Middle-age Matriarchs: Menopause Mandates Leadership in Orca Pods
Female whales that are past their childbearing years go on to become group leaders with valuable survival skills, scientists report today in the journal Current Biology.
Female killer whales breed between ages 14 and 40 but can survive well into their 90s, while male orcas, by contrast, die much younger, rarely making it past 50. In that time, the female killer whales, not burdened by childbearing, pass on important information to the other whales, says the study.
"The value gained from the wisdom of elders can help explain why female resident killer whales and humans continue to live long after they have stopped reproducing," the study said.
Scientists from the University of Exeter, the University of York and the Center for Whale Research examined 35 years' worth of observational data from an endangered population of southern resident killer whales in the Pacific Northwest.
"One way post-reproductive females may boost the survival of their kin is through the transfer of ecological knowledge," says Lauren Brent of the University of Exeter. "The value gained from the wisdom of elders can help explain why female killer whales and humans continue to live long after they have stopped reproducing."
"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," Brent said in a statement about their findings. Researchers looked at 35 years' worth of data from the Center for Whale Research and observed 102 individual killer whales in the wild.
"In humans, it has been suggested that menopause is simply an artifact of modern medicine and improved living conditions," Croft said in a statement, "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."
