...an international team of scientists claims to have found evidence for a slump in wellbeing among middle-aged chimpanzees and orangutans. The lull in happiness in the middle years, they say, is the great ape equivalent of the midlife crisis.
The study, which was published on Monday in the journal Proceedings of the National Academy of Sciences, has raised eyebrows among some scientists, but according to the authors, the findings suggest that the midlife crisis may have its roots in the biology humans share with our closest evolutionary cousins.
Maybe they should provide the apes with Viagra, as needed.
The team from the US, Japan, Germany and the UK asked zookeepers, carers and others who worked with male and female apes of various ages to complete questionnaires on the animals. The forms included questions about each ape's mood, the enjoyment they gained from socialising, and their success at achieving certain goals. The final question asked how carers would feel about being the ape for a week. They scored their answers from one to seven.Or maybe the forms revealed that zookeepers reacted more negatively to middle aged apes? Maybe they felt more remorse for keeping animals in the prime of life, and less guilty for keeping them when they were either young and unable to fend for themselves or old and feeble. I find it hard to believe that a second hand opinion by zookeepers can actually capture the animals own experiences accurately.
More than 500 apes were included in the study in three separate groups. The first two groups were chimpanzees, with the third made up of orangutans from Sumatra or Borneo. The animals came from zoos, sanctuaries and research centres in the US, Australia, Japan, Canada and Singapore.
When the researchers analysed the questionnaires, they found that wellbeing in the apes fell in middle age and climbed again as the animals moved into old age. In captivity, great apes often live to 50 or more. The nadir in the animals' wellbeing occurred, on average, at 28.3 and 27.2 years old for the chimpanzees, and 35.4 years old for the orangutans. "In all three groups we find evidence that wellbeing is lowest in chimpanzees and orangutans at an age that roughly corresponds to midlife in humans," Weiss said. "On average, wellbeing scores are lowest when animals are around 30 years old."