Chimpanzees May Consume the Equivalent of 2 Alcoholic Beverages a Day from Fermented Fruit, According to a New Study

A new study suggests that chimpanzees may consume the equivalent of about two alcoholic drinks a day, thanks to fermented fruit.

Published in the peer-reviewed journal Science Advances on Sept. 17, the research was conducted by scientists from the University of California, Berkeley. They observed two groups of chimpanzees: one in the Ivory Coast and another in Uganda.

Researchers collected random fruit samples around both chimp populations and tested them for ethanol, commonly known as alcohol. Their findings indicate that the chimps are likely ingesting about half an ounce of ethanol per day.

While that amount would equal roughly one drink for an average human, it translates to about two drinks when adjusted for a chimpanzee’s smaller body size, according to Aleksey Maro, one of the study’s authors, in a Berkeley press release.

Robert Dudley, a professor in UC Berkeley’s Department of Integrative Biology and co-author of the study, noted that this estimate might actually be conservative.

“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 in the release.

However, this doesn’t mean the chimps are walking around intoxicated. The researchers emphasize that the low-grade exposure to ethanol over the course of a day is more similar to humans consuming fermented foods like kimchi.

At this time, the study’s authors aren’t sure whether chimps are drawn to riper, more fermented fruit because of the ethanol content itself or simply due to higher sugar concentrations.

Dudley, author of 2014’s The Drunken Monkey: Why We Drink and Abuse Alcohol, suggests that humans’ attraction to alcohol may have roots in our primate ancestors.

“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.