Only 7% of our DNA is unique to modern humans, study finds

What makes humans unique? Scientists have taken another step towards solving a lingering mystery with a new tool that could allow more precise comparisons between the DNA of modern humans and that of our extinct ancestors.

Only 7% of our genome is only shared with other humans, and not shared by other ancestors, according to a study published in the journal Friday. Scientists progress.

“That’s a pretty low percentage,” said Nathan Schaefer, a computational biologist at the University of California and co-author of the new article. “This kind of discovery is the reason why scientists are turning away from thinking that we humans are so different from Neanderthals.”

The research is based on DNA extracted from the fossil remains of now extinct Neanderthals and Denisovans dating from around 40,000 to 50,000 years ago, as well as 279 modern people around the world.

Scientists already know that modern people share some DNA with Neanderthals, but different people share different parts of the genome. One of the goals of the new research was to identify genes exclusive to modern humans.

It’s a difficult statistical problem, and the researchers “have developed a valuable tool that takes into account missing data in ancient genomes,” said John Hawks, a paleoanthropologist at the University of Wisconsin, Madison, who was not involved in research.

The researchers also found that an even smaller fraction of our genome – just 1.5% – is both unique to our species and shared among all living people today. These DNA fragments may contain the most significant clues about what really sets modern human beings apart.

“We can say that these regions of the genome are highly enriched in genes related to neural development and brain function,” said Richard Green, co-author of the article, computer biologist at the University of California at Santa Cruz.

In 2010, Green helped produce the first draft sequence of a Neanderthal genome. Four years later, geneticist Joshua Akey co-wrote an article showing that modern humans carry remnants of Neanderthal DNA. Since then, scientists have continued to refine techniques for extracting and analyzing genetic material from fossils.

“Better tools allow us to ask increasingly detailed questions about human history and evolution,” said Akey, who is now at Princeton and has not been involved in the new research. He praised the methodology of the new study.

However, Alan Templeton, a population geneticist at the University of Washington in St. Louis, questioned the authors’ hypothesis that changes in the human genome are distributed randomly, rather than clustered around certain hotspots in the world. genome.

The results underscore “that we are actually a very young species,” Akey said. “It wasn’t that long ago that we shared the planet with other human lineages.”

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