Running computer models to simulate how humans might have evolved in our early history, they found that adding a few genetic mutations for infertility into the population didn’t have much of an effect on overall fertility as time wore on. The mutations just died out: ‘Fertility and survival remained high into old age. There was no menopause.’ But when they added the critical element of older men preferring to have sex with younger women into their simulations, the female menopause did pop up.
