Do Other Primates Really Have a Midlife Crisis? Do Humans?
A paper in the Proceedings of the National Academy of Science (PNAS) this week led to a slew of stories with references to red sport cars and younger girlfriends. The paper reported that a study of more than 500 captive chimps and orangutans showed that these species suffered something like a midlife crisis, in that their well-being and happiness bottomed out around what would be 50 in chimp and orangutan years. Since these animals can’t fill out a questionnaire, it was left for their caretakers to speak for them.
One of the authors of the paper drew the conclusion that the human midlife crisis is a biological rather than a social or cultural phenomenon. I’m not convinced.
Andrew Oswald, a professor of economics at the University of Warwick in England, is quoted up high in many version of the story, including this one by Michael Winter in USA Today:
“We hoped to understand a famous scientific puzzle: why does human happiness follow an approximate U-shape through life? We ended up showing that it cannot be because of mortgages, marital breakup, mobile phones, or any of the other paraphernalia of modern life. Apes also have a pronounced midlife low, and they have none of those," Oswald said.
A similar quote appeared in this LiveScience story by Tia Ghose:
"Biology and physiology have to be at the top of a list of possible explanations" for the appearance of similar crises in both apes and humans, said study author Andrew Oswald, a statistician at the University of Warwick in the United Kingdom. "That's what we share in common. Apes don't have mortgages and divorces and school fees to pay, and all of the paraphernalia of modern life."
Her story does include a skeptical comment by the famous primate researcher Frans de Waal:
"The judgment of happiness is hard enough in humans, and here we have humans judging the happiness of apes," De Waal wrote. "The study thus scores the well-being of animals through a human filter, perhaps introducing human bias."
For men and women alike, social science researchers have located the winter of our discontent somewhere near the 50-year mark, wedged neatly between the vigor and drive of youth and the quest for meaning and happiness that marks the final decades of life. More than just a cultural cliche, the midlife crisis is the well-documented nadir of human well-being on the U-shaped curve of happiness that stretches between birth and death.
I still wondered about the reliability of the zookeepers’ assessments. I had several other questions that nagged at me as I read these stories. What is the nature of the human midlife crisis? Several stories quoted social scientists saying there’s some evidence human happiness follows a U-shaped curve, bottoming out in the late 40s. What the stories didn’t say was how pronounced this effect was, or how common. Are there cross cultural studies showing a universal phenomenon? How believable are these studies? Do these studies show that most humans have a mid-life crisis? Or just a few of us?
Another question that kept bothering me was why Dr. Oswald got away with claiming the study proved that in humans, the midlife crisis wasn’t about career disappointment or mortgages. Why not? It might be fair enough to say the study suggested biology potentially plays a role too, but to say it showed the midlife crisis wasn’t about money or careers or other parts of human life seemed a leap that wasn’t justified by the data.
Some more interesting comments from the skeptics appeared in this story from Red Orbit:
“What can produce a sense of wellbeing or contentedness that varies across the lifespan like this? It’s hard to see anything in an ape’s life that would have that sort of pattern, that they would cogitate about,” said Robin Dunbar, professor of evolutionary psychology at Oxford University, during an interview with The Guardian.
“They’re not particularly good at seeing far ahead into the future, that’s one of the big differences between them and us.”
Psychology professor Alexandra Freund at the University of Zurich also found the study’s findings dubious, saying that the concept of a midlife crisis was questionable even in humans.
“In my reading of the literature, there is no evidence for the midlife crisis. If there’s any indication of decline in emotional or subjective wellbeing it is very small and in many studies, it’s not there at all,” she said.
In this story, Malcolm Ritter at AP did contact a skeptical researcher who thought the chimp and orangutan phenomena might be real, though she doubted the body of work that supported the human midlife crisis.
Even happiness researcher Sonja Lyubomirsky of the University of California, Riverside, who thinks the U-shaped pattern in people is a statistical mirage, says she can't write off the ape result the same way. "I'm not really sure what it means," she said. "I am finding this very intriguing." Maybe it will spur more thinking about what's going on in both apes and humans, she said.
While most stories included some cutesy references, this take-off in The Guardian was genuinely funny. It was written by a chimp named Greg, I think with some help from Tim Dowling:
Feeling restless. Had another go at typing Shakespeare. By lunchtime I felt as if I'd made a real breakthrough with the dialogue in the opening scene, but later when I checked it over I saw that it was actually just six pages of Xs and 9s. I know good work requires infinite patience, but some days I think I'm not getting anywhere at all. Am I wasting my life?
Looking at myself this morning, I noticed something shiny in my hair. Then I realised: it was my scalp! Why do I seem to be getting hairier everywhere but on my head? Sometimes I wish I were a dog – when they look in the mirror, they just think it's another dog. Mustbe nice to be that stupid.
All the days are worth reading.
Read the original PNAS paper here.