Orcas reveal the origin of menopause

A 40-year study of a population of killer whales off the US Pacific coast has helped British researchers to solve an evolutionary mystery - why killer whales and humans are two of only three species that go through what we call menopause - stopping reproduction part-way through their lives.
By examining a record of every birth and death in every orca family, scientists discovered that the menopause gave new calves a better chance at survival - preventing what they called "reproductive conflict" between mothers and daughters.