In nature, chimpanzees consume significantly more alcohol than previously thought.

A new study released by the University of Berkeley shows that adult chimpanzees consume alcohol from eating fermented fruit. They can have up to 14 grammes of ethanol, or alcohol, on average per day – the equivalent of a small beer. It is unclear whether the chimpanzees consciously choose to eat fermented fruit because it is sweeter, or if the consumption occurs by chance.

This supports the theory that the human taste for alcohol is deeply rooted in evolution. Early humans, who share characteristics with modern chimpanzees, mostly ate fermented or partially fermented fruit.

Alcohol as an essential part of daily life

As part of the study, scientists from Berkeley analysed the behaviour of chimpanzees in Ngogo, Uganda, and Tai, Ivory Coast. Researchers found that the animals consumed around 4.5 kilogrammes of fruit per day, meaning fruit made up around three-quarters of their diet. This means that chimpanzees consume around 5 to 10 percent of their body weight in ripe fruit.

Of the approximately 20 types of fruit analysed during the research, the alcohol content was found to be around 0.26%. Judging by the high quantity of fruit consumed by the chimpanzees on a daily basis, alcohol forms a significant part of their daily lives.

Effect of two double shots 

"Across all locations, male and female chimpanzees were found to ingest around 14 grammes of pure ethanol through their noses each day," explained biologist Aleksey Maro. This is around the equivalent of a small beer or a double shot. If this amount were to be adapted to a chimpanzee's body weight, where they weigh an average of 40 kilogrammes, it would correspond to an alcohol effect in humans of almost double the amount, so two small beers, or two double shots respectively. However, this would be spread across an entire day.

Human addiction to alcohol is likely inherited 

It is unclear whether chimpanzees deliberately choose to consume alcoholic fruit because they contain more sugar, or whether they are chosen at random. However, researchers were unable to detect signs of intoxication, so the amount consumed is not sufficient. However, the constant low level of alcohol consumption could be linked to human interactions with alcohol.