age-related changes in the brain that are mirrored in humans. Weiss conceded that, unlike men, apes are not known to pursue radical and often disastrous lifestyle changes in middle age. Robin Dunbar, Professor of Evolutionary Psychology at Oxford University, was dubious about the findings. “What can produce a sense of well-being 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 think about. They’re not particularly good at seeing far ahead into the future; that’s one of the big differences between them and us.” Alexandra Freund, Professor of Psychology at the University of Zurich, was also sceptical. She said the concept of a midlife crisis was shaky 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 well-being it is very small and, in many studies, it’s not there at all.” But Weiss believes the findings could point to a deeper understanding of the emotional crisis some men may experience. “If we want to find the answer as to what’s going on with the midlife crisis, we should look at what is similar in middle-aged humans, chimps and orangutans,” he said.