Wild chimpanzees are functional alcoholics. Not metaphorically. Literally—they consume the equivalent of 2 to 3 alcoholic drinks per day, every day, from naturally fermented fruit.
The reflexive assumption is that our closest living relatives exist in some state of primordial sobriety, unburdened by human vice. We imagine them as innocent, unspoiled by the corrupting forces that drive us toward intoxication. But a growing body of research, including a major 2025 study published in Science Advances, reveals that chimpanzees actively seek out and consume fermented fruit with remarkable consistency. They are not accidentally getting drunk. They are choosing to.
Researchers studying wild chimpanzee populations in West Africa documented the animals deliberately accessing fermented palm sap and other naturally fermented fruits, often camped beneath trees to exploit the resource. According to the Berkeley-led study published this year, the typical chimp ingests ethanol equivalent to what a human would get from 2 to 3 standard drinks daily. That's not a weekend bender. That's a sustained, deliberate intake of alcohol as part of normal behavior. Some individuals consume the equivalent of up to 10 drinks per day when fermented fruit is abundantly available. The data is unambiguous: fermentation and alcohol consumption are not human innovations.
What makes this more remarkable is the timeline. According to the Smithsonian's reporting on these findings, this behavior likely extends back 30 million years into our shared evolutionary history with apes—long before humans even existed as a species. Chimpanzees didn't learn this from us. We probably inherited the appetite from them. The ability to metabolize ethanol, to seek it out, to tolerate its effects: these are features our primate lineage has been refining since before the first hominins walked upright.
The mechanism is straightforward but revealing. Fruit-bearing trees in tropical forests occasionally ferment naturally due to yeast and bacteria. This fermentation produces ethanol. The smell of fermented fruit is pungent and easily detected. Chimpanzees, possessing keen olfactory senses and the behavioral flexibility to experiment with food sources, discovered these patches and exploited them. The caloric payoff is substantial—fermented fruit provides rapid energy—and the cognitive boost from mild intoxication may have carried advantages in social hierarchies or stress management. Once established, the behavior persisted across generations and became normalized within chimp culture.
This challenges a foundational myth about human nature: that our relationship with alcohol is uniquely ours, a defining marker of civilization (or its corruption, depending on your view). In reality, we're the descendants of a long line of primates with an evolved predisposition toward fermented food and drink. Our capacity for intoxication, our ability to enjoy it, our willingness to seek it out despite its risks—these aren't modern vices. They're ancient inheritances. We didn't invent the cocktail. We just got very good at mass-producing it.
The implication cuts deeper than a fun fact about animal behavior. If our appetite for alcohol is 30 million years old, shaped by natural selection, then the global struggle with alcohol use disorder isn't a failure of individual willpower or modern society's moral decay. It's a collision between an ancient primate drive—refined in an ancestral environment where fermented fruit was scarce and valuable—and a modern food system that makes ethanol abundant, cheap, and optimized for consumption. Understanding that origin story won't solve the problem. But it might shift how we think about it.