Faith Nyasuguta
Chimpanzees in the forests of Guinea-Bissau have been filmed sharing naturally fermented fruit, sparking scientific speculation that the origins of feasting and social drinking may stretch further back in evolutionary history than previously thought.
A team of researchers, led by scientists from the University of Exeter, documented wild chimpanzees in Cantanhez National Park engaging in what appears to be a bonding ritual involving the consumption of fermented African breadfruit. Though the alcohol content of the fruit was relatively low, peaking at 0.61% alcohol by volume, the frequency and context of the sharing hint at deeper social dynamics at play.
“Chimpanzees don’t share food very often, so when they do, it suggests the behaviour is meaningful,” said Dr. Kimberley Hockings, from the University of Exeter’s Centre for Ecology and Conservation. “The fact that they are sharing fermented fruit could indicate that they gain some sort of benefit, possibly social or emotional.”
The study was based on video footage collected using motion-activated cameras over several months. Researchers observed 10 occasions of chimps sharing the dense, fibrous fruit, and noted that the behaviour crossed age and gender lines. In one clip, two adult females, nicknamed Chip and Ate, passed up a larger piece of unfermented breadfruit for a smaller, fermented one, hinting that taste or effect may be influencing their choices.
In another scene, two adult males, Mandjambe and Gary, approached ripe breadfruit with aggressive posturing. Mandjambe secured a portion and began eating while a third male, Bobby, prevented Gary from interfering. Eventually, all three were seen sampling the fruit. This type of interaction resembles early human feasting behaviour, where social hierarchies and bonding often play out over shared food and drink.
According to Dr. Anna Bowland of the University of Exeter, “In humans, alcohol triggers the release of dopamine and endorphins, leading to feelings of relaxation and happiness. We also use alcohol in social rituals. It’s possible chimpanzees may experience similar effects, which could enhance group cohesion.”
This isn’t the first time chimpanzees have been linked to alcohol consumption. A 2015 study by Hockings’ team recorded chimps stealing palm sap fermented by humans. Some even showed signs of intoxication, disrupting the group’s nightly routines.
However, the researchers behind the current study doubt that chimpanzees intentionally seek drunkenness, suggesting that being impaired would offer no survival advantage. Instead, the study raises an intriguing evolutionary question: could human traditions of feasting and social drinking have originated with a shared ancestor?
Published in Current Biology, the paper opens the door for further research into how non-human primates metabolize ethanol and whether they intentionally seek out fermented foods.
“This could be the beginning of a much deeper understanding of the roots of human social rituals,” Hockings said.
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