Did You Know?
Studies show that apes experience dips in happiness in their middle age, much like people do.
Middle age ruts may act as natural motivators, scientist says.
New research says it's not just humans who go through midlife crises: Chimps and orangutans also experience a dip in happiness around the middle of their lives. :"There may be different things going on at the surface, but underneath it all, there's something common in all three species that's leading to this," said study leader Alexander Weiss, a primate psychologist at the University of Edinburgh in Scotland.
The study team asked longtime caretakers of more than 500 chimpanzees and orangutans at zoos in five countries to fill out a questionnaire about the well-being of each animal they work with, including overall mood, how much the animals seemed to enjoy social interactions, and how successful they were in achieving goals (such as obtaining a desired item or spot within their enclosure).
The survey even asked the humans to imagine themselves as the animal and rate how happy they'd be.
When Weiss's team plotted the results on a graph, they saw a familiar curve, bottoming out in the middle of the animals' lives and rising again in old age. It's the same U-shape that has shown up in several studies about age and happiness in people. "When you look at worldwide data, you see this U-shape," said National Geographic Fellow Dan Buettner, author of Thrive: Finding Happiness the Blue Zones Way. (National Geographic News is part of the National Geographic Society.)
"It's different for every country, but it's usually somewhere between age 45 and 55 that you hit the bottom of the curve, and it continues to go up with age. You see centenarians in good health reporting higher well-being than teenagers."
Social and economic hypotheses may partly explain this happiness curve in human lifetimes: Maybe it's tied to adjusting expectations, abandoning regret, or just getting more stuff as we grow older. But Weiss suspects there may be something more primal going on.
"We're saying, take a step back and look at the big picture: Is there any evidence that there's an evolutionary basis underlying this?" said Weiss, whose study was published today in the journal Proceedings of the National Academy of Sciences.