Amongst mammals, only humans, orcas (killer whales) and pilot whales experience menopause. That is, they’re the only mammals whose females stop being able to give birth while they still have decades left to live.
That’s pretty weird. Why wouldn’t evolution select for animals that continued to keep breeding? Wouldn’t that give them the best chance of survival?
Not always. New research by the Universities of Exeter and Cambridge show that these three groups of animals have social structures that – while different – share dynamics that means a female’s offspring stand a better chance of surviving if they stop trying to have new ones and focus on supporting the family they’re already created. In orcas, pilot whales, and us, a grandmother role is an advantage to those who are genetically related.