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What makes people unique? Scientists have taken another step towards solving an enduring mystery with the help of a new tool that can allow us to more accurately compare the DNA of modern humans and our extinct ancestors.

According to the study, only 7% of our genome is uniquely shared with other people and is not shared by other early ancestors.

"This is a fairly small percentage," said Nathan Schaefer, a biologist at the University of California and co – author of the new paper. "Thanks to this discovery, we are moving away from the idea that we, humans, are very different from Neanderthals."

The study uses DNA extracted from the fossilized remains of now extinct Neanderthals and Denisovans dating back about 40,000 or 50,000 years ago, as well as from 279 modern humans from around the world.

Scientists already know that modern humans have some DNA in common with Neanderthals, but different people have different parts of the genome. One of the goals of the new study was to identify genes that are unique to modern humans.

This is a complex statistical problem, and the researchers "have developed a valuable tool that takes into account the missing data in ancient genomes," said John Hawkes, a paleoanthropologist at the University of Wisconsin, who was not involved in the study.

The researchers also found that an even smaller part of our genome – just 1.5% – is unique to our species and is common to all people living today. These DNA fragments may contain the most important clues about what really distinguishes modern people.

"We can say that these regions of the genome are highly enriched with genes that are relevant to the development of the nervous system and brain functions," says Richard Green, co – author of the paper.

We found that only 1.5 to 7% of the modern human genome is exclusively human. We also find evidence of multiple bursts of adaptive changes characteristic of modern humans over the past 600,000 years involving genes associated with brain development and functioning.

In 2010, Green helped create the first draft of the Neanderthal genome sequence. Four years later, geneticist Joshua Eiki co-authored a paper showing that modern humans carry some remnants of Neanderthal DNA. Since then, scientists have continued to improve methods for extracting and analyzing genetic material from fossils.

"The best tools allow us to ask more and more detailed questions about the history and evolution of mankind," said Joshua Eiki. He praised the methodology of the new study.

However, Alan Templeton, a population geneticist at St. Louis University, questioned the authors ' assumption that changes in the human genome are distributed randomly, and not grouped around certain hot spots in the genome.

The results highlight that "we are actually a very young species," Eiki said. "Not so long ago, we shared a planet with other people."

The study was published in the journal Science Advances.

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