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The midlife crisis in humans and other apes

Humans tend to go through midlife crises regardless of context. So too, it appears, do apes. This column draws on recent research showing apes’ midlives to be, like humans’, dogged by the same pattern of unhappiness.

Happiness is approximately U-shaped across a person’s life. It has been known for more than two decades by behavioural scientists and wellbeing researchers that human happiness and mental health appear to follow a large, looping, U-shaped trajectory through the main part of people’s lives (cf. Feddersen, Metcalfe, and Wooden 2012). This statistical pattern has been found in dozens of countries.

  • People as young adults start happy.
  • Then comes a downhill patch for approximately two decades.

Both men and women go through their 40s at the lowest psychological ebb; the literal bottom usually hits around age 47 – so, sorry if that's your next birthday.

  • After mid-life, things look up.

People roar up the right-hand side of the U shape through their 50s and 60s. Contentment accelerates. The young just do not realise how enjoyable it is to be old (as long as you are in decent health).

Humans' midlife crisis is not unique

Recent research has shown that great apes – chimpanzees and orangutans – are the same: the U shape in happiness is not exclusive to human beings (Oswald et al 2012). This was not expected. Some of the theories that have been around for 20 years to explain the U shape are, today, in the dustbin.

It seems the curve of happiness should no longer be considered a social and economic phenomenon, the preserve of economists, sociologists, social psychologists, psychiatrists, or mysticists. Instead, intriguingly, the U shape appears to be so deep within us that it may need a natural sciences explanation.

New research

I and the global team from Edinburgh (including Alex Weiss), Arizona and Kyoto, released a paper showing that the great apes have a similar 'midlife crisis' to that in humans, and thus that our closest biological relatives also trace out the U shaped happiness over the lifespan. The parallels between the two curves are close; humans live to about a maximum of 100-110 years, and apes live at to a maximum of about 50-55 years. We have our midlife low just before 50, apes have theirs around their late 20s.

In our study we collected data on 508 orangutans and chimpanzees in 65 zoos across a wide range of nations. We recorded the keepers’ assessments of the psychological well-being of the animals. Each ape has several keepers, and every keeper was asked to assess the psychological well-being of their particular animal using a short questionnaire (including my favourite: "If you were that animal how happy do you think you would be on a scale of 1-7?"). We then averaged these responses, checking for consistency.

Why it matters

If you're not a scientist, why would you care?

One implication as to why the finding of the U shape in ape happiness is important is that it might help you, or those around you, understand, empathise or sympathise with those experiencing midlife crises. The consumption of antidepressants in Europe is highest among those in their mid-40s, a telling sign that we might want to assure those we know that are going through midlife that their crisis is, at least in part, 'natural'.

And if apes go through similar emotional turmoils to ours, they probably deserve more respect from human beings than they get.


Feddersen, John, Robert Metcalfe, and Mark Wooden (2012), “The costs of Hurricane Sandy: Life satisfaction as an alternative to GDP”, VoxEU.org, 2 November.

Weiss, A, J E King, M Inoue-Murayama, A J Oswald, and T Matsuzawa (2012), “Evidence of a ‘Midlife Crisis’ in Great Apes Consistent with the U-Shape in Human Well-being”, Proceedings of the National Academy of Sciences of the USA, November.


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