Chimpanzees love alcohol and their pee proves it
Popular Science
by Laura BaisasFebruary 25, 2026
AI-Generated Deep Dive Summary
Chimpanzees have a penchant for alcohol, and their urine provides undeniable proof. Researchers from the University of California, Berkeley discovered that wild chimps consume significant amounts of ethanol through their diet of fermented fruits. The study, published in *Biology Letters*, found that 17 out of 20 urine samples tested positive for ethyl glucuronide, a metabolic byproduct of alcohol consumption. These findings confirm the "drunken monkey hypothesis," which suggests that primates, including humans, may have evolved a tendency to seek out alcoholic beverages due to their ancestors' fruit-eating habits.
To gather this evidence, graduate student Aleksey Maro and integrative biologist Robert Dudley turned to an unconventional method: collecting chimpanzee urine. Working in Uganda's Kibale National Park, Maro used forked branches covered with plastic bags to safely collect samples without getting sprayed. This innovative technique allowed them to analyze the urine of 19 different chimps over 11 days. The results showed that most samples contained levels of ethanol byproducts comparable to what humans would have after consuming one or two drinks.
The study revealed that male and female chimps alike tested positive for alcohol metabolites, with some samples exceeding human forensic thresholds. This suggests that chimps actively seek out fermented fruits, potentially favoring the more alcoholic options. The findings not only validate the drunken monkey hypothesis but also shed light on the evolutionary origins of our own attraction to alcohol.
Understanding how and why chimps consume alcohol offers insights into human evolution and behavior. Our shared ancestry with these primates highlights a deep-rooted connection between fruit-eating and alcohol ingestion, which may have played a role in shaping both primate and human biology. This research bridges the gap between animal behavior and human health, sparking curiosity about how alcohol consumption impacts other species—and ourselves.
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Originally published on Popular Science on 2/25/2026