Doting killer whale grandmothers help their grand calves survive, particularly in times of food scarcity, scientists reported in a paper that sheds new light on the evolutionary role of menopause.
Orca females stop reproducing in their thirties or forties but can continue to live for decades more, a phenomenon known only to exist in humans and four other mammal species, all of which are whales.
It has been suggested that the trait evolved because it allowed post reproductive females to help their wider kin – referred to as the “grandmother effect” in people, but the theory had not been tested in whales until now.
I knew about the menopause bit and also the grandmother effect in people. But I thought that one of the reasons I knew about it was because it had been observed in whales – the only other species(es) which have the menopause.