Did Our Love Of Alcohol Start With Apes Eating Fermented Fruit? Scientists Say It Might Have

Scientists may finally have an answer to why humans developed a remarkable tolerance for alcohol — and it might come down to apes eating fermented fruit off the forest floor.

A new study led by Dartmouth College researchers in collaboration with the University of St. Andrews in Scotland introduces the term “scrumping” to describe apes habit of eating windfallen fruit, often already fermenting and slightly alcoholic. The term, borrowed from medieval German roots meaning “shriveled,” is meant to help scientists distinguish between fruit gathered from the ground and fruit plucked from trees — a previously ignored detail that could illuminate how humans developed their unusually high tolerance for alcohol.

“We never bothered to differentiate fruits in trees from fruits on the ground,” said Nathaniel Dominy, the Charles Hansen Professor of Anthropology at Dartmouth and corresponding author of the study published in BioScience.

“It’s a fascinating idea, but nobody studying these ape species, or Asian apes, had the data to test it. It just wasn’t on our radar,” Dominy said. “It’s not that primatologists have never seen scrumping — they observe it pretty regularly. But the absence of a word for it has disguised its importance. We’re hoping to fill an important void in scientific discourse.”

To examine how common scrumping is among great apes, researchers examined dietary reports of orangutans, chimpanzees, and mountain and western gorillas observed in the wild. The data was cross-referenced with the animal’s location relative to the ground, and the level at which the fruit is known to grow. If an ape at ground level was recorded eating a fruit known to grow at higher canopy levels, it was counted as scrumping.

The study revealed that African apes regularly scrump, but orangutans do not. That tracks with a 2015 gene-sequencing study that found the primary enzyme for metabolizing ethanol is less efficient in orangutans and other non-human primates.

The study authors suggest that the ability to efficiently metabolize ethanol allowed African apes to safely eat fermented fruit from the ground, an adaptation that would reduce competition with monkeys for the unripe fruit in trees. It could also help larger apes avoid climbing trees and getting injured falling down, a common enough hazard that previous studies suggest it influenced human evolution.

Because chimpanzees consume around 10 pounds of fruit per day, the researchers say they are likely consuming a non-trivial amount of alcohol on a regular basis.

“Scrumping by the last common ancestor of gorillas, chimpanzees, and humans about 10 million years ago could explain why humans are so astoundingly good at digesting alcohol,” Dominy said. “We evolved to metabolize alcohol long before we ever figured out how to make it, and making it was one of the major drivers of the Neolithic Revolution that turned us from hunter-gatherers into farmers and changed the world.”

There is also a social component to scrumping that humans may have retained, according to Catherine Hobaiter, a professor of psychology and neuroscience at St. Andrews and co-corresponding author of the study.

“A fundamental feature of our relationship with alcohol is our tendency to drink together, whether a pint with friends or a large social feast,” Hobaiter says. “The next step is to investigate how shared feeding on fermented fruits might also influence social relationships in other apes.”

While further research is necessary, the authors hope the scientific community finds value in the term ‘scrumping’, and continues to use it to differentiate the fruits eaten by apes. They say other novel terms have since become indispensable, such as “symbiosis,” first coined in 1877, and “meme,” coined by evolutionary biologist Richard Dawkins in 1976.

“These are great examples of words that we never knew we needed, until we did. If the term is useful, then it will catch on,” Dominy says. “That’s natural selection at work!”