Apes go through a midlife crisis.
Humans are members of the great ape family Hominidae, and the physical similarities between us and our primate cousins are clear. We have the same arrangement of internal organs and roughly the same number of bones, we lack external tails, and we even get the same diseases. So it only makes sense that we share some psychological similarities as well. A 2012 study published in the Proceedings of the National Academy of Sciences reported that chimpanzees and orangutans experienced a midlife crisis similar to that of humans.
The study analyzed the behavior of 508 chimps and orangutans in captivity at zoos in five different countries, and found that these animals’ well-being hits its nadir around their mid-20s or early 30s (the equivalent of middle age for chimps and orangutans). Of course, scientists couldn’t directly ask the chimpanzees how they felt, but instead relied on zookeeper questionnaires to assess the animals’ overall mood, level of joy in social situations, and how successful they were in achieving particular goals. Although the dataset is subjective, its sheer size highlights an overall trend that’s remarkably human, since we also tend to experience a dip in happiness and well-being around midlife. It’s just another trait that entwines us with our primate brethren.
Chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) are the closest living relatives to humans — they both share 98.8% of our DNA. Despite these similarities, these two members of the Pan genus developed entirely different social structures. While chimps form dominant (and often violent) male hierarchies, bonobos — which are only found in the central forest of the Democratic Republic of the Congo — are matriarchal. This is particularly striking because female bonobos leave their birthplace before puberty, and so often form strong female bonds with no familial ties whatsoever. Why do female bonobos form such bonds when their chimpanzee cousins do not? One theory suggests that the plentiful resources found in central DRC — compared to the drier climates of equatorial Africa where chimps live — allowed female bonobos to feel less competition when foraging, creating room for stronger bonds.
