What’s the deal with animal menopause?
Four-minute read
If you aren’t sure what menopause is, simply put it’s when a woman stops menstruating due to a hormone change. I doubt the concept is news to any of you. But I’m not sure if you know how unusual it is, biologically speaking.
Most animals don’t continue to live after losing their ability to reproduce. My favourite example is the octopus. These extremely intelligent animals live extremely short lives.
Once they’ve mated with another octopus and the eggs have been laid, they begin to die. If you want to see it for yourself, watch My Octopus Teacher on Netflix. It’s beautiful but if you’re anything like me it’ll make you cry like a jilted bride.
Human women are somewhat unique in the animal kingdom for being able to live on after their fecund years are behind them. Its emergence has a scientific explanation, because it’s not an accident that we have menopause. It’s helped us get here.
There’s a theory that grandmothers are a driving force behind the success of human evolution. Specifically, they’re the reason we live so much longer than other primates.
I don’t think it’ll be a surprise to anyone who’s had to loosen their belts after a meal at Grandma’s house to hear that the way post-menopausal women helped humanity was by feeding it.
Food gathering is no easy task, and it’s much harder when you’ve got three little kids running around. Early third generation women stepped up to pitch in with either the food gathering or child-rearing to make sure the whole family survived.
Those strong, healthy families with voluntary in-home help could have more children, who in turn would go on to have children of their own. The genes that helped their grandmother live long enough to care for them are passed down to the next generation.
That’s how it works. If something helps an animal survive, it will be selected for by nature. That’s evolutionary biologist speak for ‘life-saving genes usually get inherited’. That helps the entire species change for the better. Grandmothers pitching in throughout history has made us what we are today.
Humans are not the only animals to have evolved to experience menopause. We are in a club of three, and wouldn’t you know it? The other two members are dolphins.
Don’t be fooled by the short-finned pilot whale’s name. They’re firmly in the dolphin family within the wider toothed whale clan. It’s been known they go through menopause since 1981, just not by enough people. The discovery was hindered by sexism.
Helene Marsh and her mentor Toshio Kasuya collected samples from more than 300 whales. They checked their ovaries and determined approximate ages of each animal.
They found that female short-finned pilot whales stopped reproducing around the age of 36, but still lived for about 14 years more. They’d found the first ever example of menopause in a non-human animal.
But Marsh reported that her team’s discovery was met with derision at a conference. She presented their findings, but the other scientists wouldn’t have it. This is how she describes it -
The mainly male audience was quite scathing. They couldn’t believe that there would be females in a population that had stopped breeding, because the reason they were there was to breed.
She remembers specific comments that she described as ‘incredibly sexist’, like the following -
This cannot be true. There would be no point in the females remaining alive if they weren’t reproducing.
Gross. Men, please listen to women. And please appreciate that women menstruate from as young as eight years old and are a ticking time-bomb until the age of 50 or so, when our bodies enter a 10-year period of symptoms like heart palpitations, night sweats, hot flashes and dizziness, after which we are disregarded by society as an old lady.
The final member of the menopause club is the biggest member of the dolphin family, the mighty orca.
Female killer whales live for up to 90 years in the wild and most live an average of 22 years after menopause. Just like in humans, having a Nana around brings evolutionary benefits.
Post-menopausal killer whales share food they catch, help rear calves and lead the pod to rich hunting grounds. Grandmothers are the matriarchs, they’re in charge. Their influence is so great that their offspring stay with them for life.
Well, actually it’s complicated. Mother orcas dote on their sons, but aren’t close with their daughters. It’s a bit of a mystery, but could be a bit of a role reversal of the stereotypical 1950s father-son relationship.
The father wants his son to be a tough leader, so treats him as such to whip him into shape. The father’s happy to be affectionate with his daughter because she’ll only become a wife and mother, or a receptionist as a push. We aren’t sure exactly though.
For whatever reason, orca mothers coddle their sons from the moment they’re born and the bond they form becomes unbelievably strong. Sons are three times more likely to die in the year following their mother’s death than males with living mothers.
Older males in the 30+ category have an eightfold increase in the risk of death after losing their mother. Young daughters do okay after being bereaved but an older female’s chances of dying triple in the same situation.
Mothers and daughters get on well, but sons take up most of the older generation’s time. Recent research suggests mothers and grandmothers help their sons and grandsons out if they get in a fight.
Post-menopausal killer whales jump in to protect their sons from injuries from other orcas. Scientists have evidence, too. Males that still live with their mother have fewer rake marks on their bodies.
Rake marks are scratches left by other orcas teeth during aggressive encounters. Males are even less scarred if their matriarch is beyond childbearing age and has enough time to focus on breaking up the boys’ squabbles.
Family is insanely important to orca survival, and their close relationships at the very least appear to bring them with joy. I’m talking about wild orcas here, of course. In captivity, most of the whales are unrelated and are moved between tanks and parks in the blink of an eye. That’s not what they’ve evolved to do, and I think it’s wrong to force an animal to live a life so far removed from the natural order of things in the open ocean.
The fact that there are still 58 orcas in captivity around the world at this moment in time is a sickening reminder that profitable companies are happy to cause animal suffering and pervert nature as long as the money keeps rolling in. If we unite to shrink their profits, they’ll have no choice but to change.
