Svante Pääbo, a Swedish-born scientist and director of the Max Planck Institute for Evolutionary Anthropology, has won this year's Nobel Prize in Physiology or Medicine for "his discoveries concerning the genomes of extinct hominins and human evolution."

A 'seemingly impossible' discovery

According to the Nobel Committee, Pääbo "accomplished something seemingly impossible" by sequencing the first Neanderthal genome.

Ancient DNA is often chemically damaged and is present in ancient samples at very low levels, the New York Times reports. It can also easily be mixed up with the DNA of those handling the samples, making it hard to determine which genes are ancient and which are modern.

Pääbo utilized modern DNA sequencing technology and designed labs with high cleanliness standards called "clean rooms" that protected ancient samples from contamination. Once Pääbo and his team combed through millions of DNA fragments in fossil samples, they used statistical techniques to determine which genes were modern contaminants.

Among his discoveries, Pääbo found that modern humans and Neanderthals share a common ancestor from around 600,000 years ago, and that modern humans and Neanderthals had children together, with Neanderthals making up around 1% to 2% of the genomes in non-African people today. Pääbo also discovered an entirely new species of early hominid, called the Denisovans.

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According to Nils-Göran Larsson, chair of the Nobel Committee for Physiology or Medicine, "It was certainly considered to be impossible to recover DNA from 40,000-year-old bones."

Pääbo's high standards and "bioinformatic and chemical tricks" made his discoveries possible, Larsson said, adding that Pääbo's discoveries will "allow us to compare changes between contemporary Homo sapiens and ancient hominids. And this, over the years to come, will give us huge insights into human physiology."

David Reich, a geneticist at Harvard Medical School, said he was thrilled the Nobel Committee honored someone in the field of ancient DNA, which he worried could "fall between the cracks."

Pääbo's discoveries are "profound things that happened to human biology, and we need to know about it—it is an important part of the inheritance. It's changed our biology and the history of everybody. We all know we are all mixed," Reich said.

By determining that DNA can be preserved for thousands of years and developing ways to extract that DNA, Pääbo and his team developed an entirely new way to answer questions about our past, Reich added, saying that Pääbo's work was the basis for an "explosive growth" of ancient DNA studies in recent years.

"It's totally reconfigured our understanding of human variation and human history," Reich said, adding that Pääbo "was, more than anyone, the pioneer of this field." (Mueller, New York Times, 10/3; Johnson, Washington Post, 10/3; Keyton et al., Associated Press, 10/3; Picheta/Hunt, CNN, 10/3; AP/Los Angeles Times, 10/3; Nobel Prize press release, 10/3)