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A research team led by the University of Exeter set up cameras in Guinea-Bissau's Cantanhez National Park. Footage of chimps sharing fermented African breadfruit—confirmed to contain ethanol (alcohol)—raises fascinating questions about if and why chimps deliberately seek out alcohol.

The paper, published in the journal Current Biology, is titled "Wild chimpanzees share fermented fruits."

Humans are believed to have consumed alcohol far back into our evolutionary history, with benefits for social bonding.

And the new study suggests our closest relatives might 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," said Anna Bowland, from the Center for Ecology and Conservation at Exeter's Penryn Campus in Cornwall.

"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 researchers used motion-activated cameras, which filmed chimps sharing fermented fruits on 10 separate occasions.

Fruit shared by these chimps was tested for alcohol content. The highest level found was the equivalent of 0.61% ABV (alcohol by volume—a measure used in alcoholic drinks).

This is relatively low. But the researchers say it may be the "tip of the iceberg," as 60–85% of chimps' diet is fruit—so low levels of alcohol in various foods could add up to significant consumption.

The researchers stress that chimps are unlikely to get "drunk"—as this would clearly not improve their survival chances.

The impact of alcohol on chimps' metabolism is unknown. But recent discoveries of a molecular adaptation that greatly increased ethanol metabolism in the common ancestor of African apes suggest eating fermented fruits may have ancient origins in species including humans and chimps.

"Chimps don't share food all the time, so this behavior with fermented fruit might be important," said Dr. Kimberley Hockings, also from the University of Exeter.

"We need to find out more about whether they deliberately seek out ethanolic fruits and how they metabolize it, but this behavior 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."