jacob Bowman, lead author of the new study and a postdoctoral researcher at the University at Buffalo.

Gorillas operate in a polygynous system, in which a dominant male has near-exclusive access to females in his troop. The silverback's unwieldy physique means it has no problem securing mates, and thus, its sperm doesn't have to compete with that of other males and it can produce offspring without many, highly motile swimmers. The theory is that this lack of sperm competition led to the evolution of gorillas' small genitalia.

Related: Move over, Viagra this spider's boner-inducing venom could treat people let down by the blue pill

This got researchers "wondering if, at a genetic level, we can find genes associated with spermatogenesis [sperm production] or that we see leading to poor-quality sperm," Bowman told Live Science. Gorillas and humans share the vast majority of the same genes so if the researchers could pinpoint suspect genes in gorillas, they could next turn their attention to the human genome.

Roughly 15% of U.S. couples have trouble conceiving, according to Yale Medicine, and more than half of those cases involve male infertility. Around 30% of infertility cases have a genetic basis, said Vincent Straub, a doctoral student in population health at the University of Oxford who was not involved in the new study. However, the genes involved in male infertility are poorly understood.

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To help unravel those genetics, Bowman and colleagues combed through a database of more than 13,000 genes across 261 mammals. This involved looking at genes' underlying sequences, to see how they changed over time in related animals. The aim was to see if certain genes in the gorilla branch of the tree of life were evolving at dramatically reduced rates, Bowman said.

This can happen when there isn't strong pressure to get rid of genetic mutations that could hinder a population's survival such as those related to gorillas' low-quality sperm. This process, called "relaxed purifying selection," can result in seemingly harmful mutations becoming common in a species.

The data turned up 578 genes in the gorilla lineage that underwent this type of selection. An analysis and existing data suggested that many of these genes are involved in making sperm. However, not all the flagged genes had known roles in male fertility.

To better understand these genes' functions, the team turned to the fruit fly (Drosophila melanogaster), a commonly used genetic model in biology. They systematically silenced each of the genes in male flies to see if they affected the insects' ability to reproduce. In this way, they uncovered 41 new genes that hadn't previously been tied to male fertility.

The researchers then connected the dots back to humans using a genetic database with data from 2,100 men with infertility, who either had very low amounts or a lack of sperm in their semen. They also looked at data from fertile men, focusing on the genes they'd flagged in gorillas. They found that, in 109 of relaxed gorilla genes, the infertile men carried more loss-of-function mutations than did fertile men; loss-of-function mutations reduce a gene's ability to make the protein it codes for.

While it's likely these genes are involved in human male fertility, more research is needed to learn exactly how they work in the body. Straub emphasized that infertility is very complex, and that not all of it comes down to genetics. To fully understand it, scientists need to account for how different genes interact with one another and with an organism's environment and its behavior.

The findings drawn from gorillas open the door to future explorations about how these genes, and others closely associated with them, might influence fertility in people, Straub said. The study was published May 9 in the journal eLife.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

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The same genetic mutations behind gorillas' small penises may hinder fertility in men - Livescience.com

Lean Gene Reviews (USA) Does This Weight Loss Supplement Work? LeanGene Ingredients, Price, Where to Buy?  Outlook India

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Lean Gene Reviews (USA) Does This Weight Loss Supplement Work? LeanGene Ingredients, Price, Where to Buy? - Outlook India

The biggest shock was not having a uterus the film about intersex beauty queen Sharon-Rose Khumalo  The Guardian

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The biggest shock was not having a uterus the film about intersex beauty queen Sharon-Rose Khumalo - The Guardian

7. See man. 2-5. Male, masculine, virile are adjectives that describe men and boys or attributes and conduct culturally ascribed to them. Male, which is applied to plants and animals as well as to human beings, is often used as a biological or physiological descriptor, classifying individuals on the basis of their potential or actual ability to inseminate in bisexual reproduction. It contrasts with female in all such uses: his oldest male relative; the male parts of the flower. Masculine refers essentially to qualities, characteristics, or behaviors deemed by a culture or society to be especially appropriate to or ideally associated with men and boys. In American and Western European culture, these have traditionally included features such as strength, forthrightness, and courage: a firm, masculine handshake; a masculine impatience at indecision. Virile implies a vigor and muscularity associated with mature manhood and often carries a suggestion of sexual or procreative potency: his virile good looks; a swaggering, virile walk. See also manly.

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Male Definition & Meaning | Dictionary.com

The male genital system consists of both external and internal parts. The external male genitalia include the penis, urethra, and scrotum. The internal male genitalia include the seminal vesicle, testes, vas deferens, epididymis, prostate, bulbourethral gland, and ejaculatory duct.

The penis is the main part of external male genitalia, which has both sexual and bodily functions. It is able to ejaculate semen (containing sperm) during sex and to relieve the body of urine. The urethra transports the urine from the bladder, out of the male body. Semen also travels through the urethra.

Each male has two scrotal pouches, which house certain parts of the internal male genitalia (epididymis, testes, and lower spermatic cords). The testes are the most important part of internal male genitalia because they make and store sperm, as well as supply the male body with hormones, which control the development of male characteristics and reproductive organs.

The epididymis stores, matures, and transports sperm between the testes and the vas deferens, which channels sperm toward the urethra. The seminal vesicles are adjacent to the urethra and secrete a milky fluid that is ultimately discharged through the ejaculatory duct. The bulbourethral glands also assist in the discharge of semen.

Read more:
Male Genitalia Pictures, Anatomy & Diagram | Body Maps - Healthline

In the male social hierarchy, alpha males are at the top spot. Every man wants to be an alpha male, but only a few genuinely exhibit the characteristics that make them one. Are you wondering what the alpha male traits are and how you can become one?

This article teaches you all you need to know about becoming an alpha male and the qualities that you need to possess.

An alpha male is a powerful and inspirational individual who sits at the top of the social hierarchy.

Other men, like the betas, gammas, and omegas, look up to the alpha because of his influence and command. So naturally, an alpha finds it easy to win people over to his side because of his extroverted and charismatic personality.

To learn more about alpha males, check out this research by P.H Hawley and other authors, which explores the new look at dominance-related behaviors and beliefs among adolescent males and females.

Becoming an alpha male is quite simple. All you have to do is apply some tips that make them stand out. Some of these tips are being assertive and having good communication skills.

An alpha male is also a people person; he is excellent at maintaining relationships, making it easy for him to influence people.

Most times, alpha males are attracted to strong-willed and independent people, some of whom might be their partners in the future. They want to be around people who know what they want and are not scared to get them.

Even though an alpha likes caring for people, he loves it when you put in the effort to look after yourself.

One of the alpha male traits is his humility. He does not allow his achievements to get into his head. Also, he is always willing to help people out and encourage them to stand up to their fears.

An alpha male is usually well-groomed, has excellent communication skills, is a good leader, works out regularly, and is passionate about making society better.

John Alexanders book contains valuable tips on the signs of a real alpha male and how to become one. His book is titled How to Become an Alpha Male, helping men attract women and become great at seduction.

You might have seen some stereotypic traits of alpha males on social media or TV, but it would interest you to note that they may not be suitably represented.

Here are some alpha male traits that help you identify or know if you are.

When identifying the alpha male personality type, it is important to note that they do not avoid challenges. If they are faced with difficult moments, they tackle them head-on till they find a solution.

An alpha male believes that challenges will make him a better and more resilient individual. If other men are discouraged by these challenges, an alpha male is not.

One of the untrue alpha male traits is pride. A true alpha male is humble because he does not use his status to oppress people. Instead, he should use it for a good cause.

For example, an alpha male does not allow his success and achievements to get into his head. This means he will still communicate with others below him like they are equals. Doing this makes the alpha male a loveable leader everyone wants to follow.

When it comes to achieving goals, one of the characteristics of an alpha male is working towards achieving them.

An alpha male loves to set goals and meet them. If they experience any roadblock, they strategize and try other means to meet those goals. He is always self-motivated to smash his goals and set bigger goals.

Being a natural leader is one of the traits of an alpha male. He loves to be in charge of situations where people are unwilling to volunteer. He can easily inspire people because of his superior mindset that many people dont have.

Most alpha males are at the helm of affairs in organizations and politics because of their remarkable leadership qualities. You can also include leadership as alpha male traits in bed to look out for.

One of the qualities of an alpha male is that he knows his flaws. You cannot find an alpha male denying his weaknesses.

An alpha male knows that being aware of your flaws is strength. Therefore, they work towards making their flaws strengths in the long run. They also check in with trusted friends and acquaintances to know whether they are getting better.

An alpha male knows that health is wealth. So when it comes to working out or staying physically active, it is one of the alpha male traits.

An alpha male has made working out his lifestyle. He needs it to remain healthy and also boost his self-esteem. It is important to mention that staying active helps the alpha male to remain calm in turbulent situations.

Honesty is one of the alpha male traits. An alpha male knows that no one would punish him for telling the truth, so he remains honest regardless.

Alpha men are also great at being sincere, even if it is hurtful. However, they try to be diplomatic so that you dont feel bad about it, and at the same time, you will learn the necessary lessons.

Everyone has emotions, but only some people are great at mastering their emotions. Alpha males have a high emotional intelligence quotient. This is what makes them get along with people.

The alpha male personality knows how to manage their emotions; this is why they dont have outbursts. They can read peoples emotions and relate with them without causing a fuss.

Watch this video on how to manage your emotions:

It is easy to spot an alpha male among several men because of the way he carries himself. If you want to know how to act like an alpha male, your physical appearance has to be in top gear. Alpha males wear good cologne and clean clothes, and their hygiene is top-notch.

They also have a good command of their body language and use it to communicate properly. Alpha has a great posture, a firm handshake, good eye contact, etc.

Taking care of his loved ones is one of the key signs of alpha males. You cannot see an alpha male who is not protective of those he cares about. He does everything to ensure that they are safe and cared for.

Anyone who tries to pick on an alpha males loved ones might see his aggressive side because he is fiercely protective.

Good communication skills are one of the alpha male traits. This is one of the attributes that attract other people to him.

An alpha male enjoys conversing with people and keeping them engaged. While they talk, they exude charisma and confidence. They also know when and how to listen when other people are speaking.

One of the alpha male traits is saying no when he is not up for something.

He understands that sometimes, he has to inconvenience himself so that other people will be happy. However, if it gets to a point where people need his input for selfish reasons, he will politely decline without any hard feelings. He is a selfless man who does not rub the back of selfish people.

Assertiveness is one of the answers to the question of what is alpha male personality.

Unlike the passive beta male, the alpha male has a good sense of self-awareness, and he is always determined to get what he wants. This means he is not afraid to set boundaries and inform people when they cross them.

Seeking solid and authentic connections is one of the alpha male traits. He does not crave validation from people because he knows his worth. Instead, he wants to connect with people and build good relationships. If he allows people into his life, he wants a casual, healthy relationship.

An alpha male is not always satisfied with his status quo. He is always looking for means to improve and remain an asset to society.

Unlike beta males who are satisfied with mediocrity, an alpha male wants to be the best at what he does. So, he frowns at any sign of being average in his life.

To learn more about the traits of an alpha male, read Marco Angelos book, Alpha Male. This book is an exhaustive guide that teaches you how to be an irresistible alpha male.

The alpha male traits in this article point to the fact that this category of men is individuals without any toxic attributes. They are at peace with everyone, set clear boundaries, influence society positively, and seek to build healthy relationships.

If you need help adopting some of these traits, you can see a counselor to help out. You can also take a course on becoming an alpha male.

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15 Alpha Male Traits Characteristics of Real Alpha Males

Start with a less expensive model, Fleming advises beginners. Sometimes trying a more affordable model gives you a sense of what a sensation is like and whether you like it. Of course, if you already know what feeling you like and you need a recommendation for the best sex toy that aligns with that, weve got you too.

Whip out that new toy when youre actually turned on (and not as a way to turn yourself on). Think of it as foreplay, Fleming says. If you want to build up reception to a new toy, start off when youre already highly aroused. The research is clear that people tend to be more open and receptive when already aroused.

And if you dont like the sensation of a new toy the very first time you use it, dont give up on it just yet. The first time we try anything, were doing what we call spectatoring, which is observing ourselves, how its going, what we thought, what our partner thought. Were in our heads and not so much in the experience, says Fleming. So try, try again.

Below, find our experts top picks for masturbation sleeves, prostate massagers, cock rings, butt plugs, dildos, and more, from best-selling retailers and brands such as Lovehoney, We-Vibe, Lelo, Hot Octopuss, and Tenga. Just dont forget to throw good lube in your cart and clean up your toys after.

Masturbation sleeves (also known as strokers or penis sleeves) are cylindrical sleeves or canal-shaped sex toys that envelop the penis and are either open-ended or closed. These sleeves work well for solo stimulation, as theyre like giving yourself a hand job, or your partner can stimulate you with it, Frye-Nekrasova says.

These various strokers can be textured on the inside (like the Tenga Egg, an egg-shaped disposable masturbation sleeve), while others (such as the Fleshlight Pink Lady) mimic human anatomy in look and feel (and are usually closed-ended). Because of the suction or vibration, theres an arousing, pleasurable sensation, Fleming says. Most men will get erect and it will bring them to orgasm.

Often made of soft silicone, the sleeves come in both non-vibrating and vibrating models. The vibrating models are known as power strokers or penis stimulators, as theyre powered by a motor that adds a stroking motion. To really explore a different stimulation thats not just digital, manual stimulation, go for a power stroker, Frye-Nekrasova says. For the majority of your life with a penis, youve likely stimulated yourself only by hand, so introducing a new form of stimulation by way of a power stroker is going to do things for you that you probably never expected.

Ella Paradis

The Hot Octopuss Pulse Duo masturbation sleeve has an adjustable design that fits to any girth, and its open design makes it possible to wear during penetrative sex as well. Sex educator Cassandra Corrado told SELF that this is a nice option for men who have difficulties with erections because you can use it without getting hard. Instead of a motor, the remote-controlled Pulse Duo uses oscillation to create an intense sensation for the wearer, she explains.

Arcwave

Frye-Nekrasova highly recommends the ArcWave Ion, a unique male masturbator that focuses on stimulating the frenulum (the highly sensitive vein on the underside of the penis shaft) with pulsating airwaves. This offers a completely new world of stimulation that many male sex toy users are not used to because theres no other product like it, she says.

Lovehoney

For a vibrating masturbation sleeve, Frye-Nekrasova likes the Blowmotion, which warms and mimics the feel of engaging in penetration with a human partner or receiving a blow job.

Looking to give anal sex toys a try? Prostate massagers are one way to get started. These toys are shaped and designed to target the prostate gland, which is a walnut-size gland behind the penis, inside the pelvis, and between the bladder and rectum. Similar to the female G-spot, this gland is known as the P-spot, and stimulating it can feel amazing. For those who have never explored the prostate, hand stimulation can be intimidating, Frye-Nekrasova says, which is why a sex toy is helpful: Using a toy allows for more exploration without having to step out of your comfort zone too much, and I will die on the hill of encouraging everyone with a prostate to stimulate it.

Lelo

Complete with remote control and vibrating motors in its tip and base, the Lelo Hugo is a smooth, medium-size prostate massager that leads to large-size orgasms. Its a favorite of Adina Mahalli, MSW, relationship expert, and womens health specialist at Maple Holistics, who previously noted to SELF that the Hugo makes an excellent toy for women to try too.

Babeland

Aneros is a brand whose entire line is designed specifically for not only providing prostate pleasure but with prostate health in mind, Lisa Finn, sex educator and brand manager for Babeland, told SELF. The sleekly contoured, self-pivoting design of the Trident prostate massager allows for blissful stimulation of both the prostate and perineum (which lies between the anus and genitals for men), and its flared base and P-tab stops provide external sensations and ensure the toy doesnt move around. You can comfortably massage and stimulate this hot spot internally and externally at onceup and down or in and out, and in any position, Finn says.

Lovehoney

The We-Vibe Vector is a Bluetooth-enabled, app-controlled prostate massager, that can be controlled from a phone (even remotely). Fleming previously told SELF that the Vector works both for masturbation and partnered play, and she appreciates its 10 whisper-quiet, powerful vibration settings.

Another safe and satisfying way to dip your, er, toe in the anal sex pool? Butt plugs are great for starting out in anal stimulation so that you can get used to the feeling of something inserted anally, Frye-Nekrasova says, advising that newbies start small before working their way up to larger anal toys like dildos. Butt plugs come in a range of sizes, textures, and materials. Some vibrate, others are made of heavy metal that provides lots of pressure, while others mimic the sensation of rimming.

