A new paper in Nature Communications documents a strange bottleneck event occurring about 7,000 years ago, where the genetic diversity of the Y chromosome completely collapsed leaving about one male to 17 females. We all know the agricultural revolution happened around 12,000 years ago. Societies grew in size and many organized around patrilineal kinships. Turning to mathematical models, they found that wars between these clans drastically reduced Y chromosome diversity over time. Among the male lineages that survived the Y-chromosome bottleneck, a few lineages underwent dramatic expansions, consistent with the patrilineal clan model. The coolest figure from the paper is below:

Screen Shot 2018-06-02 at 2.51.05 PM