Humans inherited their love of booze from their primate ancestors

by MikeB · April 12, 2022

Provided you believe in human evolution from primates as most people do, it seems pretty certain that humans have inherited their love of alcohol from their primate ancestors who gorged on fruit containing alcohol. This is the conclusion of a study by Christina Campbell and of a book written by evolutionary physiologist Robert Dudley: The Drunken Monkey, why we drink and abuse alcohol (UC Press 2014).

The Drunken Monkey. Screenshot from YouTube video.

Dudley postulates that humans’ love of alcohol goes back at least 18 million years and perhaps to 45 million years ago with the origin of diurnal fruit-eating primates. Christina Campbell, a professor in anthropology at the Department of Anthropology at California State University, Northridge, led a team looking at fruit collected from black-handed spider monkeys in Panama.

They discovered that the alcohol content in the ripe fruit was between 1% and 2% by volume. When they analysed the urine of the monkeys, they found it contained secondary metabolites of alcohol. This demonstrated that they were using alcohol as a source of energy.

Christina Campbell said:

“For the first time, we have been able to show, without a shadow of a doubt, that wild primates, with no human interference, consume fruit containing ethanol. This is just one study, and more needs to be done, but it looks like there may be some truth to the drunken monkey hypothesis – that the proclivity of humans to consume alcohol stems from a deep-rooted affinity of fruit-eating primates for naturally occurring ethanol within ripe fruit.”

The American scientists believe that the smell of alcohol led primates to eat ripe fruit millions of years ago.

Dudley wrote that some of the fruit eaten by primates has a naturally high alcohol content at around 7% which is about half that of wine. At the time he didn’t have the information to demonstrate that monkeys or apes actively sought out fermented fruit or digested the alcohol in the fruit. Campbells work appears to have plugged that lacuna.

In fact, Dudley worked with the CSUN team on this research, which has been published in the journal Royal Society Open Science. They are currently studying the fruit eaten by chimpanzees in Uganda and the Ivory Coast.

Dudley said:

“They are probably not getting drunk, their guts are filling before they reach inebriated levels, but it is providing some physiological benefit.”

My gut feeling (sorry for the pun) is that he is incorrect but I am in no position to disagree with him. I would suggest that the monkeys are deliberately eating the fruit because it does make them a little bit drunk. And they want to get a bit drunk because it makes them feel better. I wonder whether there are any alcoholics among the monkey population anywhere in the world? And if so, they need to be studied because the world needs to find a way to genuinely tackle the problem of alcoholism which is so devastating to the individual and their families and loved ones.