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Modern humans have small amounts of Neanderthal DNA, and these genes still influence our health today.
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Scientists think they have figured out when the two groups began to interbreed and exchange DNA.
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The results could help scientists understand how Neanderthal genes evolved in humans over thousands of years.
We may view Neanderthals as ancient and unknown relatives, but humans were once in close contact with them.
For example, our ancestors had babies with shorter, stockier types and modified DNA for thousands of years.
Now researchers think they’ve figured out when most of this interspecies mixing occurred; This may provide clues as to why humans outlast their older cousins.
Examining genomic data from both ancient and modern humans, scientists learned that Neanderthals and humans had sex about 47,000 years ago and stopped having sex less than 7,000 years later; This is a relatively short period of time in evolutionary terms.
“This study gives us the most accurate picture of how some Neanderthals joined the modern human gene pool and what happened to their genes afterwards,” said John Hawks, an anthropologist at the University of Wisconsin-Madison who was not involved in the research. He told Business Insider:
A 2020 study found that all humans have at least some Neanderthal DNA. These genes can affect everything from metabolism to our risk of diabetes.
Learning when humans acquired them could help scientists understand how these genes evolved and why they may have been beneficial to our ancestors and have been in our DNA for thousands of years.
When did humans and Neanderthals start interbreeding?
The basic story of human-Neanderthal relations is this: We shared a common ancestor 500,000 years ago, then went our separate ways.
Later, about 75,000 years ago, Neanderthals lived in Asia and Europe when some humans began to leave Africa. The two groups began having children together shortly thereafter, around 60,000 to 50,000 years ago.
But 40,000 years ago, Neanderthals became extinct.
For this latest study, researchers at the Max Planck Institute for Evolutionary Anthropology and the University of California, Berkeley, examined the DNA of 59 people who lived between 45,000 and 2,200 years ago.
To understand when our ancient human ancestors made contact with Neanderthals, researchers compared sections of Neanderthal DNA in their genomes. Individuals about 40,000 years ago had chromosomes containing long genes that matched those of other species.
After just a few thousand years, the researchers found that these segments became shorter. This means these people were more distantly related to Neanderthals, Hawks said.
Using computer software, scientists created models to estimate how many generations had passed since a Neanderthal entered the family tree. From this, they determined the start date of the human-Neanderthal merger as approximately 47,124 years ago and estimated that interbreeding took approximately 6,832 years.
“The result is quite strong,” Hawks said, because the predictions fit both the earlier and later human genomes.
Neanderthals living among us
In addition to ancient human DNA, the researchers also examined the genomes of 275 modern humans from a variety of backgrounds to learn more about how human and Neanderthal genes evolved over millennia.
“It is possible to trace the fate of individual chromosome segments that were once found in a Neanderthal individual, passed down to that individual’s modern descendants, and passed down to the present day,” Hawks said.
For example, researchers found that both current and ancient humans had Neanderthal genes that affected metabolism, immunity, and skin pigmentation.
They think these traits may have benefited ancient humans who inherited them and then continued to pass them on. One hypothesis is that paler skin may help increase Vitamin D levels in drearier climates.
Other studies have linked Neanderthal genes to autoimmune diseases and diabetes. On the other hand, some DNA from the species appears to protect people from West Nile, hepatitis C and SARS.
The results of the study do not necessarily apply to everyone. For example, no modern-day humans of African descent were included because only 0.5% of their DNA came from Neanderthals.
However, about 2% of almost everyone in the world is Neanderthal; Therefore, learning more about the species’ genes could shed light on the susceptibility of many people to certain diseases.
The researchers published their work in a preprint study that has not yet been peer-reviewed.
Read the original article on Business Insider