Why Killer Whales Go Through Menopause

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For anyone with ovaries, menopause is a fact of life — seemingly mundane, perhaps, in its inevitability. In fact, menopause is a biological rarity, one scientists haven’t managed to fully explain. Only three species outlive their fertility: humans, killer whales and short-finned pilot whales. Figuring out what commonalities exist among these species might help scientists understand why menopause happens.

A new study on killer whales, published on Thursday in Current Biology, suggests reproductive conflict between mothers and daughters may have played an important role in the evolution of menopause. Analyzing four decades of data on killer whales in the Pacific Northwest, the authors found that when mothers and daughters breed around the same time, the calves of the older females had higher mortality rates than those of the younger females.