Wild Chimps Unknowingly Drink Alcohol Every Day, Study Reveals Evolutionary Link

Wild chimpanzees in parts of Africa are unknowingly consuming the equivalent of a bottle of beer each day through their diet of fermented fruit, according to new research from the University of California, Berkeley.

The study, conducted in Côte d’Ivoire and Uganda, found that chimps ingest approximately 14 grams of ethanol daily — nearly two UK alcohol units by eating ripe fruits such as figs and plums that naturally ferment on the forest floor.

Researchers believe this behaviour may offer insight into the origins of human alcohol consumption.

Aleksey Maro, a researcher involved in the study, said the human attraction to alcohol likely stems from a shared dietary history with chimpanzees.

“Human attraction to alcohol probably arose from this dietary heritage of our common ancestor with chimpanzees,” he explained.

The findings support the “drunken monkey” hypothesis, first introduced by Professor Robert Dudley of UC Berkeley.

The theory suggests that early primates developed a taste for alcohol through their dependence on sugary, fermented fruits.

Dudley noted that chimps consume large quantities of ripe fruit daily, resulting in a measurable intake of ethanol.

“The chimps are eating 5 to 10% of their body weight a day in ripe fruit, so even low concentrations yield a substantial dosage of alcohol,” he said.

BBC News reported that while scientists were initially sceptical of the hypothesis, growing evidence has shifted expert opinion.

Professor Catherine Hobaiter, a primatologist at the University of St Andrews who was not involved in the study, said the findings suggest our relationship with alcohol may stretch back roughly 30 million years in evolutionary history.

“What we’re realising from this work is that our relationship with alcohol goes deep back into evolutionary time, probably about 30 million years,” she said.

She added that for chimpanzees, gathering and eating fallen fruit may also serve as a way to strengthen social bonds.

Despite the alcohol intake, researchers emphasised that the chimpanzees do not appear to become intoxicated.

Dr Kimberley Hockings of the University of Exeter, who was also not part of the research team, said the alcohol levels consumed are not high enough to cause drunkenness.

“This would clearly not improve their survival chances,” she noted.

The study offers a compelling glimpse into how evolutionary biology may influence modern human behaviour and how our primate relatives might be enjoying nature’s own brew without even realising it.