Turns out killer whales revere their grandmas, too.

After observing 102 killer whales in the wild, British researchers have determined that female killer whales become key leaders in their pods only after they age out of fertility, according to a study published in Current Biology on Thursday.

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The reason, the researchers report, is that these older females know all the best places to find their favorite fish when pickings become lean.

Menopause, it turns out, is quite rare in the animal kingdom: human women and only two whale species outlive their reproductive lives in a major way, says the study’s lead author, Lauren Brent, an associate research fellow in animal behavior at the University of Exeter. Female killer whales typically become mothers between the ages of 12 and 40, but they can live for more than 90 years as compared to the males who rarely make it past 50.

The evolutionary reason, Brent says, is probably similar across the species. Older females become valued for their accumulated knowledge and wisdom. In the whales, the oldest members of the pod have been around long enough, through times of plenty and paucity, to have learned all the spots that salmon hang out. Observations of whales by Brent and her colleagues bear this out.

Back when humans were still on the savannah—and writing hadn’t been invented—similar forces were probably at work, Brent says.

“The families of humans and resident killer whales are structured in a very kin-focused way,” she explains. “As humans did not develop writing for almost the entirety of our evolution, information was necessarily stored in the minds of individuals. The oldest and most experienced people were those who were most likely to know where and when to find food, especially during dangerous conditions such as drought.”

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