Excerpt from:
The 15 Best Sex Toys for Men, According to Experts - SELF

Diabetes is increasing in younger population, finds study: Doctors share early signs that might help in early medical intervention  Times of India

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Diabetes is increasing in younger population, finds study: Doctors share early signs that might help in early medical intervention - Times of India

Condition where males and females exhibit different characteristics

Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction.[1] The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, or behavioural or cognitive traits. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is monomorphism, which is when both biological sexes are phenotypically indistinguishable from each other.[2]

Common and easily identified types of dimorphism consist of ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is called sexual dichromatism, which is commonly seen in many species of birds and reptiles.[3] Sexual selection leads to the exaggerated dimorphic traits that are used predominantly in competition over mates. The increased fitness resulting from ornamentation offsets its cost to produce or maintain suggesting complex evolutionary implications, but the costs and evolutionary implications vary from species to species.[4][5][pageneeded] The costs and implications differ depending on the nature of the ornamentation (such as the colour mechanism involved).[citation needed]

The peafowl constitute conspicuous illustrations of the principle. The ornate plumage of peacocks, as used in the courting display, attracts peahens. At first sight one might mistake peacocks and peahens for completely different species because of the vibrant colours and the sheer size of the male's plumage; the peahen being of a subdued brown coloration.[6] The plumage of the peacock increases its vulnerability to predators because it is a hindrance in flight, and it renders the bird conspicuous in general.[6] Similar examples are manifold, such as in birds of paradise and argus pheasants.[citation needed]

Another example of sexual dichromatism is that of the nestling blue tits. Males are chromatically more yellow than females. It is believed that this is obtained by the ingestion of green Lepidopteran larvae, which contain large amounts of the carotenoids lutein and zeaxanthin.[7] This diet also affects the sexually dimorphic colours in the human-invisible ultraviolet spectrum.[8][9] Hence, the male birds, although appearing yellow to humans actually have a violet-tinted plumage that is seen by females. This plumage is thought to be an indicator of male parental abilities.[10] Perhaps this is a good indicator for females because it shows that they are good at obtaining a food supply from which the carotenoid is obtained. There is a positive correlation between the chromas of the tail and breast feathers and body condition.[11] Carotenoids play an important role in immune function for many animals, so carotenoid dependent signals might indicate health.[12]

Frogs constitute another conspicuous illustration of the principle. There are two types of dichromatism for frog species: ontogenetic and dynamic. Ontogenetic frogs are more common and have permanent color changes in males or females. Ranoidea lesueuri is an example of a dynamic frog that has temporary color changes in males during breeding season.[13] Hyperolius ocellatus is an ontogenetic frog with dramatic differences in both color and pattern between the sexes. At sexual maturity, the males display a bright green with white dorsolateral lines.[14] In contrast, the females are rusty red to silver with small spots. The bright coloration in the male population serves to attract females and as an aposematic sign to potential predators.

Females often show a preference for exaggerated male secondary sexual characteristics in mate selection.[15] The sexy son hypothesis explains that females prefer more elaborate males and select against males that are dull in color, independent of the species' vision.[16]

Similar sexual dimorphism and mating choice are also observed in many fish species. For example, male guppies have colorful spots and ornamentations while females are generally grey in color. Female guppies prefer brightly colored males to duller males.[17][pageneeded]

In redlip blennies, only the male fish develops an organ at the anal-urogenital region that produces antimicrobial substances. During parental care, males rub their anal-urogenital regions over their nests' internal surfaces, thereby protecting their eggs from microbial infections, one of the most common causes for mortality in young fish.[18]

Most flowering plants are hermaphroditic but approximately 6% of species have separate males and females (dioecy).[19] Sexual dimorphism is common in dioecious plants[20]:403 and dioicous species.[21]:71

Males and females in insect-pollinated species generally look similar to one another because plants provide rewards (e.g. nectar) that encourage pollinators to visit another similar flower, completing pollination. Catasetum orchids are one interesting exception to this rule. Male Catasetum orchids violently attach pollinia to euglossine bee pollinators. The bees will then avoid other male flowers but may visit the female, which look different from the males.[22]

Various other dioecious exceptions, such as Loxostylis alata have visibly different sexes, with the effect of eliciting the most efficient behaviour from pollinators, who then use the most efficient strategy in visiting each gender of flower instead of searching say, for pollen in a nectar-bearing female flower.[citation needed]

Some plants, such as some species of Geranium have what amounts to serial sexual dimorphism. The flowers of such species might for example present their anthers on opening, then shed the exhausted anthers after a day or two and perhaps change their colours as well while the pistil matures; specialist pollinators are very much inclined to concentrate on the exact appearance of the flowers they serve, which saves their time and effort and serves the interests of the plant accordingly. Some such plants go even further and change their appearance again once they have been fertilised, thereby discouraging further visits from pollinators. This is advantageous to both parties because it avoids damage to the developing fruit and avoids wasting the pollinator's effort on unrewarding visits. In effect the strategy ensures that the pollinators can expect a reward every time they visit an appropriately advertising flower.[citation needed]

Females of the aquatic plant Vallisneria americana have floating flowers attached by a long flower stalk that are fertilized if they contact one of the thousands of free floating flowers released by a male.[23][bettersourceneeded] Sexual dimorphism is most often associated with wind-pollination in plants due to selection for efficient pollen dispersal in males vs pollen capture in females, e.g. Leucadendron rubrum.[24]

Sexual dimorphism in plants can also be dependent on reproductive development. This can be seen in Cannabis sativa, a type of hemp, which have higher photosynthesis rates in males while growing but higher rates in females once the plants become sexually mature.[25]

Every sexually reproducing extant species of vascular plant actually has an alternation of generations; the plants we see about us generally are diploid sporophytes, but their offspring really are not the seeds that people commonly recognise as the new generation. The seed actually is the offspring of the haploid generation of microgametophytes (pollen) and megagametophytes (the embryo sacs in the ovules). Each pollen grain accordingly may be seen as a male plant in its own right; it produces a sperm cell and is dramatically different from the female plant, the megagametophyte that produces the female gamete.[citation needed]

Insects display a wide variety of sexual dimorphism between taxa including size, ornamentation and coloration.[26] The female-biased sexual size dimorphism observed in many taxa evolved despite intense malemale competition for mates.[27] In Osmia rufa, for example, the female is larger/broader than males, with males being 810mm in size and females being 1012mm in size.[28] In the hackberry emperor females are similarly larger than males.[29] The reason for the sexual dimorphism is due to provision size mass, in which females consume more pollen than males.[30]

In some species, there is evidence of male dimorphism, but it appears to be for the purpose of distinctions of roles. This is seen in the bee species Macrotera portalis in which there is a small-headed morph, capable of flight, and large-headed morph, incapable of flight, for males.[31] Anthidium manicatum also displays male-biased sexual dimorphism. The selection for larger size in males rather than females in this species may have resulted due to their aggressive territorial behavior and subsequent differential mating success.[32] Another example is Lasioglossum hemichalceum, which is a species of sweat bee that shows drastic physical dimorphisms between male offspring.[33] Not all dimorphism has to have a drastic difference between the sexes. Andrena agilissima is a mining bee where the females only have a slightly larger head than the males.[34]

Weaponry leads to increased fitness by increasing success in malemale competition in many insect species.[35] The beetle horns in Onthophagus taurus are enlarged growths of the head or thorax expressed only in the males. Copris ochus also has distinct sexual and male dimorphism in head horns.[36] These structures are impressive because of the exaggerated sizes.[37] There is a direct correlation between male horn lengths and body size and higher access to mates and fitness.[37] In other beetle species, both males and females may have ornamentation such as horns.[36]Generally, insect sexual size dimorphism (SSD) within species increases with body size.[38]

Sexual dimorphism within insects is also displayed by dichromatism. In butterfly genera Bicyclus and Junonia, dimorphic wing patterns evolved due to sex-limited expression, which mediates the intralocus sexual conflict and leads to increased fitness in males.[39] The sexual dichromatic nature of Bicyclus anynana is reflected by female selection on the basis of dorsal UV-reflective eyespot pupils.[40] The common brimstone also displays sexual dichromatism; males have yellow and iridescent wings, while female wings are white and non-iridescent.[41] Naturally selected deviation in protective female coloration is displayed in mimetic butterflies.[42]

Many arachnid groups exhibit sexual dimorphism,[43] but it is most widely studied in the spiders. In the orb-weaving spider Zygiella x-notata, for example, adult females have a larger body size than adult males.[44] Size dimorphism shows a correlation with sexual cannibalism,[45] which is prominent in spiders (it is also found in insects such as praying mantises). In the size dimorphic wolf spider Tigrosa helluo, food-limited females cannibalize more frequently.[46] Therefore, there is a high risk of low fitness for males due to pre-copulatory cannibalism, which led to male selection of larger females for two reasons: higher fecundity and lower rates of cannibalism.[46] In addition, female fecundity is positively correlated with female body size and large female body size is selected for, which is seen in the family Araneidae. All Argiope species, including Argiope bruennichi, use this method. Some males evolved ornamentation[vague] including binding the female with silk, having proportionally longer legs, modifying the female's web, mating while the female is feeding, or providing a nuptial gift in response to sexual cannibalism.[46] Male body size is not under selection due to cannibalism in all spider species such as Nephila pilipes, but is more prominently selected for in less dimorphic species of spiders, which often selects for larger male size.[47] In the species Maratus volans, the males are known for their characteristic colorful fan which attracts the females during mating.[48]

Ray finned fish are an ancient and diverse class, with the widest degree of sexual dimorphism of any animal class. Fairbairn notes that "females are generally larger than males but males are often larger in species with malemale combat or male paternal care ... [sizes range] from dwarf males to males more than 12 times heavier than females."[49][pageneeded]

There are cases where males are substantially larger than females. An example is Lamprologus callipterus, a type of cichlid fish. In this fish, the males are characterized as being up to 60 times larger than the females. The male's increased size is believed to be advantageous because males collect and defend empty snail shells in each of which a female breeds.[50] Males must be larger and more powerful in order to collect the largest shells. The female's body size must remain small because in order for her to breed, she must lay her eggs inside the empty shells. If she grows too large, she will not fit in the shells and will be unable to breed. The female's small body size is also likely beneficial to her chances of finding an unoccupied shell. Larger shells, although preferred by females, are often limited in availability.[51] Hence, the female is limited to the growth of the size of the shell and may actually change her growth rate according to shell size availability.[52] In other words, the male's ability to collect large shells depends on his size. The larger the male, the larger the shells he is able to collect. This then allows for females to be larger in his brooding nest which makes the difference between the sizes of the sexes less substantial. Malemale competition in this fish species also selects for large size in males. There is aggressive competition by males over territory and access to larger shells. Large males win fights and steal shells from competitors. Another example is the dragonet, in which males are considerably larger than females and possess longer fins.

Sexual dimorphism also occurs in hermaphroditic fish. These species are known as sequential hermaphrodites. In fish, reproductive histories often include the sex-change from female to male where there is a strong connection between growth, the sex of an individual, and the mating system it operates within.[53] In protogynous mating systems where males dominate mating with many females, size plays a significant role in male reproductive success.[54] Males have a propensity to be larger than females of a comparable age but it is unclear whether the size increase is due to a growth spurt at the time of the sexual transition or due to the history of faster growth in sex changing individuals.[55] Larger males are able to stifle the growth of females and control environmental resources.[citation needed]

Social organization plays a large role in the changing of sex by the fish. It is often seen that a fish will change its sex when there is a lack of dominant male within the social hierarchy. The females that change sex are often those who attain and preserve an initial size advantage early in life. In either case, females which change sex to males are larger and often prove to be a good example of dimorphism.

In other cases with fish, males will go through noticeable changes in body size, and females will go through morphological changes that can only be seen inside of the body. For example, in sockeye salmon, males develop larger body size at maturity, including an increase in body depth, hump height, and snout length. Females experience minor changes in snout length, but the most noticeable difference is the huge increase in gonad size, which accounts for about 25% of body mass.[56]

Sexual selection was observed for female ornamentation in Gobiusculus flavescens, known as two-spotted gobies.[57] Traditional hypotheses suggest that malemale competition drives selection. However, selection for ornamentation within this species suggests that showy female traits can be selected through either femalefemale competition or male mate choice.[57] Since carotenoid-based ornamentation suggests mate quality, female two-spotted guppies that develop colorful orange bellies during the breeding season are considered favorable to males.[58] The males invest heavily in offspring during the incubation, which leads to the sexual preference in colorful females due to higher egg quality.[58]

In amphibians and reptiles, the degree of sexual dimorphism varies widely among taxonomic groups. The sexual dimorphism in amphibians and reptiles may be reflected in any of the following: anatomy; relative length of tail; relative size of head; overall size as in many species of vipers and lizards; coloration as in many amphibians, snakes, and lizards, as well as in some turtles; an ornament as in many newts and lizards; the presence of specific sex-related behaviour is common to many lizards; and vocal qualities which are frequently observed in frogs.[citation needed]

Anole lizards show prominent size dimorphism with males typically being significantly larger than females. For instance, the average male Anolis sagrei was 53.4mm vs. 40mm in females.[59] Different sizes of the heads in anoles have been explained by differences in the estrogen pathway.[60] The sexual dimorphism in lizards is generally attributed to the effects of sexual selection, but other mechanisms including ecological divergence and fecundity selection provide alternative explanations.[61] The development of color dimorphism in lizards is induced by hormonal changes at the onset of sexual maturity, as seen in Psamodromus algirus, Sceloporus gadoviae, and S. undulates erythrocheilus.[61] Sexual dimorphism in size is also seen in frog species like P. bibronii.

Male painted dragon lizards, Ctenophorus pictus. are brightly conspicuous in their breeding coloration, but male colour declines with aging. Male coloration appears to reflect innate anti-oxidation capacity that protects against oxidative DNA damage.[62] Male breeding coloration is likely an indicator to females of the underlying level of oxidative DNA damage (a significant component of aging) in potential mates.[62]

Sexual dimorphism in birds can be manifested in size or plumage differences between the sexes. Sexual size dimorphism varies among taxa with males typically being larger, though this is not always the case, e.g. birds of prey, hummingbirds, and some species of flightless birds.[63][64] Plumage dimorphism, in the form of ornamentation or coloration, also varies, though males are typically the more ornamented or brightly colored sex.[65] Such differences have been attributed to the unequal reproductive contributions of the sexes.[66] This difference produces a stronger female choice since they have more risk in producing offspring. In some species, the male's contribution to reproduction ends at copulation, while in other species the male becomes the main caregiver. Plumage polymorphisms have evolved to reflect these differences and other measures of reproductive fitness, such as body condition[67] or survival.[68] The male phenotype sends signals to females who then choose the 'fittest' available male.

Sexual dimorphism is a product of both genetics and environmental factors. An example of sexual polymorphism determined by environmental conditions exists in the red-backed fairywren. Red-backed fairywren males can be classified into three categories during breeding season: black breeders, brown breeders, and brown auxiliaries.[67] These differences arise in response to the bird's body condition: if they are healthy they will produce more androgens thus becoming black breeders, while less healthy birds produce less androgens and become brown auxiliaries.[67] The reproductive success of the male is thus determined by his success during each year's non-breeding season, causing reproductive success to vary with each year's environmental conditions.

Migratory patterns and behaviors also influence sexual dimorphisms. This aspect also stems back to the size dimorphism in species. It has been shown that the larger males are better at coping with the difficulties of migration and thus are more successful in reproducing when reaching the breeding destination.[69] When viewing this in an evolutionary standpoint many theories and explanations come to consideration. If these are the result for every migration and breeding season the expected results should be a shift towards a larger male population through sexual selection. Sexual selection is strong when the factor of environmental selection is also introduced. The environmental selection may support a smaller chick size if those chicks were born in an area that allowed them to grow to a larger size, even though under normal conditions they would not be able to reach this optimal size for migration. When the environment gives advantages and disadvantages of this sort, the strength of selection is weakened and the environmental forces are given greater morphological weight. The sexual dimorphism could also produce a change in timing of migration leading to differences in mating success within the bird population.[70] When the dimorphism produces that large of a variation between the sexes and between the members of the sexes multiple evolutionary effects can take place. This timing could even lead to a speciation phenomenon if the variation becomes strongly drastic and favorable towards two different outcomes. Sexual dimorphism is maintained by the counteracting pressures of natural selection and sexual selection. For example, sexual dimorphism in coloration increases the vulnerability of bird species to predation by European sparrowhawks in Denmark.[71] Presumably, increased sexual dimorphism means males are brighter and more conspicuous, leading to increased predation.[71] Moreover, the production of more exaggerated ornaments in males may come at the cost of suppressed immune function.[67] So long as the reproductive benefits of the trait due to sexual selection are greater than the costs imposed by natural selection, then the trait will propagate throughout the population. Reproductive benefits arise in the form of a larger number of offspring, while natural selection imposes costs in the form of reduced survival. This means that even if the trait causes males to die earlier, the trait is still beneficial so long as males with the trait produce more offspring than males lacking the trait. This balance keeps the dimorphism alive in these species and ensures that the next generation of successful males will also display these traits that are attractive to the females.

