New Study Challenges Old Theories on Y Chromosome Diversity Loss

Y Chromosome

A study highlights that Neolithic patrilineal social systems, not violent conflicts, led to a major reduction in Y chromosome diversity, reshaping our understanding of ancient human social organization.

The development of patrilineal social systems during the Neolithic period, where children inherit their father’s lineage, could be the reason for a notable decrease in Y chromosome genetic diversity globally between 3,000 and 5,000 years ago. In a study recently published in the journal Nature Communications, a team of scientists from the CNRS, MNHN, and Université Paris Cité suggest that these patrilineal organizations had a greater impact on the Y chromosome than mortality during conflict.

This conclusion was reached after analyzing twenty years of anthropological field data – from contemporary non-warlike patrilineal groups, particularly from the scientists’ own fieldwork carried out in Asia – and modeling various socio-demographic scenarios. The team compared warrior and non-warrior scenarios and showed that two processes play a major role in genetic diversity: the splitting of clans into several sub-clans and differences in social status that lead to the expansion of certain lineages to the detriment of others.

Central Asian Population

The scientists studied contemporary patrilineal populations. Here, a photo of a Central Asian population. Credit: Heyer Evelyne, Segurel Laure

This study calls into question the previously proposed theory that violent clashes, supposedly due to competition between different clans, in which many men died, were at the origin of the loss of genetic diversity of the Y chromosome. The results of this study also provide new hypotheses on human social organization in the Neolithic and Bronze Ages.

Reference: “Patrilineal segmentary systems provide a peaceful explanation for the post-Neolithic Y-chromosome bottleneck” by Léa Guyon, Jérémy Guez, Bruno Toupance, Evelyne Heyer and Raphaëlle Chaix, 24 April 2024, Nature Communications.
DOI: 10.1038/s41467-024-47618-5

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