It’s not just humans who can get hungover on the weekends. In an article published on Wednesday, biology and wildlife researchers argue that alcohol consumption in the animal kingdom is probably much more widespread than is commonly believed. But there’s still a lot we don’t know about it, including whether there are animals that actively seek out the high.
There is no shortage of stories in the wild about animals that look drunk, from chimpanzees to elephants to various species of birds. But while some animals are known to regularly ingest alcohol-rich foods, such as cedar waxwings and robins, the phenomenon of alcohol consumption among wild animals is generally considered rare and isolated. Evolutionary biochemist Matthew Kerrigan and his colleagues say that this assumption doesn’t hold up when you look at the bigger picture.
“I wouldn’t be surprised to find that humans are not the only animals that have neurological and psychological benefits from drinking ethanol.”
First, the type of alcohol that people regularly consume, ethanol, has been around for a long time. In nature, it is formed by the fermentation of sugars commonly found in nectars and fruits by yeast fungi. According to the researchers, molecular evidence suggests that yeast has been producing ethanol for at least 100 million years. And today, ethanol sources can be found in almost all types of ecosystems. Just like drinks in a bar, some fermented fruits have a much higher alcohol concentration than others; these fruits tend to grow in more tropical parts of the world.
“Since the Cretaceous period, fleshy fruits have been a sugar-rich resource for fermenting yeast and natural ethanol production. Thus, the inclusion of ethanol in the animal diet is probably as old as that,” the researchers write in their article published in the journal Trends in Ecology & Evolution.
Another piece of evidence is that some animals have evolved to cope better with alcohol. The basic genes associated with the enzymes that allow living things to break down ethanol have been around for a long time, perhaps even before yeast, but some animals that regularly eat nectar and fruit are more adept at doing so. Humans, chimpanzees, and gorillas, in particular, have an important mutation related to a specific stomach enzyme, while tree shrews seem to have improved an enzyme related to alcohol produced by their liver. Another study published this week found that eastern hornets can consume unlimited amounts of alcohol without any negative effects. These adaptations indicate that alcohol consumption is quite common for at least some members of the wild.
Although alcohol consumption in the animal kingdom may be more widespread than we think, there are still many unanswered questions, the researchers say. For example, as fun as a drink in a bar might be for us, for animals in the wild, the potential intoxicating effect would likely be an undesirable aspect, as it would impair their ability to defend themselves against or escape from danger. This raises the question of why animals are attracted to alcohol-rich foods in the first place.
It is not known whether wild animals can even detect whether there is alcohol in their potential food, for example, which reduces the likelihood that animals intentionally choose such food. Fermented fruits are also lower in calories than their non-fermented counterparts, which means they don’t have an inherent nutritional advantage. But it may be that these fruits are simply the best option for some animals at the moment, or have other nutritional benefits that are worth any trade-offs (e.g., fruits with a high alcohol content are likely still high in sugar). Other animals may use ethanol for medicinal purposes, such as fruit flies, which lay their eggs in an alcohol-rich environment to protect themselves from parasites.
And yes, for those who are wondering, it is possible that some animals feel the euphoric high that humans experience when they drink and actively seek out this food despite the risks.
“I would not be surprised if we find that humans are not the only animals that have neurological and psychological benefits from consuming ethanol. Whether that motivates them to seek it out is a good question,” Kerrigan, a professor at the College of Central Florida, told Gizmodo.
Next, Kerrigan and his colleagues plan to investigate how nonhuman primates interact with alcohol, including what effects alcohol may have on the behavior and social life of these animals. They also hope to better understand the chemistry of alcohol metabolism in animals.
Personally, the next time I see a robin or a robin with its beak buried in fermented berries, I will definitely express my sympathy to them – we’ve all been there, buddy.