Such differences in form and reproductive roles often cause differences in behavior. As previously stated, males and females often have different roles in reproduction. The courtship and mating behavior of males and females are regulated largely by hormones throughout a bird's lifetime.[72] Activational hormones occur during puberty and adulthood and serve to 'activate' certain behaviors when appropriate, such as territoriality during breeding season.[72] Organizational hormones occur only during a critical period early in development, either just before or just after hatching in most birds, and determine patterns of behavior for the rest of the bird's life.[72] Such behavioral differences can cause disproportionate sensitivities to anthropogenic pressures.[73] Females of the whinchat in Switzerland breed in intensely managed grasslands.[73] Earlier harvesting of the grasses during the breeding season lead to more female deaths.[73] Populations of many birds are often male-skewed and when sexual differences in behavior increase this ratio, populations decline at a more rapid rate.[73] Also not all male dimorphic traits are due to hormones like testosterone, instead they are a naturally occurring part of development, for example plumage.[74] In addition, the strong hormonal influence on phenotypic differences suggest that the genetic mechanism and genetic basis of these sexually dimorphic traits may involve transcription factors or cofactors rather than regulatory sequences.[75]

Sexual dimorphism may also influence differences in parental investment during times of food scarcity. For example, in the blue-footed booby, the female chicks grow faster than the males, resulting in booby parents producing the smaller sex, the males, during times of food shortage. This then results in the maximization of parental lifetime reproductive success.[76] In Black-tailed Godwits Limosa limosa limosa females are also the larger sex, and the growth rates of female chicks are more susceptible to limited environmental conditions.[77]

Sexual dimorphism may also only appear during mating season, some species of birds only show dimorphic traits in seasonal variation. The males of these species will molt into a less bright or less exaggerated color during the off breeding season.[75] This occurs because the species is more focused on survival than reproduction, causing a shift into a less ornate state.[dubious discuss]

Consequently, sexual dimorphism has important ramifications for conservation. However, sexual dimorphism is not only found in birds and is thus important to the conservation of many animals. Such differences in form and behavior can lead to sexual segregation, defined as sex differences in space and resource use.[78] Most sexual segregation research has been done on ungulates,[78] but such research extends to bats,[79] kangaroos,[80] and birds.[81] Sex-specific conservation plans have even been suggested for species with pronounced sexual segregation.[79]

The term sesquimorphism (the Latin numeral prefix sesqui- means one-and-one-half, so halfway between mono- (one) and di- (two)) has been proposed for bird species in which "both sexes have basically the same plumage pattern, though the female is clearly distinguishable by reason of her paler or washed-out colour".[82]:14 Examples include Cape sparrow (Passer melanurus),[82]:67 rufous sparrow (subspecies P.motinensis motinensis),[82]:80 and saxaul sparrow (P.ammodendri).[82]:245

In a large proportion of mammal species, males are larger than females. Both genes and hormones affect the formation of many animal brains before "birth" (or hatching), and also behaviour of adult individuals. Hormones significantly affect human brain formation, and also brain development at puberty. A 2004 review in Nature Reviews Neuroscience observed that "because it is easier to manipulate hormone levels than the expression of sex chromosome genes, the effects of hormones have been studied much more extensively, and are much better understood, than the direct actions in the brain of sex chromosome genes." It concluded that while "the differentiating effects of gonadal secretions seem to be dominant," the existing body of research "support the idea that sex differences in neural expression of X and Y genes significantly contribute to sex differences in brain functions and disease."[83]

Marine mammals show some of the greatest sexual size differences of mammals, because of sexual selection and environmental factors like breeding location.[84] The mating system of pinnipeds varies from polygamy to serial monogamy. Pinnipeds are known for early differential growth and maternal investment since the only nutrients for newborn pups is the milk provided by the mother.[85] For example, the males are significantly larger (about 10% heavier and 2% longer) than the females at birth in sea lion pups.[86] The pattern of differential investment can be varied principally prenatally and post-natally.[87] Mirounga leonina, the southern elephant seal, is one of the most dimorphic mammals.[88]

According to Clark Spencer Larsen, modern day Homo sapiens show a range of sexual dimorphism, with average body mass between the sexes differing by roughly 15%.[89] Considerable discussion in academic literature concerns potential evolutionary advantages associated with sexual competition (both intrasexual and intersexual) and short- and long-term sexual strategies.[90] According to Daly and Wilson, "The sexes differ more in human beings than in monogamous mammals, but much less than in extremely polygamous mammals."[91]

The average basal metabolic rate is about 6 percent higher in adolescent males than females and increases to about 10 percent higher after puberty. Females tend to convert more food into fat, while males convert more into muscle and expendable circulating energy reserves. Aggregated data of absolute strength indicates that females have, on average, 4060% the upper body strength of males, and 7075% the lower body strength.[92] The difference in strength relative to body mass is less pronounced in trained individuals. In Olympic weightlifting, male records vary from 5.5 body mass in the lowest weight category to 4.2 in the highest weight category, while female records vary from 4.4 to 3.8, a weight adjusted difference of only 1020%, and an absolute difference of about 40% (i.e. 472kg vs 333kg for unlimited weight classes; see Olympic weightlifting records). A study, carried about by analyzing annual world rankings from 1980 to 1996, found that males' running times were, on average, 11% faster than females'.[93]

In early adolescence, females are on average taller than males (as females tend to go through puberty earlier), but males, on average, surpass them in height in later adolescence and adulthood. In the United States, adult males are on average 9% taller[94] and 16.5% heavier[95] than adult females.

Males typically have larger tracheae and branching bronchi, with about 30 percent greater lung volume per body mass. On average, males have larger hearts, 10 percent higher red blood cell count, higher hemoglobin, hence greater oxygen-carrying capacity. They also have higher circulating clotting factors (vitamin K, prothrombin and platelets). These differences lead to faster healing of wounds and lower sensitivity to nerve pain after injury.[96] In males, pain-causing injury to the peripheral nerve occurs through the microglia, while in females it occurs through the T cells (except in pregnant women, who follow a male pattern).[97]

Females typically have more white blood cells (stored and circulating), as well as more granulocytes and B and T lymphocytes. Additionally, they produce more antibodies at a faster rate than males, hence they develop fewer infectious diseases and succumb for shorter periods.[96] Ethologists argue that females, interacting with other females and multiple offspring in social groups, have experienced such traits as a selective advantage.[98][99][100][101][102][excessive citations] Females have a higher sensitivity to pain due to aforementioned nerve differences that increase the sensation, and females thus require higher levels of pain medication after injury.[97] Hormonal changes in females affect pain sensitivity, and pregnant women have the same sensitivity as males. Acute pain tolerance is also more consistent over a lifetime in females than males, despite these hormonal changes.[103] Despite differences in the physical feeling, both sexes have similar psychological tolerance to (or ability to cope with and ignore) pain.[104]

In the human brain, a difference between sexes was observed in the transcription of the PCDH11X/Y gene pair unique to Homo sapiens.[105] Sexual differentiation in the human brain from the undifferentiated state is triggered by testosterone from the fetal testis. Testosterone is converted to estrogen in the brain through the action of the enzyme aromatase. Testosterone acts on many brain areas, including the SDN-POA, to create the masculinized brain pattern.[106] Brains of pregnant females carrying male fetuses may be shielded from the masculinizing effects of androgen through the action of sex hormone-binding globulin.[107]

The relationship between sex differences in the brain and human behavior is a subject of controversy in psychology and society at large.[108][109] Many females tend to have a higher ratio of gray matter in the left hemisphere of the brain in comparison to males.[110][111] Males on average have larger brains than females; however, when adjusted for total brain volume the gray matter differences between sexes is almost nonexistent. Thus, the percentage of gray matter appears to be more related to brain size than it is to sex.[112][113] Differences in brain physiology between sexes do not necessarily relate to differences in intellect. Haier et al. found in a 2004 study that "men and women apparently achieve similar IQ results with different brain regions, suggesting that there is no singular underlying neuroanatomical structure to general intelligence and that different types of brain designs may manifest equivalent intellectual performance".[114] (See the sex and intelligence article for more on this subject.) Strict graph-theoretical analysis of the human brain connections revealed[115] that in numerous graph-theoretical parameters (e.g., minimum bipartition width, edge number, the expander graph property, minimum vertex cover), the structural connectome of women are significantly "better" connected than the connectome of men. It was shown[116] that the graph-theoretical differences are due to the sex and not to the differences in the cerebral volume, by analyzing the data of 36 females and 36 males, where the brain volume of each man in the group was smaller than the brain volume of each woman in the group.

Sexual dimorphism was also described in the gene level and shown to extend from the sex chromosomes. Overall, about 6500 genes have been found to have sex-differential expression in at least one tissue. Many of these genes are not directly associated with reproduction, but rather linked to more general biological features. In addition, it has been shown that genes with sex-specific expression undergo reduced selection efficiency, which lead to higher population frequencies of deleterious mutations and contributing to the prevalence of several human diseases.[117][118]

Sexual dimorphism in immune function is a common pattern in vertebrates and also in a number of invertebrates. Most often, females are more 'immunocompetent' than males. This trait is not consistent among all animals, but differs depending on taxonomy, with the most female-biased immune systems being found in insects.[119] In mammals this results in more frequent and severe infections in males and higher rates of autoimmune disorders in females. One potential cause may be differences in gene expression of immune cells between the sexes.[120] Another explanation is that endocrinological differences between the sexes impact the immune system for example, testosterone acts as an immunosuppressive agent.[121]

Phenotypic differences between sexes are evident even in cultured cells from tissues.[122] For example, female muscle-derived stem cells have a better muscle regeneration efficiency than male ones.[123] There are reports of several metabolic differences between male and female cells[124] and they also respond to stress differently.[125]

In theory, larger females are favored by competition for mates, especially in polygamous species. Larger females offer an advantage in fertility, since the physiological demands of reproduction are limiting in females. Hence there is a theoretical expectation that females tend to be larger in species that are monogamous.Females are larger in many species of insects, many spiders, many fish, many reptiles, owls, birds of prey and certain mammals such as the spotted hyena, and baleen whales such as blue whale. As an example, in some species, females are sedentary, and so males must search for them. Fritz Vollrath and Geoff Parker argue that this difference in behaviour leads to radically different selection pressures on the two sexes, evidently favouring smaller males.[126] Cases where the male is larger than the female have been studied as well,[126] and require alternative explanations.

One example of this type of sexual size dimorphism is the bat Myotis nigricans, (black myotis bat) where females are substantially larger than males in terms of body weight, skull measurement, and forearm length.[127] The interaction between the sexes and the energy needed to produce viable offspring make it favorable for females to be larger in this species. Females bear the energetic cost of producing eggs, which is much greater than the cost of making sperm by the males. The fecundity advantage hypothesis states that a larger female is able to produce more offspring and give them more favorable conditions to ensure their survival; this is true for most ectotherms. A larger female can provide parental care for a longer time while the offspring matures. The gestation and lactation periods are fairly long in M. nigricans, the females suckling their offspring until they reach nearly adult size.[128] They would not be able to fly and catch prey if they did not compensate for the additional mass of the offspring during this time. Smaller male size may be an adaptation to increase maneuverability and agility, allowing males to compete better with females for food and other resources.

Some species of anglerfish also display extreme sexual dimorphism. Females are more typical in appearance to other fish, whereas the males are tiny rudimentary creatures with stunted digestive systems. A male must find a female and fuse with her: he then lives parasitically, becoming little more than a sperm-producing body in what amounts to an effectively hermaphrodite composite organism. A similar situation is found in the Zeus water bug Phoreticovelia disparata where the female has a glandular area on her back that can serve to feed a male, which clings to her (note that although males can survive away from females, they generally are not free-living).[129] This is taken to the logical extreme in the Rhizocephala crustaceans, like the Sacculina, where the male injects itself into the female's body and becomes nothing more than sperm producing cells, to the point that the superorder used to be mistaken for hermaphroditic.[130]

Some plant species also exhibit dimorphism in which the females are significantly larger than the males, such as in the moss Dicranum[131] and the liverwort Sphaerocarpos.[132] There is some evidence that, in these genera, the dimorphism may be tied to a sex chromosome,[132][133] or to chemical signalling from females.[134]

Another complicated example of sexual dimorphism is in Vespula squamosa, the southern yellowjacket. In this wasp species, the female workers are the smallest, the male workers are slightly larger, and the female queens are significantly larger than her female worker and male counterparts.[citation needed]

In 1871, Charles Darwin advanced the theory of sexual selection, which related sexual dimorphism with sexual selection.[136]

The first step towards sexual dimorphism is the size differentiation of sperm and eggs (anisogamy).[137] Anisogamy and the usually large number of small male gametes relative to the larger female gametes usually lies in the development of strong sperm competition,[138][139] because small sperm enable organisms to produce a large number of sperm, and make males (or male function of hermaphrodites[140]) more redundant.

This intensifies male competition for mates and promotes the evolution of other sexual dimorphism in many species, especially in vertebrates including mammals. However, in some species females compete for mates in ways more usually associated with males (usually species in which males invest a lot in rearing offspring and thus are no longer considered as so redundant).[citation needed]

Sexual dimorphism by size is evident in some extinct species such as the velociraptor. In the case of velociraptors the sexual size dimorphism may have been caused by two factors: male competition for hunting ground to attract mates, and/or female competition for nesting locations and mates, males being a scarce breeding resource.[141]

Volvocine algae have been useful in understanding the evolution of sexual dimorphism [142] and species like the beetle C. maculatus, where the females are larger than the males, are used to study its underlying genetic mechanisms. [143]

In many non-monogamous species, the benefit to a male's reproductive fitness of mating with multiple females is large, whereas the benefit to a female's reproductive fitness of mating with multiple males is small or nonexistent.[144] In these species, there is a selection pressure for whatever traits enable a male to have more matings. The male may therefore come to have different traits from the female.

These traits could be ones that allow him to fight off other males for control of territory or a harem, such as large size or weapons;[145] or they could be traits that females, for whatever reason, prefer in mates.[146] Malemale competition poses no deep theoretical questions[147] but mate choice does.

Females may choose males that appear strong and healthy, thus likely to possess "good alleles" and give rise to healthy offspring.[148] In some species, however, females seem to choose males with traits that do not improve offspring survival rates, and even traits that reduce it (potentially leading to traits like the peacock's tail).[147] Two hypotheses for explaining this fact are the sexy son hypothesis and the handicap principle.

The sexy son hypothesis states that females may initially choose a trait because it improves the survival of their young, but once this preference has become widespread, females must continue to choose the trait, even if it becomes harmful. Those that do not will have sons that are unattractive to most females (since the preference is widespread) and so receive few matings.[149]

The handicap principle states that a male who survives despite possessing some sort of handicap thus proves that the rest of his genes are "good alleles". If males with "bad alleles" could not survive the handicap, females may evolve to choose males with this sort of handicap; the trait is acting as a hard-to-fake signal of fitness.[150]

Originally posted here:
Sexual dimorphism - Wikipedia

If your hairline is receding or your crown is thinning, you may wonder why this is happening and what exactly is causing your thinning hair. You may also be wondering what, if anything, you can do to reverse this trend.

Read on to learn more about the reasons why men lose their hair and the treatments that may help slow down the balding process.

The vast majority of men who go bald do so because of a hereditary condition known as androgenetic alopecia, more commonly known as male pattern baldness.

According to the American Hair Loss Association, 95 percent of hair loss in men is caused by androgenetic alopecia.

This inherited trait that tends to give guys a receding hairline and a thinning crown is caused by genetic sensitivity to a byproduct of testosterone called dihydrotestosterone (DHT).

So, how exactly does this hormonal byproduct cause hair loss?

Well, hair follicles that are sensitive to DHT have a tendency to shrink over time. As the affected hair follicles get smaller, the life span of each hair becomes shorter. Eventually, the affected follicles stop producing hair, or at least the type of hair youre used to.

With male pattern baldness, hair loss typically follows a predictable pattern. The two most common patterns of hair loss include the following:

The degree and progression of balding in men is assessed by the Norwood classification system. It has seven stages that measure the severity and pattern of hair loss and balding.

If you find that your hair is thinner than it used to be, you can draw some comfort from the fact that youre not alone. Male pattern baldness affects the majority of men at some stage in their lives.

According to the American Hair Loss Association:

Although male pattern baldness is the leading cause of balding, it isnt the only condition that can trigger hair loss.

With male pattern baldness, you typically dont have other symptoms aside from thinning hair. But with other hair loss causes, you may notice you have other symptoms, too.

Also, with most other causes, there isnt always a predictable hair loss pattern like there is with male pattern baldness. Instead, hair loss is more likely to happen all over, or in a few spots.

The following conditions can cause varying degrees of hair loss. Some types of hair loss may be permanent, while others may be reversible:

Hair loss from certain medications is usually temporary and once you stop taking the medication, hair growth will likely resume. Some of the known drugs associated with hair loss include:

Hair loss treatments, for male pattern baldness in particular, range from products you rub into your scalp to more invasive treatments aimed at restoring hair growth or replacing lost hair.

Here are some of the more popular and effective treatment options for balding.

There are both prescription and over-the-counter drugs approved for the treatment of male pattern baldness.

The two medications proven to treat or stave off further male pattern hair loss are finasteride (Propecia, Proscar) and minoxidil (Rogaine, Ioniten). Finasteride comes in a pill form and is only available by prescription. Minoxidil is a topical treatment thats available over the counter.

It can take at least 6 months for either treatment to start showing results.

Low-level laser therapy can be used to help invigorate circulation in the scalp and to stimulate hair follicles. Although this is a fairly new treatment option, it has been deemed safe and tolerable. It is also a less invasive option compared to hair transplant surgery.

Although research is limited for laser therapy and hair growth, some studies have shown encouraging results.

For instance, a 2013 study that included 41 men between the ages of 18 and 48 found a 39 percent increase in hair growth for participants who had laser hair surgery.

The two most common hair transplant procedures are follicular unit transplantation (FUT) and follicular unit extraction (FUE).

FUT involves the removal of a section of skin from the back of the scalp where hair is still growing. This section of skin is then divided into hundreds of tiny pieces called grafts. These grafts are then inserted into parts of the scalp where hair currently isnt growing.

With FUE, the surgeon takes individual healthy hair follicles out of the scalp and then makes small holes, where hair isnt growing, and puts the healthy follicles into these holes.

Male pattern baldness is commonly an inherited condition. Its very difficult to nonsurgically reverse any of the hair loss thats seen with this condition.

