Chimpanzees going through a midlife crisis? It sounds like a setup for a joke.
But there it is, in the title of a report published Monday in a scientific journal: “Evidence for a midlife crisis in great apes.”
So what do these apes do? Buy red Ferraris? Leave their mates for some cute young bonobos?
“I believe no ape has ever purchased a sports car,” said Andrew Oswald, an author of the study. But researchers report that captive chimps and orangutans do show the same low ebb in emotional well-being at midlife that some studies find in people.
That suggests the human tendency toward midlife discontent may have been passed on through evolution, rather than resulting simply from the hassles of modern life, said Oswald, a professor of economics at the University of Warwick in England who presented his work Monday in the Proceedings of the National Academy of Sciences.
Several studies have concluded that happiness in human adults tends to follow a certain course between age 20 and 70: It starts high and declines over the years to reach a low point in the late 40s, then turns around and rises to another peak at 70. On a graph, that’s a U-shaped pattern. Some researchers question whether that trend is real, but to Oswald the mystery is what causes it.
He and co-authors assembled data on 508 great apes from zoos and research centers in the U.S., Australia, Canada, Singapore and Japan. Caretakers and other observers had filled out a four-item questionnaire to assess well-being in the apes.
Oswald and his co-authors found that the survey results produced that familiar U-shaped curve, adjusted to an ape’s shorter lifespan.
“We find it for these creatures that don’t have a mortgage and don’t have to go to work and don’t have marriage and all the other stuff,” Oswald said. “It’s as though the U shape is deep in the biology of humans” rather than a result of uniquely human experiences.