Menopausal Whales Makes Good Leaders
It is well known that women after a certain age undergo menopause, a trait that is rare in the animal kingdom. However, outside of the human species, killer whales also experience menopause, and these older females apparently make good leaders, a new study says.
Female killer whales typically become mothers between the ages of 12 and 40, but they can live for more than 90 years. For comparison, males of the species rarely make it past age 50. While menopause among animals is a rare and rather bizarre trait, new findings suggest that, evolutionary speaking, it does serve a purpose.
According to a report in the journal Current Biology, older individuals serve as key leaders, directing younger members of whale society - especially their sons. This leadership role gives a new and different meaning to the old saying, "respect your elders."
Specifically, menopausal whales can guide younger members of their pod towards all the best spots for finding salmon, their favorite fish. Especially when pickings are slim, this can prove useful in helping others survive and prolong the species.
When it comes to killer whales, apparently older is wiser.
"Menopause is one of nature's great mysteries," lead author Lauren Brent of the University of Exeter said in a press release. "Our study is the first to demonstrate that the value gained from the wisdom of elders may be one reason female killer whales continue to live long after they have stopped reproducing."
To better understand the role of menopause among female killer whales, Brent and her colleagues observed 102 killer whales in the wild, taking into account birth and death dates, as well as genetic and social relationships between whales.
It turns out that females past their reproductive prime were especially strong group leaders in years when salmon availability was low. Not only does this shed light on reproduction and survival in whales, but it also suggests that the origin of menopause in humans may have a similar explanation.
"In humans, it has been suggested that menopause is simply an artifact of modern medicine and improved living conditions," explained Darren Croft of the University of Exeter, the study's senior author. "However, mounting evidence suggests that menopause in humans is adaptive. In hunter-gatherers, one way that menopausal women help their relatives, and thus increase the transmission of their own genes, is by sharing food. Menopausal women may have also shared another key commodity: information."
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