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.