Why postmenopausal women are so crucial to our evolutionary success


Close up shot of female walkers laughing in the countryside.

Close up shot of female walkers laughing in the countryside.

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AROUND the age of 50, women stop releasing eggs and can no longer have children. We consider this menopause a natural part of life, but in one respect, it is really rather unusual – there are hardly any other species in which females experience reproductive shutdown when they typically still have decades of healthy life ahead.

So what is the point of menopause? The latest findings support the idea that it is to do with our uniquely demanding offspring and the need to keep relatives who could care for them healthy and mentally sharp for as long as possible.

Classic evolutionary theory predicts that organisms should only live as long as they can pass on their genes. This mostly holds true across the animal kingdom: besides humans, only female orcas, short-finned pilot whales, belugas and narwhals tend to survive well beyond their fertile years.

Does menopause serve a purpose?

The reason we have menopause may simply be because there are biological constraints on how long it is possible to maintain high-quality eggs, says Michael Gurven at the University of California, Santa Barbara. The average age of the onset of menopause in humans has barely budged even as life expectancy has soared, he says. “We definitely seem to be hitting a wall.”

Men may not experience the same clear-cut end to their fertility because they can keep creating new sperm as they age, albeit with declining quantity and quality, whereas…

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