AFRICANGLOBE – From now on, if someone calls you a Neanderthal, they might not mean it as an insult. Two recent studies have shown that non-Africans have a significant number of Neanderthal genes lurking in their DNA, influencing their skin and hair, their response to certain diseases and even their smoking behaviour.
Neanderthals are closely related to modern humans, having split off from the same common ancestor hundreds of thousands of years ago. After this split, one branch spread out into Europe and Asia eventually evolving into Neanderthal, while the other stayed in Africa and evolved into Homo sapiens/modern humans or “intelligent man“.
It was only tens of thousands of years afterwards, when Africans began to spread out onto other continents as well, that the two species met up again. Researchers have found that this reunion resulted in some interbreeding, and this passed on over 20 per cent of Neanderthal DNA into our genetic code.
Not everyone is one-fifth Neanderthal, though. The genes are spread out among the population so that those of us from Europe, Asia and other regions of the world except Africa have around 2 per cent of our DNA from Neanderthals.
“The 2 percent of your Neanderthal DNA might be different than my 2 percent of Neanderthal DNA, and it’s found at different places in the genome,” Joshua Akey, a geneticist from the University of Washington who led the study published in Science, told reporters. This meant that gathering enough samples from the population gave them a large portion of the Neanderthal genome.
Researchers from Harvard University, who published their findings in Nature, have found an increased Neanderthal ‘influence’ on genes that produce keratin — a protein that makes skin, hair and nails tough, and can help us endure colder environments.
“It’s tempting to think that Neanderthals were already adapted to the non-African environment and provided this genetic benefit to humans,” said David Reich, a professor of genetics at Harvard Medical School who was the senior author of the paper, according to a Harvard news release.
Neanderthal genes also, apparently, affect our ability to fight infections, our response to diseases like type 2 diabetes, Crohn’s disease, and lupus, and they can influence our ability to quit smoking as well.
If regions of our DNA that influence skin, hair and immune response are considered to be ‘abundant’ in Neanderthal genes, there are other areas that are exceptionally ‘poor’ — namely the genes that are active in the testicles and on the X-chromosome.
“This suggests that when ancient Africans met and mixed with Neanderthals, the two species were at the edge of biological incompatibility,” Reich said in the statement. So the interbreeding between our ancestors and Neanderthal produced children, but typically the male children were infertile.
Finding more samples of Neanderthal remains and DNA will definitely help to confirm these findings and likely even show more connections between our two species, but all of this serves to increase our knowledge of where we came from and where we’re going.
“The story of early human evolution is captivating in itself, yet it also has far-reaching implications for understanding the organization of the modern human genome,” Irene Eckstrand of the National Institutes of Health, said in the Harvard press release.
“Every piece of this story that we uncover tells us more about our ancestors’ genetic contributions to modern human health and disease.”
By: Scott Sutherland