Humans and killer whales are two of the only creatures that experience menopause in the natural world. Although scientists may hypothesize the reasons for this, it is not 100% understood. The rule in nature states that menopause should not occur because their is no perceived reason for a non-reproducing female to survive.
Orcas sexually mature by about age 7 and reproduce every 2.7 years with gestation lasting 15 – 18 months. All offspring remain with their mother/ matriline group for life. Resident killer whales reproduce until they are about 40 but can survive into their 90s, with males rarely living past 50. (1)
Research has lead us to believe that female resident killer whales live half their lives as non-reproducing "leaders" of their offspring (and her offspring’s offspring) by teaching them how to navigate the complex social interactions of resident killer whales and showing them locations of rich salmon foraging areas and rubbing beaches. She also benefits her female offspring, as a non-breeding female, by eliminating further competition for food and potential mates.
Kristen Hawkes, an Anthropologist, was one of the researchers who created the “grandmother hypothesis”.
“In this hypothesis, an older woman helps her children’s children thrive. After menopause, when she can no longer have children, she devotes her time and accumulated knowledge to aid her descendants.” (2)
Fall Whales & Totems