-
Modern humans have small amounts of Neanderthal DNA, and these genes still influence our health today.
-
Scientists thought they had figured it 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 an ancient and unknown relative, but humans were once related to them.
Our ancestors, for example, had babies with shorter and shorter species and changed their DNA over thousands of years.
Now, researchers think they have figured out when much of this inter-species intermingling occurred, which could provide clues as to why humans outshone their ancient cousins.
Studying genomic data from ancient and modern humans, scientists know that Neanderthals and humans had intercourse about 47,000 years ago and then stopped less than 7,000 years later – a relatively short time in terms of evolution.
“This study provides the most accurate picture showing how some Neanderthals merged into the gene pool of modern humans, and then what happened to those genes,” said John Hawks, an anthropologist at the University of Wisconsin-Madison who was not involved in the research. , told Business Insider.
All humans have at least some Neanderthal DNA, which was discovered in 2020. This gene can affect everything from metabolism to diabetes risk.
Finding out when humans acquired them can help scientists understand how these genes evolved and why they were useful to our ancestors and persisted in our DNA for millennia.
When did humans and Neanderthals start interbreeding?
The basic story of the human-Neanderthal relationship goes something like this: We shared a common ancestor more than 500,000 years ago, then went our separate ways.
Then, around 75,000 years ago, Neanderthals settled in Asia and Europe when some humans began to migrate out of Africa. The two groups began to have children together shortly thereafter, roughly between 60,000 and 50,000 years ago.
But in the last 40,000 years, Neanderthals became extinct.
For this latest study, researchers at the Max Planck Institute for Evolutionary Anthropology and the University of California, Berkeley looked at the DNA of 59 humans who lived between 45,000 and 2,200 years ago.
To find out when the ancestors of ancient humans intermingled with Neanderthals, researchers compared the length of Neanderthal DNA in their genomes. Individuals from about 40,000 years ago had chromosomes that contained genes that corresponded to other species.
The researchers noticed that after a few thousand years, the segment was shorter. This means that humans were more closely related to Neanderthals, Hawks said.
Using computer software, the scientists created a model to estimate how many generations had passed since Neanderthals entered their family trees. From that, they set the start date of the human-Neanderthal hookup at around 47,124 years ago and estimated that the interbreeding lasted for about 6,832 years.
“The conclusion is quite strong,” Hawks said, because the estimate matches earlier and later human genomes.
Neanderthals live inside us
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 have evolved over the millennia.
“You can trace the fate of a single chromosome segment that once existed in a Neanderthal individual, came to the modern descendants of that individual, and was passed down to the present day,” Hawks said.
For example, researchers have discovered that modern and ancient humans have Neanderthal genes that affect metabolism, immunity, and skin pigmentation.
They speculate that these characteristics may have benefited from ancient humans who inherited them and then passed them on. One hypothesis is that pale skin would help increase Vitamin D levels in a dreary climate.
Other studies have linked Neanderthal genes to autoimmune diseases and diabetes. On the other hand, some DNA from these 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 Africans today are included because only about 0.5% of their DNA comes from Neanderthals.
However, almost everyone in the world is about 2% Neanderthal, so 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 pre-print study, which has not yet been peer-reviewed.
Read the original article on Business Insider
