Most of us have a little bit of Neanderthal DNA.
Far from being the lumbering brutes that we once thought they were, a slew of recent studies suggest Neanderthals not only interacted with Homo sapiens, but also had children with them.
These sexual encounters mean Neanderthal genes have been passed down through the generations, and today most people can thank Neanderthals for about 2% of their genomes.
But that proportion varies, and some people have slightly more Neanderthal DNA than others. People in East Asia, notably, tend to have more Neanderthal DNA in their genomes, but why they have more has long baffled scientists.
That’s because Neanderthals are thought to have mostly been European. Some Neanderthal remains were found as far East as the Altai Mountains of Siberia, but their bones are usually found in European countries.
The most logical conclusion is that Homo sapiens and Neanderthals had their first offspring in Europe. The next logical step is that Neanderthal DNA would get more diluted as Homo sapiens mingled with other humans and hominins when they spread away from the area where Neanderthals lived.
“It’s strange that in an area we have never seen any Neanderthals, the DNA is more Neanderthal,” Mathias Currat told CNN .. Currat was a geneticist from University of Geneva.
A new study, published in the journal Science Advances Wednesday, may provide some answers.
Currat and his co-authors drew from a database of 4,000 human genomes extracted from human remains dating back up to 40,000 years ago, and held by the Harvard Medical School.
Their study found that up to about 20,000 years ago, European genomes were indeed richer in Neanderthal DNA than the Asian genomes they have on record.
But that proportion shifted about 5,000 to 10,000 years ago. Scientists believe that in the past, a farming Homo Sapiens group from Anatolia (now Western Turkey) began mixing with hunters-gatherers of Western Europe.
These farmers had a little less Neanderthal in them, so Western Europeans lost some of that ancestry as they mixed, Currat said, per CNN.
What’s not quite clear, however, is what happened in Asia. This is partly because of the fact that the database they were using had less data about Asian genomes.
“It appears that there have been more archaeological digs in Europe. This has made it easier to study the genomes of Europeans,” Claudio Quilodran said, a geneticist from the UNIGE Faculty of Science.