Wild Chimpanzees Drink Alcohol, Hinting at Ancient Human Attraction

Scientists have found that wild African chimpanzees consume alcohol by eating fermented fruit, suggesting that human attraction to alcohol may have ancient evolutionary origins.

Researchers Track Chimpanzee Alcohol Consumption

Aleksey Maro, a Ph.D. student at UC Berkeley, led the effort to collect chimpanzee urine samples in the Ugandan rainforest, assisted by Sharifah Namaganda, a Ph.D. candidate at the University of Michigan. Samples were typically collected in the morning, often using a plastic bag to catch droplets from overhead, ensuring minimal contamination.

Fermented Fruit and the Calorie Connection

Maro's team tested these samples for alcohol metabolism. Chimpanzees consume an average of 10 pounds of fruit pulp daily, including African star apples. When such fruits ripen, they can ferment and produce alcohol.

Maro suggested that for primates, the smell of alcohol might signal the presence of sugars, potentially serving as a shortcut for obtaining more calories. Primates are not believed to consume enough alcohol to become intoxicated.

For primates, the smell of alcohol might signal the presence of sugars, potentially serving as a shortcut for obtaining more calories.

Evidence for Ancient Evolutionary Origins

This association with a sugary reward is hypothesized to explain the evolutionary origin of human attraction to alcohol. Namaganda noted that great apes offer valuable insights into human evolutionary behavior, including the origins of alcohol preference.

Previous research indicated that many fruits consumed by chimpanzees contain ethanol. The current study definitively confirmed actual consumption: 17 out of 19 tested chimpanzees showed positive results for ethanol. At least 10 of these samples contained alcohol concentrations equivalent to one or two standard human drinks. Maro acknowledged the small sample size but described the finding as 'tantalizing.'

Maro described the finding as 'tantalizing,' suggesting that alcohol may have been a natural component of ancestral diets.

Publication, Expert Views, and Next Steps

The research was published in the journal Biology Letters. Primatologist Cat Hobaiter, who was not involved in the study, commented that these findings could open new avenues for understanding chimpanzee behavior and the evolutionary origins of human cultural rituals.

These findings could open new avenues for understanding chimpanzee behavior and the evolutionary origins of human cultural rituals.

A subsequent research step will involve determining whether chimpanzees exhibit a preference for fruits containing alcohol.