Did Drunk Apes Help Us Evolve? New Research Reveals Why Humans Digest Alcohol So Well

Long before humans learned to brew beer or wine, our ape ancestors may have been enjoying nature’s own alcohol. A new study in BioScience suggests that apes eating fermented fruit, sometimes called “drunk apes,” could explain why humans today digest alcohol better than most animals.

Scientists have introduced a new word for this behavior: scrumping. It describes the act of picking up and eating fallen fruit that has started to ferment on the ground. Chimpanzees, gorillas, and other African apes do this often, and in the process, they consume small amounts of natural alcohol.

The researchers stress that naming this behavior is more than wordplay. Without a clear term, field scientists often lump fruit from trees and fruit from the ground together, which hides the real importance of scrumping in ape diets.

“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,” says Nathaniel Dominy, an anthropology professor at Dartmouth.

Interestingly, the word scrumping has roots in medieval Europe. It comes from the German word schrimpen, meaning “shriveled,” used to describe overripe fruit. In England today, scrumpy is still the name of a strong, cloudy apple cider.

What the researchers found

The research team looked at how apes interact with fruit in their natural habitats. They discovered that African apes are regular “scrumpers.” This means they often eat overripe fruit that has begun to produce ethanol, the same alcohol found in drinks.

Genetic studies have also revealed something remarkable. African apes, unlike many other primates, carry a mutation in a gene called ADH4. This tiny change made their bodies about forty times better at breaking down ethanol. In simple terms, apes developed a natural upgrade that allowed them to handle alcohol without getting as sick as other animals would.

To test how common scrumping is, researchers compared feeding data across species. They found that chimpanzees and gorillas frequently scrump, while orangutans almost never do. This matches the genetic evidence, since orangutans lack the same alcohol-processing mutation.

Why this discovery matters

This finding matters because it helps explain why humans have such a high tolerance for alcohol compared to other species. It may also show how a simple dietary habit influenced the course of evolution.

By eating fermented fruits, apes gained more calories from ethanol itself. They also saved energy by eating fruit from the ground instead of climbing trees, which can be dangerous. A 2023 study even showed that the risk of falling from trees was so severe it helped shape human anatomy.

Scrumping may have also reduced food competition with monkeys, who prefer unripe fruit in the canopy. For chimpanzees, who eat up to 10 pounds of fruit every day, this means they likely take in a steady trickle of ethanol. Scientists believe this chronic low-level exposure may have been a major force in human evolution.

For humans, this ancient advantage may have laid the groundwork for something much bigger: the cultural role of alcohol in feasting, rituals, and social bonding.

How fermented fruit shaped survival

The study suggests that scrumping offered several survival benefits.

• Extra calories: Ethanol contains energy, so fermented fruit gave apes a bonus source of nutrition.
• Safer access: Eating from the ground reduced risky climbs and possible falls.
• Competition relief: Apes avoided direct competition with tree-dwelling monkeys.
• Cognitive push: Deciding which fruits to eat may have sharpened planning and problem-solving skills.

But what kinds of fruits were most often scrumped? The researchers found that chimpanzees in Budongo, Uganda, preferred fruits with inedible exocarps, thick skins or husks that protect the fruit on the forest floor. These tougher outer layers likely slowed decay, making the fruit more attractive and nutritious when eaten later.

Did feasting start with apes?

Perhaps the most fascinating idea from this research is the link between scrumping and social life. Apes are known to share food, and fermented fruits may have been high-value items worth sharing. Eating these fruits together could have encouraged group bonding.

In humans, alcohol has long been part of social gatherings, from small feasts to sacred rituals. The researchers suggest that the roots of this tradition may lie in the rainforests of Africa, where our ancestors shared fermented fruits long before the first human-made drink.

“A fundamental feature of our relationship with alcohol is our tendency to drink together, whether a pint with friends or a large social feast,” says Catherine Hobaiter, a primatologist at the University of St Andrews.

Who is most affected by this discovery

This research affects several groups:

• Scientists gain a new way of understanding how diet and genetics shaped human evolution.
• Anthropologists and historians can connect ancient ape behavior with human cultural traditions.
• The general public learns why our bodies are so efficient at processing alcohol compared to other animals.

It also challenges long-held views about ape diets, showing that fermented fruit was more important than previously thought.

A new way to think about alcohol

The idea of “drunk apes” is more than a funny image. It is a serious clue about how biology and culture developed together. The ability to handle ethanol may have been a survival tool first and a social tool later.

When you think about happy hour or a holiday feast, you might actually be seeing the echoes of a habit that began millions of years ago. Eating fermented fruit did not just help apes survive. It may have helped humans become the social and community-driven species we are today.

Researchers say the next step is to measure ethanol levels in fruits eaten in the trees versus fruits found on the ground. This will help them calculate how much alcohol chimpanzees and other apes actually consume.

Final takeaway

The next time you raise a glass, consider this: our ancestors may have been sharing fermented fruit on the forest floor long before breweries and vineyards ever existed. This research shows that something as simple as overripe fruit may have shaped both our biology and our culture.

“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 says. “We evolved to metabolize alcohol long before we ever figured out how to make it.”

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