This could explain the reasons for our penchant for drinking: our chimpanzee cousins ​​consume the equivalent of several glasses of alcohol.

Conducted in African forests where these animals live, the study supports the theory that humans inherited this attraction from monkeys as well as their ability to metabolize alcohol , which is toxic.

By collecting fruits commonly eaten by chimpanzees and measuring their ethanol content, a form of alcohol produced by the fermentation of sugars, researchers were able to establish that our closest cousins ​​were exposed to this substance daily through their diet .

And not just a little. According to their calculations based on the measured content and the very large quantity of fruit ingested per day by these primates, they estimate that their daily consumption is around 14 grams of ethanol .

"You could say it's the equivalent of a pint" of beer for a human, weighing much more than a chimpanzee, Aleksey Maro, lead author of the study published in the journal Science Advances, told AFP.

Are they drunk? The question remains open, because while this consumption "is not negligible , " it "is very diluted and more associated with food," notes this doctoral student in systems biology at the University of California at Berkeley.

"Drunken Monkey" Theory

In any case, these experiments carried out in Uganda and Ivory Coast have made it possible to show "for the first time that our closest living relatives consume physiologically significant doses of alcohol on a daily basis," he continues.

This is an element that reinforces the "drunken monkey" hypothesis formulated more than ten years ago by an American biologist, Robert Dudley, who is also a co-author of the study.

According to this postulate, human beings' appetite for alcohol and their ability to metabolize it come from the fact that our primate ancestors were exposed to this substance daily through their frugivorous diet.

"The name is a misnomer; it should be called the evolutionary hangover theory," jokes Mr. Maro.

Initially received with skepticism by several experts, this theory has gained popularity in recent years, with several research studies showing an interest among certain monkeys in alcoholic substances or even in very ripe fruits with a high ethanol content.

"Many new questions"

For Nathaniel Dominy, professor of anthropology and evolutionary biology at Dartmouth College, interviewed by AFP, the study published Wednesday is "a real tour de force" but raises "many new questions" , notably on the biological and behavioral consequences of such chronic exposure in these monkeys.

Or even on the real attraction of these primates for this psychoactive substance, the researchers were unable to determine whether or not the chimpanzees deliberately sought out fruits with a high ethanol content.

Far from being anecdotal, this subject should continue to be explored to enable a better understanding of the origins of human alcohol consumption and to better assess its risks and potential benefits, argues Aleksey Maro: "We can learn more about ourselves through chimpanzees."