Animals, birds and even insects enjoy the odd bit of ethanol in their diets at rates far higher than previously believed, with naturally-occurring alcohol found in nearly every ecosystem on Earth, research published Wednesday in the Trends in Ecology & Evolution, a peer-reviewed scientific journal, suggests.
“We’re moving away from this anthropocentric view that ethanol is just something that humans use,” University of Exeter behavioral ecologist Kimberley Hockings, the paper’s senior author, said in a press statement.
“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,” she added.
Fermented fruit-based concentrations of ethanol typically reach about 1-2% of the fruits' total volume, but can reach 10% or more in some cases -like fermenting palm fruit found in Panama, according to researchers. For some animals, including birds and small mammals, even a 1-2% dose can be intoxicating, if not deadly, the study’s authors noted.
“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,” paper co-author Matthew Carrigan, a professor of molecular ecology at the College of Central Florida, said.
However, unlike humans, who often seek to use alcohol to forget their troubles or as an aid or crutch (depending on one's perspective) for social occasions, wild animals apparently seek the sustenance that naturally-sourced alcohol can provide.
“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,” Carrigan said.
Researchers say further research is needed to determine whether animals deliberately consume ethanol-laced foods, and what impact consumption has on evolutionary patterns and animal physiology.
But besides calories, they say fermentation helps animals and insects find food in the wild, and for some species, including fruit flies laying their eggs in fruit, ethanol is said to have an important benefit – protection from parasites.
“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,” University of Exeter behavioral ecologist and co-author Anna Bowland said.
“To test that, we'd really need to know if ethanol is producing a physiological response in the wild,” she noted.