Humans and Neanderthals only had sex for a short time, but it still fundamentally changed our DNA

  • Modern humans have a small amount of Neanderthal DNA, and those genes still influence our health today.

  • Scientists think they know when the two groups started interbreeding and exchanging DNA.

  • The findings can help scientists understand how Neanderthal genes evolved in humans over thousands of years.

We might consider the Neanderthals to be ancient and ignorant relatives, but people were once on very close terms with them.

Our ancestors, for example, had children with the shorter, stockier species and exchanged DNA for thousands of years.

Now researchers think they have figured out when much of this interspecies interlinking occurred, which could provide clues as to why humans outlived their ancient cousins.

Studying genomic data from both ancient and modern humans, scientists learned that Neanderthals and humans were having sex around 47,000 years ago and stopped less than 7,000 years later – relatively short in terms of evolution of.

“This study gives us the most accurate picture of how some Neanderthals entered the modern human gene pool, and then what happened to their genes afterward,” said John Hawks, an anthropologist at the University of Wisconsin-Madison who was not involved. with the research. , said Business Insider.

Everyone has at least a little Neanderthal DNA, a 2020 study found. These genes may influence everything from metabolism to our risk of diabetes.

Finding them can help scientists understand how these genes evolved and why they may have been beneficial to our ancestors by being stuck in our DNA for thousands of years.

When did humans and Neanderthals start interbreeding?

Two Neanderthal skeletons on display at the Smithsonian Museum of Natural History

A pair of Neanderthal skeletons at the Smithsonian’s Museum of Natural History show how the species’ body changed over thousands of years.Bill O’Leary/The Washington Post via Getty Images

The basic story of the human-Neanderthal relationship goes like this: We shared a common ancestor over 500,000 years ago and then went our separate ways.

Then, around 75,000 years ago, Neanderthals were living in Asia and Europe when some people started to move out of Africa. The two groups began having children together shortly thereafter, sometime between 60,000 and 50,000 years ago.

But by 40,000 years ago, the Neanderthals had disappeared.

For this latest study, researchers at 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 figure out when our ancient human ancestors clashed with the Neanderthals, the researchers compared stretches of Neanderthal DNA in their genomes. Humans from about 40,000 years ago had long stretches of chromosomes containing genes that were consistent with other species.

The researchers saw that these segments became shorter after a few thousand years. This means that those people were more distantly related to Neanderthals, Hawks said.

Using computer software, the scientists created models to estimate how many generations had passed since Neanderthals joined their family tree. From there, they dated the beginning of the human-Neanderthal hoofs to about 47,124 years ago and estimated that interbreeding lasted about 6,832 years.

“The conclusion is quite strong,” said Hawks, because the estimates match the earlier and later human genomes.

The Neanderthals who live within us

Neanderthal evolutionNeanderthal evolution

An exhibition at the Neanderthal Museum imagines what the lives of human relatives were like. Reuters/Nikola Solic

In addition to ancient human DNA, the researchers also studied the genomes of 275 modern people from different backgrounds to learn more about how humans and Neanderthal genes evolved over thousands of years.

“It is possible to trace the fate of single parts of a chromosome that were once present in a Neanderthal individual, became part of that individual’s modern offspring, and were passed on to the present day,” Hawks said.

For example, the researchers found that both modern and ancient humans have Neanderthal genes that affect metabolism, immunity, and skin pigmentation.

They speculate that these traits may have benefited ancient people who inherited them and carried them on. One hypothesis is that lighter skin would help increase Vitamin D levels in harsher 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 people of modern day African ancestry were counted because only about 0.5% of their DNA comes from Neanderthals.

However, almost everyone else in the world is about 2% Neanderthal, so learning more about the genes of the species could shed light on the susceptibility of many people to certain diseases.

The researchers published their work in a pre-print study, which has not yet been peer-reviewed.

Read the original article on Business Insider

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