Why did male lineages drop to 17 women per man 7,000 years ago, according to David Geary?

David Geary says Y-chromosome and mitochondrial DNA show that around 5,000 to 7,000 years ago humans had about 17 female ancestors for every male one. Disease or famine would have hit both sexes, so Geary argues the pattern requires organized violence aimed at men: related male groups with better weapons wiped out rival men and usually kept the women.

• Geary cites the Yamnaya, who used wagons, horses and weapons to push into Europe and displace hunter-gatherers.
• Ancient DNA shows a mix of interbreeding and outright replacement of one group of men by another, Geary says.

▸In their words

“The only way you could get the pattern of the 17 to 1 ratio is intense organized violence.” David Geary · at 10:38 — open in the transcript →

Source: our own transcription of the episode. The full conversation is on Modern Wisdom (2026-11-05). Read the whole episode summary →

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