Chimpanzees regularly consume fermented fruit in the wild – ingesting significant amounts of alcohol in the process, according to a new studypublished by Science. Researchers led by Aleksey Maro from the University of California reported this month that each day the animals consume a dose equivalent to approximately one small bottle of beer for humans.
In Uganda’s Kibale National Park and the Ivory Coast’s Taï National Park, the researchers analyzed the 20 most popular fruit varieties, whose ripe pulp contains an average alcohol content of 0.3%.
Since a chimpanzee consumes around 4.5 kilograms of these fruits each day, the amount adds up to just under 14 grams of alcohol. Measured against the animals’ body weight of around 41 kilograms, this corresponds to the consumption of more than half a liter of beer in humans.
The research suggests that regular alcohol consumption is not solely a cultural phenomenon for humans in evolutionary biology, but could have deeper roots in the behavior of our closest relatives.
These findings echo the results of another study published this spring, in which a team from the University of Exeter also observed chimpanzees consuming alcoholic fruits together in Cantanhez Forests National Park in Guinea-Bissau, West Africa.
The majority of the African breadfruit tree fruits examined had an alcohol content of up to 0.61%. However, it was unclear whether the low concentration of alcohol caused intoxication in the chimpanzees.
Using camera traps, the team recorded a total of 70 events in which chimpanzees almost always consumed alcoholic fruit together. Chimpanzees of both sexes and from different age groups participated in the party.
“Our data provide the first evidence for ethanolic food sharing and feeding by wild nonhuman great apes, and supports the idea that the use of alcohol by humans is not ‘recent’ but rather rooted in our deep evolutionary history,” the team wrote in the journal Current Biology in April.
Alcohol consumption not uncommon among animals
For a long time, researchers assumed that wild animals consumed ethanol, as alcohol is scientifically known, only rarely and accidentally. However, in January 2025, a study published in the journal Trends in Ecology & Evolution found that alcohol consumption among wild monkeys, birds, and insects is not uncommon after all.
“It’s much more abundant in the natural world than we previously thought, and most animals that eat sugary fruits are going to be exposed to some level of ethanol,” behavioral ecologist Kimberley Hockings from the University of Exeter, who was also involved in the previous study, told the university’s website, adding that the substance can be found in nearly every ecosystem.
A precursor for human drinking?
The research team said more work was needed to understand why the fermented food was shared and whether the alcohol was consumed deliberately.
“From an ecological perspective, it is not advantageous to be inebriated as you’re climbing around in the trees or surrounded by predators at night – that’s a recipe for not having your genes passed on,” study co-author Matthew Carrigan from the College of Central Florida told the website.
However, the observation supports the idea that the shared consumption of ethanol-containing foods is widespread and may have long played a role in human societies.
“On the cognitive side, ideas have been put forward that ethanol can trigger the endorphin and dopamine system, which leads to feelings of relaxation that could have benefits in terms of sociality,” said the study’s lead author Anna Bowland, from the University of Exeter. “To test that, we’d really need to know if ethanol is producing a physiological response in the wild.”
This article was originally written in German.
