Wild chimpanzees in Uganda and Côte d’Ivoire are reported to consume approximately two human-sized alcoholic drinks daily, primarily from the fermented fruits they eat. A study conducted by researchers at the University of California, Berkeley, revealed that these chimpanzees ingest about 14 grams of ethanol from nearly 10 pounds of fruit each day, which translates to the equivalent of two drinks for an average human when adjusted for body weight.
The researchers discovered this by analyzing the alcohol content in the fruits consumed by chimps in Kibale National Park and Taï National Park, indicating that alcohol forms a significant part of their diet. UC Berkeley graduate student Aleksey Maro noted that while chimps weigh around 40 kilos compared to a typical human weight of about 70 kilos, their daily alcohol intake is substantial enough to yield a high total dosage of alcohol.
Interestingly, it’s still unclear why these chimps are drawn to such fermenting fruits. However, it is suggested that the sweetness and riper nature of these fruits, which contain higher levels of sugars, may attract them. UC Berkeley Professor Robert Dudley theorizes that this behavior could be linked to the "drunken monkey" hypothesis, which proposes that the alcohol-drinking habits of humans may have roots in the preferences of our primate ancestors for energy-dense, fermented fruit.
Despite their impressive alcohol consumption, researchers indicate that the chimpanzees do not exhibit signs of intoxication due to the quantity of fruit required for them to feel bloated and experience a buzz. This study highlights that an inclination towards alcohol consumption may not only be a characteristic of modern humans but could also be traced back to shared behaviors with our primate relatives.