However, preventing further hair loss at the first sign of thinning is possible. Finasteride and Rogaine are two known treatments that might prevent further hair loss seen with androgenetic alopecia.

Once you discontinue use of these medications, the hair loss may resume. Talk to your doctor about if these medications may be right for you.

To keep your hair healthy and to prevent hair loss from other causes, try the following:

If you have a bald spot or a receding hairline, its likely due to your genes.

In 95 percent of cases, balding is due to androgenetic alopecia, more commonly known as male pattern baldness, which is a hereditary condition. It can affect men of all ages, and may even start before the age of 21.

Although you cant prevent male pattern baldness, there are ways to slow down hair loss. Some options include medications such as Finasteride (Propecia, Proscar) and minoxidil (Rogaine, Ioniten), laser therapy, and hair transplant surgery.

If youre concerned about going bald, be sure to speak to your doctor or dermatologist. They can work with you to figure out the treatment options that are right for you.

Read more from the original source:
Why Do Men Go Bald: Male Baldness Causes, Treatment, Prevention

Ethnic group in the United States

African Americans (also referred to as Black Americans and Afro-Americans) are an ethnic group consisting of Americans with partial or total ancestry from sub-Saharan Africa.[3][4] The term "African American" generally denotes descendants of enslaved Africans who are from the United States.[5][6][7] While some Black immigrants or their children may also come to identify as African-American, the majority of first generation immigrants do not, preferring to identify with their nation of origin.[8][9]

African Americans constitute the second largest racial group in the U.S. after White Americans, as well as the third largest ethnic group after Hispanic and Latino Americans.[10] Most African Americans are descendants of enslaved people within the boundaries of the present United States.[11][12] On average, African Americans are of West/Central African with some European descent; some also have Native American and other ancestry.[13]

According to U.S. Census Bureau data, African immigrants generally do not self-identify as African American. The overwhelming majority of African immigrants identify instead with their own respective ethnicities (~95%).[9] Immigrants from some Caribbean and Latin American nations and their descendants may or may not also self-identify with the term.[7]

African-American history began in the 16th century, with Africans from West Africa being sold to European slave traders and transported across the Atlantic to the Thirteen Colonies. After arriving in the Americas, they were sold as slaves to European colonists and put to work on plantations, particularly in the southern colonies. A few were able to achieve freedom through manumission or escape and founded independent communities before and during the American Revolution. After the United States was founded in 1783, most Black people continued to be enslaved, being most concentrated in the American South, with four million enslaved only liberated during and at the end of the Civil War in 1865.[14] During Reconstruction, they gained citizenship and the right to vote; due to the widespread policy and ideology of White supremacy, they were largely treated as second-class citizens and found themselves soon disenfranchised in the South. These circumstances changed due to participation in the military conflicts of the United States, substantial migration out of the South, the elimination of legal racial segregation, and the civil rights movement which sought political and social freedom. In 2008, Barack Obama became the first African American to be elected President of the United States.[15]

African-American culture has a significant influence on worldwide culture, making numerous contributions to visual arts, literature, the English language, philosophy, politics, cuisine, sports and music. The African American contribution to popular music is so profound that virtually all American music, such as jazz, gospel, blues, disco, hip hop, R&B, soul and rock all have their origins at least partially or entirely among African Americans.[16][17]

The vast majority of those who were enslaved and transported in the transatlantic slave trade were people from Central and West Africa, who had been captured directly by the slave traders in coastal raids,[18] or sold by other West Africans, or by half-European "merchant princes"[19] to European slave traders, who brought them to the Americas.[20]

The first African slaves arrived via Santo Domingo to the San Miguel de Gualdape colony (most likely located in the Winyah Bay area of present-day South Carolina), founded by Spanish explorer Lucas Vzquez de Aylln in 1526.[21] The ill-fated colony was almost immediately disrupted by a fight over leadership, during which the slaves revolted and fled the colony to seek refuge among local Native Americans. De Aylln and many of the colonists died shortly afterward of an epidemic and the colony was abandoned. The settlers and the slaves who had not escaped returned to Haiti, whence they had come.[21]

The marriage between Luisa de Abrego, a free Black domestic servant from Seville, and Miguel Rodrguez, a White Segovian conquistador in 1565 in St. Augustine (Spanish Florida), is the first known and recorded Christian marriage anywhere in what is now the continental United States.[22]

The first recorded Africans in English America (including most of the future United States) were "20 and odd negroes" who came to Jamestown, Virginia via Cape Comfort in August 1619 as indentured servants.[23] As many Virginian settlers began to die from harsh conditions, more and more Africans were brought to work as laborers.[24]

An indentured servant (who could be White or Black) would work for several years (usually four to seven) without wages. The status of indentured servants in early Virginia and Maryland was similar to slavery. Servants could be bought, sold, or leased and they could be physically beaten for disobedience or running away. Unlike slaves, they were freed after their term of service expired or was bought out, their children did not inherit their status, and on their release from contract they received "a year's provision of corn, double apparel, tools necessary", and a small cash payment called "freedom dues".[26] Africans could legally raise crops and cattle to purchase their freedom.[27] They raised families, married other Africans and sometimes intermarried with Native Americans or European settlers.[28]

By the 1640s and 1650s, several African families owned farms around Jamestown and some became wealthy by colonial standards and purchased indentured servants of their own. In 1640, the Virginia General Court recorded the earliest documentation of lifetime slavery when they sentenced John Punch, a Negro, to lifetime servitude under his master Hugh Gwyn for running away.[29][30]

In the Spanish Florida some Spanish married or had unions with Pensacola, Creek or African women, both slave and free, and their descendants created a mixed-race population of mestizos and mulattos. The Spanish encouraged slaves from the colony of Georgia to come to Florida as a refuge, promising freedom in exchange for conversion to Catholicism. King Charles II issued a royal proclamation freeing all slaves who fled to Spanish Florida and accepted conversion and baptism. Most went to the area around St. Augustine, but escaped slaves also reached Pensacola. St. Augustine had mustered an all-Black militia unit defending Spanish Florida as early as 1683.[31]

One of the Dutch African arrivals, Anthony Johnson, would later own one of the first Black "slaves", John Casor, resulting from the court ruling of a civil case.[32][33]

The popular conception of a race-based slave system did not fully develop until the 18th century. The Dutch West India Company introduced slavery in 1625 with the importation of eleven Black slaves into New Amsterdam (present-day New York City). All the colony's slaves, however, were freed upon its surrender to the English.[34]

Massachusetts was the first English colony to legally recognize slavery in 1641. In 1662, Virginia passed a law that children of enslaved women took the status of the mother, rather than that of the father, as under common law. This legal principle was called partus sequitur ventrum.[35][36]

By an act of 1699, the colony ordered all free Blacks deported, virtually defining as slaves all people of African descent who remained in the colony.[37] In 1670, the colonial assembly passed a law prohibiting free and baptized Blacks (and Indians) from purchasing Christians (in this act meaning White Europeans) but allowing them to buy people "of their owne nation".[38]

In the Spanish Louisiana although there was no movement toward abolition of the African slave trade, Spanish rule introduced a new law called coartacin, which allowed slaves to buy their freedom, and that of others.[41] Although some did not have the money to buy their freedom, government measures on slavery allowed many free Blacks. That brought problems to the Spaniards with the French Creoles who also populated Spanish Louisiana, French creoles cited that measure as one of the system's worst elements.[42]

First established in South Carolina in 1704, groups of armed White menslave patrolswere formed to monitor enslaved Black people.[43] Their function was to police slaves, especially fugitives. Slave owners feared that slaves might organize revolts or slave rebellions, so state militias were formed in order to provide a military command structure and discipline within the slave patrols so they could be used to detect, encounter, and crush any organized slave meetings which might lead to revolts or rebellions.[43]

The earliest African-American congregations and churches were organized before 1800 in both northern and southern cities following the Great Awakening. By 1775, Africans made up 20% of the population in the American colonies, which made them the second largest ethnic group after English Americans.[44]

During the 1770s, Africans, both enslaved and free, helped rebellious American colonists secure their independence by defeating the British in the American Revolutionary War.[45] Blacks played a role in both sides in the American Revolution. Activists in the Patriot cause included James Armistead, Prince Whipple, and Oliver Cromwell.[46][47] Around 15,000 Black Loyalists left with the British after the war, most of them ending up as free Black people in England[48] or its colonies, such as the Black Nova Scotians and the Sierra Leone Creole people.[49][50]

In the Spanish Louisiana, Governor Bernardo de Glvez organized Spanish free Black men into two militia companies to defend New Orleans during the American Revolution. They fought in the 1779 battle in which Spain captured Baton Rouge from the British. Glvez also commanded them in campaigns against the British outposts in Mobile, Alabama, and Pensacola, Florida. He recruited slaves for the militia by pledging to free anyone who was seriously wounded and promised to secure a low price for coartacin (buy their freedom and that of others) for those who received lesser wounds. During the 1790s, Governor Francisco Luis Hctor, baron of Carondelet reinforced local fortifications and recruit even more free Black men for the militia. Carondelet doubled the number of free Black men who served, creating two more militia companiesone made up of Black members and the other of pardo (mixed race). Serving in the militia brought free Black men one step closer to equality with Whites, allowing them, for example, the right to carry arms and boosting their earning power. However, actually these privileges distanced free Black men from enslaved Blacks and encouraged them to identify with Whites.[42]

Slavery had been tacitly enshrined in the U.S. Constitution through provisions such as Article I, Section 2, Clause 3, commonly known as the 3/5 compromise. Because of Section 9, Clause 1, Congress was unable to pass an Act Prohibiting Importation of Slaves until 1807.[51] Fugitive slave laws (derived from the Fugitive Slave Clause of the ConstitutionArticle IV, Section 2, Clause 3) were passed by Congress in 1793 and 1850, guaranteeing the right for a slaveholder to recover an escaped slave within the U.S.[40] Slave owners, who viewed slaves as property, made it a federal crime to assist those who had escaped slavery or to interfere with their capture.[39] Slavery, which by then meant almost exclusively Black people, was the most important political issue in the Antebellum United States, leading to one crisis after another. Among these were the Missouri Compromise, the Compromise of 1850, the Dred Scott decision, and John Brown's raid on Harpers Ferry.

Prior to the Civil War, eight serving presidents owned slaves, a practice protected by the U.S. Constitution.[52] By 1860, there were 3.5 to 4.4million enslaved Black people in the U.S. due to the Atlantic slave trade, and another 488,000500,000 Blacks lived free (with legislated limits)[53] across the country.[54] With legislated limits imposed upon them in addition to "unconquerable prejudice" from Whites according to Henry Clay,[55] some Black people who were not enslaved left the U.S. for Liberia in West Africa.[53] Liberia began as a settlement of the American Colonization Society (ACS) in 1821, with the abolitionist members of the ACS believing Blacks would face better chances for freedom and equality in Africa.[53]

The slaves not only constituted a large investment, they produced America's most valuable product and export: cotton. They not only helped build the U.S. Capitol, they built the White House and other District of Columbia buildings. (See Slavery in the District of Columbia.[56]) Similar building projects existed in the slave states.

By 1815, the domestic slave trade had become a major economic activity in the United States; it lasted until the 1860s.[57] Historians estimate nearly one million in total took part in the forced migration of this new "Middle Passage." The historian Ira Berlin called this forced migration of slaves the "central event" in the life of a slave between the American Revolution and the Civil War, writing that whether slaves were directly uprooted or lived in fear that they or their families would be involuntarily moved, "the massive deportation traumatized black people."[58] Individuals lost their connection to families and clans, and many ethnic Africans lost their knowledge of varying tribal origins in Africa.[57]

The 1863 photograph of Wilson Chinn, a branded slave from Louisiana, like the one of Gordon and his scarred back, served as two early examples of how the newborn medium of photography could encapsulate the cruelty of slavery.[59]

Emigration of free Blacks to their continent of origin had been proposed since the Revolutionary war. After Haiti became independent, it tried to recruit African Americans to migrate there after it re-established trade relations with the United States. The Haitian Union was a group formed to promote relations between the countries.[60] After riots against Blacks in Cincinnati, its Black community sponsored founding of the Wilberforce Colony, an initially successful settlement of African-American immigrants to Canada. The colony was one of the first such independent political entities. It lasted for a number of decades and provided a destination for about 200 Black families emigrating from a number of locations in the United States.[60]

In 1863, during the American Civil War, President Abraham Lincoln signed the Emancipation Proclamation. The proclamation declared that all slaves in Confederate-held territory were free.[61] Advancing Union troops enforced the proclamation, with Texas being the last state to be emancipated, in 1865.[62]

Slavery in Union-held Confederate territory continued, at least on paper, until the passage of the Thirteenth Amendment in 1865.[63] While the Naturalization Act of 1790 limited U.S. citizenship to Whites only,[64][65] the 14th Amendment (1868) gave Black people citizenship, and the 15th Amendment (1870) gave Black males the right to vote (which would still be denied to all women until 1920).[66]

African Americans quickly set up congregations for themselves, as well as schools and community/civic associations, to have space away from White control or oversight. While the post-war Reconstruction era was initially a time of progress for African Americans, that period ended in 1876. By the late 1890s, Southern states enacted Jim Crow laws to enforce racial segregation and disenfranchisement.[67] Segregation, which began with slavery, continued with Jim Crow laws, with signs used to show Blacks where they could legally walk, talk, drink, rest, or eat.[68] For those places that were racially mixed, non-Whites had to wait until all White customers were dealt with.[68] Most African Americans obeyed the Jim Crow laws, to avoid racially motivated violence. To maintain self-esteem and dignity, African Americans such as Anthony Overton and Mary McLeod Bethune continued to build their own schools, churches, banks, social clubs, and other businesses.[69]

In the last decade of the 19th century, racially discriminatory laws and racial violence aimed at African Americans began to mushroom in the United States, a period often referred to as the "nadir of American race relations". These discriminatory acts included racial segregationupheld by the United States Supreme Court decision in Plessy v. Ferguson in 1896which was legally mandated by southern states and nationwide at the local level of government, voter suppression or disenfranchisement in the southern states, denial of economic opportunity or resources nationwide, and private acts of violence and mass racial violence aimed at African Americans unhindered or encouraged by government authorities.[70]

The desperate conditions of African Americans in the South sparked the Great Migration during the first half of the 20th century which led to a growing African-American community in Northern and Western United States.[72] The rapid influx of Blacks disturbed the racial balance within Northern and Western cities, exacerbating hostility between both Blacks and Whites in the two regions.[73] The Red Summer of 1919 was marked by hundreds of deaths and higher casualties across the U.S. as a result of race riots that occurred in more than three dozen cities, such as the Chicago race riot of 1919 and the Omaha race riot of 1919. Overall, Blacks in Northern and Western cities experienced systemic discrimination in a plethora of aspects of life. Within employment, economic opportunities for Blacks were routed to the lowest-status and restrictive in potential mobility. At the 1900 Hampton Negro Conference, Reverend Matthew Anderson said: "...the lines along most of the avenues of wage earning are more rigidly drawn in the North than in the South."[74] Within the housing market, stronger discriminatory measures were used in correlation to the influx, resulting in a mix of "targeted violence, restrictive covenants, redlining and racial steering".[75] While many Whites defended their space with violence, intimidation, or legal tactics toward African Americans, many other Whites migrated to more racially homogeneous suburban or exurban regions, a process known as White flight.[76]

Despite discrimination, drawing cards for leaving the hopelessness in the South were the growth of African-American institutions and communities in Northern cities. Institutions included Black oriented organizations (e.g., Urban League, NAACP), churches, businesses, and newspapers, as well as successes in the development in African-American intellectual culture, music, and popular culture (e.g., Harlem Renaissance, Chicago Black Renaissance). The Cotton Club in Harlem was a Whites-only establishment, with Blacks (such as Duke Ellington) allowed to perform, but to a White audience.[77] Black Americans also found a new ground for political power in Northern cities, without the enforced disabilities of Jim Crow.[78][79]

By the 1950s, the civil rights movement was gaining momentum. A 1955 lynching that sparked public outrage about injustice was that of Emmett Till, a 14-year-old boy from Chicago. Spending the summer with relatives in Money, Mississippi, Till was killed for allegedly having wolf-whistled at a White woman. Till had been badly beaten, one of his eyes was gouged out, and he was shot in the head. The visceral response to his mother's decision to have an open-casket funeral mobilized the Black community throughout the U.S.[80] Vann R. Newkirk| wrote "the trial of his killers became a pageant illuminating the tyranny of White supremacy".[80] The state of Mississippi tried two defendants, but they were speedily acquitted by an all-White jury.[81] One hundred days after Emmett Till's murder, Rosa Parks refused to give up her seat on the bus in Alabamaindeed, Parks told Emmett's mother Mamie Till that "the photograph of Emmett's disfigured face in the casket was set in her mind when she refused to give up her seat on the Montgomery bus."[82]

The March on Washington for Jobs and Freedom and the conditions which brought it into being are credited with putting pressure on presidents John F. Kennedy and Lyndon B. Johnson. Johnson put his support behind passage of the Civil Rights Act of 1964 that banned discrimination in public accommodations, employment, and labor unions, and the Voting Rights Act of 1965, which expanded federal authority over states to ensure Black political participation through protection of voter registration and elections.[83] By 1966, the emergence of the Black Power movement, which lasted from 1966 to 1975, expanded upon the aims of the civil rights movement to include economic and political self-sufficiency, and freedom from White authority.[84]

