• Posted August 10, 2025

New Study Links Apes' Fermented Fruit Habit to Human Alcohol Metabolism

Scientists suspect African apes’ historic fondness for noshing on fermented fruit from the forest floor triggered a genetic change that helps explain why modern-day humans digest alcohol so well.

But they never had a name for it, so it didn’t get the focus that it deserved, said Nathaniel Dominy, a professor of anthropology at Dartmouth College in Hanover, N.H.

In the new issue of the journal BioScience, U.S. and Scottish researchers set out to rectify that. 

They named it "scrumping."

"It’s not that primatologists have never seen scrumping — they observe it pretty regularly," Dominy said in a college news release. "But the absence of a word for it has disguised its importance."

Scientists reported in 2015 that eating fermented fruit may have triggered a single amino acid change in the last common ancestor of African apes and people that kicked up their ability to metabolize alcohol by 40 times.

"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," he added, "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."

Scrumping is the act of gathering — or sometimes swiping — fallen apples and other fruits off the ground. 

It’s an offshot of a German word used to describe overripe or fermented fruit. In modern-day England, scrumpy is a cloudy apple cider that is 6% to 9% alcohol. 

After giving the primates’ habit a name, researchers took a closer look at scrumping among wild orangutans, chimps, and mountain and western gorillas.

They paid attention to the height at which fruit grows, how far off the ground an animal was when it ate. It counted as scrumping if an ape was seen eating a fruit known to grow in middle or upper levels of the forest canopy.

Chimpanzees are especially fond of fruit, consuming about 10 pounds a day, and the new study suggests they ingest "a non-trivial amount of alcohol," Dominy said. 

Researchers say that suggests that chronic low-level exposure to ethanol may be a key component of their life — and a major force of human evolution.

Not all great apes enjoy a tipsy treat, however. African apes scrump regularly. Oraguntans don’t. 

Researchers said their findings mesh with the 2015 study, which found that the primary enzyme for metabolizing ethanol isn’t very efficient in orangutans and other non-human primates. 

Authors of the new paper suspect that metabolizing ethanol may let African apes safely eat the boozy fruit they find on the ground — a genetic adaptation that may free them from competing with monkeys for fruit still on the tree. It may also spare big apes the risk of climbing and possibly falling out of trees, they add.

Study co-author Catherine Hobaiter, a professor of psychology and neuroscience at the University of St. Andrews in Scotland, said humans might have retained some of the social aspects that apes bring to their scrumping.

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

Researchers hope other scientists will see the value of their new term. Other words have been invented over the years to capture new concepts — such as "symbiosis," in 1877 and "meme" in 1976.

"These are great examples of words that we never knew we needed, until we did," Dominy said. "That’s natural selection at work."

More information

Harvard University’s Center for Wellness and Health Promotion has more about alcohol tolerance.

SOURCE: Science Daily, news release, Aug. 1, 2025