As a child, alcoholism was something that surrounded evolutionary physiologist Robert Dudley from the University of California Berkeley. Watching first-hand as his father descended into the addictive disease, Dudley's first fascinations as a scientist were with what predispositions led to humans' strong attraction to the intoxicating libations.
Looking to jungle trees to find his answers, it was eighteen years ago when Dudley, as a young researcher, discovered that the answer may be something instinctual; a trait we may share with many of our relatives in the great apes clade of our evolutionary history. While on an unrelated 5-year-long research stint down into the monkey-filled jungles of Panama, Dudley observed something he had not noted of monkeys and apes in captivity; that they too enjoyed fermented drinks. Scattered along the jungle floor lie fruits overripe and fallen, sweet with the scent of alcohol. And above, in the trees, monkeys foraged upon the lush blossoms that the fermented fruit revealed. An observation which led Dudley down a path of research that would follow back the evolutionary timeline of our own clade.
"The argument here is that our attraction to alcohol goes back about 18 million years, to the origin of the great apes, if not 45 million years with the origin of diurnal fruit-eating primates" Dudley says. "Chimps, our closest relatives, are getting about 90 percent of their caloric expenditure from ripe fruits; and where there is sugar in the tropics, there is alcohol."
"They are not drinking down gin and tonics, but they are getting a long, sustained, low-level exposure."
A physiologist who primarily studies the biomechanics of animal flight, Dudley spent nearly 18 years accumulating anecdotal evidence and refining a working hypothesis for human's attraction to alcohol, a hypothesis he fully presents in his new book "The Drunken Monkey, Why We Drink and Abuse Alcohol" published just this month.
"I hypothesize that social facilitation of communication and food sharing and all these bright, warm fuzzy feelings we get when we have a drink have basically evolved to facilitate rapid identification of fruit at a distance; you smell a plume, go upwind, and you get to the fruit" Dudley says. "The positive psychoactive effects of alcohol may simply exist to enhance the efficacy of these behaviors and ultimately, they are the targets of natural selection."
Relating primal instincts used as foraging tactics with an average night at a local bar, the research Dudley presents is an interesting view on many activities associated with imbibing. For example, hunger associated with alcohol intake and the communal atmosphere that takes place when alcohol lowers inhibitions may have originated in ancient forests over a mid-afternoon meal on abundant fruit.
"It was kind of a fun realization that there is an ancestral, almost neurological bias associating ethanol with nutritional reward and caloric gain" Dudley says.
However, Dudley does make a distinction between the New World primates and those of our clade: that humans are no longer imbibing on low levels of alcohol, and as we have decoupled alcohol from the fruit, humans are much more apt to abuse the consumption in excess. By looking at the predisposition and defining differences between the natural phenomena and modern practices, Dudley hopes that clinicians can begin to look at alcoholism as a disease of nutritional excess, much like diabetes which would make it treatable by limiting supplies of the addictive nutritional content.
