Wild Chimpanzees Likely Ingest Large Amounts Of Alcohol Each Day

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Two male chimpanzees eating the plum-like fruit of the evergreen Parinari excelsa tree at Taï National Park in the Ivory Coast in 2021. Credit: Aleksey Maro/UC Berkeley

University of California - Berkeley

Sept. 17, 2025

The first-ever measurements of the ethanol content of fruits available to chimpanzees in their native African habitat show that the animals could easily consume the equivalent of more than two standard alcoholic drinks each day, according to researchers at the University of California, Berkeley.

It's not clear whether they actively seek out fruit with high ethanol levels, which are typically riper fruit with more sugars to ferment. But the availability of ethanol in many species of fruit that they normally eat suggests that alcohol is a regular part of their diet and likely was a part of the diets of our human ancestors.

"Across all sites, male and female chimpanzees are consuming about 14 grams of pure ethanol per day in their diet, which is the equivalent to one standard American drink," said UC Berkeley graduate student Aleksey Maro of the Department of Integrative Biology. "When you adjust for body mass, because chimps weigh about 40 kilos versus a typical human at 70 kilos, it goes up to nearly two drinks."

A "standard drink" in the United States contains 14 grams of ethanol, irrespective of the consumer's body size, although in much of Europe the standard is 10 grams.

The 21 species of fruit Maro sampled at two chimp study sites—Ngogo in Uganda and Taï in Ivory Coast—had an average alcohol content of 0.26 percent by weight. Primatologists who have studied chimps at these sites estimate that the animals consume about 10 pounds (4.5 kilograms) of fruit per day, on average, and that fruit makes up about three-quarters of their diet.

The researchers have also recorded for each site the approximate proportion of each fruit species in the chimp diet. This information allowed the Berkeley biologists to calculate an average rate of dietary ethanol consumption.

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