Ecologists have uncovered new evidence that contradicts previous assumptions that animal consumption of ethanol is rare and largely incidental. According to the study, ethanol is a natural substance found in nearly all ecosystems, and it is quite likely that animals feeding on fruits or nectar encounter it regularly, writes Phys.org.
"We are moving away from the human-centered idea that ethanol is something unique to human consumption," explained the lead author of the study, behavioral ecologist Kimberley Hocking from the University of Exeter. She adds that ethanol exists in nature in greater quantities than previously believed, making it accessible to many fruit-eating animals.
The widespread occurrence of ethanol dates back approximately 100 million years, coinciding with the emergence of flowering plants that began producing nectar and fruits. These sugary substances allowed yeasts to start fermentation, leading to the formation of ethanol.
While the ethanol level in naturally fermented fruits typically ranges from 1-2% by volume, some overripe palm fruits in Panama have been recorded with ethanol concentrations as high as 10.2% by volume.
Many animals, particularly primates, possess genetic adaptations that enable them to effectively metabolize ethanol. It is believed that this evolutionary development was finely tuned to help these animals avoid the negative effects of intoxication.
Molecular ecologist Matthew Kerrigan from the College of Central Florida notes that disorientation in trees or evasion of predators can jeopardize survival and reproduction.
However, the intentionality of ethanol consumption by animals remains uncertain. While some researchers believe that animals seek calories in fermented fruits rather than the intoxicating effect, debates continue about whether ethanol consumption may have additional benefits.
For instance, compounds released during fermentation may assist animals in locating food sources, although it is unlikely that animals can detect ethanol itself.
Moreover, ethanol consumption may have medical benefits. One example is that fruit flies intentionally lay their eggs in ethanol-containing substances to protect them from parasites. When fruit fly larvae encounter parasites, they increase their ethanol consumption, potentially as a defensive measure.
Behavioral ecologist Anna Bowland from the University of Exeter adds, "There are theories suggesting that ethanol might activate endorphin and dopamine systems, leading to a sense of relaxation that could have social advantages for animals."
While many questions remain about the role of ethanol in animal behavior and physiology, researchers plan to explore its social implications and continue studying the enzymes involved in alcohol metabolism.
We also reported on an experiment that confirmed the findings of volunteers in Norway.