What do middle-aged women and killer whales have in common? Menopause, new research says.
After monitoring 500 killer whales for the last 30 years, biologists at the United Kingdom’s University of Exeter and the University of York have found that female killer whales experienced “the change” in their 30s. That is, the whales stopped reproducing, while continuing to care for their offspring – and their offspring’s offspring – for up to another 40 or 50 years. This makes killer whales one of only three known species (with humans and pilot whales) to go through menopause.
The researchers theorize that killer whale menopause is likely linked to the animal’s unusual social system, which makes the benefits of menopause outweigh the costs.
The killer whales’ social system is rare because they continue to live in close-knit family pods, with calves remaining with their mothers their entire lives. Male offspring will briefly leave to mate, but then return to mom. In the rest of the animal kingdom, the young usually leave the family unit for good. The scientists say that the killer whale system makes it beneficial for the mothers to stop reproducing later in life, allowing them better ensure the survival of their genes by protecting their young.
Previous research has shown that orphaned male killer whales are 14 times more likely to die in the year following their mothers’ death than they would be if she were around.
In addition, halting reproduction in their 30s allows the older female whales to avoid competition with their daughters for mates. It also prevents calves of mother and daughter from being in competition for survival.
Whether killer whales experience hot flashes and mood swings is still a mystery, the scientists say. Regardless, it’s fair to say that a 16,000-pound carnivore that snacks on seals and sea lions is not to be reckoned with.