Why are wild animals getting ‘drunk?’ Study finds it’s more common than thought
Humans are no longer “drinking alone,” a new study finds. Animals are getting drunk on a regular basis, but they’re not mixing a cocktail.
Instead, wild animals are consuming a “sugary nectar” in the wild with the naturally made chemical compound that’s also in alcoholic drinks consumed by humans.
While researchers knew ethanol could naturally appear in fruits fed on by wild animals, they thought the phenomenon of drunk animals was much more rare. A study published Oct. 30 by Trends in Ecology & Evolution determined that’s not the case.
“Anecdotes of vertebrates consuming ethanol are common, but very few are validated and described in academic literature,” the study said. While the stories may not be vetted, the study revealed animals consuming fruit containing ethanol goes back to ancient times.
The ethanol produced in the fruit comes from a natural fermentation process creating a yeast. The study found this has been happening for 100 million years, and animals, in nearly ever ecosystem, have been consuming it regularly.
“We’re moving away from this anthropocentric view that ethanol is just something that humans use,” senior author Kimberley Hockings of the University of Exeter said in a news release. “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.”
Naturally fermented fruits typically have a 1% to 2% alcohol by volume, but some have been found as high as 10.3%, such as “over-ripe palm fruit” found in Panama.
“Lower-latitude and humid tropical environments, however, are most conducive to natural fruit fermentation, yeast colonisation, and ethanol production throughout the year,” the study said.
Though the alcoholic volume found in a naturally fermented fruit in the wild parallels a common alcoholic beverage consumed by humans, it has a much different effect on an animal’s blood alcohol content.
The study used an example of an animal that weighs 5 kilograms. If it ate a grapefruit with 1.7 milliliters of ethanol, its BAC would be 0.05%.
“A human with an equivalent BAC would metabolise most of the ethanol within (two hours), but with minimal ethanol metabolic capacity, eating a second grapefruit within a few hours would double the BAC of our hypothetical animal to 0.10%,” the study said.
Eating a third grapefruit in a matter of hours could “impair all motor function,” the study said. Eating six would likely make the animal unconscious.
The study found that animals are not equipped to digest ethanol as fast as humans can.
“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,” senior author Matthew Carrigan of the College of Central Florida said in the news release. “It’s the opposite of humans who want to get intoxicated but don’t really want the calories—from the non-human perspective, the animals want the calories but not the inebriation.”
Ecologists say more research is needed to understand exactly how alcohol affects different animals.
The research team includes Anna Bowland, Amanda Melin, David Hosken, Kimberley Hockings and Matthew Carrigan.
This story was originally published October 30, 2024 at 6:00 PM with the headline "Why are wild animals getting ‘drunk?’ Study finds it’s more common than thought."
