Chimpanzees May Consume 2 Alcoholic Beverages a Day from Fermented Fruit

A new study has found that chimpanzees may consume the equivalent of about two alcoholic beverages a day through fermented fruit.

The study, which was published in the peer-reviewed journal Science Advances by researchers from the University of California, Berkeley, on Sept. 17, was based on the observation of two groups of chimpanzees: one in the Ivory Coast and the other in Uganda. 

Researchers collected random samples of fruits in the area around both groups of chimps and tested them for the presence of ethanol — a.k.a alcohol. They found that the animals were likely consuming about half an ounce of ethanol per day. 

While this amount would equate to about one drink for the average human, it comes out to approximately two drinks when adjusted to reflect a chimpanzee’s smaller size, per Aleksey Maro, one of the study’s authors in a press release from Berkeley. 

Robert Dudley, a professor at the university’s Department of Integrative Biology and study co-author, additionally pointed out that the current estimate for alcohol consumption among chimps may be on the conservative side.

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“If the chimps are randomly sampling ripe fruit […], then that’s going to be their average consumption rate, independent of any preference for ethanol. But if they are preferring riper and/or more sugar-rich fruits, then this is a conservative lower limit for the likely rate of ethanol ingestion,” he explained, per the release.

However, this doesn’t mean that the chimps are roaming around intoxicated. The study’s authors note that the low-grade exposure to ethanol over the course of a whole day is more akin to humans eating fermented foods like kimchi.

The study’s authors do not currently know if chimps are drawn to riper, more fermented fruits because of the ethanol itself or because those are the foods with a higher concentration of sugar. 

Dudley, who is the author of 2014’s The Drunken Monkey: Why We Drink and Abuse Alcohol, posits that humans may trace our penchant for alcohol consumption back to our primate ancestors.

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“It just points to the need for additional federal funding for research into alcohol attraction and abuse by modern humans. It likely has a deep evolutionary background,” he said in the press release.