Happier orangutans are more likely to live for longer, according to a new study.
A team of researchers in the UK and US devised a method to measure the happiness, or subjective well-being, of captive orangutans in zoos. In a follow-up study seven years later, the scientists found that happier primates were much more likely still to be alive.
The team, led by Dr Alex Weiss from the University of Edinburgh, asked the people who worked closely with each captive orangutan to participate in the study. He asked the keepers to complete a questionnaire about individual animals they knew well; assessing the orangutans' personalities and attitude. The assessment was modelled on established methods of assessing human well-being.
The keepers were asked how often the orangutans were in a good mood as opposed to a bad mood, how much they enjoyed social interactions and whether they were effective at achieving their goals. The keepers were also asked to speculate as to how happy they would be if they were the animals in question.
By working out a happiness score for each of 184 animals, the team was able to see how happiness influenced the orangutans' lives. Seven years later, when they revisited the study, they could see a clear association between happiness and longevity. The happiest orangutans lived up to 11 years longer than the least happy apes.
"[In captivity], we might be able to extend life by more closely monitoring the health of an animal that seems unhappy," explained Dr Weiss. He also thinks the work could be usefully applied to wild orangutans. "There are lots of sanctuaries that are temporary homes for animals that are rescued having been captured by traders and hunters. These happiness or well-being measures could be used to work out if an animal is ready to be reintroduced into the wild. I'd love to see this questionnaire being used more broadly."
These results could shed light on how happiness evolved, not just in orangutans but all primates, including ourselves. Dr. Weiss says "Already we have shown that certain personality traits linked to happiness share the same genetic basis in humans and chimpanzees. Studying these relationships across a wide range of species could yield fascinating insights into the evolutionary bases of happiness, depression and a host of other psychological characteristics that impact the lives of humans and, most likely, a range of other species."
This study gives an interesting insight into the effects of degrees of happiness on captive orangutans, based on the subjective assumptions of zoo keepers. However given the findings of recent research that mental illness is endemic in chimpanzees kept in zoos one must question whether the finding of this latest study is actually that the most unhappy orangutans in zoos die sooner than those who are less unhappy.
What do you think - can animals be happy in zoos?