- Modern humans have a small amount of Neanderthal DNA, and those genes still influence our health.
- Scientists think they have figured out when the two groups started interbreeding and exchanging DNA.
- The results could help scientists understand how Neanderthal genes evolved in humans over millennia.
We may think of Neanderthals as ancient and unknowable relatives, but humans were once on very intimate terms with them.
For example, our ancestors had babies of the shorter, stockier variety and exchanged DNA for thousands of years.
Now researchers think they have figured out when much of this mixing between species occurred, which could provide clues as to why humans outlived their ancient cousins.
By studying genomic data from both ancient and modern humans, scientists found that Neanderthals and humans had sex about 47,000 years ago and stopped less than 7,000 years later — a relatively short time in terms of evolution.
“This study gives us the most accurate picture of how some Neanderthals joined the modern human gene pool, and what happened to their genes afterward,” said John Hawks, an anthropologist at the University of Wisconsin-Madison who was not involved the research was involved. , Business Insider told.
All humans have at least some Neanderthal DNA, a 2020 study found. These genes can influence everything from metabolism to our risk of diabetes.
Finding out when humans acquired them could help scientists understand how these genes evolved and why they may have been beneficial to our ancestors and stuck in our DNA for millennia.
When did humans and Neanderthals start interbreeding?
The basic story of human-Neanderthal relations goes like this: over 500,000 years ago we shared a common ancestor and then went our separate ways.
Than, About 75,000 years ago, Neanderthals were living in Asia and Europe when some people began to leave Africa. Shortly afterwards, the two groups had children together. somewhere between 60,000 and 50,000 years ago.
But 40,000 years ago the Neanderthals were extinct.
For this latest study, researchers from the Max Planck Institute for Evolutionary Anthropology and the University of California, Berkeley looked at DNA from 59 people who lived between 45,000 and 2,200 years ago.
To find out when our ancient human ancestors linked to Neanderthals, the researchers compared stretches of Neanderthal DNA in their genomes. Individuals from about 40,000 years ago had long stretches of gene-containing chromosomes that matched those of other species.
The researchers saw that these segments were shorter after just a few thousand years. This means these people were more distantly related to Neanderthals, Hawks said.
Using computer software, the scientists created models to estimate how many generations had passed since a Neanderthal entered their family tree. From that, they put the start date of human-Neanderthal contact at about 47,124 years ago and estimated that the interbreeding lasted about 6,832 years.
“The conclusion is fairly strong,” Hawks said, because the estimates fit both the earlier and later human genomes.
The Neanderthals who live on in us
Next to the old man DNA, the researchers also studied the genomes of 275 modern humans from different backgrounds to learn more about how humans and Neanderthal genes are evolved through the millennia.
“It is possible to trace the fate of individual parts of chromosomes that were once in a Neanderthal individual, ended up in that individual’s modern descendants, and have been passed down to the present day,” Hawks said.
For example, the researchers found that both current and ancient humans have Neanderthal genes that influence metabolism, immunity and skin pigmentation.
They speculate that these characteristics may have benefited the ancient people who inherited them and then continued to pass them on. One hypothesis is that pale skin would have helped boost vitamin D levels in gloomy climates.
Other studies have linked Neanderthal genes to autoimmune diseases and diabetes. On the other hand, some of the species’ DNA appears to protect people against West Nile, hepatitis C and SARS.
The results of the study do not necessarily apply to everyone. For example, no contemporary humans of African descent are included, as only about 0.5% of their DNA comes from Neanderthals.
However, almost everyone else in the world is made up of about 2% Neanderthals, so learning more about the species’ genes could shed light on many people’s susceptibility to certain diseases.
The researchers published their work in a pre-print study, which has not yet been peer-reviewed.