Scientists have long agreed that early humans mated with Neanderthals, but two recent studies have shed light on exactly when this DNA mixing occurred. Such a revelation could help geneticists learn more about our past – and, more importantly, our future.
The studies, published on December 12 in the journals Science And Natureprovide information on the chronologies of Neanderthals and early human interactions, and reveal that ancient interbreeding left strands in modern DNA which can still be seen today. That Neanderthals and early humans interbred has been known since the first Neanderthal genome was sequenced in 2010, but these studies suggest that the interactions occurred more recently than scientists once thought.
What did the studies find?
The Science study researchers “analyzed the genomes of 275 current humans and 59 prehistoric humans who lived between 2,200 and 45,000 years ago,” said The Washington Postdetermining that “Neanderthals and humans interbred for 7,000 years starting around 50,500 years ago.” At the same time, Nature study researchers discovered “a new line of evidence by sequencing the oldest human genome to date, giving life to a 45,000-year-old human family.”
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By combining data from both studies, it was concluded that early humans and Neanderthals reached their peak of interbreeding around 47,000 years ago. The extent of this crossbreeding was not “exceptional” “dating but a way of life,” the Post said. Scientists “can’t travel in time, but this data allows us to travel in time and see what happened 50,000 years ago in our history,” Priya Moorjani, lead author of the study Science and professor at UC Berkeley, told the Post.
Around this time, early humans “met Neanderthals, had sex and gave birth to children on a fairly regular basis,” said CNN. An estimated 1 to 3 percent of people have DNA that may be related to that of Neanderthals, and studies are also shedding light on these genes. Some, such as “those related to the immune system, benefited humans during the last ice age, when temperatures were much cooler, and they continue to confer benefits today.”
This updated timeline of interbreeding between Neanderthal and modern humans “changes and narrows the possible range of time during which humans spread to places like present-day China and Australia,” said NBC News. These latest findings “are consistent with archaeological evidence that suggests Neanderthals and humans overlapped geographically as humans moved out of Africa.”
The new studies are also “much more of a direct estimate compared to the previous inference, which involved fitting a fairly complex statistical model with a lot of uncertainty,” said Joshua Akey, a genomicist at the University of Princeton. NPR. These findings are “really important because they constrain a number of other things about human migration patterns,” Benjamin Peter, a geneticist at the University of Rochester, told the outlet.
The study also shows that we perhaps owe to this crossbreeding modern immunity. Neanderthal genes “may have played a crucial role in our success in protecting us from new diseases that we had not encountered before,” said the BBC. This Neanderthal DNA could have given us “better adaptive capabilities outside of Africa,” Chris Stringer of the Natural History Museum in London told the outlet. Early humans “evolved in Africa, while Neanderthals evolved outside of Africa” and “by interbreeding with Neanderthals, we got a quick fix to our immune system.”
