Modern men's genes suggest that something peculiar happened 5,000 to 7,000 years ago: Most of the male population across Asia, Europe and Africa seems to have died off, leaving behind just one man for every 17 women.
This so-called population "bottleneck" was first proposed in 2015, and since then, researchers have been trying to figure out what could've caused it. One hypothesis held that the drop-off in the male population occurred due to ecological or climatic factors that mainly affected male offspring, while another idea suggested that the die-off happened because some males had more power in society, and thus produced more children.
Now, a new paper, published May 25 in the journal Nature Communications, offers yet another explanation: People living in patrilineal clans (consisting of males from the same descent) might have fought with each other, wiping out entire male lineages at a time. [Image Gallery: Our Closest Human Ancestor]
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