Once upon a time, 4,000 to 8,000 years after humanity invented agriculture, something very strange happened to human reproduction. Across the globe, for every 17 women who were reproducing, passing on genes that are still around today—only one man did the same.
“It wasn’t like there was a mass death of males. They were there, so what were they doing?” asks Melissa Wilson Sayres, a computational biologist at Arizona State University, and a member of a group of scientists who uncovered this moment in prehistory by analyzing modern genes.