The human penchant for alcoholic beverages may have a truly remote origin. A study from California State University Northridge (CSUN) determined that it could be an inheritance from primates.
Anthropology professor Christina J. Campbell’s theory is based on observations of spider monkeys in their natural habitat. Together with graduate student Victoria Weaver, she spent months analyzing the behavior of animals on Barro Colorado Island, Panama.
During the work, they discovered that the quadrupeds preferred fruit that contained ethanol, a byproduct of fermentative yeasts present within the pulp, which metabolizes sugar in the ripening process.
“For the first time, we have been able to show beyond a shadow of a doubt that wild primates, without human interference, consume fruit containing ethanol,” she said in a UCSN press release.
According to Campbell, “there seems to be some truth to the ‘drunken monkey’ hypothesis: that the human proclivity to consume alcohol stems from a deep-seated affinity of frugivorous primates for ethanol that occurs naturally within the ripe fruit.
According to the study published in the journal Royal Society Open Science, black-handed spider monkeys sniff fruit before selecting it. The scientists collected leftover pieces and measured the ethanol content of the pulp.
In that way, they found that the ethanol content in the pulp of the partially consumed fruit regularly ranged between 1% and 2%. Later, they determined that five of six urine samples from the monkeys tested positive for ethanol.
“It is likely that the monkeys ate the fruit with ethanol for the calories. They would get more calories from fermented fruit than from unfermented fruit. Higher calories mean more energy, ”explained the professor.
In parallel, the ripe fruit could also be attractive due to its “psychoactive and hedonic effects”. For the same reason, he concluded that “alcohol abuse, like diabetes or obesity, can be considered conceptually as a disease of nutritional excess.”