Cheers! Wild Chimps Filmed Sharing 'Boozy' Fruits in World First

Two adult males feed on fermented African breadfruit (Credit: Bowland et al.)

In a nutshell

Wild chimpanzees in Guinea-Bissau regularly share fermented fruits containing alcohol (0.01-0.61%), offering the first evidence of “social drinking” in non-human primates
Chimps often chose to share more fermented fruits even when fresher options were available, suggesting potential preference for alcohol-containing foods
This behavior indicates that social alcohol consumption might have deep evolutionary roots dating back millions of years before human brewing began

EXETER, England — Next time you toast with friends over dinner, your primate cousins might be doing something remarkably similar in the forests of West Africa.

Scientists have caught wild chimpanzees not only eating naturally fermented fruits containing alcohol but actively sharing these “boozy snacks” with their companions. This breakthrough finding, just published in Current Biology, points to social drinking behaviors that possibly existed millions of years before humans started brewing beer.

Boozy Breadfruit: What the Researchers Found

The research team spent months in Guinea-Bissau’s Cantanhez National Park tracking wild chimpanzees and their eating habits. Using hidden cameras (these chimps aren’t comfortable around humans), they captured footage of the apes consuming and sharing African breadfruit that had naturally fermented on the forest floor.

Tests revealed these fruits contained measurable alcohol levels—between 0.01% and 0.61% alcohol by volume. That’s much less than beer, but the chimps seemed drawn to fruits with higher alcohol content. The ripest fruits, which had been fermenting longer, contained around 0.26% alcohol on average and were frequently selected for sharing.

In 10 separate incidents, chimps passed fermented fruits among at least 17 individuals of various ages and sexes. Even more revealing, in seven cases, chimps chose to share the boozy fruits even when non-fermented options were readily available nearby.

Chimpanzees sharing fruit. (Credit: Bowland et al.)

Why Do Chimps Prefer Fermented Fruit?

Humans and African apes share a genetic mutation that dramatically improves our ability to process alcohol. This adaptation appeared around 10 million years ago, hinting that our ancestors regularly encountered fermented foods in their diet.

Fermentation offers several advantages. It softens tough fruit rinds—researchers noted chimps sometimes struggled with fresher breadfruits, while the softer, fermented versions required much less effort. Fermentation also boosts vitamin content and breaks down some plant toxins.

The social aspect appears crucial. Just as humans often find that alcohol reduces stress and promotes bonding, chimps may experience similar effects. During sharing, fruit possessors showed no signs of aggression and didn’t appear pressured into sharing.

“Alcohol consumption triggers endorphin release, which may further promote sociality and sharing,” the research team noted in their paper.

Two adult females feed on a remnant of fermented African breadfruit (Credit: Bowland et al.)

New Chapter in Human Evolution?

Dr. Kimberley Hockings, study co-author, believes these observations could be just the beginning. Given how common natural fermentation is in forests, similar behaviors likely occur across different ape populations.

“Chimps don’t share food all the time, so this behavior with fermented fruit might be important,” Hockings says in a statement. “We need to find out more about whether they deliberately seek out ethanolic fruits and how they metabolize it, but this behaviour could be the early evolutionary stages of ‘feasting.’ If so, it suggests the human tradition of feasting may have its origins deep in our evolutionary history.“

Answering this, of course, requires longer-term studies tracking specific individuals and their food choices.

Many behaviors we consider uniquely human clearly have deeper evolutionary roots than previously recognized. That glass-clinking tradition at your dinner table? You’re participating in a social ritual that may have begun millions of years ago, when our ancestors were still swinging through the trees.

VIDEO: (A) Clip shows an adult female (Eva) sharing an early ripe T. africana fruit found to contain 0.14% ethanol, with her young infant. She first places her hands on the fruit and takes a bite bipedally, the female then tries to pull the fruit apart using both her hands and feet but is unsuccessful. While the female is still holding the fruit, and chewing on a piece, her infant takes a small bite from the fruit. The female takes a final bite and departs with her infant. (B) Two adult females (Chip and Até) share a remnant of fermented T. africana fruit, small enough to be monopolised, and found to contain 0.61% ethanol. This was the smallest T. africana fruit present during the sharing event and visually the most fermented. Chip closely observes Até and looks between the food item and Até’s mouth. Chip then sits, picks up and feeds on a very small piece of T. africana, no aggression is shown by Até. When Até departs, Chip takes a handful from the remaining fruit to feed on. At the time of sharing, a larger T. africana fruit is available (not in possession) but was visually less fermented. Two minutes following the sharing event a juvenile chimpanzee approaches the fermented fruit and smells it. They then extract a stick from the fruit that has some pulp attached and bring it to their nose. Following this they choose not to feed on the fruit. (C) Two adult males, Mandjambé and Gary, approach a late ripe T. africana fruit in an aggressive stance. Mandjambé claims the fruit and begins to feed, while another adult male, Bobby, defends him against Gary. Gary then grooms Mandjambé, while Bobby goes to feed on an alternate late ripe, T. africana fruit (containing 0.20% ABV). Mandjambé and Gary approach the fruit possessed by Bobby. In the absence of aggression, Gary feeds on the fruit while still in Bobby’s possession. (Credit: Current Biology)

Paper Summary

Methodology

Researchers studied wild chimpanzees in Cantanhez National Park, Guinea-Bissau between April and July 2022. They measured ethanol content in 28 African breadfruit (Treculia africana) samples using a portable breathalyzer across different ripeness stages. Since the chimpanzees were unhabituated to human presence, camera traps were deployed at three locations to record feeding and sharing behaviors. The researchers classified sharing events as either “passive” (tolerating others feeding from the fruit) or “active-passive” (allowing others to take food from the mouth).

Results

Twenty-four of 28 (86%) sampled fruits contained ethanol with levels ranging from 0.01-0.61% alcohol by volume, with “late ripe” fruits containing significantly higher ethanol (averaging 0.26%). Chimpanzees were observed feeding on these fruits in 70 separate events, with sharing documented in 10 distinct occasions between 17 individuals across all age and sex classes. At the time of sharing, 90% of shared fruits contained measurable ethanol. Nine of ten sharing events were “passive,” with one “active-passive” sharing event observed. Most notably, in seven of ten events, sharing occurred even when other non-monopolized fruits were available, and in two events, chimpanzees clearly selected more fermented fruits over less fermented ones.

Limitations

The researchers acknowledge several limitations to their study. The chimpanzees observed are unhabituated, and their relatedness is unknown except between mothers and their offspring, making it difficult to assess the role of kin selection in sharing behavior. Additionally, the sample size of sharing events (10) is insufficient to draw definitive conclusions about motivations for sharing or whether ethanol ingestion was deliberate. Long-term observations of individuals with established relationships would be necessary to fully understand the social context and intentionality of fermented food sharing.

Funding and Disclosures

The research was supported by funding from the Primate Society of Great Britain (PSGB), Darwin Initiative, Natural Environment Research Council (NERC), Wenner-Gren Foundation, Canada Research Chairs program, and Natural Sciences and Engineering Research Council of Canada. The authors declared no competing interests.

Publication Information

The study “Wild chimpanzees share fermented fruits” was published in Current Biology (Volume 35, R273-R280, April 21, 2025) by Anna C. Bowland, Elena Bersacola, Marina Ramon, Joana Bessa, Amanda D. Melin, Matthew A. Carrigan, Xavier A. Harrison, and Kimberley J. Hockings.

Cheers! Wild Chimps Filmed Sharing ‘Boozy’ Fruits in World First