Humans are not the only animals to enjoy a good buzz. Scientists have found evidence that several primates, as well as fruit bats, will consume alcohol in the form of fermenting fruit or nectar. And then there's the occasional koala or bear that finds its way to vineyards and avails itself of the excellent fruit.
But, a new book suggests that alcohol may have been more than a fun tipple for mankind's forebears. Our early simian ancestors' ability to process moderate amounts of alcohol may have given them a critical edge in the fight to survive.
Alcohol and Humans: A Long and Social Affair is a collection of scientific essays co-edited by Dr. Kimberly Hockings, a lecturer in conservation science at the University of Exeter, and Dr. Robin Dunbar, a professor of evolutionary psychology at Oxford University. "About 10 million years ago, our African ape ancestors were eating fallen fruits on the forest floor—many of which would have begun to ferment and become alcoholic," Hockings told Wine Spectator via email. "At the time, ape populations were crashing, in the face of competition with monkey species which were able to eat unripe fruit—which apes, like humans, struggle to digest."
Critically, the apes adapted to eating overripe, fermenting fruit around this time. Monkeys are unable to process ethanol, which means that same fruit was unavailable to them. That caloric advantage enabled our ancestors to survive through challenging periods. This consumption may have continued onwards through human history as alcohol, often safer than drinking water in many places, became tightly linked to the advancement of our species.
Hockings and Dunbar write about the nature of alcohol consumption in humans and point out that behaviors in a species don't continue if they don't serve some purpose. "The issue for evolution is simply whether the benefits exceed the costs," they write. "If they do, a trait will evolve; if they don’t, it won't. Evolution is all about trade-offs, and that sometimes means accepting things that have deleterious side effects."
Alcohol's ill effects of over-consumption are well-documented. So the question becomes: What were the benefits of alcohol consumption for our ancestors and what benefits remain today? In addition to the caloric aspect, there is also evidence that alcohol offers some health benefits in moderation.
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The third benefit is something you might not immediately associate with survival—community. "Alcohol enable[s] us to build and maintain friendships and social communities," the authors write. Apes and humans are extremely social creatures. So in addition to a basic caloric advantage, moderate consumption of alcohol may have greased the gears of social communities in our early ancestors.
This adaptation toward alcohol consumption might have ramifications for us right now. "Ethanol consumption via frugivory [fruit-eating] would ... have resulted in physiological and sensory adaptations that link nutritional reward with dietary exposure to this molecule," writes Dr. Robert Dudley, chairman of the department of integrative biology at the University of California, Berkeley, in one chapter. Diet patterns in an animal family across thousands of years can indelibly etch an association—and a need—into the brains of its progeny.
Scientists have seen a similar relationship with humans and high-calorie foods. Once, calories were crucial for survival. Modern human society, with much of its food being highly refined, processed, high-calorie options, plays into our ancestors' necessary practice of consuming as much as possible. But for many of us, food is no longer scarce—in fact, it's overabundant, which leads to many people having problems with maintaining a proper diet.
Dudley writes that a similar concept applies to alcohol. "Excessive consumption of ethanol by modern humans (e.g. alcoholism) may be viewed conceptually as a disease of nutritional excess." Those who drink too much are consuming more concentrated alcoholic beverages than our simian ancestors had, and much more of them.
While excess consumption is a danger, Hockings points out that humanity's relationship with alcohol is multifaceted. "Alcohol is often viewed only as a 'social problem' or as a means to get drunk—but this overlooks its importance in the social and cultural fabric of many human societies both past and present."