During the post-war period, many African Americans continued to be economically disadvantaged relative to other Americans. Average Black income stood at 54 percent of that of White workers in 1947, and 55 percent in 1962. In 1959, median family income for Whites was $5,600, compared with $2,900 for non-White families. In 1965, 43 percent of all Black families fell into the poverty bracket, earning under $3,000 a year. The Sixties saw improvements in the social and economic conditions of many Black Americans.[85]

From 1965 to 1969, Black family income rose from 54 to 60 percent of White family income. In 1968, 23 percent of Black families earned under $3,000 a year, compared with 41 percent in 1960. In 1965, 19 percent of Black Americans had incomes equal to the national median, a proportion that rose to 27 percent by 1967. In 1960, the median level of education for Blacks had been 10.8 years, and by the late Sixties the figure rose to 12.2 years, half a year behind the median for Whites.[85]

Politically and economically, African Americans have made substantial strides during the postcivil rights era. In 1967, Thurgood Marshall became the first African-American Supreme Court Justice. In 1968, Shirley Chisholm became the first Black woman elected to the U.S. Congress. In 1989, Douglas Wilder became the first African American elected governor in U.S. history. Clarence Thomas succeeded Marshall to become the second African-American Supreme Court Justice in 1991. In 1992, Carol Moseley-Braun of Illinois became the first African-American woman elected to the U.S. Senate. There were 8,936 Black officeholders in the United States in 2000, showing a net increase of 7,467 since 1970. In 2001, there were 484 Black mayors.[86]

In 2005, the number of Africans immigrating to the United States, in a single year, surpassed the peak number who were involuntarily brought to the United States during the Atlantic Slave Trade.[87] On November 4, 2008, Democratic Senator Barack Obama defeated Republican Senator John McCain to become the first African American to be elected president. At least 95 percent of African-American voters voted for Obama.[88][89] He also received overwhelming support from young and educated Whites, a majority of Asians,[90] and Hispanics,[90] picking up a number of new states in the Democratic electoral column.[88][89] Obama lost the overall White vote, although he won a larger proportion of White votes than any previous nonincumbent Democratic presidential candidate since Jimmy Carter.[91] Obama was reelected for a second and final term, by a similar margin on November 6, 2012.[92] In 2021, Kamala Harris became the first woman, the first African American, and the first Asian American to serve as Vice President of the United States.[93]

Proportion of African Americans in each U.S. state, the District of Columbia, and Puerto Rico as of the 2020 United States Census

In 1790, when the first U.S. Census was taken, Africans (including slaves and free people) numbered about 760,000about 19.3% of the population. In 1860, at the start of the Civil War, the African-American population had increased to 4.4million, but the percentage rate dropped to 14% of the overall population of the country. The vast majority were slaves, with only 488,000 counted as "freemen". By 1900, the Black population had doubled and reached 8.8million.[94]

In 1910, about 90% of African Americans lived in the South. Large numbers began migrating north looking for better job opportunities and living conditions, and to escape Jim Crow laws and racial violence. The Great Migration, as it was called, spanned the 1890s to the 1970s. From 1916 through the 1960s, more than 6million Black people moved north. But in the 1970s and 1980s, that trend reversed, with more African Americans moving south to the Sun Belt than leaving it.[95]

The following table of the African-American population in the United States over time shows that the African-American population, as a percentage of the total population, declined until 1930 and has been rising since then.

By 1990, the African-American population reached about 30million and represented 12% of the U.S. population, roughly the same proportion as in 1900.[97]

At the time of the 2000 Census, 54.8% of African Americans lived in the South. In that year, 17.6% of African Americans lived in the Northeast and 18.7% in the Midwest, while only 8.9% lived in the western states. The west does have a sizable Black population in certain areas, however. California, the nation's most populous state, has the fifth largest African-American population, only behind New York, Texas, Georgia, and Florida. According to the 2000 Census, approximately 2.05% of African Americans identified as Hispanic or Latino in origin,[10] many of whom may be of Brazilian, Puerto Rican, Dominican, Cuban, Haitian, or other Latin American descent. The only self-reported ancestral groups larger than African Americans are the Irish and Germans.[98]

According to the 2010 U.S. Census, nearly 3% of people who self-identified as Black had recent ancestors who immigrated from another country. Self-reported non-Hispanic Black immigrants from the Caribbean, mostly from Jamaica and Haiti, represented 0.9% of the U.S. population, at 2.6million.[99] Self-reported Black immigrants from Sub-Saharan Africa also represented 0.9%, at about 2.8million.[99] Additionally, self-identified Black Hispanics represented 0.4% of the United States population, at about 1.2million people, largely found within the Puerto Rican and Dominican communities.[100] Self-reported Black immigrants hailing from other countries in the Americas, such as Brazil and Canada, as well as several European countries, represented less than 0.1% of the population. Mixed-Race Hispanic and non-Hispanic Americans who identified as being part Black, represented 0.9% of the population. Of the 12.6% of United States residents who identified as Black, around 10.3% were "native Black American" or ethnic African Americans, who are direct descendants of West/Central Africans brought to the U.S. as slaves. These individuals make up well over 80% of all Blacks in the country. When including people of mixed-race origin, about 13.5% of the U.S. population self-identified as Black or "mixed with Black".[101] However, according to the U.S. census bureau, evidence from the 2000 Census indicates that many African and Caribbean immigrant ethnic groups do not identify as "Black, African Am., or Negro". Instead, they wrote in their own respective ethnic groups in the "Some Other Race" write-in entry. As a result, the census bureau devised a new, separate "African American" ethnic group category in 2010 for ethnic African Americans.[102]

Historically, African-Americans have been undercounted in the U.S. Census due to a number of factors and biases.[103][104] In the 2020 census, the African American population was undercounted at an estimated rate of 3.3%, up from 2.1% in 2010.[105]

After 100 years of African Americans leaving the south in large numbers seeking better opportunities and treatment in the west and north, a movement known as the Great Migration, there is now a reverse trend, called the New Great Migration. As with the earlier Great Migration, the New Great Migration is primarily directed toward cities and large urban areas, such as Atlanta, Charlotte, Houston, Dallas, Raleigh, Tampa, San Antonio, Memphis, Nashville, Jacksonville, and so forth.[106] A growing percentage of African-Americans from the west and north are migrating to the southern region of the U.S. for economic and cultural reasons. New York City, Chicago, and Los Angeles have the highest decline in African Americans, while Atlanta, Dallas, and Houston have the highest increase respectively.[106]

Among cities of 100,000 or more, Detroit, Michigan had the highest percentage of Black residents of any U.S. city in 2010, with 82%. Other large cities with African-American majorities include Jackson, Mississippi (79.4%), Miami Gardens, Florida (76.3%), Baltimore, Maryland (63%), Birmingham, Alabama (62.5%), Memphis, Tennessee (61%), New Orleans, Louisiana (60%), Montgomery, Alabama (56.6%), Flint, Michigan (56.6%), Savannah, Georgia (55.0%), Augusta, Georgia (54.7%), Atlanta, Georgia (54%, see African Americans in Atlanta), Cleveland, Ohio (53.3%), Newark, New Jersey (52.35%), Washington, D.C. (50.7%), Richmond, Virginia (50.6%), Mobile, Alabama (50.6%), Baton Rouge, Louisiana (50.4%), and Shreveport, Louisiana (50.4%).

The nation's most affluent community with an African-American majority resides in View ParkWindsor Hills, California with an annual median household income of $159,618.[107] Other largely affluent and African-American communities include Prince George's County in Maryland (namely Mitchellville, Woodmore, and Upper Marlboro), Dekalb County and South Fulton in Georgia, Charles City County in Virginia, Baldwin Hills in California, Hillcrest and Uniondale in New York, and Cedar Hill, DeSoto, and Missouri City in Texas. Queens County, New York is the only county with a population of 65,000 or more where African Americans have a higher median household income than White Americans.[108]

Seatack, Virginia is currently the oldest African-American community in the United States.[109] It survives today with a vibrant and active civic community.[110]

During slavery, anti-literacy laws were enacted in the U.S. that prohibited education for Black people. Slave owners saw literacy as a threat to the institution of slavery. As a North Carolina statute stated, "Teaching slaves to read and write, tends to excite dissatisfaction in their minds, and to produce insurrection and rebellion."[111]

In 1863, enslaved Americans became free citizens during a time when public educational systems were expanding across the country. By 1870, around seventy-four institutions in the south provided a form of advanced education for African American students, and by 1900, over a hundred programs at these schools provided training for Black professionals, including teachers. Many of the students at Fisk University, including W. E. B. Du Bois when he was a student there, taught school during the summers to support their studies.[112]

African Americans were very concerned to provide quality education for their children, but White supremacy limited their ability to participate in educational policymaking on the political level. State governments soon moved to undermine their citizenship by restricting their right to vote. By the late 1870s, Blacks were disenfranchised and segregated across the American South.[113] White politicians in Mississippi and other states withheld financial resources and supplies from Black schools. Nevertheless, the presence of Black teachers, and their engagement with their communities both inside and outside the classroom, ensured that Black students had access to education despite these external constraints.[114][115]

During World War II, demands for unity and racial tolerance on the home front provided an opening for the first Black history curriculum in the country.[116] For example, during the early 1940s, Madeline Morgan, a Black teacher in the Chicago public schools, created a curriculum for students in grades one through eight highlighting the contributions of Black people to the history of the United States. At the close of the war, Chicago's Board of Education downgraded the curriculum's status from mandatory to optional.[117]

Predominantly Black schools for kindergarten through twelfth grade students were common throughout the U.S. before the 1970s. By 1972, however, desegregation efforts meant that only 25% of Black students were in schools with more than 90% non-White students. However, since then, a trend towards re-segregation affected communities across the country: by 2011, 2.9million African-American students were in such overwhelmingly minority schools, including 53% of Black students in school districts that were formerly under desegregation orders.[118][119]

As late as 1947, about one third of African Americans over 65 were considered to lack the literacy to read and write their own names. By 1969, illiteracy as it had been traditionally defined, had been largely eradicated among younger African Americans.[120]

U.S. Census surveys showed that by 1998, 89 percent of African Americans aged 25 to 29 had completed a high-school education, less than Whites or Asians, but more than Hispanics. On many college entrance, standardized tests and grades, African Americans have historically lagged behind Whites, but some studies suggest that the achievement gap has been closing. Many policy makers have proposed that this gap can and will be eliminated through policies such as affirmative action, desegregation, and multiculturalism.[121]

Between 1995 and 2009, freshmen college enrollment for African Americans increased by 73 percent and only 15 percent for Whites.[122] Black women are enrolled in college more than any other race and gender group, leading all with 9.7% enrolled according to the 2011 U.S. Census Bureau.[123][124] The average high school graduation rate of Blacks in the United States has steadily increased to 71% in 2013.[125] Separating this statistic into component parts shows it varies greatly depending upon the state and the school district examined. 38% of Black males graduated in the state of New York but in Maine 97% graduated and exceeded the White male graduation rate by 11 percentage points.[126] In much of the southeastern United States and some parts of the southwestern United States the graduation rate of White males was in fact below 70% such as in Florida where 62% of White males graduated from high school. Examining specific school districts paints an even more complex picture. In the Detroit school district the graduation rate of Black males was 20% but 7% for White males. In the New York City school district 28% of Black males graduate from high school compared to 57% of White males. In Newark County[where?] 76% of Black males graduated compared to 67% for White males. Further academic improvement has occurred in 2015. Roughly 23% of all Blacks have bachelor's degrees. In 1988, 21% of Whites had obtained a bachelor's degree versus 11% of Blacks. In 2015, 23% of Blacks had obtained a bachelor's degree versus 36% of Whites.[127] Foreign born Blacks, 9% of the Black population, made even greater strides. They exceed native born Blacks by 10 percentage points.[127]

College Board, which runs the official college-level advanced placement (AP) programs in American high schools, have has received criticism in recent years that its curricula have focused too much on Euro-centric history.[128] In 2020, College Board reshaped some curricula among history-based courses to further reflect the African diaspora.[129] In 2021, College Board announced it would be piloting an AP African American Studies course between 2022 and 2024. The course is expected to launch in 2024.[130]

Historically Black colleges and universities (HBCUs), which were founded when segregated institutions of higher learning did not admit African Americans, continue to thrive and educate students of all races today. There are 101 HBCUs representing three percent of the nation's colleges and universities with the majority established in the Southeast.[131][132] HBCUs have been largely responsible for establishing and expanding the African-American middle-class by providing opportunities not usually given to African Americans.[133][134]

African Americans have benefited from the advances made during the civil rights era. The racial disparity in poverty rates has narrowed. In the first quarter of 2021, 45.1% of African Americans owned their homes, compared to 65.3% of all Americans.[136] The poverty rate among African Americans has decreased from 24.7% in 2004 to 18.8% in 2020, compared to 10.5% for all Americans.[137][138]

African Americans have a combined buying power of over $892billion currently and likely over $1.1trillion by 2012.[140][141] In 2002, African American-owned businesses accounted for 1.2million of the US's 23million businesses.[142] As of 2011[update] African American-owned businesses account for approximately 2million US businesses.[143] Black-owned businesses experienced the largest growth in number of businesses among minorities from 2002 to 2011.[143]

Twenty-five percent of Blacks had white-collar occupations (management, professional, and related fields) in 2000, compared with 33.6% of Americans overall.[144][145] In 2001, over half of African-American households of married couples earned $50,000 or more.[145] Although in the same year African Americans were over-represented among the nation's poor, this was directly related to the disproportionate percentage of African-American families headed by single women; such families are collectively poorer, regardless of ethnicity.[145]

In 2006, the median earnings of African-American men was more than Black and non-Black American women overall, and in all educational levels.[146][147][148][149][150] At the same time, among American men, income disparities were significant; the median income of African-American men was approximately 76 cents for every dollar of their European American counterparts, although the gap narrowed somewhat with a rise in educational level.[146][151]

Overall, the median earnings of African-American men were 72 cents for every dollar earned of their Asian American counterparts, and $1.17 for every dollar earned by Hispanic men.[146][149][152] On the other hand, by 2006, among American women with post-secondary education, African-American women have made significant advances; the median income of African-American women was more than those of their Asian-, European- and Hispanic American counterparts with at least some college education.[147][148][153]

The U.S. public sector is the single most important source of employment for African Americans.[154] During 20082010, 21.2% of all Black workers were public employees, compared with 16.3% of non-Black workers.[154] Both before and after the onset of the Great Recession, African Americans were 30% more likely than other workers to be employed in the public sector.[154] The public sector is also a critical source of decent-paying jobs for Black Americans. For both men and women, the median wage earned by Black employees is significantly higher in the public sector than in other industries.[154]

In 1999, the median income of African-American families was $33,255 compared to $53,356 of European Americans. In times of economic hardship for the nation, African Americans suffer disproportionately from job loss and underemployment, with the Black underclass being hardest hit. The phrase "last hired and first fired" is reflected in the Bureau of Labor Statistics unemployment figures. Nationwide, the October 2008 unemployment rate for African Americans was 11.1%,[155] while the nationwide rate was 6.5%.[156]

The income gap between Black and White families is also significant. In 2005, employed Blacks earned 65% of the wages of Whites, down from 82% in 1975.[137] The New York Times reported in 2006 that in Queens, New York, the median income among African-American families exceeded that of White families, which the newspaper attributed to the growth in the number of two-parent Black families. It noted that Queens was the only county with more than 65,000 residents where that was true.[108] In 2011, it was reported that 72% of Black babies were born to unwed mothers.[157] The poverty rate among single-parent Black families was 39.5% in 2005, according to Walter E. Williams, while it was 9.9% among married-couple Black families. Among White families, the respective rates were 26.4% and 6% in poverty.[158]

Collectively, African Americans are more involved in the American political process than other minority groups in the United States, indicated by the highest level of voter registration and participation in elections among these groups in 2004.[159] African Americans also have the highest level of Congressional representation of any minority group in the U.S.[160]

Since the mid 20th century, a large majority of African Americans support the Democratic Party. In the 2020 Presidential election, 91% of African-American voters supported Democrat Joe Biden, while 8% supported Republican Donald Trump.[161] Although there is an African-American lobby in foreign policy, it has not had the impact that African-American organizations have had in domestic policy.[162]

Many African Americans were excluded from electoral politics in the decades following the end of Reconstruction. For those that could participate, until the New Deal, African Americans were supporters of the Republican Party because it was Republican President Abraham Lincoln who helped in granting freedom to American slaves; at the time, the Republicans and Democrats represented the sectional interests of the North and South, respectively, rather than any specific ideology, and both conservative and liberal were represented equally in both parties.

