Many people in their late 40s or early 50s suffer a strange, empty feeling; a lack of contentment that they ascribe to the awareness of being halfway through life, yet fearing that their best is behind them. It's been dubbed the "midlife crisis" and, until now, it was thought to be a symptom of modern human existence and its attendant pressures.
However, research published this week in the US journal Proceedings of the National Academy of Science shows that apes display almost identical symptoms at the same stage of their lives.
The study of 508 chimpanzees and orang-utans in the US, Singapore, Japan, Canada and Australia surprised scientists, because apes lack the social and financial pressures - and the sense of their own mortality - that have long been thought to be causes of the malady.
Something we thought was a by-product of a life spent in the fast lane, struggling to pay bills, raising a family, adapting to changing technologies and workplace demands, and just keeping up with the Joneses, appears to be a fact of biology that also applies to other primates.
The good news is that it's the nadir of a U-shaped "happiness curve", and things improve as we get older. So, instead of racing out to get plastic surgery or a Ferrari, all we really have to do is keep calm and carry on.
