Chimpanzees Consume Alcohol equivalent to Multiple Drinks Daily, Study Finds
Researchers from the University of California, Berkeley, have discovered that wild chimpanzees ingest a meaningful amount of ethanol through their natural diet of fruit. The findings,published in Science Advances,reveal that chimpanzees likely consume around 14 grams of pure ethanol daily – the equivalent of a standard alcoholic drink in the United States.
The study involved measuring ethanol content in 21 species of fruit available to chimpanzees at two research sites: Ngogo in Uganda and Taï in Ivory Coast. The average alcoholic graduation of the sampled fruits was 0.26% by weight. Considering chimpanzees consume approximately 4.5 kilograms of fruit per day, constituting roughly three-quarters of their diet, researchers were able to calculate their average ethanol intake.
Adjusting for body mass – chimpanzees average around 40 kilograms compared to a typical human’s 70 kilograms – the equivalent consumption for a human would be nearly two alcoholic drinks per day.
“In all sites, male and female chimpanzees consume about 14 grams of pure ethanol per day in their diet,” explained Aleksey Maro, a postgraduate student at UC Berkeley’s Department of Integrative Biology.
Researchers note that while it’s unclear if chimpanzees actively seek out fruits with higher ethanol levels (frequently enough found in more mature, fermenting fruits), the widespread availability of ethanol in their diet suggests that our human ancestors were likely similarly exposed to alcohol from fermented fruits.
Professor Robert Dudley, of UC Berkeley’s Department of Integrative Biology, emphasized the impact of consistent fruit consumption. “Chimpanzees consume between 5 and 10% of their body weight per day in ripe fruit, so even low concentrations produce a high daily total: a substantial dose of alcohol.” He added that the calculated intake represents a conservative estimate, as chimpanzees may preferentially select fruits with higher sugar content and, therefore, higher ethanol levels.
despite this consistent intake, chimpanzees do not exhibit obvious signs of intoxication. Maro explained that a chimpanzee would need to consume an excessive amount of fruit to become visibly drunk. Though, this chronic, low-level exposure suggests a potential evolutionary link between alcohol consumption and the dietary habits of our shared ancestors with chimpanzees – our closest living relatives among the apes.
Maro concluded, “Chimpanzees consume an amount of alcohol similar to what we would consume if we ate fermented foods. Human attraction for alcohol probably arose from this dietary inheritance of our common ancestor with chimpanzees.”