The African-American trend of voting for Democrats can be traced back to the 1930s during the Great Depression, when Franklin D. Roosevelt's New Deal program provided economic relief to African Americans. Roosevelt's New Deal coalition turned the Democratic Party into an organization of the working class and their liberal allies, regardless of region. The African-American vote became even more solidly Democratic when Democratic presidents John F. Kennedy and Lyndon B. Johnson pushed for civil rights legislation during the 1960s. In 1960, nearly a third of African Americans voted for Republican Richard Nixon.[163]

"Lift Every Voice and Sing" is often referred to as the Black national anthem in the United States.[164] In 1919, the National Association for the Advancement of Colored People (NAACP) had dubbed it the "Negro national anthem" for its power in voicing a cry for liberation and affirmation for African American people.[165]

According to a Gallup survey, 4.6% of Black or African-Americans self-identified as LGBT in 2016,[166] while the total portion of American adults in all ethnic groups identifying as LGBT was 4.1% in 2016.[166]

The life expectancy for Black men in 2008 was 70.8 years.[167] Life expectancy for Black women was 77.5 years in 2008.[167] In 1900, when information on Black life expectancy started being collated, a Black man could expect to live to 32.5 years and a Black woman 33.5 years.[167] In 1900, White men lived an average of 46.3 years and White women lived an average of 48.3 years.[167] African-American life expectancy at birth is persistently five to seven years lower than European Americans.[168] Black men have shorter lifespans than any other group in the US besides Native American men.[169]

Black people have higher rates of obesity, diabetes, and hypertension than the U.S. average.[167] For adult Black men, the rate of obesity was 31.6% in 2010.[170] For adult Black women, the rate of obesity was 41.2% in 2010.[170] African Americans have higher rates of mortality than any other racial or ethnic group for 8 of the top 10 causes of death.[171] In 2013, among men, Black men had the highest rate of getting cancer, followed by White, Hispanic, Asian/Pacific Islander (A/PI), and American Indian/Alaska Native (AI/AN) men. Among women, White women had the highest rate of getting cancer, followed by Black, Hispanic, Asian/Pacific Islander, and American Indian/Alaska Native women.[172] African Americans also have higher prevalence and incidence of Alzheimer's disease compared to the overall average.[173][174]

Violence has an impact upon African-American life expectancy. A report from the U.S. Department of Justice states "In 2005, homicide victimization rates for blacks were 6 times higher than the rates for whites".[175] The report also found that "94% of black victims were killed by blacks."[175] Black boys and men age 1544 are the only race/sex category for which homicide is a top-five cause of death.[169]

In December 2020, African Americans were less likely to be vaccinated against COVID-19 due to mistrust in the U.S. medical system related to decades of abuses and anti-black treatment. From 2021 to 2022, there was an increase in African Americans who became vaccinated.[176][177][178] Still, in 2022, COVID-19 complications became the third leading cause of death for African Americans.[179]

According to the Centers for Disease Control and Prevention, African Americans have higher rates of sexually transmitted infections (STIs) compared to Whites, with 5 times the rates of syphilis and chlamydia, and 7.5 times the rate of gonorrhea.[180]

The disproportionately high incidence of HIV/AIDS among African-Americans has been attributed to homophobic influences and lack of access to proper healthcare.[181] The prevalence of HIV/AIDS among Black men is seven times higher than the prevalence for White men, and Black men are more than nine times as likely to die from HIV/AIDS-related illness than White men.[169]

African Americans have several barriers for accessing mental health services. Counseling has been frowned upon and distant in utility and proximity to many people in the African American community. In 2004, a qualitative research study explored the disconnect with African Americans and mental health. The study was conducted as a semi-structured discussion which allowed the focus group to express their opinions and life experiences. The results revealed a couple key variables that create barriers for many African American communities to seek mental health services such as the stigma, lack of four important necessities; trust, affordability, cultural understanding and impersonal services.[182]

Historically, many African American communities did not seek counseling because religion was a part of the family values.[183] African American who have a faith background are more likely to seek prayer as a coping mechanism for mental issues rather than seeking professional mental health services.[182] In 2015 a study concluded, African Americans with high value in religion are less likely to utilize mental health services compared to those who have low value in religion.[184]

Most counseling approaches are westernized and do not fit within the African American culture. African American families tend to resolve concerns within the family, and it is viewed by the family as a strength. On the other hand, when African Americans seek counseling, they face a social backlash and are criticized. They may be labeled "crazy", viewed as weak, and their pride is diminished.[182] Because of this, many African Americans instead seek mentorship within communities they trust.

Terminology is another barrier in relation to African Americans and mental health. There is more stigma on the term psychotherapy versus counseling. In one study, psychotherapy is associated with mental illness whereas counseling approaches problem-solving, guidance and help.[182] More African Americans seek assistance when it is called counseling and not psychotherapy because it is more welcoming within the cultural and community.[185] Counselors are encouraged to be aware of such barriers for the well-being of African American clients. Without cultural competency training in health care, many African Americans go unheard and misunderstood.[182]

Although suicide is a top-10 cause of death for men overall in the US, it is not a top-10 cause of death for Black men.[169]

Recent surveys of African Americans using a genetic testing service have found varied ancestries which show different tendencies by region and sex of ancestors. These studies found that on average, African Americans have 73.282.1% West African, 16.7%24% European, and 0.81.2% Native American genetic ancestry, with large variation between individuals.[187][188][189] Genetics websites themselves have reported similar ranges, with some finding 1 or 2 percent Native American ancestry and Ancestry.com reporting an outlying percentage of European ancestry among African Americans, 29%.[190]

According to a genome-wide study by Bryc et al. (2009), the mixed ancestry of African Americans in varying ratios came about as the result of sexual contact between West/Central Africans (more frequently females) and Europeans (more frequently males). Consequently, the 365 African Americans in their sample have a genome-wide average of 78.1% West African ancestry and 18.5% European ancestry, with large variation among individuals (ranging from 99% to 1% West African ancestry). The West African ancestral component in African Americans is most similar to that in present-day speakers from the non-Bantu branches of the Niger-Congo (Niger-Kordofanian) family.[187][note 2]

Correspondingly, Montinaro et al. (2014) observed that around 50% of the overall ancestry of African Americans traces back to the Niger-Congo-speaking Yoruba of southwestern Nigeria and southern Benin, reflecting the centrality of this West African region in the Atlantic Slave Trade. The next most frequent ancestral component found among African Americans was derived from Great Britain, in keeping with historical records. It constitutes a little over 10% of their overall ancestry, and is most similar to the Northwest European ancestral component also carried by Barbadians.[192] Zakharaia et al. (2009) found a similar proportion of Yoruba associated ancestry in their African-American samples, with a minority also drawn from Mandenka and Bantu populations. Additionally, the researchers observed an average European ancestry of 21.9%, again with significant variation between individuals.[186] Bryc et al. (2009) note that populations from other parts of the continent may also constitute adequate proxies for the ancestors of some African-American individuals; namely, ancestral populations from Guinea Bissau, Senegal and Sierra Leone in West Africa and Angola in Southern Africa.[187]

Altogether, genetic studies suggest that African Americans are a genetically diverse people. According to DNA analysis led in 2006 by Penn State geneticist Mark D. Shriver, around 58 percent of African Americans have at least 12.5% European ancestry (equivalent to one European great-grandparent and his/her forebears), 19.6 percent of African Americans have at least 25% European ancestry (equivalent to one European grandparent and his/her forebears), and 1 percent of African Americans have at least 50% European ancestry (equivalent to one European parent and his/her forebears).[13][193] According to Shriver, around 5 percent of African Americans also have at least 12.5% Native American ancestry (equivalent to one Native American great-grandparent and his/her forebears).[194][195] Research suggests that Native American ancestry among people who identify as African American is a result of relationships that occurred soon after slave ships arrived in the American colonies, and European ancestry is of more recent origin, often from the decades before the Civil War.[196]

Africans bearing the E-V38 (E1b1a) likely traversed across the Sahara, from east to west, approximately 19,000 years ago.[197] E-M2 (E1b1a1) likely originated in West Africa or Central Africa.[198] According to a Y-DNA study by Sims et al. (2007), the majority (60%) of African Americans belong to various subclades of the E-M2 (E1b1a1, formerly E3a) paternal haplogroup. This is the most common genetic paternal lineage found today among West/Central African males, and is also a signature of the historical Bantu migrations. The next most frequent Y-DNA haplogroup observed among African Americans is the R1b clade, which around 15% of African Americans carry. This lineage is most common today among Northwestern European males. The remaining African Americans mainly belong to the paternal haplogroup I (7%), which is also frequent in Northwestern Europe.[199]

According to an mtDNA study by Salas et al. (2005), the maternal lineages of African Americans are most similar to haplogroups that are today especially common in West Africa (>55%), followed closely by West-Central Africa and Southwestern Africa (<41%). The characteristic West African haplogroups L1b, L2b,c,d, and L3b,d and West-Central African haplogroups L1c and L3e in particular occur at high frequencies among African Americans. As with the paternal DNA of African Americans, contributions from other parts of the continent to their maternal gene pool are insignificant.[200]

Formal political, economic and social discrimination against minorities has been present throughout American history. Leland T. Saito, Associate Professor of Sociology and American Studies & Ethnicity at the University of Southern California, writes, "Political rights have been circumscribed by race, class and gender since the founding of the United States, when the right to vote was restricted to White men of property. Throughout the history of the United States race has been used by Whites for legitimizing and creating difference and social, economic and political exclusion."[65]

Although they have gained a greater degree of social equality since the civil rights movement, African Americans have remained stagnant economically, which has hindered their ability to break into the middle class and beyond. As of 2020, the racial wealth gap between Whites and Blacks remains as large as it was in 1968, with the typical net worth of a White household equivalent to that of 11.5 black households.[201] Despite this, African Americans have increased employment rates and gained representation in the highest levels of American government in the postcivil rights era.[202] However, widespread racism remains an issue that continues to undermine the development of social status.[202][203]

One of the most serious and long-standing issues within African-American communities is poverty. Poverty is associated with higher rates of marital stress and dissolution, physical and mental health problems, disability, cognitive deficits, low educational attainment, and crime.[204] In 2004, almost 25% of African-American families lived below the poverty level.[137] In 2007, the average income for African Americans was approximately $34,000, compared to $55,000 for Whites.[205] African Americans experience a higher rate of unemployment than the general population.[206]

African Americans have a long and diverse history of business ownership. Although the first African-American business is unknown, slaves captured from West Africa are believed to have established commercial enterprises as peddlers and skilled craftspeople as far back as the 17th century. Around 1900, Booker T. Washington became the most famous proponent of African-American businesses. His critic and rival W. E. B. DuBois also commended business as a vehicle for African-American advancement.[207]

Forty percent of prison inmates are African American.[208] African American males are more likely to be killed by police when compared to other races.[209] This is one of the factors that led to the creation of the Black Lives Matter movement in 2013.[210] A historical issue in the U.S. where women have weaponized their White privilege in the country by reporting on Black people, often instigating racial violence,[211][212] White women calling the police on Black people became widely publicized in 2020.[213][214] In African-American culture there is a long history of calling a meddlesome White woman by a certain name, while The Guardian called 2020 "the year of Karen".[215]

Although in the last decade Black youth have had lower rates of cannabis (marijuana) consumption than Whites of the same age, they have disproportionately higher arrest rates than Whites: in 2010, for example, Blacks were 3.73 times as likely to get arrested for using cannabis than Whites, despite not significantly more frequently being users.[216][217]

After over 50 years, marriage rates for all Americans began to decline while divorce rates and out-of-wedlock births have climbed.[218] These changes have been greatest among African Americans. After more than 70 years of racial parity Black marriage rates began to fall behind Whites.[218] Single-parent households have become common, and according to U.S. census figures released in January 2010, only 38 percent of Black children live with both their parents.[219]

More here:
African Americans - Wikipedia

A risk factor is anything that affects your chance of getting a disease, such as breast cancer.

But having a risk factor, or even many, does not mean that you are sure to get the disease. Some men with one or more breast cancer risk factors never develop the disease, while most men with breast cancer have no apparent risk factors.

We don't yet completely understand the causes of breast cancer in men, but researchers have found several factors that may increase the risk of getting it. As with female breast cancer, many of these factors are related to your body's sex hormone levels.

Aging is an important risk factor for the development of breast cancer in men. The risk of breast cancer goes up as a man ages. On average, men with breast cancer are about 72 years old when they are diagnosed.

Breast cancer risk is increased if other members of the family (blood relatives) have had breast cancer. About 1 out of 5 men with breast cancer have a close relative, male or female, with the disease.

Men with a mutation (defect) in the BRCA2 gene have an increased risk of breast cancer, with a lifetime risk of about 6 in 100. BRCA1 mutations can also cause breast cancer in men, but the risk is lower, about 1 in 100.

Although mutations in these genes most often are found in members of families with many cases of breast and/or ovarian cancer, they have also been found in men with breast cancer who did not have a strong family history.

Mutations in CHEK2, PTEN and PALB2 genesmight also be responsible for some breast cancers in men.

Klinefelter syndrome is a congenital (present at birth) condition that affects about 1 in 1,000 men. Normally the cells in men's bodies have a single X chromosome along with a Y chromosome, while women's cells have two X chromosomes. Men with Klinefelter syndrome have cells with a Y chromosome plus at least two X chromosomes (but sometimes more).

Men with Klinefelter syndrome also have small testicles and are often infertile because they are unable to produce functioning sperm cells. Compared with other men, they have lower levels of androgens (male hormones) and more estrogens (female hormones). For this reason, they often develop gynecomastia (benign male breast growth).

Men with Klinefelter syndrome are more likely to get breast cancer than other men. Having this condition can increase the risk anywhere between 20 - 60 times the risk of a man in the general population.

A man whose chest area has been treated with radiation (such as for the treatment of a cancer in the chest, like lymphoma) has an increased risk of developing breast cancer.

Heavy drinking (of alcoholic beverages) increases the risk of breast cancer in men. This may be because of its effects on the liver (see next paragraph).

The liver plays an important role in balancing the levels of sex hormones. In cases of severe liver disease, such as cirrhosis, the liver is not working well and the hormone levels are uneven, causinglower levels of androgens and higher levels of estrogen. Men with liver disease can also have a higher chance of developing benign male breast growth (gynecomastia) and also have an higher risk of developing breast cancer.

Estrogen-related drugs were once used in hormonal therapy for men with prostate cancer. This treatment may slightly increase breast cancer risk.

There is concern that transgender/transsexual individuals who take high doses of estrogens as part of sex reassignment could also have a higher breast cancer risk. Still, there havent been any studies of breast cancer risk in transgendered individuals, so it isnt clear what their breast cancer risk is.

Studies have shown that women's breast cancer risk is increased by obesity (being extremely overweight) after menopause. Obesity is also a risk factor for male breast cancer as well. The reason is that fat cells in the body convert male hormones (androgens) into female hormones (estrogens). This means that obese men have higher levels of estrogens in their body.

Certain conditions, such as having an undescended testicle, having mumps as an adult, or having one or both testicles surgically removed (orchiectomy) may increase male breast cancer risk.

View post:
Risk Factors for Breast Cancer in Men - American Cancer Society

A

Adenine

Allele

Amino Acid

Aneuploidy

Animal Model

Anticodon

Antisense

Autism

Autosomal Dominant Disorder

Autosomal Recessive Disorder

Autosome

Base Pair

Bioinformatics

Birth Defect

BRCA1/BRCA2

Cancer

Cancer-Susceptibility Gene

Candidate Gene

Carcinogen

Carrier

Carrier Screening

Copy DNA (cDNA)

Cell-Free DNA Testing

Centimorgan (cM)

Central Dogma

Centromere

Chromatid

Chromatin

Chromosome

Cloning

Codominance

Codon

Complex Disease

Congenital

Contig

Copy Number Variation (CNV)

CRISPR

Crossing Over

Cystic Fibrosis (CF)

Cytogenetics

Cytosine

Data Science

Deletion

Deoxyribonucleic Acid (DNA)

Diploid

DNA Fingerprinting

DNA Replication

DNA Sequencing

Dominant Traits and Alleles

Double Helix

Down Syndrome (Trisomy 21)

Duplication

Electrophoresis

Environmental Factors

Epigenetics

Epistasis

Eugenics

Evolution

Exome

Exon

Family History

Fibroblast

First-Degree Relative

Fluorescence In Situ Hybridization (FISH)

Founder Effect

Fragile X Syndrome

Frameshift Mutation

Fraternal Twins

Gamete

Gender

Gene

Gene Amplification

Gene Expression

Gene Mapping

Gene Pool

Gene Regulation

Gene Therapy

GeneEnvironment Interaction

Genetic Ancestry

Genetic Code

Genetic Counseling

Genetic Discrimination

Genetic Drift

Genetic Engineering

Genetic Epidemiology

Genetic Imprinting

Genetic Information Nondiscrimination Act (GINA)

Genetic Map

Genetic Testing

Genetics

Genome

Genome-Wide Association Study (GWAS)

Genomic Medicine

Genomic Variation

Genomics

Genotype

Germ Line

Gigabase (Gb)

GMO (Genetically Modified Organism)

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Talking Glossary of Genetic Terms | NHGRI - Genome

We have the killers DNA, we just need a name: Genetic game changer offers hope for near-unsolvable Ontario cold cases  Toronto Star

Original post:
We have the killers DNA, we just need a name: Genetic game changer offers hope for near-unsolvable Ontario cold cases - Toronto Star

Overview

Hair loss (alopecia) can affect just your scalp or your entire body, and it can be temporary or permanent. It can be the result of heredity, hormonal changes, medical conditions or a normal part of aging. Anyone can lose hair on their head, but it's more common in men.

Baldness typically refers to excessive hair loss from your scalp. Hereditary hair loss with age is the most common cause of baldness. Some people prefer to let their hair loss run its course untreated and unhidden. Others may cover it up with hairstyles, makeup, hats or scarves. And still others choose one of the treatments available to prevent further hair loss or restore growth.

