Text written in Basque and translated automatically by Elia without any subsequent editing. SEE ORIGINAL

Neanderthal males and female sapiens

When Neanderthals and modern humans hybridized, mostly male Neanderthals hybridized to female sapiens. This is the conclusion reached by researchers at the University of Pennsylvania in a study published in the Science journal.

In modern humans, DNA from Neanderthals is not homogeneously distributed in the genome, but is scarce on X chromosomes. Two hypotheses have been proposed to explain this. On the one hand, it is possible that the Neanderthal variants on the X chromosome disappeared by natural selection because they did not bring advantages. On the other hand, it is possible that in the hybridizations between Neanderthals and Sapiens there is a sexual bias and that less X Neanderthals pass to the descendants.

To solve this, researchers have studied the reverse gene flow: DNA passed from sapiens to Neanderthals. And they have observed that after the initial hybridizations, the proportion of DNA of sapiens origin on the X chromosomes of the Neanderthals is 62% higher than on the rest of the chromosomes. This suggests that the crosses occurred mainly between female sapiens and male Neanderthals. In any case, the researchers recognize that other demographic sexual biases, such as the one that may have been present during migrations, cannot be ruled out.