Origin of celebration? Monkeys consume alcohol together

Chimpanzees in the wild regularly consume fermented fruit – and in the process, they ingest surprisingly large amounts of alcohol . Researchers led by Aleksey Maro from the University of California report that the animals reach a dose roughly equivalent to consuming a small bottle of beer in humans .

In Kibale National Park (Uganda) and Taï National Park (Ivory Coast), the researchers analyzed the 20 most popular fruit varieties whose ripe pulp contains an average ethanol content of 0.3 percent.

Since a chimpanzee consumes around 4.5 kilograms of these fruits daily, the amount adds up to just under 14 grams of alcohol. Based on the animals' body weight—around 41 kilograms—this is equivalent to consuming more than half a liter of beer for humans.

The studies indicate that, from an evolutionary perspective, regular alcohol consumption is not just a cultural phenomenon of humans, but may have deeper roots in the behavior of our closest relatives.

As early as the beginning of 2025, a team from the University of Exeter had observed chimpanzees consuming alcoholic fruits together for the first time in the Cantanhez National Park in Guinea-Bissau, West Africa.

The majority of the African breadfruit fruits examined on the ground had an alcohol content of up to 0.61 percent. However, it was unclear whether alcohol at such low concentrations caused intoxication in the chimpanzees.

Using camera traps, the team recorded a total of 70 events in which chimpanzees almost always consumed alcoholic fruits together. Chimpanzees of both sexes and from different age groups participated in the party. "Our data provide the first evidence of the sharing of alcoholic food by great apes," the team writes in the journal Current Biology.

Alcohol consumption is not uncommon in animals

For a long time, researchers assumed that wild animals consumed ethanol, as alcohol is scientifically known, rarely and randomly. However, in 2024, a study published in the journal "Trends in Ecology & Evolution" found that alcohol consumption is not uncommon among wild monkeys, birds, and insects . Behavioral ecologist Kimberley Hockings from the University of Exeter in the UK was involved in both studies. "Alcohol consumption is much more common in nature than we previously thought," Hockings said. Ethanol is found in almost every ecosystem.

Model for human drinking parties?

The team from Exeter did not provide an explanation as to why the fermented food was shared or whether the alcohol was actually consumed intentionally.

Co-author of the first study, Matthew Carrigan of the College of Central Florida, has his doubts. "It's not beneficial to be drunk when climbing trees or being surrounded by predators at night," Carrigan says.

However, the observation supports the idea that the shared consumption of ethanol-containing foods is widespread and may have long played a role in hominoid, i.e. human, societies, the new study says.

"We know that drinking alcohol causes people to release dopamine and endorphins, which induce feelings of happiness and relaxation," says lead author Bowland. "And we also know that sharing alcohol—including as part of traditions like celebrations—contributes to the formation and strengthening of social connections."

This raises the question of whether this is similar in chimpanzees. In this case, it could be a primal form of celebration , says the ecologist.