In the wild, some animals have a taste for fermented fruit–which contains small amounts of alcohol. Now, for the first time, wild chimpanzees have been filmed eating and sharing this boozy fruit with one another. The fruit sharing is described in a study published April 21 in the journal Current Biology.
In the study, a research team set up cameras in Cantanhez National Park, a 408-square mile-wide preserve in Guinea-Bissau in West Africa. They documented the chimps sharing African breadfruit, which contains ethanol aka alcohol.
Why our evolutionary cousins deliberately seek out the alcohol remains unanswered. Humans have consumed alcohol for millennia, with social bonding being one of the primary benefits. The team from this new study suggests that our closest primate relatives could be doing something similar.
“For humans, we know that drinking alcohol leads to a release of dopamine and endorphins, and resulting feelings of happiness and relaxation,” Anna Bowland, a study co-author and University of Exeter conservation biologist and ecologist, said in a statement. “We also know that sharing alcohol–including through traditions such as feasting–helps to form and strengthen social bonds. So–now we know that wild chimpanzees are eating and sharing ethanolic fruits–the question is: could they be getting similar benefits?”
The team used motion-activated cameras in the park that recorded chimps sharing fermented fruits with one another on 10 separate occasions. The researchers then tested the fruit the chimps shared for alcohol content. The highest alcohol content was the
equivalent of 0.61 percent Alcohol By Volume (ABV). By comparison, a regular beer is about five percent ABV and the average red wine is 13.5 percent ABV.
[ Related: ‘Drunk’ animals might be more common. ]
While 0.61 percent ABV is pretty low, the team says it could be the “tip of the iceberg” for chimps as far as consumption. Fruit makes up 60 to 85 percent of the chimp’s diet, so the low levels of alcohol can add up quickly.
Importantly, the researchers stress that the chimps likely don’t get “drunk,” since that would make surviving in the wild difficult. The exact impact of the alcohol on their metabolism is currently unknown. However, recent discoveries of a molecular adaptation that increased the ethanol metabolism in the common ancestor of African apes suggests that eating fermented fruits may have ancient origins–including in both humans and chimpanzees.
“Chimps don’t share food all the time, so this behaviour with fermented fruit might be important,” study co-author and University of Exeter conservation ecologist Kimberley Hockings said in a statement. “We need to find out more about whether they deliberately seek out ethanolic fruits and how they metabolise it, but this behaviour could be the early evolutionary stages of ‘feasting.’ If so, it suggests the human tradition of feasting may have its origins deep in our evolutionary history.”
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