Study suggests many cases of cross between Neanderthal and early humans

Comparison of modern human and Neanderthal skulls from the Cleveland Museum of Natural History. Credit: DrMikeBaxter / Wikipedia

Two researchers from Temple University found evidence suggesting that Neanderthals had mated and had produced offspring with anatomically modern humans several times – not once, as had suggested previous research. In their article published in the newspaper Nature Ecology and EvolutionFernando Villanea and Joshua Schraiber describe their genetic analysis of East Asian and European populations and how they compare to people in other countries. Fabrizio Mafessoni of the Max Planck Institute of Evolutionary Anthropology offers an article of news and opinions about the work done by the couple in the same journal issue.

In recent years, scientists have discovered that early humans leaving Africa had met Neanderthals living in parts of present-day Europe and East Asia. By comparing Neanderthal DNA to modern humans, the researchers found that there was at least one couple that had led to offspring, which is reflected in human DNA: about 2% of the DNA of the non-African man is today Neanderthal. In this new effort, researchers found evidence suggesting that there was more than one such encounter.

Their conclusions are logical, given that anatomically modern humans and Neanderthals coexisted for about 30,000 years. Recent research by other groups has suggested the existence of multiple unions producing children. Some people from East Asia, for example, possessed up to 20% of Neanderthal DNA in addition to people of strictly European descent. In this new effort, researchers took a closer look at knowing once and for all whether there were multiple matches or just one. They extracted and analyzed the 1000 Genomes project data, measuring the amount of Neanderthal DNA in the volunteer genetic material. The first step was to separate the data between people of European and Asian origin. This suggests that both groups have evidence of early multiple mating. The researchers then studied the rates of the two groups by creating simulations showing the results of different numbers of mating events between the two groups. The data from the simulations were then introduced into an automatic learning algorithm that showed percentage patterns of DNA based on the number of crossover events.

The researchers concluded that the most likely scenario was that there were many cases of crossbreeding between novice humans in East Asia and Europe with Neanderthals.

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More information:
Fabrizio Mafessoni. Dating with archaic hominins, Nature Ecology & Evolution (2018). DOI: 10.1038 / s41559-018-0729-6

Fernando A. Villanea et al. Multiple episodes of miscegenation between Neanderthal man and modern man, Nature Ecology & Evolution (2018). DOI: 10.1038 / s41559-018-0735-8

Journal reference:
Nature Ecology & Evolution

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