EARTH, Laniakea Supercluster—It turns out Chimpanzees like to knock one back every so often too.

In the dense jungle canopies of Uganda’s Kibale National Park and ­Côte d’Ivoire’s Taï National Park, wild chimpanzees are reportedly consuming something akin to two cocktails a day, not through a bartender’s offer, but via ripe, naturally fermented fruit. A new study published in Science Advances finds that these apes ingest about 14 grams of ethanol daily from the fruit they eat.

The scientists collected fallen fruit from trees chimps regularly feed on, measured ethanol levels (averaging about 0.3% by weight) and estimated consumption based on how much fruit the animals eat — roughly 10 pounds per day for adult chimps. Because chimps are smaller than humans, that daily dose of alcohol by body weight is roughly equivalent to two standard drinks in humans.

Despite the numbers, researchers found no evidence that the chimps are stumbling or showing signs of intoxication. The alcohol enters their systems gradually, spread over their foraging hours.

“It’s difficult to say how much consuming this amount of dietary alcohol would affect the behavior of chimpanzees,” said Aleksey Maro, lead author of the study.

Professor Robert Dudley, who first proposed the “drunken monkey” hypothesis,
told Reuters that the “ingestion of alcohol would thus be advantageous for caloric gain and ultimately survival.”

"The underlying attraction mechanisms may have been retained in modern humans, rendering our tendencies to consume liquid alcohol - sometimes to excess - an evolutionary hangover,’” said Dudley.

This work isn’t just adorable primate trivia. The findings feed into a larger argument: that humans taste for alcohol didn’t start with the invention of wine or beer, but with ancestors who routinely encountered ethanol whenever they ate fruit left too long in the sun. Wild chimps are specialists in ripe fruit; more than 70% of their diet comes from these sugary, often fermenting sources.

The researchers also wonder whether chimps deliberately choose more ethanol-rich fruit — fruit that smells slightly of fermentation, or that’s riper and sugarier. There may be selection, not just accident. If so, it offers clues to how early hominins might have developed preferences that eventually led to fermentation, brewing, and later, complex human alcohol culture.

The study also raises several open questions. Scientists still don’t know exactly how chimpanzees metabolize alcohol — whether they possess genetic adaptations that protect them from harm or if the amounts they consume are simply too low to cause damage. Another uncertainty is whether ethanol influences social behavior. Could slightly fermented fruit affect interactions during mating season, alter the dynamics of territorial patrols, or shift how groups behave when food is especially abundant? As Reuters noted, researchers see these as important directions for future work.

Beyond immediate health and behavior, the findings may also touch on human evolution. It’s possible that human ancestors’ exposure to naturally occurring ethanol shaped more than just taste preferences. Researchers wonder if it could have influenced neurological development, risk-taking tendencies, tool use, or even the origins of cultural rituals around alcohol. Or maybe it’s just nature’s way of showing Earthlings the roots of intoxication, pleasure, and perhaps their own complicated relationship with alcohol.