As one of only a handful of animals on the planet to live many years after menopause, killer whales have just provided new insight into the benefits of this seemingly strange reproductive strategy. Females that are past their child-bearing years go on to become group leaders with valuable survival skills, scientists report today in the journal Current Biology.

Theoretically, menopause should not exist. If the purpose of survival is reproduction, then there is no reason for an animal to stay alive when it can no longer have offspring. For killer whales, females stop reproducing at around 50 years old, which is also the age when most male killer whales are nearing the ends of their lives. Typically, though, post-menopausal females still have another 40 years to go.


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. They poured over decades' worth of photographs capturing whales on the move and noticed a pattern: Post-menopausal females, the oldest in the group, typically swam at the front and directed their pods’ movements in a variety of scenarios. To explain this behavior, the team focused their dataset to years when killer whales’ primary food supply, salmon, was critically low.

"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."


Read more: http://www.smithsonianmag.com/science-nature/after-menopause-killer-whale-moms-become-pod-leaders-180954480/#rH13m7u0RIW43ZI4.99