Patrilineal Systems and the Decline in Male Population during the Neolithic Period: A French Study Challenges Previous Assumptions

In a groundbreaking study, a team of French researchers from CNRS, MNHN, and Paris Cité University have proposed a new theory for the notable decline in the male population thousands of years ago worldwide. According to their findings, this decline was more likely due to a social change rather than an unprecedented wave of violence.

The study took place during the end of the Neolithic period, between 3,000 and 5,000 years ago, resulting in a significant decrease in Y chromosome diversity. This decline was only recently identified through analysis of current men’s Y chromosomes. A study in 2015 revealed that one man for every 17 women was involved in reproduction in Europe at that time.

The decline was particularly severe in Europe but also affected regions like the Near East, Siberia, and Africa over a broader timeframe. Contradicting previous theories of violent clan warfare leading to the loss of Y chromosome diversity, the new study suggests that social organization played a key role. The shift from a hunter-gatherer lifestyle to agro-pastoralism favored patrilineal systems, where clans with more power or resources were more successful in reproduction.

To support their theory, the team collected over a thousand genomes from patrilineal populations and found significant loss of Y chromosome diversity in segmental patrilineal systems. They attribute this social transition to the rise of agro-pastoral economies, which favored patrilocality and patrilineality. Future research aims to explore these patterns across different continents to provide region-specific insights into this historical shift.

This new theory challenges previous assumptions about the causes of the male population decline and offers valuable insights into human history and evolutionary biology.