For now, the Neanderthal genome is an abstract string of billions of DNA letters stored in computer databases. But it naturally sparks the imagination: Could scientists use that genetic blueprint to create neo-Neanderthals in the flesh?

In the not-so-distant future, advances in genetic engineering might enable that feat, experts say. But whether such a resurrection should happen is another story.

Since the 1996 birth of Dolly the sheep, the world's first cloned mammal, scientists have greatly expanded and improved on cloning techniques. They have cloned dogs, cats, rats, pigs, and cows, among other species. In 2003, researchers in Spain were the first to bring back an extinct speciesthe Pyrenean ibex, a wild mountain goat also called a bucardothough the clone only lived for a few minutes.

All of these examples relied on a technique called nuclear transfer. Starting with an intact cell (fresh or frozen) of the animal they'd like to clone, scientists first remove the nucleus, where DNA resides, and insert it into a hollowed-out egg cell of the same or a related species. This hybrid egg is then implanted into the uterus of a female surrogate for gestation, and voil: The surrogate gives birth to a clone.

But there are no intact Neanderthal cellsfar from it. Decoding the Neanderthal genome meant piecing together many DNA fragments painstakingly extracted from 40,000-year-old bones. So how could cloning be possible?

In his 2012 book Regenesis, Harvard geneticist George Church proposes a different approach for cloning extinct animals whose genome has been sequenced. It starts with a healthy cell of a closely related speciescloning a Neanderthal, for example, could start with a stem cell from a modern human. Using new tricks of genetic engineering, researchers could make adjustments to the DNA in the human cell so it matches the code of the Neanderthal.

That's more difficult than it sounds, as there are millions of spots in the genome that are different in modern humans and Neanderthals. Church points to a new technique called CRISPR that makes it possible to edit multiple sites in the genome at once. A paper describing the process was published in Science in January. With that publication, "genome engineering of mammalian cells just took a big step forward," he says.

Though the techniques aren't sophisticated or cheap enough yet to recreate a Neanderthal genome, Church thinks the idea is plausible. "Going from engineered cells to whole organism has been especially well established in mice, and [there's] no obvious reason why it would fail in other mammals."

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Return of the Neanderthals

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