Great apes may have 'midlife crisis', a study suggests

By Jeremy ColesReporter, BBC Nature

"What we are testing is whether the U-shaped curve can describe the association between age and well-being in non-human primates as it does in humans," psychologist and lead author Dr Alexander Weiss of the University of Edinburgh told BBC Nature.

An international team of researchers is suggesting that orangutans and chimpanzees might be going through a "mid life crises" aswell, just as humans. 
Experiments have shown that happiness and enjoying life is rich in the younger ages of apes, they tend to be unhappy while being an "adult" but return to the state of happiness again when reaching the old age. This is the known u-shaped curve, which humans also go through. 

Dr Weiss predicted and was hoping that the results would have a similar curve due to the close relationship between humans, chimpanzees and orangutans and in fact, the curve is the same. 

Testings :

The study constisted of 508 chimpanzees and orangutans from varying age levels, from zoos, sanctuaries and research centres. Zoo keepers, volunteers, researchers and caretakers who had worked with this subject for a couple of years watched the apes. They knew everything about their behaviour. The helpers had to score the animals numerically for well being and happiness on a short questionnaire. This was based on a human well being model, but made for use in non human primates. 
"Dr Weiss said that the similarities between humans, chimps and orangutans go beyond genetics and physiology. You don't have the chimpanzee hitting midlife and suddenly they want a bright red sports car. But there may be other things that they want like mating with more females or gaining access to more resources."

So in fact, chimpanzees and orangutans go through a very similar mid life crisis just as humans do. I found it really interesting to see that apes are actually that similar to us humans. No one would have thought that they tend to question their life or go crazy when they are in the middle of their lifes. But as the research showed, apes are more similar to us than we think, even on the psychological level.