Chimpanzees caught at a "drink-in-the-mouth party"

Great apes share alcoholic fruit with their peers

Drinking binges in the animal kingdom:

Chimpanzees may have alcoholic "parties" similar to humans – and thus strengthen the sense of community within the group, biologists have discovered. They observed the great apes in the wild several times communally consuming fermented breadfruit. Chimpanzees rarely share their food. The celebratory mood of humans and apes could, in this case, be traced back to a common ancestor, the team suggests.

Sangria buckets, monkey style: Chimpanzees share alcoholic breadfruit. © Bowland et al.

Alcohol consumption is part of numerous human cultures – and has been for thousands of years. But great apes and other animals also consciously consume alcohol from time to time. Among other animals, wild spider monkeys have been observed preferring to eat slightly fermented fruit.

Alcohol as a social glue?

But why? Fermented, alcohol-containing fruits primarily serve a purely practical purpose: They are softer and therefore much easier to crack. This allows animals to access high-calorie food with little effort. But at least in primates closely related to us, alcohol consumption could serve a second purpose.

"Similar to grooming, alcohol can reduce stress and activate the endorphin system," report Anna Bowland of the University of Exeter and her colleagues. Chimpanzees and others may therefore also eat alcohol-containing fruits because they find the relaxed, slightly intoxicated feeling of well-being pleasant afterwards. When enjoyed together, this could also promote harmony and cohesion within the group – similar to the way we celebrate together.

Chimpanzees enjoy eating fermented fruits, like breadfruit shown here. But why? © Bowland et al.

Chimpanzee Parties in the National Park

In fact, biologists have now caught these great apes at such "alcohol-fueled parties" several times. Bowland and her colleagues observed ten cases of communal alcohol consumption among wild chimpanzees in Cantanhez National Park in Guinea-Bissau. A total of 17 animals of all ages and sexes shared fermented breadfruit weighing up to 30 kilograms.

As analyses revealed, 90 percent of the consumed fruit contained alcohol, but only at a level of up to 0.61 percent. By comparison, a standard beer contains approximately five percent. Accordingly, the chimpanzees did not stagger through the forest in a daze. Nevertheless, they probably ate enough of these fruits to feel the effects of the alcohol in some way, as the biologists report.

"An early evolutionary stage of celebration"

Interestingly, in seven out of ten cases, the chimpanzees shared the fermented fruits with their conspecifics even when there were still plenty of unclaimed fruits lying around. Bowland and her colleagues therefore suspect that these "drinking bouts" among chimpanzees could serve to strengthen social bonds – similar to what happens in humans. "Chimpanzees don't consistently share food, so this behavior with fermented fruit could be important," emphasizes senior author Kimberley Hockings.

"This behavior could represent an early evolutionary stage of celebration. If so, it suggests that the human tradition of celebration may have its origins deep in our evolutionary history," Hockings continues. It's conceivable, for example, that we share a common ancestor with some primates who also had a predilection for communal consumption of alcoholic beverages. (Current Biology, 2025; doi: 10.1016/j.cub.2025.02.067)

Source: University of Exeter