[Why do people think of me when a new piece comes out on drunken monkeys? I choose to be flattered. SB SM]
Chimps Consume the Equivalent of 2.5 Alcoholic Drinks per Day by Eating Fermented Fruit, Study Finds
Scientists report that chimpanzees consume about 14 grams of alcohol daily and suggest the result might help explain humans’ interest in booze
Sara Hashemi – Daily Correspondent, September 23, 2025
Wild chimpanzees consume vast amounts of fruit every day. Some of these fruits, however, are very ripe and fermented—making them “boozy,” with high levels of ethanol. As it turns out, that means the primates are consuming a lot of alcohol: the equivalent of multiple drinks daily, according to a new study.
To understand just how much alcohol chimpanzees consume, researchers measured the ethanol content in 21 kinds of fruit eaten by chimpanzees in Uganda’s Kibale National Park and Ivory Coast’s Taï National Park. They then calculated how much alcohol the chimpanzees would be ingesting based on prior research on the animals’ fruit consumption.
While the fruits only had an average alcohol content of about 0.3 percent, chimpanzees consume so much fruit that it all adds up. “The chimps are eating 5 to 10 percent of their body weight a day in ripe fruit, so even low concentrations yield a high daily total—a substantial dosage of alcohol,” senior author Robert Dudley, a biologist at the University of California, Berkeley, and a research associate at the Smithsonian Tropical Research Institute, says in a statement.
Overall, the researchers found that male and female chimpanzees are consuming an average of 14 grams of alcohol per day. A standard drink for humans contains about ten grams of alcohol—but when the team accounted for chimps’ lower body mass, they found that the animals consume the equivalent of about 2.5 human drinks daily. The findings were published in the journal Science Advances on September 17.
“The data set is convincing, representing a wide array of fruits ingested at sites in East and West Africa,” says Nathaniel Dominy, an evolutionary biologist at Dartmouth College who was not involved in the study, to Tim Vernimmen at National Geographic. “These findings are bound to stir debate and move the discipline forward.”
The researchers say their work further supports the “drunken monkey” hypothesis that Dudley proposed two decades ago, which argues that humans inherited an appetite for alcohol from our primate ancestors.
At the time, scientists were skeptical of this idea. But now, “what we’re realizing from this work is that our relationship with alcohol goes deep back into evolutionary time, probably about 30 million years,” Catherine Hobaiter, a primatologist at the University of St. Andrews in Scotland who was not part of the study, tells BBC News’ Elizabeth Dawson and Helen Briggs. “Maybe for chimpanzees, this is a great way to create social bonds, to hang out together on the forest floor, eating those fallen fruits.”
Other scientists point to the study’s limitations. Matthew Carrigan, a biologist at the College of Central Florida who was not involved in the research, notes to National Geographic that the authors didn’t actually calculate how much fruit the chimpanzees ate, just how much time they spent eating different types of fruit.
The study doesn’t mean chimpanzees are actually getting drunk on the regular—that would likely be dangerous for the wild animals. The chimps’ fruit consumption is spread out over the course of a day, so this prevents too much alcohol from building up in their bodies at once.
But, as with many humans, scientists say alcohol might help the animals strengthen social bonds by reducing tension. Study lead author Aleksey Maro, a biologist at the University of California, Berkeley, tells National Geographic that sometimes chimpanzees will go hunt or patrol together after eating lots of fruit.
“Patrolling is a dangerous activity, since chimps of different groups risk death in an encounter,” Maro adds. “It’s tantalizing to think that the alcohol in the fruits might help them to gather up their courage first.”