Before pursuing hair loss treatment, talk with your doctor about the cause of your hair loss and treatment options.

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Male-pattern baldness typically appears first at the hairline or top of the head. It can progress to partial or complete baldness.

Close

Female-pattern baldness typically starts with scalp hairs becoming progressively less dense. Many women first experience hair thinning and hair loss where they part their hair and on the top-central portion of the head.

Close

In the type of patchy hair loss known as alopecia areata, hair loss occurs suddenly and usually starts with one or more circular bald patches that may overlap.

Close

Hair loss can occur if you wear pigtails, braids or cornrows, or use tight hair rollers. This is called traction alopecia.

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Early treatment of a receding hairline (frontal fibrosing alopecia) might help avoid significant permanent baldness. The cause of this condition is unknown, but it primarily affects older women.

Hair loss can appear in many different ways, depending on what's causing it. It can come on suddenly or gradually and affect just your scalp or your whole body.

Signs and symptoms of hair loss may include:

See your doctor if you are distressed by persistent hair loss in you or your child and want to pursue treatment. For women who are experiencing a receding hairline (frontal fibrosing alopecia), talk with your doctor about early treatment to avoid significant permanent baldness.

Also talk to your doctor if you notice sudden or patchy hair loss or more than usual hair loss when combing or washing your or your child's hair. Sudden hair loss can signal an underlying medical condition that requires treatment.

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People typically lose 50 to 100 hairs a day. This usually isn't noticeable because new hair is growing in at the same time. Hair loss occurs when new hair doesn't replace the hair that has fallen out.

Hair loss is typically related to one or more of the following factors:

A number of factors can increase your risk of hair loss, including:

Most baldness is caused by genetics (male-pattern baldness and female-pattern baldness). This type of hair loss is not preventable.

These tips may help you avoid preventable types of hair loss:

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Hair loss - Symptoms and causes - Mayo Clinic

Some cells are visible to the unaided eye

The smallest objects that the unaided human eye can see are about 0.1 mm long. That means that under the right conditions, you might be able to see an amoeba proteus, a human egg, and a paramecium without using magnification. A magnifying glass can help you to see them more clearly, but they will still look tiny.

Smaller cells are easily visible under a light microscope. It's even possible to make out structures within the cell, such as the nucleus, mitochondria and chloroplasts. Light microscopes use a system of lenses to magnify an image. The power of a light microscope is limited by the wavelength of visible light, which is about 500 nm. The most powerful light microscopes can resolve bacteria but not viruses.

To see anything smaller than 500 nm, you will need an electron microscope. Electron microscopes shoot a high-voltage beam of electrons onto or through an object, which deflects and absorbs some of the electrons. Resolution is still limited by the wavelength of the electron beam, but this wavelength is much smaller than that of visible light. The most powerful electron microscopes can resolve molecules and even individual atoms.

The label on the nucleotide is not quite accurate. Adenine refers to a portion of the molecule, thenitrogenous base. It would be more accurate to label the nucleotide deoxyadenosine monophosphate, as itincludes the sugar deoxyribose and a phosphate group in addition to the nitrogenous base. However, the morefamiliar "adenine" label makes it easier for people to recognize it as one of the building blocks of DNA.

No, this isn't a mistake. First, there's less DNA in a sperm cell than there is in a non-reproductive cellsuch as a skin cell. Second, the DNA in a sperm cell is super-condensed and compacted into a highly dense form. Third, the head of a sperm cell is almost all nucleus. Most of the cytoplasm has been squeezed out in order to make the sperm an efficient torpedo-like swimming machine.

The X chromosome is shown here in a condensed state, as it would appear in a cell that's going through mitosis. It has also been duplicated, so there are actually two identical copies stuck together at their middles. A human sperm cell contains just one copy each of 23 chromosomes.

A chromosome is made up of genetic material (one long piece of DNA) wrapped around structural support proteins (histones). Histones organize the DNA and keep it from getting tangled, much like thread wrapped around a spool. But they also add a lot of bulk. In a sperm cell, a specialized set of tiny support proteins (protamines) pack the DNA down to about one-sixth the volume of a mitotic chromosome.

The size of the carbon atom is based on its van der Waals radius.

Original post:
Cell Size and Scale - University of Utah

We created the world's first donkey embryo using IVF in a bid to save species from extinction  The Conversation

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We created the world's first donkey embryo using IVF in a bid to save species from extinction - The Conversation

Diagnosis

Many infertile couples have more than one cause of infertility, so it's likely you will both need to see a doctor. It might take a number of tests to determine the cause of infertility. In some cases, a cause is never identified.

Infertility tests can be expensive and might not be covered by insurance find out what your medical plan covers ahead of time.

Diagnosing male infertility problems usually involves:

Your semen is then sent to a laboratory to measure the number of sperm present and look for any abnormalities in the shape (morphology) and movement (motility) of the sperm. The lab will also check your semen for signs of problems such as infections.

Often sperm counts fluctuate significantly from one specimen to the next. In most cases, several semen analysis tests are done over a period of time to ensure accurate results. If your sperm analysis is normal, your doctor will likely recommend thorough testing of your female partner before conducting any more male infertility tests.

Your doctor might recommend additional tests to help identify the cause of your infertility. These can include:

Often, an exact cause of infertility can't be found. Even if an exact cause isn't clear, your doctor might be able to recommend treatments or procedures that will lead to conception.

In cases of infertility, it's recommended that the female partner also be checked. There may be specific treatments recommended for your partner. Or, you may learn that proceeding with assisted reproductive techniques is appropriate in your situation.

Treatments for male infertility include:

In rare cases, male fertility problems can't be treated, and it's impossible for a man to father a child. Your doctor might suggest that you and your partner consider using sperm from a donor or adopting a child.

Our caring team of Mayo Clinic experts can help you with your health concerns. Visit Mayo Clinic Men's Health to get started.

There are a few steps you can take at home to increase your chances of achieving pregnancy:

Evidence is limited on whether or how much herbs or supplements might help increase male fertility. None of these supplements treats a specific underlying cause of infertility, such as a sperm duct defect or chromosomal disorder.

Supplements with studies showing possible benefits for improving sperm count or quality include:

Talk with your doctor before taking dietary supplements for male infertility. There is no clear evidence that they work, and some supplements may cause side effects or interact adversely with medications you take.

Coping with infertility can be difficult. It's an issue of the unknown you can't predict how long it will last or what the outcome will be. Infertility isn't necessarily solved with hard work. The emotional burden on a couple is considerable, and plans for coping can help.

If you have never been evaluated by a doctor, you might begin by seeing your family doctor. If, however, you have a known condition resulting in infertility or have any abnormalities on your testing by your primary care doctor, then you may be referred to a specialist.

Here's some information to help you get ready for your appointment, and what to expect from your doctor.

Examples of questions to ask include:

Don't hesitate to ask additional questions at any time during your appointment.

Be ready to answer questions your doctor is likely to ask, including:

Our caring team of Mayo Clinic experts can help you with your health concerns. Visit Mayo Clinic Men's Health to get started.

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Male infertility - Diagnosis and treatment - Mayo Clinic

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Sexual male enhancement, as the euphemism goes, is big business. Last year, Viagra, the pharmaceutical market leader, raked in about $2 billion.

That success has spawned a shadow industry of largely unregulated "natural male enhancement," or sex pill, products. But according to the FDA, some of these products aren't natural, aren't tested and some might even be dangerous.

Here's a list of 10 sex pill products the FDA issued health warnings about this year or told manufacturers to get them off the shelves.

The issue, says the agency, is the product uses "sulfoaildenafil, a chemical similar to sildenafil, the active ingredient in Viagra."

Like Viagra, sulfoaildenafil can have dangerous interactions with other prescription drugs such as nitrates, and can cause dangerously low blood pressure. But because consumers think they are taking a "natural" product they are usually not under a doctor's care.

Also, sulfoaildenafil has not undergone the same clinical trials as sildenafil, so all its effects are not known.

FDA Warning

It's not clear if "Stiff Nights" is a "dietary supplement" as its maker claims, or a bad b-movie title, but in either case the FDA says men looking to "regain the thunder" should stay clear because the pill really contains sulfoaildenafil, an untested chemical similar to the active ingredient in Viagra, which can interact badly with nitrates and cause low blood pressure.

FDA Warning.

The marketing geniuses behind "Stiff Nights" also sell "Rock Hard Weekend." Same unregulated chemical, says the FDA, different laugh out loud brand.

FDA Warning.

It's not clear who Don Wands is or how he became so magical, but the FDA didn't seem to care.

In August 2010, they told the manufacturer of this supplement to drop the magic act and take it off the shelves because the product's two main ingredients, hydroxyhomosildenafil and sulfoaildenafil, aren't listed on the box, aren't "supplements" and aren't really tested.

FDA Warning.

Magic Power Coffee's website says the extra mojo comes from honey goat weed and goji berries.

FDA Warning.

If you wind up with Duro Extend in your stocking this year, you might want to send it back to Santa.

The FDA recalled the product in early December 2010 because the "dietary supplement" is secretly supplemented with sulfoaidenafil, a drug similar to Viagra, but not tested.

FDA Warning.

"This product is dangerous to consumers because it claims to contain only natural ingredients when it actually contains a prescription drug ingredient," says the FDA's warning letter.

Dangerous interactions with nitrates and low blood pressure are possible.

FDA Warning.

FDA Warning.

The FDA doesn't recommend hitting up Luong for pills, however. They say Vitalex's "all natural" and "herbal" concoction is really acetildenafil, another chemical similar to the drug in Viagra, but not tested.

FDA Warning.

Eager men trying to get their hands on a box of Xiadafil VIP, might have to wait in line. In July 2010, U.S. Marshals seized almost $75,000 worth of it after the manufacturer refused an FDA request to recall it.

The problem? The FDA says the product's VIP power comes from hydroxyhomosildenafil, a drug similar to Viagra, but untested.

FDA Warning.

Read more:
Dangerous Male Sex Pills - CBS News

Male honey bee

A drone is a male honey bee. Unlike the female worker bee, drones do not have stingers. They gather neither nectar nor pollen and are unable to feed without assistance from worker bees. A drone's only role is to mate with an unfertilized queen.

Drones carry only one type of allele at each chromosomal position, because they are haploid (containing only one set of chromosomes from the mother). During the development of eggs within a queen, a diploid cell with 32 chromosomes divides to generate haploid cells called gametes with 16 chromosomes. The result is a haploid egg, with chromosomes having a new combination of alleles at the various loci. This process is called arrhenotokous parthenogenesis or simply arrhenotoky.

Because the male bee technically has only a mother, and no father, its genealogical tree is unusual. The first generation has one member (the male). One generation back also has one member (the mother). Two generations back are two members (the mother and father of the mother). Three generations back are three members. Four back are five members. This sequence 1, 1, 2, 3, 5, 8, and so on is known as the Fibonacci sequence.[1]

Much debate and controversy exists in scientific literature about the dynamics and apparent benefit of the combined forms of reproduction in honey bees and other social insects, known as the haplodiploid sex-determination system. The drones have two reproductive functions: each drone grows from the queen's unfertilized haploid egg and produces some 10 million male sperm cells, each genetically identical to the egg. Drones also serve as a vehicle to mate with a new queen to fertilize her eggs. Female worker bees develop from fertilized eggs and are diploid in origin, which means that the sperm from a father provides a second set of 16 chromosomes for a total of 32: one set from each parent. Since all the sperm cells produced by a particular drone are genetically identical, full sisters are more closely related than full sisters of other animals where the sperm is not genetically identical.

A laying worker bee exclusively produces totally unfertilized eggs, which develop into drones. As an exception to this rule, laying worker bees in some subspecies of honey bees may also produce diploid (and therefore female) fertile offspring in a process called thelytoky, in which the second set of chromosomes comes not from sperm, but from one of the three polar bodies during anaphase II of meiosis.

In honey bees, the genetics of offspring can best be controlled by artificially inseminating (referred to in beekeeping as 'instrumental insemination') a queen with drones collected from a single hive, where the drones' mother is known. In the natural mating process, a queen mates with multiple drones,[2] which may not come from the same hive. Therefore, batches of female offspring have fathers of a completely different genetic origin.

A drone is characterized by eyes that are twice the size of those of worker bees and queens, and a body size greater than that of worker bees, though usually smaller than the queen bee. His abdomen is stouter than the abdomen of workers or queen. Although heavy bodied, the drone must be able to fly fast enough to accompany the queen in flight. The average flight time for a drone is about 20 minutes.

An Apis cerana colony has about 200 drones during high summer peak time.Drones depend on worker bees to feed them.

Drones die off or are ejected from the hive by the worker bees in late autumn, dying from exposure and the inability to protect or feed themselves, and do not reappear in the bee hive until late spring. The worker bees evict them as the drones would deplete the hive's resources too quickly if they were allowed to stay.[3]

The drones' main function is to be ready to fertilize a receptive queen. Drones in a hive do not usually mate with a virgin queen of the same hive because the queen flies further to a drone congregation area than the drones do. Mating generally takes place in or near drone congregation areas. How these areas are selected is not understood, but they do exist. When a drone mates with a queen of the same hive, the resultant queen will have a spotty brood pattern (numerous empty cells on a brood frame) due to the removal of diploid drone larvae by nurse bees (i.e., a fertilized egg with two identical sex genes will develop into a drone instead of a worker). The worker bees remove the inbred brood and consume it to recycle the protein.

Mating occurs in flight, which accounts for drones needing better vision, which is provided by their large eyes. Should a drone succeed in mating, the first thing that happens is all of the drone's blood in his body rushes to his endophallus which causes him to lose control over his entire body. His body falls away, leaving a portion of his endophallus attached to the queen which helps guide the next drone in the queen.

Honey bee queen breeders may breed drones to be used for instrumental insemination[4] or open mating. A queen mating yard must have many drones to be successful.

In areas with severe winters, all drones are driven out of the hive in the autumn. A colony begins to rear drones in spring and drone population reaches its peak coinciding with the swarm season in late spring and early summer. The life expectancy of a drone is about 90 days.

Although the drone is highly specialized to perform one function, mating and continuing the propagation of the hive, they may have other purposes. All bees, when they sense the hive's temperature deviating from proper limits, either generate heat by shivering, or exhaust heat by moving air with their wingsbehaviours which drones share with worker bees.

Drones do not exhibit typical worker bee behaviors such as nectar and pollen gathering, nursing, or hive construction. While drones are unable to sting, if picked up, they may swing their tails in an attempt to frighten the disturber.[5] In some species, drones buzz around intruders in an attempt to disorient them if the nest is disturbed.

Drones fly in abundance in the early afternoon and are known to congregate in drone congregation areas a good distance away from the hive.

The everted endophallus, with the cornua in focus, resembling hooks.

The extended bulbus of the endophallus, containing sperm, is in focus.

The drone endophallus is designed to disperse a large quantity of seminal fluid and spermatozoa with great speed and force. The endophallus is held internally in the drone. During mating, the organ is everted (turned inside out), into the queen. The eversion of the endophallus is achieved by contracting abdominal muscles, which increases hemolymph pressure, effectively "inflating" the endophallus. Cornua claspers at the base of the endophallus help to grip the queen.

Mating between a single drone and the queen lasts less than 5 seconds, and it is often completed within 12 seconds. Mating occurs mid-flight, and 1040m (33131ft) above ground. Since the queen mates with 519 drones, and drones die after mating, each drone must make the most of his single shot. The drone makes first contact from above the queen, his thorax above her abdomen, straddling her. He then grasps her with all six legs, and everts the endophallus into her opened sting chamber. If the queen's sting chamber is not fully opened, mating is unsuccessful, so some males that mount the queen do not transfer semen. Once the endophallus has been everted, the drone is paralyzed, flipping backwards as he ejaculates. The process of ejaculation is explosivesemen is blasted through the queen's sting chamber and into the oviduct. The process is sometimes audible to the human ear, akin to a "popping" sound. The ejaculation is so powerful that it ruptures the endophallus, disconnecting the drone from the queen. The bulb of the endophallus is broken off inside of the queen during matingso drones mate only once, and die shortly after. The leftover endophallus remaining in the queen's vagina is referred to as the "mating sign". The plug will not prevent the next drone from mating with the same queen, but may prevent semen from flowing out of the vagina.[6]

Mating between the drones and a virgin queen takes place away from the colony, in mid-air mating sites. These mating sites, called 'congregation areas', are specific locations, where drones wait for the arrival of virgin queens. A congregation area is typically 1040m (33131ft) above ground, and can have a diameter of 30200m (98656ft). The boundaries of a congregation area are distinct; queens flying a few meters outside the boundaries are mostly ignored by the drones. Congregation areas are typically used year after year, with some spots showing little change over 12 years. Since drones are expelled from a colony during the winter, and new drones are raised each spring, inexperienced drones must find these congregation areas anew. This suggests some environmental cues define a congregation area, although the actual cues are unknown.

Congregation areas are typically located above open ground, away from trees or hills, where flight is somewhat protected from the wind (calm winds may be helpful during mating flight). At the same time, many congregation areas do not show such characteristics, such as those located above water or the forest canopy. Some studies have suggested that magnetic orientation could play a role, since drones older than 6 days contain cells in the abdomen that are rich in magnetite.

