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

When Neanderthals and modern humans had offspring together, little Neanderthal DNA from the X chromosome entered the human gene pool. A study published in the journal Science traced ancient gene flow and found a relative excess of 62% modern human ancestry on Neanderthal X chromosomes. This suggests that the couples who had children were mostly Neanderthal men and modern human women, although the authors cannot rule out the possibility that demographic processes played a significant role.

26/02/2026 - 20:00 CET
Expert reactions

José Yravedra - pelirrojos

José Yravedra Sainz de los Terreros

Professor in the Department of Prehistory, Ancient History and Archaeology at the Complutense University of Madrid

Science Media Centre Spain

The study raises an interesting point that is worth discussing. However, there are aspects that are not mentioned and that could be interesting to address.

An alternative explanation could be that there were few women in the last Neanderthal groups, which forced greater mobility, and in that mobility, Sapiens women may have had a greater relationship with Neanderthals. We must not forget the example of Sidrón, where a group of Neanderthals appear with males related to each other by close kinship, unlike the three women, who apparently have no genetic relationship with the rest of the group.

The author has not responded to our request to declare conflicts of interest
EN

Javier Baena - pelirrojos

Javier Baena Preysler

Professor of Prehistory at the Autonomous University of Madrid.

Science Media Centre Spain

Does the press release accurately reflect the study?

“Yes, it is somewhat limited, possibly due to the content of the article, but it is clear and reflects the study well. However, it is often the case that many interpretations of an anthropological or historical nature lack an archaeological foundation—something that, without wishing to downplay the work, is quite common.”

Is the study of good quality?

“The work is very interesting, although I fear it may be somewhat limited in its interpretation—an assessment I make without full knowledge of the study as a whole. On the other hand, since it is confined to the paleogenetic field, I would say that its conclusions are indeed well supported.”

How does this work fit with the existing evidence?

“That is the key question. The results obtained are of enormous interest, especially when analyzing the relationships that both population groups may have had in ancient times. The implications at a technocultural and mobility level may be just as interesting as the type of sex-based interrelationships that occurred.”

Are there important limitations that should be taken into account?

“In general, these paleogenetic studies tend to suffer from a lack of integration with archaeological data. The results must be interpreted within a context in which both human groups developed distinct strategies and possessed clearly different histories. Therefore, the existence of a specific instance of interbreeding at relatively early dates deserves a deeper interpretation in light of the existing record.”

What are the implications for the real world?

“Beyond the anecdotal nature of the results obtained, at a historical scale—and especially for our real lives—the implications are limited. We already knew about this interbreeding, although with current data we are able to analyze it in greater anthropological and chronological detail. In any case, it should teach us that the configuration of our species has been the result of complex processes of hybridization in which individual actions have played their part.”

The author has declared they have no conflicts of interest
EN

Martín Lerma - pelirrojos

Ignacio Martín Lerma

Professor of Prehistory at the University of Murcia.

Science Media Centre Spain

This study provides relevant evidence for better understanding the interaction between Neanderthals and anatomically modern humans. The genetic pattern it identifies, consistent with a sex bias in episodes of interbreeding, introduces an interesting nuance into our reconstruction of that contact. It is important to remember, however, that these are demographic inferences based on population models rather than direct evidence of specific behaviors.

From archaeology, we know that the encounter between the two groups was a prolonged and varied process, unfolding across different territories and cultural contexts. If interbreeding was predominantly carried out by Neanderthal males and modern human females, this points to specific social dynamics—possibly related to mobility, group structure, or demographic imbalances—although it does not allow us to define exactly what those interactions were like.

This work refines and enriches the narrative of the encounter between Neanderthals and modern humans, and shows that, with new tools, we continue to deepen our understanding of a key episode in our evolutionary history.

The author has not responded to our request to declare conflicts of interest
EN
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Platt et al.

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