Scientists Coin "Scrumping" for Ape Behavior That May Explain Human Love of Alcohol

Scrumping of fruit by left; a gorilla, and right; a chimpanzee.

July

/ 2025

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Scientists have introduced a new term for an ancient behavior that may hold the key to understanding humanity's complex relationship with alcohol. Researchers from Dartmouth and the University of St Andrews have coined "scrumping" to describe African apes' preference for eating fallen, fermented fruit from the forest floor, a behavior that could explain how our ancestors first developed the ability to metabolize alcohol millions of years before humans learned to brew it.

The new study, published in the journal BioScience, suggests that this seemingly simple foraging behavior may have been a crucial evolutionary stepping stone that led to the sophisticated alcohol metabolism that allows humans to enjoy everything from wine with dinner to weekend celebrations.

The Mystery of Missing Terminology

For decades, primatologists have observed African apes regularly consuming fruit that had fallen to the forest floor, but the significance of this behavior remained hidden in plain sight. The problem wasn't a lack of observation, it was a lack of proper terminology to distinguish this specific feeding pattern from general fruit consumption.

"We never bothered to differentiate fruits in trees from fruits on the ground," explains Nathaniel Dominy, the Charles Hansen Professor of Anthropology at Dartmouth and corresponding author of the study. "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."

The researchers borrowed the term from English dialect, where "scrumping" traditionally describes gathering or stealing windfall apples and other fruits. The word derives from the medieval German "schrimpen," meaning "shriveled" or "shrunken," used to describe overripe or fermented fruit. Today, "scrumpy" refers to a cloudy apple cider containing 6-9% alcohol.

Naturally fermented fruit demonstrates how ethanol occurs in wild primate diets. (Cristie Guevara/Public Domain)

The Genetic Revolution That Changed Everything

The importance of scrumping behavior gained new significance following a 2015 genetic study that revealed a crucial evolutionary development. Researchers discovered that eating fermented fruit may have triggered a single amino acid change in the last common ancestor of humans and African apes approximately 10 million years ago, boosting their ability to metabolize alcohol by an astounding 40 times.

This genetic mutation, known as A294V in the alcohol dehydrogenase enzyme ADH4, represents one of the most significant metabolic adaptations in primate evolution. The enhanced ability to process ethanol would have provided African apes with a substantial advantage, allowing them to safely consume energy-rich fermented fruits that other animals couldn't tolerate.

Catherine Hobaiter, professor of psychology and neuroscience at St Andrews and co-corresponding author of the study, emphasizes the social implications:

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

African Apes vs Asian Cousins: A Tale of Two Metabolisms

To investigate scrumping behavior across different ape species, the research team analyzed dietary reports from wild orangutans, chimpanzees, and both mountain and western gorillas. Their methodology was straightforward but revealing: if an ape was observed eating fruit at ground level that was known to grow in the forest canopy, it was classified as scrumping behavior.

The results were striking. African apes - chimpanzees and gorillas - regularly engage in scrumping, while Asian orangutans do not. This finding perfectly aligns with the 2015 genetic study showing that the enhanced alcohol metabolism enzyme remains relatively inefficient in orangutans and other non-African primates.

The metabolic advantage of processing ethanol appears to serve multiple evolutionary purposes beyond simple intoxication tolerance. It may allow African apes to avoid competing with smaller monkeys for unripe fruit in trees, and perhaps more importantly, it reduces the need for dangerous tree climbing that could result in potentially fatal falls.

The Staggering Scale of Alcohol Consumption

The implications of regular scrumping behavior become even more significant when considering the sheer volume of fruit consumption among African apes. Chimpanzees consume approximately 10 pounds (4.5kg) of fruit daily, suggesting they regularly ingest substantial amounts of naturally occurring alcohol. This chronic low-level exposure to ethanol may represent a significant and previously overlooked component of chimpanzee life.

"Given that chimpanzees consume about 10 pounds of fruit each day, the team's analysis suggests they ingest a nontrivial amount of alcohol," Dominy notes. This level of consumption indicates that our closest living relatives may have been engaged in regular alcohol consumption for millions of years, long before humans developed agricultural societies capable of producing fermented beverages.

From Forest Floor to Human Civilization

The evolutionary journey from scrumping to human alcohol production represents one of the most fascinating examples of how ancient biological adaptations can influence modern culture. The enhanced alcohol metabolism that developed 10 million years ago may have laid the groundwork for one of humanity's most significant technological achievements: controlled fermentation.

"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 explains. "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 that turned us from hunter-gatherers into farmers and changed the world."

This perspective reframes the development of fermentation technology not as a purely cultural innovation, but as the culmination of millions of years of biological preparation. The ability to safely process alcohol may have provided the foundation for the development of beer, wine, and other fermented beverages that became central to early agricultural societies.

A Social Aspect

The research also opens intriguing questions about the social aspects of alcohol consumption. If African apes demonstrate social behaviors around fermented fruit consumption, it suggests that the communal aspects of human drinking - from ancient ritual feasts to modern social gatherings - may have evolutionary roots stretching back to our primate ancestors.

A group of monkeys sharing fermented fruit

Chimpanzees sharing fruit. (Anna Bowland / Cantanhez Chimpanzee Project / University of Exeter)

A study by research by the University of Exeter recently published in Current Biology has provided the first visual evidence of wild chimpanzees deliberately sharing fermented fruit containing alcohol, offering compelling support for the scrumping hypothesis. A research team from the University of Exeter captured this unprecedented behavior using motion-activated cameras in Guinea-Bissau's Cantanhez National Park, documenting chimpanzees sharing fermented African breadfruit on 10 separate occasions.

"For humans, we know that drinking alcohol leads to a release of dopamine and endorphins, and resulting feelings of happiness and relaxation," explains Anna Bowland from Exeter's Centre for Ecology and Conservation. "We also know that sharing alcohol - including through traditions such as feasting - helps to form and strengthen social bonds. So now we know that wild chimpanzees are eating and sharing ethanolic fruits - the question is: could they be getting similar benefits?"

The footage reveals particularly intriguing social dynamics, as chimpanzees don't typically share food regularly. Dr. Kimberley Hockings, also from the University of Exeter, suggests this selective sharing behavior around fermented fruit might represent "the early evolutionary stages of 'feasting.'" If confirmed, this would indicate that human feasting traditions may have origins stretching back millions of years to our common ancestors with African apes.

The coining of "scrumping" represents more than simple terminology; it provides scientists with a crucial tool for understanding one of the most significant evolutionary adaptations in primate history. As researchers continue to investigate this behavior, we may gain unprecedented insights into the deep evolutionary roots of human culture, sociality, and our complex relationship with alcohol.

Top image: Left; Scrumping of Pentadesma butyracea (Clusiaceae) by a western gorilla; photograph: M. Robbins. Right: Scrumping of Gambeya albida (syn. Chrysophyllum albidum; Sapotaceae) by an eastern chimpanzee; photograph: C. Hobaiter. Source: BioScience

By Gary Manners