• Wild chimpanzees consume the equivalent of two cocktails daily from eating fermented fruit.
• The study provides chemical measurements of ethanol in fruits normally eaten by chimps.
• Research supports the "drunken monkey" hypothesis, suggesting human alcohol attraction has ancestral roots.

In the forests of Uganda and Côte d'Ivoire, chimpanzees are observed indulging in fruit that naturally ferments, leading to their daily alcohol consumption, which has been quantified to about 14 grams of ethanol, equivalent to two cocktails for a human. Scientists from UC Berkeley and other institutions conducted research revealing that these wild chimps consume substantial amounts of ripe fruits like figs and plums, which have an average alcohol content of about 0.3% by weight. This discovery highlights a surprisingly high intake, adjusting for their body mass, which is lower than that of humans, making their alcohol consumption effectively more significant than it appears at first glance, according to CBS News and SFGATE.

This extensive field research took place in major chimp habitats, collecting fruits from beneath feeding trees and testing for ethanol levels using several methods, including a device akin to a breathalyzer. They found that the chimps typically eat around 10 pounds of fruit daily. Robert Dudley, a key researcher and UC Berkeley professor, expressed surprise at the quantities, noting the findings bolster the "drunken monkey" hypothesis positing that the human affinity for alcohol may have derived from our fruit-eating primate ancestors. This hypothesis was further manifested in the results, which indicated that both male and female chimps consume averages that align with this theory, according to Reuters and BBC.

The research encompassed 21 distinct fruit species in the studied locations, discovering a significant role of figs in chimps' diets. While these findings are remarkable, experts pointed out that the chimps do not display signs of intoxication due to the gradual consumption of the fermented fruit over hours, which diffuses any potential alcohol effects. According to researchers, there remains a question whether chimps actively seek out higher-ethanol fruits or prefer them based on other traits such as sweetness. These insights are critical for understanding the evolutionary grounds of alcohol preference in humans and reflect patterns seen in both chimps and other foraging animals, as noted by UC Berkeley researchers and corroborated by independent primatologists, according to BBC and Reuters.