GreenTracker| Researchers have studies female great apes and toothed whales (cetaceans) because they have lifespans beyond their reproductive years.
The “grandmother hypothesis” was first proposed in the 1950s. It stated that menopause, which stops a female’s fertility well before the end of her lifespan, may have evolved to benefit a social group. Grandmothers went on to play a critical role in caring for offspring that were already born.
Typically researchers don’t study a constellation of humans, apes and cetaceans. It’s believe that the origin of menopause may have well-suited these long-lived mammals. via BBC News