The ancestors of both modern Europeans and Asians have interbred with Neanderthals some 50,000 years ago. Researchers who are looking at DNA by race have wondered why East Asians have greater proportion of the ancestry compared to Europeans. New research reveals that the heavy-browed Neanderthals bred with East Asians on numerous occasions thus contemporary East Asians have higher levels of Neanderthal DNA according to studies which were published in the American Journal of Human Genetics.

The study that was published in Science Advances is the first to obtain data on nuclear genome from ancient mainland in East Asia and compare the results to modern East Asian population. Findings of the study revealed that there were no major migratory interruption for over seven millennia. As a result of this, some contemporary ethnic groups share a very similar genetic makeup with ancient hunters from the Stone Age.

In contrast, Western Europe have had sustained migrations of early farmers from the Levant who overwhelmed the hunter-gatherer populations. A wave of horse riders from Central Asia soon came after the farmers during the Bronze Age. These events have been driven by the success of emergent technologies like metallurgy and agriculture as reported in Science Daily.

The two studies both concluded that for living East Asians to carry a high percent of Neanderthal genes, their ancestors must have bred with them on multiple occasions. However, findings published in the journal Nature revealed that Neanderthals in Europe died out around 40,000 years ago which baffled scientists. How could Neanderthals breed with East Asians for a second time if they died out.

According to researchers, it is also possible that Europeans have watered down their Neanderthal DNA by breeding with a yet to be identified ancient human species. East Asians may have also bred with an unknown human species that carried Neanderthal DNA which could have given them more Neanderthal genes as reported by the International Business Times.