Humans and five whale species are the only mammals known to go through menopause. Why is unclear but a new study sought answers.

Scientists found that females of short-finned pilot whales, false killer whales, killer whales, narwhals and beluga whales and experience menopause live around 40 years longer than other female whale species of a similar size and speculation is that by living longer without extending their reproductive lifespan they have more time to help their children and grandchildren, without increasing the “overlap” period when they compete with their daughters by breeding and raising calves at the same time.

Some of that will be a science biological challenge, since if it increased offspring fitness more would have evolved that trait in the 90 million years of evolution that separates whales and us.

Credit David Ellifrit, Center for Whale Research. Reference Permit NMFS-27038

Not only do menopausal whales outlive other species, they outlive males of their own kind. Males are typically dead by age 40 while females may live into their 80s. For this to take place in biology likely means a species must have a social structure in which females spend their lives in close contact with their offspring and grand-offspring. If post-menopausal female toothed whales share food and use their knowledge to guide the group to find food when it is in short supply, they have a great deal of value.