Scientists have found that wild African chimpanzees consume alcohol by eating fermented fruit, raising the possibility that human attraction to alcohol has deep evolutionary origins.
Late last summer, Aleksey Maro, a Ph.D. student at UC Berkeley, collected chimpanzee urine in a Ugandan rainforest to test whether the animals were metabolizing ethanol. The team typically collected samples in the morning, when chimps first urinate. One method involved catching droplets in a plastic bag stretched over a forked branch; field assistant Sharifah Namaganda of the University of Michigan described that uncontaminated “plastic bag pee” as the best sample.
Many fruits chimps eat—such as African star apple—can ferment when ripe and produce alcohol. Maro notes chimps eat about 10 pounds of fruit pulp per day. The researchers hypothesize that the scent of alcohol could signal sugar-rich food, a shortcut to calories, and that this association might help explain why humans are drawn to alcohol today, even though primates likely don’t consume enough to become intoxicated.
The urine analyses showed ethanol in 17 of 19 chimpanzees sampled. At least 10 individuals had ethanol concentrations roughly equivalent to a human having one or two drinks, though Maro cautions the sample size is small and not definitive. Still, he says it’s tantalizing to think alcohol was a routine part of ancestral diets.
The study appears in the journal Biology Letters. Cat Hobaiter, a primatologist at the University of St. Andrews not involved in the research, said the work opens new avenues for understanding chimpanzee behavior and possibly the evolutionary origins of human rituals and social practices involving alcohol. The researchers plan to investigate whether chimpanzees preferentially choose fruits that contain alcohol.
For NPR News, Ari Daniel. Copyright © 2026 NPR. All rights reserved.