Recent studies indicate that certain whale types have adapted to have a menopause stage and longer lifespan similar to humans, which helps them better care for their families. This research points out the similarities in extended post-reproductive lifespan between humans and whales due to evolution.
Recent research suggests that female whales of specific species have evolved to have much longer lifespans to look after their families.
The research focused on five whale species that, like humans, are the only mammals known to go through menopause. The results reveal that menopausal female whales of these species live approximately 40 years longer than other female whales of similar size.
By living longer without extending their breeding period, these females have more time to assist their offspring and grandchildren, without increasing the period of competition with their daughters for breeding and raising calves simultaneously. This recent research demonstrates that despite being separated by 90 million years of evolution, whales and humans exhibit remarkably similar life histories that have evolved independently.
The study was conducted by the universities of Exeter and York, and the Center for Whale Research.
A post-reproductive mother killer whale (K14) leading her young son (K42) and adult son (K26). Credit: David Ellifrit, Center for Whale Research. Reference Permit NMFS-27038
Study Origins and Evolutionary Insights
“The process of evolution favors traits and behaviors by which an animal passes its genes to future generations,” said lead author Dr Sam Ellis, from the University of Exeter. “The most obvious way for a female to do this is to breed for the entire lifespan – and this is what happens in almost all animal species. There are more than 5,000 mammal species, and only six are known to go through menopause. So the question is: how and why did menopause evolve? Our study provides some of the answers to this fascinating puzzle.”
Menopause is known to exist in five species of toothed whales: short-finned pilot whales, false killer whales, killer whales, narwhals, and beluga whales. Aside from outlasting females of other similar-sized species, females of these five species outlive the males of their respective species. For example, female killer whales can live into their 80s, while males typically die by 40.
Evolutionary Conditions for Menopause
“The evolution of menopause and a long post-reproductive life could only happen in very specific circumstances,” said Professor Darren Croft, of the University of Exeter and Executive Director at the Center for Whale Research “Firstly, a species must have a social structure in which females spend their lives in close contact with their offspring and grand-offspring. Secondly, the females must have an opportunity to help in ways that improve the survival chances of their family. For example, female toothed whales are known to share food and use their knowledge to guide the group to find food when it is in short supply.”
Post reproductive mother (L5) and son. Credit: David Ellifrit, Center for Whale Research. Reference Permit NMFS-27038
Professor Dan Franks, from the University of York, said: “Previous research on the evolution of menopause has often focused on individual species, usually humans or killer whales. This study is the first to look at multiple species, made possible by the recent discovery of menopause in several types of toothed whales. Our research provides proof that menopause developed by extending the lifespan of females beyond their reproductive years, rather than by shortening their reproductive period. This is a question that has long been asked in anthropology, but can only be directly answered with a comparative study.”
Discussing similarities with the emergence of menopause in humans, Professor Croft commented: “It’s interesting that we share this life history with a group that we are so different from.
“Despite these distinctions, our findings demonstrate that humans and toothed whales display similar life patterns – just like in humans, menopause in toothed whales evolved due to the selection for increased overall lifespan without extending their reproductive period as well.”
Reference: “The evolution of menopause in toothed whales” by Samuel Ellis, Daniel W. Franks, Mia Lybkær Kronborg Nielsen, Michael N. Weiss and Darren P. Croft, 13 March 2024, Nature.
DOI: 10.1038/s41586-024-07159-9
The study was funded by the Leverhulme Trust and the Natural Environment Research Council (NERC).
