A lot more animals are alcoholics than we thought! Here’s how they get their booze

If you thought alcohol was just a human vice, think again! Animals might be indulging in nature’s own happy hour more often than we ever imagined. Ecologists are starting to turn this idea on its head, revealing that boozy snacks are far more common in the wild than previously thought.

How animals stumble upon alcohol

When fruits are left to ripen a little too long, especially when drenched in warm sunlight, they naturally ferment into a natural brew. Stories of “drunk” animals like elephants, monkeys, and birds toppling around after munching on fermented fruits have been around for ages, but scientists used to think these incidents were rare flukes. But now, they’re rethinking it.

"We’re moving away from this anthropocentric view that ethanol is just something that humans use," says study author Kimberley Hockings. "It's much more abundant in the natural world than we previously thought, and most animals that eat sugary fruits are going to be exposed to some level of ethanol."
In fact, ethanol — yep, the stuff in booze — has been around for over 100 million years. When flowering plants first started making nectar and fruits, natural yeast joined the party, creating alcohol in the process. Today, it’s pretty much everywhere, especially in humid, tropical regions, where fermentation-friendly conditions are available year-round.

Built for the booze

For most wild critters, alcohol isn’t about the buzz; it’s about the calories. According to molecular ecologist Matthew Carrigan, animals prioritise the energy found in these boozy treats rather than the “fun” side effects.

“From an ecological perspective, it is not advantageous to be inebriated as you're climbing around in the trees or surrounded by predators at night — that's a recipe for not having your genes passed on,” Carrigan points out. Unlike us humans, animals want the energy but prefer to skip the hangover.

Interestingly, animals seem to be pretty well-equipped to handle alcohol. They’ve harboured genes that can degrade ethanol for millions of years, long before natural yeast even got into the game. Primates, birds, and tree shrews that enjoy fruit and nectar have evolved a strong tolerance for it, allowing them to take advantage of ethanol’s calories without too much of a head-spin.

Why do animals bother?

It might seem counterintuitive, but ethanol could have a few perks for wild animals. It’s calorie-dense, helping to fuel their bodies when food is scarce, and some of the odorous byproducts of fermentation can act as a food signal. So, while animals likely aren’t sniffing around for alcohol itself, they could be drawn to the scent of rotting fruits.
Insects like fruit flies have even shown a medicinal benefit to ethanol. Fruit fly larvae consume more ethanol when they're fighting off parasites like wasps. The ethanol seems to make their internal environment less hospitable to invaders, which is an intriguing example of self-medicating in the wild.

“On the cognitive side, ideas have been put forward that ethanol can trigger the endorphin and dopamine system, which leads to feelings of relaxation that could have benefits in terms of sociality.” as behavioral ecologist Anna Bowland points out. You can imagine animals bonding over a boozy snack – kind of how humans sharing a beer!

There’s still a lot we don’t know about how alcohol impacts animals in the wild. Do certain species seek it out more than others? Does ethanol consumption affect their social lives, family dynamics, or evolutionary adaptations? Hockings and her team plan to dig deeper, studying how alcohol impacts behavior and metabolism in animals, particularly primates.

The findings of this research have been published in Trends in Ecology & Evolution and can be accessed here.