Primate Midlife Crisis

Midlife crisis is not just a human phenomenon, according to a recent survey of 508 great apes. Social science strongly suggests that humans, regardless of culture, gender, or socioeconomic circumstances, tend to experience a midlife dip in their overall happiness. A wide variety of unsubstantiated theories abound to explain the phenomenon. Until now, about the only thing no one had suggested was the origin of our species. Now an international team led by psychologist Alexander Weiss suggests the clue to crisis may lie in a shared ancestry with our supposed “evolutionary cousins.”1

“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,” explains economist Andrew Oswald, coauthor of the study published in Proceedings of the National Academy of Sciences. “Apes also have a pronounced midlife low, and they have none of those.”

“The U-shape found in human studies of age and well-being evolved in the common ancestors of humans and nonhuman primates, particularly the great apes,”2 the team suggests. While they acknowledge there could be other contributing factors, they believe work like theirs “could affirm Darwin’s view that ‘He who understands baboon would do more towards metaphysics than Locke.’”3

Apes, according to the assessment of their caregivers, suffer from a midlife crisis just as many humans do. The 508 apes surveyed were, like these two orangutans, in captivity. Their caregivers assessed not only general ape happiness and moodiness but also such factors as the creatures’ satisfaction and success in achieving their goals. Humans do tend to anthropomorphize animal behavior, and readers looking into the expressive faces of these orangutans have doubtless already decided what they’re thinking. As psychology professor Clive Wynne of the University of Florida, Gainesville, told BBC Nature last May when commenting on another study by psychologist Alexander Weiss, “Human beings have a very natural tendency to project human agency into almost anything that moves. It’s very deeply ingrained into our ways of trying to understand the world around us.”4 The problem with the current study, however, is not the question of whether apes in their thirties need a little more excitement in their lives but rather whether evolutionists can convince economists, psychologists, and others who determine policy for human society to base their plans on the false interpretations of evolution. Image credit: Left ape © Smileus / Fotolia at www.sciencedaily.com; right ape Tim Davis/CORBIS at www.nature.com.

The researchers opted not to have the chimpanzees and orangutans in zoos and sanctuaries around the world fill out their own surveys. Instead, they adapted happiness-assessment questionnaires used with humans by having zookeepers and caretakers answer for the apes. For instance, primate caregivers were asked, “How successful do you think the subject (the ape) is in achieving its goals?” and “How happy would (you) be if (you) were the subject for a week?”5 Though he admits the surveys were somewhat anthropomorphic, lead author Alexander Weiss considers them reliable.6

Humans may manifest behavior associated with midlife crisis by abandoning marriages for younger partners, changing careers, and buying fancy cars.

Humans may manifest behavior associated with midlife crisis by abandoning marriages for younger partners, changing careers, and buying fancy cars. Lest we ask what sort of goals an ape might set, Weiss says, “You don’t have the chimpanzee hitting mid-life and suddenly they want a bright red sports car. But there may be other things that they want like mating with more females or gaining access to more resources.”7

Oswald speculates that midlife crisis spurs adaptive changes, saying, “Maybe evolution needed us to be at our most dissatisfied in midlife.”8 Emory University primatologist Frans de Waal, author of Our Inner Ape, commenting on the study, suggested that less subjective measurements such as levels of stress-related hormones might have been more reliable but agrees with the evolutionary implications.9

If objective measurements confirm the primates’ U-shaped dip, then the results could ultimately contribute to the capacity of primate care facilities to optimize primate quality of life. After all, while primates do not share any evolutionary ancestry with humans, we as humans should be good stewards of the animals in our care.

The proposed applications of this study’s evolutionary conclusions, however, are disturbing. The researchers suggest governments design economic policies affecting human well-being on the basis of evolutionary considerations.10 They imply that evolutionary understanding could enlighten our grasp of the spiritual and the intellectual. To follow these suggestions would be foolhardy, building policies and principles of philosophy and psychology on fairy tales.

Nothing about this study supports the notion that humans and apes share a common ancestor. Owners of horses and dogs and cats and even milk-cows can attest to the fact that their animals can seem happy or moody. These owners can also note trends over time and even anthropomorphize human emotions and thoughts onto the animals. But such observations are no more indicative of common evolutionary ancestry than similar anatomical designs.