Congregation areas can be located by attaching a virgin queen (in a cage) to a balloon floating above ground. The person then moves around, taking note of where drones are attracted to the caged queen. Congregation areas are not found closer than 90m (300ft) from an apiary, and congregation areas located farther away from apiaries receive more drones. In a congregation area, drones accumulate from as many as 200 colonies, with estimates of up to 25,000 individual drones. This broad mixing of drones is how a virgin queen can ensure she will receive the genetic diversity needed for her colony. By flying to congregation areas further away from her colony, she further increases the probability of out-breeding.

A single drone visits multiple congregation areas during his lifetime, often taking multiple trips per afternoon. A drone's mating flight averages 2025 minutes, before he must return to the colony to refuel with honey. While at the site, the drones fly around passively, waiting for the arrival of a virgin. When the virgin queen arrives to the congregation area, the drones locate her by visual and olfactory cues. At this point, it is a race to mate with the virgin queen, to be genetically represented in the newly founded colony. The swarming drones, as they actively follow the queen, reportedly resemble a "drone comet", dissolving and reforming as the drones chase the virgin queen. Drones greatly outnumber the quantity of virgin queens produced per season, so even with multiple mating by the queen, very few drones mate successfully (estimated at less than one in 1,000). If needed, a virgin queen can embark on multiple 'nuptial flights', to be sure to receive enough semen from enough drones.

Varroa destructor, a parasitic mite, propagates within the brood cell of bees. The Varroa mite prefers drone brood as it guarantees a longer development period, which is important for its own propagation success. The number of Varroa mites can be kept in check by removing the capped drone brood and either freezing the brood comb or heating it.

Read more here:
Drone (bee) - Wikipedia

Jamie Lo, M.D., M.C.R.,associate professor of obstetrics and gynecology (perinatology and maternal-fetal medicine), OHSU School of Medicine, and Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center at OHSU. (OHSU/Christine Torres Hicks)

A physician-scientist at Oregon Health & Science University is one of just six researchers across the country to receive an Avenir Award in Genetics and Epigenetics of Substance Abuse from the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health.

Jamie Lo, M.D., M.C.R., will use the award to develop and execute creative and transformative research to explore how parents behavior and environment affects their offspring before birth in some cases, even before conception.

The award is expected to provide $1.5 million over five years. NIDAs DP1 Avenir Awards support early-career investigators proposing new areas of research for the genetics or epigenetics of addiction.

Lo is an associate professor of obstetrics and gynecology (maternal-fetal medicine) in the OHSU School of Medicine and the Division of Reproductive and Developmental Sciences at the Oregon National Primate Research Center (ONPRC) at OHSU.

Being a scientist at ONPRC has allowed for leading-edge scientific pursuits across scientific and clinical disciplines with researchers at OHSU and at other institutions, and has allowed me to leverage the translational strength of nonhuman primate models that drive scientific discovery, she said. Im grateful and really looking forward to new discoveries we can achieve next.

In her clinical practice, Lo focuses on caring for people with high-risk pregnancies. She frequently encounters patients asking about the safety of cannabis use and other substances while theyre trying to conceive, while pregnant and during breastfeeding..

Most recently, Lo published two widely publicized studies suggesting that chronic use of cannabis may greatly affect male fertilityand reproductive outcomes, and female reproductive health, including increased menstrual cycle length. The male fertility study, in nonhuman primates, used edible cannabis similar to human dosages and found significant decreases in male reproductive hormones, including testosterone, and greater than 50% shrinkage of the testicles.

In earning the elite Avenir Award, Lo credits the support shes received from her clinical and academic departments, along with collaborations forged with other scientists at OHSU, including those in the departments of urology and biomedical engineering, and researchers at other top academic institutions.

Lo plans to use the new funding to delve into how the active ingredient in cannabis, THC, affects the expression of genes in the brains of offspring. The research will set out to determine how a fathers or mothers consumption of cannabis may affect their offspring both in early childhood and later in life or even their childrens offspring.

Were going to look at whether or not those changes that happen to the sperm, egg, fetus or infant are then inherited and how they impact offspring development, she said.

Generally, due to the lack of safety data and the preliminary findings of her work, she advises expectant parents to refrain from cannabis use while pregnant and for those who cannot quit to limit use.

Lo said she feels privileged to be part of ONPRCs team of scientists making discoveries that she can bring back to patients in the clinic.

We do know that cannabis use seems likely to impact reproductive health and fertility in both males and females, and that prenatal cannabis exposure can adversely affect the placenta and fetus, Lo said. But its very hard to study cannabis in humans, especially in pregnancy, because people are often using other substances, affected by their socioeconomic conditions, limited by the inaccuracies of self-reporting, and the quantity and dose of THC used is often difficult to determine.

Using a nonhuman primate model, scientists can control background variables, including diet and exercise, that would not be possible to achieve in people. The award number is 1DP1DA056493-01, through the National Institute on Drug Abuse of the NIH.

OHSU IACUC

All research involving animal subjects at OHSU must be reviewed and approved by the universitysInstitutional Animal Care and Use Committee(IACUC). The IACUCs priority is to ensure the health and safety of animal research subjects. The IACUC also reviews procedures to ensure the health and safety of the people who work with the animals. The IACUC conducts a rigorous review of all animal research proposals to ensure they demonstrate scientific value and justify the use of live animals.

Excerpt from:
Prestigious award advances OHSU research on impact of drug use over generations - OHSU News

While looking towards the excitement of candy and costumes this Halloween, October is also a time to pull out the pink for Breast Cancer Awareness Month. While women who are 40 years old have the option to begin an annual breast cancer screening with mammograms, familiarizing oneself with their lemonsregardless of agecan assist with early detection if breast cancer occurs.

Breast cancer is fairly common. About 1 in 8 women are going to be diagnosed with breast cancer at some point in their lives, said Marianne Vivien, a genetic counselor at Overlake Clinics & Medical Center.

According to Vivien about 5-10% of cancer cases are due to genetic mutations or hereditary conditions, while over 90% of cancer cases are random, sporadic, and are usually due to age, and environmental and lifestyle factors.

We all have cancer genes and their job is to protect us from cancer generally, but if someone is born with a mutation or inherits that mutation from a parent, all that really means is theres a change in the DNA, said Vivien.

The change in the DNA causes the gene to no longer function properly, and when this happens to a cancer gene, tumors develop more easily and at earlier ages. BRCA 1 and BRCA 2 are the most common breast cancer genes that are also associated with ovarian cancer, pancreatic cancer, melanoma and prostate cancer, said Vivien.

The general population risk for female breast cancer over a lifetime is 12%, according to Vivien, which increases to greater than 60% with BRCA mutations.

Male breast cancer is pretty rare in the general population. I believe its roughly a half a percent chance over a lifetime for someone who was born male to develop breast cancer, said Vivien, who said that risk increases to about 7% over a lifetime with BRCA mutations.

Vivien expressed that if an individual has any breast tissue, regardless of gender, its important to screen for breast cancer.

We definitely have that conversation with our patients who are Trans[gender], said Vivien. Depending on what surgeries they may or may not have had already, we would discuss essentially what screening or management would be recommended based on the particular gene that were concerned with and what other cancers are associated with that gene.

A breakdown of breast cancer rates on the Eastside

The Washington State Cancer Registry collects incidence data for numerous types of cancer across the state, including female breast cancer. Incidence rates are per 100,000 and the registry data for female breast cancer from 2014-2018 include:

Further data from the National Cancer Institutes state cancer profiles shows that the age-adjusted incidence rate cases per 100,000 for females in King County who are under 50 years old is 50.7; the average annual count is 372 cases and that the recent trends of rates for this demographic are rising.

The lens of a genetic counselor

Part of Viviens work as a genetic counselor includes talking to patients who have received a cancer diagnosis from their primary care physician, or those who received a referral to see if genetic testing would be beneficial.

Im starting to see a lot younger peoplewomen in their twentiescoming in and having that conservation, said Vivien. It doesnt necessarily mean were doing testing right now or were starting screening right now, but were having a conversation so that we can determine when testing or when screening should start and what that might look like for them.

In addition to seeing younger women, Vivien has also been seeing patients who want to know their risks because they were adopted and have no information on their family history.

During the counseling sessions, Viven conducts a thorough family history and medical history to decide if genetic testing is appropriate and to assist with developing a personalized management care plan moving forward. Red flags with genetics include individuals diagnosed at 50 years of age or younger and multiple generations having been affected by breast and other types of cancer, said Vivien.

Ideally, if were getting this information ahead of time, or even if somebody is already diagnosed with breast cancer, were able to make better decisions in terms of treatment, surgical decisions and then management moving forward, said Vivien.

Vivien mentioned how genetic testing and breast cancer screenings are generally covered by health insurance if an individual meets specific criteria. If the criteria is not met and health insurance wont cover, the majority of labs offer genetic testing for approximately $250, said Vivien. For those who are uninsured or underinsured, Vivien feels like breast cancer screenings can be moreso a barrier when compared to genetic testing.

Testing can only get you so far. If youre not going to follow through with the management then testing is a little bit pointless, said Vivien.

You can call them lemons, or you can call them limes

While Vivien believes that Breast Cancer Awareness Month shouldnt be merely one month, she said a good way to celebrate the month is by learning how to conduct a self breast exam.

Know Your Lemons, a nonprofit organization focused on improving early detection of breast cancer through education, provides signs and symptoms of breast cancer, which include:

While theres never a bad time to conduct a self breast exam, Know Your Lemons suggests conducting the exam after ones period, which is when the breast is the least tender and swollen.

A self breast exam can be conducted while standing, sitting or lying down. One should flatten their breast by stretching their arm behind their head. Then, the individual should feel the area (using any pattern such as circles, side to side, and up-down/all around) from their armpit to their collarbone, and then to the bottom of their ribs where lymph nodes live. According to Know Your Lemons, sometimes the areas where lymph nodes are located swell when cancer is present.

Milk lobes and lymph nodes are normal lumps in breasts that feel like soft peas or beans. To be more specific, the soft feeling peas are milk lobes while the soft feeling beans are lymph nodes. Cancerous lumps feel hard like a lemon seed, are usually immovable and can be any shape or size. On the other hand, those hard feeling lemon seeds could potentially be cysts.

See the rest here:
Breast Cancer Awareness Month: The importance of getting to know your lemons - Bothell-Kenmore Reporter

Identification of DEGs after weight loss

After standardizing gene sets (Fig.1), 1011 DEGs (|logFC|>1, p<0.05) were screened out from GSE103766, GSE35411, GSE112307, GSE43471, and GSE35710 based on the above method. The results included 513 downregulated and 498 upregulated genes, as shown in the volcano plot (Fig.2 and Supplementary Table S1). The abscissa in the volcano plot is log2 (fold change) value, and the ordinate is log10 (p-value).

Box-plots of the expression profiles after consolidation and standardization. The x-axis label represents the sample symbol and the y-axis label represents gene expression values. The black line in the box-plot represents the median value of gene expression. (a) Standardization of GSE43471, (b) Standardization of GSE35411, (c) Standardization of GSE103766, (d) Standardization of GSE35710, (e) Standardization of GSE112307.

Volcano plot to identify differentially expressed genes (DEGs). (a) GSE43471, (b) GSE35710, (c) GSE35411, (d) GSE103766, (e) GSE112307. The x-axis label represents fold changes and the y-axis label represents the p-values. Red dots represent the 498 upregulated genes and green dots represent the 513 downregulated genes.

As shown in Supplementary Fig. S1, the PPI network of DEGs, based on the Search Tool for the Retrieval of Interacting Genes (STRING) database, includes 584 nodes and 1417 edges. Using the MCODE plugin in Cytoscape software, the most significant modules (score=6.667) were recognized from the PPI network as comprising 27 hub genes, including ACP5, CETP, COL1A1, COL1A2, CSF1, DNMT3B, EED, HIST1H2AI, HIST1H2BB, HIST1H2BD, HIST1H4B, HIST1H4H, HIST2H3C, HP, LCN2, LIPC, LPA, MMP2, MMP7, MMP9, MSR1, MUC1, PLA2G7, SPP1, THBS1, THBS2, and VLDLR (Table 1 and Fig.3).

Subnetwork of 27 hub genes from the proteinprotein interaction (PPI) network. Node size and temperature color reflect the degree of connectivity (bigger node represents a higher degree and smaller node represents a lower degree; red node represents a higher degree and yellow node represents a lower degree).

An enrichment analysis bubble chart was drawn under GO level 2 classifications using Omicshare tools (Fig.4 and Supplementary Table S2). As shown in the figure, hub genes were significantly enriched in regulating plasma lipoprotein particle levels, lipid transport, extracellular matrix (ECM) organization, response to reactive oxygen species, and the oxygen-containing compound for biological process (BP). The hub genes were significantly enriched for cell composition (CC) in lipoprotein particles, extracellular regions, ECM, extracellular exosomes, and secretory granules. For molecular function (MF), the hub genes were significantly elevated in lipoprotein particle binding, glycosaminoglycan binding, ECM structural constituents, and peptidase activity.

Biological functions based on Gene Ontology (GO) analysis of obesity-related hub genes. Advanced bubble chart shows significance in GO enrichment items of hub genes in three functional groups: biological process (BP), cell composition (CC), and molecular function (MF). The x-axis label represents the gene ratio (Rich Factor) and the y-axis label represents GO terms.

KEGG pathway enrichment analysis showed that the hub genes were primarily enriched in ECMreceptor interaction, cholesterol metabolism, PI3K-Akt, IL-17, and TNF signaling pathways, endocrine resistance, and leukocyte transendothelial migration (Fig.5 and Supplementary Table S3).

Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of hub genes. The x-axis label represents the gene ratio (Rich factor) and the y-axis label represents the pathway.

We converted 27 gene names of the hub genes into protein names that could be recognized through the TCMSP database using the Universal Protein Resource (Uniprot). Moreover, the hub genes can be input in the required format to identify potential herbs with anti-obesity effects from the TCMSP database. After excluding the genes that were not present in the databases or those that had no related ingredients, nine were screened for further research, namely, COL1A1, MMP2, MMP9, SPP1, DNMT3B, MMP7, CETP, COL1A2, and MUC1. These genes corresponded to 16 ingredients [(-)-epigallocatechin-3-gallate (EGCG), arachidonic acid, arctiin, baicalein, beta-carotene, capillarisin, deoxypodophyllotoxin, ellagic acid, fisetin, irisolidone, luteolin, matrine, nobiletin, quercetin, rutaecarpine, tanshinone IIa] showing adequate OB and DL values (OB30%, DL0.18) (Supplementary Table S4).

There were 254 herbs with active ingredients in the databases. The top 10 herbs were Aloe, Portulacae Herba, Mori Follum, Silybum Marianum, Phyllanthi Fructus, Pollen Typhae, Ginkgo Semen, Leonuri Herba, Eriobotryae Folium, and Litseae Fructus. These were associated with more DEGs (related genes=6) and were, therefore, selected as crucial herbs in our study and annotated using Chinese pharmaceutical properties (CMPs), including characters, tastes, and meridian tropisms (Table 2).

We screened the key ingredients in treating obesity using an Ingredients-Targets network containing 25 nodes and 27 edges (Fig.6). The nine orange nodes represent the target genes and 16 green nodes represent the active ingredients. As most genes could be linked (degree=4), quercetin and EGCG were considered the most critical components in the treatment of obesity.

Ingredients-Targets network. Nine orange nodes represent the target genes, whereas the 16 green nodes represent the active compounds. The edges represent the interaction between the compounds and targets.

As shown in Fig.7a, the Herbs-Ingredients-Targets network containing 24 nodes and 43 edges was constructed to demonstrate the relationship between them: the 10 green nodes represent the key herbs and the six yellow nodes represent the active ingredients in them; the eight blue nodes depict the target genes. By analyzing the network, Phyllanthi Fructus and Portulacae Herba were associated with the most ingredients (degree=4). Moreover, quercetin was the most frequent active ingredient (degree=23) found in all herbs. Regarding gene targets, MMP2 was targeted by most ingredients (degree=5) followed by MMP9 (degree=4). Other genes were only acted upon by one component (degree=1).

Herbs-Ingredients-Targets network (a) and Herbs-Taste-Meridian tropism (b) network. (a) Yellow nodes represent the active ingredients and the blue nodes represent the target genes. (b) Yellow nodes represent tastes and purple nodes represent meridian tropisms. In all networks, the light green nodes represent cold-cool herbs, medium green nodes represent calm herbs, and dark green nodes represent warm herbs.

We also established the Herbs-Taste-Meridian tropism network containing 24 nodes and 40 edges to clarify the distribution of CMPs (Fig.7b). Five yellow nodes represent tastes and eight purple nodes represent meridian tropisms. To indicate different characters, we presented 10 nodes of herbs having different greens (light green, medium green, and dark green). Regarding characters, cold-cool herbs like Mori Follum were the most frequent (nodes=7), followed by herbs having calm (nodes=2) and warm (nodes=1) characters. In terms of taste, herbs were mostly bitter (edges=6), followed by sweet (edges=4), acid (edges=2), symplectic (edges=2), and astringent (edges=2). Regarding meridian tropism, most herbs belonged to the liver meridian (edges=6), followed by the stomach and lung (edges=4), large intestine (edges=2), bladder (edges=2), kidney (edges=2), pericardium (edges=2), spleen (edges=1), and gallbladder (edges=1) meridians.

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Identification of hub genes and candidate herbal treatment in obesity through integrated bioinformatic analysis and reverse network pharmacology |...