EXETER, United Kingdom — Move over, hot flashes! A new study reveals surprising benefits of menopause in whales. It turns out that female whales going through menopause can actually live up to 40 years longer than those that don’t!
This research sheds light on the purpose of menopause, a biological change that’s unique to humans and just a handful of whale species.
“The process of evolution favors traits and behaviors by which an animal passes its genes to future generations. 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,” says the study’s lead author, Dr. Sam Ellis of the University of Exeter. “So the question is: how and why did menopause evolve? Our study provides some of the answers to this fascinating puzzle.”
The findings suggest that certain female whale species with menopause live substantially longer than other female whales of comparable size. This additional lifespan allows them to support their offspring and grandchildren without competing for resources with their daughters by simultaneously breeding and raising calves.
“This study is the first to cross several species, enabled by the recent discovery of menopause in multiple species of toothed whales. Previous research on menopause evolution has tended to focus on single species, typically humans or killer whales,” Professor Dan Franks from the University of York elaborates in a media release. “Our study provides evidence that menopause evolved by expanding female lifespan beyond their reproductive years, rather than from reduced reproductive lifespan.”
The research highlights menopause in five species of toothed whales: short-finned pilot whales, false killer whales, killer whales, narwhals, and beluga whales. Females often outlive their male counterparts. For example, a female killer whale can live twice as long as males, who typically die by age 40.
“The evolution of menopause and a long post-reproductive life could only happen in very specific circumstances. Firstly, a species must have a social structure in which females spend their lives in close contact with their offspring and grand-offspring,” explains Professor Darren Croft, Executive Director at the Center for Whale Research. “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.”
Despite the vast evolutionary gap of 90 million years separating them, whales and humans share similar life histories.
“It’s fascinating that we share this life history with a taxonomic group we’re so different from. Despite these differences, our results show that humans and toothed whales show convergent life history – just like in humans, menopause in toothed whales evolved by selection to increase the total lifespan without also extending their reproductive lifespan,” concludes Prof. Croft.
The findings are published in the journal Nature.