Great apes also go through a “midlife crisis” – TVA Nouvelles

Great apes, like their human cousins, are most unhappy when they reach mid-life, according to a study published in Proceedings of the National Academy of Sciences. This discovery suggests that the famous midlife crisis could have biological causes in addition to social factors.

This slump, which we call the “midlife crisis,” is seen in all human societies and across different socioeconomic statuses, and even in other primates. We still don’t agree on the origin of the phenomenon.

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Although great apes cannot afford a luxury car or give up established jobs to learn pottery, they experience a period of dissatisfaction in midlife comparable to that of humans, according to a study. Research team from the University of Edinburgh.

An observation of chimpanzees and orangutans in captivity shows that the latter are happier at the beginning and end of their lives than in the middle. As for humans, the curve of their well-being takes the shape of a “U”, the low point of which corresponds to the late twenties and thirties, which corresponds to the human forties or fifties for these great apes.

Experience and its limits

To reach this conclusion, the research team monitored the well-being of more than five hundred chimpanzees and orangutans of all ages in captivity in zoos, research centers and sanctuaries in Japan, the United States, Australia, Canada and Singapore.

The primates’ level of satisfaction was measured using a survey given to their keepers. Four factors were assessed: the animal’s general mood, the enjoyment of socializing with other animals, how well the animal managed to complete tasks such as obtaining food or objects, and finally how satisfied the caretaker would be if he were there the animal’s skin for a week.

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Other scientists have pointed out that the chosen method relies on the subjectivity of caregivers and lacks quantitative data, such as measurement of stress hormones.

However, the zookeepers are the ones who maintain the closest relationships with the observed great apes. Previous research has shown that their assessment of primate moods is generally quite close to reality as measured by biological witnesses.


A biological origin?

If humans and their closest relatives, primates, experience a darker period in midlife, does that mean that the midlife crisis is a biological phenomenon? Despite the results of the University of Edinburgh study, it is still too early to be sure.

Three hypotheses are considered to explain the “U” curve of well-being by age. The first suggests that the brains of humans and great apes undergo changes in the areas responsible for well-being at this age. Logically, these changes would have an evolutionary advantage if they still existed today, such as the fact that they could provoke measures to improve one’s own life situation or to find one or more partners.

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The second hypothesis states that since well-being is generally associated with longer life expectancy, individuals who are already happier will, by simple elimination, live longer and therefore find themselves more numerous in the older portion of the curve.

The third hypothesis explains the phenomenon by older people benefiting from a wider range of behaviors that help them regulate their emotions through experience.

In any case, scientists agree that the midlife crisis, although it may be based on a still poorly understood biological phenomenon, finds expression through the prism of human culture. Such research represents a step forward toward better understanding and alleviating the stresses associated with midlife in both humans and primates.

With information from Nature and PNAS

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