The Mercury News

Just 7% of our DNA is unique to modern humans, study shows

- By Christina Larson

WASHINGTON >> What makes humans unique? Scientists have taken another step toward solving an enduring mystery with a new tool that may allow for more precise comparison­s between the DNA of modern humans and that of our extinct ancestors.

Just 7% of our genome is uniquely shared with other humans, and not shared by other early ancestors, according to a study published Friday in the journal Science Advances.

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

The research draws upon DNA extracted from fossil remains of now-extinct Neandertha­ls and Denisovans dating back to around 40,000 or 50,000 years ago, as well as from 279 modern people from around the world.

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

It’s a difficult statistica­l problem, and the researcher­s “developed a valuable tool that takes account of missing data in the ancient genomes,” said John Hawks, a paleoanthr­opologist at the University of Wisconsin, Madison, who was not involved in the 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 people alive today. Those slivers of DNA may hold the most significan­t clues as to what truly distinguis­hes modern human beings.

“We can tell those regions of the genome are highly enriched for genes that have to do with neural developmen­t and brain function,” said UC Santa Cruz computatio­nal biologist Richard Green, a co-author of the paper.

In 2010, Green helped produce the first draft sequence of a Neandertha­l genome. Four years later, geneticist Joshua Akey coauthored a paper showing that modern humans carry some remnants of Neandertha­l DNA. Since then, scientists have continued to refine techniques to extract and analyze genetic material from fossils.

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

 ?? FRANK FRANKLIN II — THE ASSOCIATED PRESS ?? A reconstruc­ted Neandertha­l skeleton, right, and a modern human skeleton. According to a study published Friday in the journal Science Advances, just 7% of our genome is uniquely shared with other humans, and not shared by other early ancestors.
FRANK FRANKLIN II — THE ASSOCIATED PRESS A reconstruc­ted Neandertha­l skeleton, right, and a modern human skeleton. According to a study published Friday in the journal Science Advances, just 7% of our genome is uniquely shared with other humans, and not shared by other early ancestors.

Newspapers in English

Newspapers from United States