Wild chimpanzees drink the equivalent of almost two glasses of alcohol a day

If we test chimpanzees for blood alcohol levels, we would most likely see that they test positive as sI would have had a drink or two. And here the fault is not in the fact that they have a hidden bottle of whiskey, but in the sugars present in the fruits they consume and their microbial fermentation. But from here on, science has debated whether our attraction to alcohol It is due to an ‘evolutionary accident’ or a direct inheritance from our primate ancestors. Something that has been determined now.

A new study. Published by researchers at the University of California and which suggests that wild chimpanzees consume substantial amounts of ethanol in their daily diet.

To demonstrate this, the team went to Kibale National Park, Ugandato be able to monitor several chimpanzees. And instead of doing a blood test, the researchers opted for a non-invasive method by analyzing the urine of the 19 wild chimpanzees. In this case, what was being sought was not raw ethanol, but a very specific biomarker called ethylglucuronide which tells us that ethanol has been processed.

Your diet. As we have said before, the secret of this discovery is not in the alcohol that we know, but in the fruit. That is why during the research the chimpanzees fed almost exclusively on a species of canopy tree called the African star apple.

When specifically analyzing this apple, it was found that it contained alcohol in a proportion of 0.09%, while in some harvests it could reach 0.4%.

The results. After performing urine analyzes on the chimpanzees, it was possible to see that, of the 20 individual urine samples collected, 17 tested positive for ethylglucuronide, exceeding a threshold of 300 ng per milliliter of urine. But in addition, of a set of 11 of these positive samples, 10 tested positive again when subjected to a much higher clinical threshold of 500 ng/ml.

The “drunk monkey.” The researchers point out here that this continuous intake of fermented fruit translates into an average dose of 14 grams of ethanol per day for the chimpanzees. In human terms, it is as if they had drunk one and a half drinks a day.

These findings offer vital physiological support to the famous “drunken monkey” hypothesis which suggests that the attraction that modern humans feel for alcohol has its evolutionary origin precisely here: in an adaptation of our ancestors to locate, through long-distance smell, crops of ripe fruit and, therefore, more caloric thanks to the smell of ethanol.

A mismatch. The problem is that this vestige of the past has gone down the wrong path, since the current problem lies in an evolutionary imbalance. While our ancestors chronically consumed ethanol in low concentrations through a fruit-centered diet, today humans have access to distilled alcohol in massive quantities and not through a survival system.

Now, this discovery not only changes our understanding of primate feeding ecology, but opens the door to future research into how this natural alcohol consumption could affect the social behavior of chimpanzees, including factors such as aggression or reproduction.

Images | David Trinks Brian Jones

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