They’re calling it “the grandmother effect”. In a new study published on Thursday in Current Biology, there’s some interesting details about the post-menopausal orca mamas swimming around our Pacific Northwest coastal waters.
Unfortunately, Octo-woman, who wasn’t consulted before the study was published, feels it is necessary to publish this blob as an Errata (Erratum?) regarding one of the study’s hypotheses.
Before we get into that though, as you may know, orcas are called “killer whales” but there’s no record of them ever killing a human. They don’t have to. They’re already at the top of the food chain and they don’t have any predators (except humans). The killer designation came from ancient sailors who observed the orcas preying on larger whales, and they called them “whale killers”. The moniker later gradually got reversed to “killer whales”, but the only way one of those rather overweight whales would kill you is if one of them accidentally sat on you
There’s 75 orcas living off our coast. They’re known as the Southern Resident population, and they’re critically endangered. They been studied at the Center for Whale Research Center in Friday Harbor, Washington since 1976. The purpose of the newly published study of these interesting creatures is to try to uncover more clues about the evolutionary purpose of menopause, a rare phenomenon in the animal world. So far humans and certain toothed orca whales are the only animals known to experience it. By “humans”, that seems to mean us, ladies, and how do we get so lucky?
The scientists found that an orca matriarch can live another 22 years after menopause and can continue to contribute productively to the pod till she’s 90 years old or so. “The grandmother effect” is the term they’re using to describe it. Earlier research had suggested that the post-menopausal females are believed to boost the life chances of their offspring and grandchildren.
The leader of each family or whale pod – always an older female – shares her knowledge of the best hunting spots and she shares more than half the fish she catches with her family members. The orcas in the resident pods stay together all of their lives. Males mate with females in other pods but then return to live with their mother and the rest of the family.
Nobody seems to get married and move out. And none of the elderly mothers, grandmothers or aunties get to retire to a nice senior living community near the Seashell Casino. They have to keep slinging the hash, maintaining order in the court, and trying to keep the pod flushed and tidy.
According to the new study, the elderly orca matriarchs spend much of their retirement “helicoptering” their sons and grandsons. They try to help the young males navigate the orca social life and try to keep them out of fights. To study this phenomenon, the scientists counted “tooth rake bites” – the scarring left when one whale scrapes his teeth off the skin of another.
Because they have no other predators in the ocean, the wounds can only come from other killer whales. The orca males in the study whose mothers or grandmothers were present had 31% less scars and according to drone footage, it appears the female may join the conflict if that’s what it takes to protect the male.
Oddly though, while the matriarchs helicopter their sons and grandsons, they don’t do the same for their daughters and granddaughters who also get their share of tooth rake bites. It seems that the young females are expected to face on their own the slings and arrows and maybe harpoons of their undersea life.
The question is: why do the matriarchs protect the young males and not the young females? The lead author of the study is Charli Grimes, an animal behavior scientist at the Centre for Research in Animal Behaviour at the UK’s University of Exeter. Grimes hypothesizes that it makes more evolutionary sense for the orca matriarchs to focus on the sons because they have more potential to pass on the mothers genes – and in a way that doesn’t put any additional burden on the rest of the group.
“Males have the opportunity to mate with multiple females outside their own social group” Grimes said. “When a male’s calf is born,… then the cost of raising it lies with the other group.”
Octo-woman isn’t buying that fancy explanation for why the young males get all the attention. The orca matriarchs are obviously paragons of strength and maternal responsibility but they may be a bit weak on their comprehension of evolution and need for sharing their genes.
I have a more reasonable explanation and I feel I am fairly well qualified to explain the issue. I don’t know how to swim, and I’m not critically endangered, but, otherwise I can certainly identify with these elderly post-menopausal females. I have children, I have grandchildren, I have had my share of hot flashes. I am generous about sharing with my family my best hunting sites for bargains. Also, I eat a lot of fish, at least during Lent. I make sure there’s enough to share, and I, too, have never killed anybody, so far.
So here it is. You may want to write this down. As any red-blooded feminist would attest, the reason the orca boys get all the attention is because they get into more mischief and their mothers or grandmothers have to step in to bust up their fights and patch up their ow-wies with some kind of seaweed band-aids. The girls on the other hand don’t need any help because they have been taught to handle any situation with firmness, grace, creative thinking, conflict resolution, and executive leadership.
I bet you already knew that, though.
Fascinating, and also wise, Mama Whale.
Duh!
Being the eldest of 6, and often left in charge of the pod while the elders went off to party (dinner and cards), I can verify Octowoman’s hypothesis. It’s definitely the males who are always getting into mischief, trying to ignite water heaters, chase until someone rams a stick through the roof of their mouth, jump out of closets and clock someone in the head with a doorknob…must I go on? So I defend Octowoman’s research 100%!
You can’t swim?