Reacción a "A study suggests that interbreeding between Neanderthals and modern humans occurred mostly between Neanderthal males and modern human females"

It is a fascinating piece of research because it sheds light on far-reaching questions that, without the contribution of paleogenomics, could not be addressed. Thus, the article by Platt and colleagues shows that the X chromosome of Neanderthals (Homo neanderthalensis) is very different from that of anatomically modern humans (Homo sapiens). The researchers at the University of Pennsylvania conclude that most interbreeding occurred between Neanderthal men and anatomically modern women, and not the other way around. Moreover, this relationship between anatomically modern women and Neanderthal men appears to have persisted over time until the Neanderthals’ disappearance and therefore was not the result of sporadic sexual encounters. All of this would point to the extremely limited contribution of Neanderthal women to our lineage.

On the other hand, the results by Platt and colleagues help resolve a paradox: the nuclear DNA of anatomically modern humans shows the influence of the Neanderthal genome, but their mitochondrial DNA—transmitted exclusively through the maternal line—does not. The reason may lie precisely in the core finding of the study published today: the minimal gene flow that occurred between Neanderthal women and anatomically modern men. Their influence would have been very limited.

This study also has two very interesting social implications.

First, despite the evident morphological differences, there was genetic transfer through sexual reproduction between Neanderthals and anatomically modern human women.

Second, it is possible that anatomically modern women left their native groups to integrate into Neanderthal clans or bands. This phenomenon, known as patrilocality (a reproductive residence pattern in which males remain in their birthplace), which reduces inbreeding and its associated problems, had already been identified in a previous study of the mitochondrial DNA of twelve Neanderthal individuals from El Sidrón Cave in Asturias.

In short, the arrival of anatomically modern humans on the Eurasian continent did not entail the extermination of preceding species. Quite the contrary: a logic of interaction seems to have prevailed.

The main limitation of the research presented is the small sample size on which it is based: three individuals. Nevertheless, it represents an interesting and undeniable step forward in a discipline—paleogenomics—that is constantly evolving and advancing, and which will undoubtedly continue to yield remarkable surprises.