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Midlife crisis strikes chimps, orangs too

Primate ageing Men in the throes of a midlife crisis should probably stop blaming a troubled marriage, their kid's education costs, or technology that makes them feel ancient compared to their younger colleagues.

A new study has found that chimpanzees and orangutans, too, often experience a midlife crisis, suggesting the causes are inherent in primate biology and not specific to human society.

"We were just stunned" when data on the apes showed a U-shaped curve of happiness, says economist Andrew Oswald of the University of Warwick in England and a co-author of the paper published in the Proceedings of the National Academy of Sciences.

The U-shaped curve of human happiness and other aspects of well-being are as thoroughly documented as the reasons for it are controversial.

Since 2002 studies in some 50 countries have found that well-being is high in youth, plunges in midlife and rises in old age.

The euphoria of youth comes from unlimited hopes and good health, while the contentment and serenity of the elderly likely reflects "accumulated wisdom and the fact that when you've seen friends and family die, you value what you have," says Oswald.

The reasons for the plunge in wellbeing in middle age, when suicides and use of anti-depressants both peak, are murkier.

In recent years researchers have emphasised sociological and economic factors, from the accountant's recognition that she will never realise her dream of starring on Broadway to the middle manager's fear of being downsized, not to mention failing marriages and financial woes.

'Burst of madness'

In what Oswald, 58, calls "a burst of madness," since no such study had ever been attempted, he and his colleagues decided to see whether creatures that don't have career regrets or underwater mortgages might nevertheless suffer a well-being plunge in middle age.

They enlisted colleagues to assess the well-being of 155 chimps in Japanese zoos, 181 in US and Australian zoos and 172 orangs in zoos in the United States, Canada, Australia and Singapore. Keepers, volunteers, researchers and caretakers who knew the apes well used a four-item questionnaire to assess the level of contentment in the animals, says psychologist Alex Weiss of Scotland's University of Edinburgh. One question, for instance, asked how much pleasure the animals - which ranged from infants to greybeards - get from social interactions.

All three groups of apes experienced midlife malaise: a U-shaped contentment curve with the nadir at ages 28, 27 and 35, respectively, comparable to human ages of 45 to 50.

Do primates feel despair?

Why would chimps and orangs have a midlife crisis? It could be that their societies are similar enough to the human variety that social, and not only biological, factors are at work, says Oswald. Perhaps apes feel existential despair, too, when they realise they'll never be the alpha male or female.

An evolutionary explanation is even more intriguing.

"Maybe nature doesn't want us to be contented in middle age, doesn't want us sitting around contentedly with our feet up in a tree," he says. "Maybe discontent lights a fire under people, causing them to achieve more" for themselves and their family.

"By knowing our results, people might be gentler on themselves" when they experience a midlife crisis, says Oswald. "Knowing that it's biological, they'll realise that if they can just hang on they'll likely come out the other side."