Neanderthal vs. Human DNA
Modern humans and Neanderthals both came from a common ancestor around 700,000 years ago, but they split up close to 300,000 years ago. Back in 2010, a group of scientists discovered that around 50,000 years ago, humans and Neanderthals met again during their migration from Africa to Eurasia. The result? Interbreeding, which is the reason that Europeans and Asians have a small percentage of Neanderthal DNA in them. Moreover, Asians are said to have 20% more Neanderthal DNA than Europeans, and a couple of hypotheses have arisen to explain this difference.
One theory suggests that natural selection was the reason for Asians having this DNA boost. It has been suggested that the Neanderthal genes may have had some negative effects on the early Europeans and Asians, which may have caused them to have less children than the people with the human gene only. Therefore, the Neanderthal DNA kept getting rarer with time, and it disappeared faster among the Europeans because of their larger population, compared to that of the Asians.
This theory- which was proposed by Dr. Sankararaman- was challenged as another more rational theory was proposed. The extra Neanderthal DNA that Asians carry was probably the product of a second encounter with the Neanderthals as the Asians moved farther East. To farther prove this theory, a computer model was created that showed how the Asian and European populace reproduced and evolved. A second addition of Neanderthal DNA to the Asian population was the only explanation as to why they have a higher percentage of this DNA than the Europeans. However, the timelines of the Neanderthals’ existence somewhat challenges this theory, as there were none left to interbreed with the Asians for a second time. There were probably more Neanderthals in Asia at the time of the second encounter whose remains are yet to be discovered, or maybe the Asians interbred with other humans who had previously interbred with the Neanderthals, thus boosting this DNA in present-day Asians.
Although the Neanderthals are commonly described as less astute and more brutish than humans, their genomes are more than 99.5% identical to ours. However, we do have some distinct differences in our DNA. This is because some of the genes present in humans today were ‘off’ in the Neanderthals, and vice versa. When a gene is off, the trait that it would produce, would not be produced. That’s probably why our limbs are stronger and shaped differently from theirs.
The Neanderthal DNA present in today’s humans has had a number of effects. One is that the Tibetans are known to have a higher tolerance to low oxygen levels compared to other people. This is probably because the Neanderthals had lived in Eurasia thousands of years before the humans, thus giving them more time to adjust to the harsh climatic conditions. These adaptive genes were passed on to the Tibetans’ as they interbred. Neanderthal genes are also known to have affected the immune response system, and some of their genetic variants are also linked to some neurological and psychiatric problems.
In conclusion, Neanderthal DNA does have a small, but significant effect on humans’ traits.