Asked by: Louise Sanders, Sheffield
Humans, killer whales and pilot whales are the only mammals that experience menopause. We all share a relatively long lifespan that involves mothers living in close quarters with their daughters. It is thought that the older females have therefore evolved to forfeit their ability to reproduce so that they can use their time and energy to nurture their daughters’ offspring, as they are more likely to survive than the ageing female’s young. This is known as the ‘grandmother hypothesis’. Also, grandmothers do not want to compete for vital resources, such as food – another good reason to evolve a menopausal strategy.