Is There a Benefit to Having Neanderthal DNA in the Human Genome?

Most people are made up of between 1 and 4 percent Neanderthal DNA, depending on what part of the world you live in, according to the National Institutes of Health (NIH).

According to a study published in Genetic.

So how did DNA from an archaic human who died out 40,000 years ago end up in our genome and are there any benefits?

Learn more: Everyone has Neanderthal DNA in their genome, new genetic analysis shows

Why do modern humans still have Neanderthal DNA?

According to John Anthony Capra, a professor of evolutionary genomics at the University of California, San Francisco, modern humans and Neanderthals met when modern humans left Africa about 40,000 years ago to settle Neanderthal territory in Europe and Asia.

“Neanderthals were a group that separated from the lineage that would eventually become us. [500,000] to 700,000 years ago, and they lived in large swathes of Europe, Asia, and the Middle East for hundreds of thousands of years before our most immediate ancestors settled these environments,” says Capra.

But once they came into contact, they interacted and were close enough genetically that they could interbreed and have children who would then carry Neanderthal DNA. All these years later, we still carry a Neanderthal imprint in our genome.

Individuals of African origin have very little Neanderthal DNA because they never left the continent and therefore never came into contact with these archaic humans. But the average person living outside Africa still has an average of 2 percent Neanderthal DNA, Capra says.

This is also true of another group of archaic humans called Denisovans, which still appears prominently in the DNA of populations in Oceania and Southeast Asia. This group of archaic humans, which are more genetically similar to Neanderthals than modern humans, appeared about 370,000 years ago, according to Britannica.

How did we interact with Neanderthals?

According to the Human Origins Initiative, if you saw a Neanderthal walking down the street, you would know they were very different, but that wouldn’t have stopped you from getting together. We don’t know for sure how often modern humans interbred with Neanderthals, but we do know that it happened frequently because they probably overlapped for many years before the Neanderthals became extinct.

The Neanderthal specimens that have been sequenced also contain remains of modern human DNA, suggesting some regularity.

“This kind of crossbreeding was not uncommon,” Capra explains.

It may be hard to imagine today, but just before that, about 100,000 years ago, the world would have been populated by many groups of human-like ancestors, who were not the same as us but who had interbred. At that time, depending on where in the world you lived, you could encounter Homo sapiens, Homo neanderthalensis, Homo erectus, Homo floresiensis, Or the Denisovans, according to the Australian Museum.

Neanderthal DNA found in genome

Some aspects of the Neanderthal genome remained because they were beneficial. Others left because, you guessed it, they didn’t.

“Many parts of our genome that code for genes expressed in the brain are very highly depleted for Neanderthal ancestry,” says Capra.

This means that our brains are very different from those of Neanderthals, and this was probably true when the two groups interbred. The resulting hybrids were less likely to thrive and retain their characteristics over generations.

On the other hand, parts of the genome related to the immune system are more likely to include Neanderthal DNA. This is linked to the fact that when modern humans left Africa, they had to adapt to pathogens found in Europe and Asia.

Many experts say modern humans and Neanderthal tribes lived together, which would support a theory about the disappearance of Neanderthals, according to a July 2024 study published in the journal Science. Basically, instead of disappearing, perhaps the DNA of modern humans simply subsumed that of Neanderthals because those traits were the most successful.

Learn more: How much Neanderthal DNA do humans have?

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