There is no reason to suppose that age and reproduction are necessarily incompatible. Female African elephants breed into their 60s, and blue whales, into their 90s. If there were a reproductive payoff to making babies in one’s 50s, 60s, or 70s, you can rest assured that women would ovulate in their golden years. But they don’t. Perhaps, then, menopause is an incidental result of our increased life spans. In short, what if it’s an aberration rather than an adaptation, something that has arisen because our reproductive biology was tuned to prehistoric times when people simply didn’t live as long as they do today? After all, if most of our ancestors were dead before age 50, it is no surprise that our bodies haven’t evolved to make productive use of those tacked-on decades.
Chimps don’t undergo menopause, and [Jane Goodall’s chimpanzee] Flo bred into extreme old age. Her struggle to care for her last two offspring led to the death of both and to her own demise. On the other hand, it would be suboptimal to be excessively prudent and bet too low—that is, to quit reproducing too soon, underplaying one’s hand. You’ve got to know when to hold ’em, know when to fold ’em. The prudent-mother hypothesis is that menopause tells women when to fold ’em.