So maybe, the theory goes, ancient human women evolved to support that kind of society: males doing whatever they’re doing, young mothers tending to their children, and a significantly large, eusocial “grandmother” class assisting in child rearing. Assuming their granddaughters would benefit by such an arrangement, a “menopause gene”[*3] would spread quickly through the population. Over time, it would be so useful that every girl would be born with the genetic code that switched off her ovaries by age fifty.
