How Much Alcohol Are Chimps Imbibing?

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HUmans began to brew alcohol for consumption thousands of years ago, and researchers suggested that our ability to break alcohol in our body has evolving roots dating back millions of years. Alcohol, known to scientists under the name of ethanol, occurs naturally throughout nature, when microbes such as bacteria and yeast decompose sugars. This fermentation process, exploited by humans since ancient times, gave us the gifts of cheese, tofu and wine, among other delights.

But humans are far from being the only creatures soaking – Ayes, a kind of lemur, will seek nectar with a higher alcohol content, and the spider monkey urine has proven to contain secondary metabolites of alcohol. Wild chimpanzees, with whom humans share more than 95% of our DNA, were captured on the film on fruit fermentation with their friends earlier this year.

It’s like taking a third of beer at breakfast, lunch and dinner.

Now, for the first time, the researchers discovered the amount of alcohol that some chimpanzees come out of their fermented fruit snacks. In a new article published in Scientific advances, A team of scientists from the United States and Côte d’Ivoire reported that, during a day, the wild chimpanzees of their study had consumed about 14 grams of pure ethanol. This is the equivalent, by adjusting body mass, of a human imbued with more than one standard drink per day, explains Aleksey Maro, a graduate student and study author of the University of California.

“We can say, quite officially, that animals chronically ingest ethanol, in particular our parents of chimpanzees,” explains Maro.

Maro and his colleagues have discovered by following wild chimpanzees in two national parks in Africa – Kibale in Uganda and Tai in Côte d’Ivoire – and by picking up trial samples of 20 species of ripe fruit that chimpanzees generally like to eat. What they found is that these fruits have an average alcohol content of approximately 0.26% in weight. It might not seem much, but primatologists in these places estimate that chimpanzees eat 10 pounds – or about 7 to 14% of their body weight – fruit per day. The monkeys tended to prefer a fig called Ficus mucuso in kibale and plum fruits Parinari Excelsa Tai trees. These treats were among the fruits with the highest alcohol content.

These chimpanzees are probably not wasted.

The chimpanzees in captivity are a bit different – these animals do not eat as much fruit because of their more sedentary lifestyles, explains Maro. The fruits they eat come from domesticated plants by humans to have a hearty shelf life and are less likely to ferment in a good water.

But the big question – Chimpanzees get drunk on their daily diet – still needs a little research. Maro works on it. This summer, he spent time finding chimpanzee urine – striking it in an umbrella or the use of a pipette to bring it together with a leaf – to see if the chimpanzees metabolized alcohol like humans. “If the chimpanzees metabolize ethanol in their liver, it means that it circulates in their blood and also goes to their brain,” he adds.

Since the average quantity of alcohol that the ordinary wild chimpanzee takes every day would be equivalent in human terms to blur a third of beer with each meal, it is unlikely that the chimpanzees are wasted, says Maro. But the results could always have evolutionary implications for humans, whether it is the unpacking of human attraction for alcohol or the risk of alcohol dependence from which millions of people suffer. The capacity of chimpanzees to get drunk is limited to the speed at which they can engulf the fruits and how much they can adapt in their stomach. For humans, these same limits do not apply.

“Why are humans like that, why do we have the diseases we have and problems and ills?” Maro asks. “Much of this can be answered by evolutionary medicine, or the intersection of medicine and the study of the evolution of humans.”

To find out more about Nautilus About soaking animals, consult our functionality of Marco Altamirano: “Do animals get drunk?”

Lead image: Morevector / Shutterstock

• Sara Kiley Watson

  Published on September 19, 2025

  Sara Kiley Watson is a climate and scientific journalist currently based in the Netherlands.