Editor's Note: The following is the introduction to the March 2015 issue of Scientific American Classics: Intoxicating: The Science of Alcohol

Alcohol has long perplexed our species. Wherever we look in the ancient or modern world, people have shown remarkable ingenuity in discovering how to make fermented and distilled beverages and in incorporating them into their cultures. Africa, where Homo sapiens first emerged some 200,000 years ago, sets the pattern, which is repeated over and over again as humans spread out across the globe. Africa’s thousands of distinct cultures today are awash in sorghum and millet beers, honey mead, and banana and palm wines, many of which were likely “hangovers” from long ago. Nearly every aspect of life, from birth to death—everyday meals, rites of passage and major religious festivals—revolve around one or more of these alcoholic beverages. Similarly, grape wine is central to Western religions, rice and millet beers held court in ancient China, and a fermented cacao beverage was the beverage of the elite in pre-Colombian Americas.

Despite the popularity of alcoholic beverages the world over, their potential dangers play a sinister leitmotif in human history. Wine might gladden the heart, according to biblical psalmists, but it could also sting like an adder. The great Chinese Shang emperors of the late second millennium B.C.E. are said to have succumbed to too much drink, going crazy and committing suicide. Prohibition movements inevitably rose up to meet the challenge in various parts of the world, from India, where Buddhism emphasized meditative techniques for gaining transcendence, to the more recent attempts in 19th- and 20th-century America and Europe to stamp out alcohol consumption altogether. This long and often polarizing history is described in this in-depth collection of articles from the Scientific American archives.

If alcohol is so often cast in a negative light, how does one explain its allure? Alcohols, including ethanol, are not unique to our species’ creations—or even to our planet. Billions of liters of alcohols compose massive clouds in the star-forming regions at the center of our Milky Way. Moreover, some of the earliest single-celled life-forms on Earth most likely nourished themselves by anaerobic fermentation, or glycolysis. The process leads to the excretion of ethanol and carbon dioxide, similar to the way that natural fermented beverages are made today.

Given the prevalence of alcohol, it is perhaps little wonder that nearly all animals are physiologically adapted to the compound and enticed by it and its sugars—from the lowly fruit fly, which feeds its young with it, to birds, to elephants. We primates, of course, are no exception, but among this order, perhaps no other animal most elegantly demonstrates its penchant for alcohol than the Malaysian pen-tailed treeshrew. Among the earliest primates on the planet (emerging some 55 million years ago), this creature feeds principally on fermented palm nectar, drinking the human equivalent of nine glasses of wine a night—without obvious signs of inebriation. This shrew’s diet sets the pattern for alcohol consumption among primates for millions of years.

Most modern primates have diets consisting of roughly three-quarters fruit, and they are known to consume as much fermented fruit or drink as possible when the opportunity presents itself. Such considerations have been summed up in the “Paleolithic” or “drunken monkey” hypotheses, which posit that drinking is in our genes, whether for good or evil. These genes include those related to inebriation, which we share with fruit flies and which carry such fanciful names as barfly, cheapdate and happyhour. Other genes are involved in the so-called hormetic response, in which low-level exposure to a potential poison might contribute to positive physiological effects.

Given these genetic foundations and lengthy animal history, it takes no great leap of imagination to posit that our ancestral early hominins were probably already making wines, beers, meads and mixed fermented beverages from wild fruits, chewed roots and grains, honey, and all manner of herbs and spices culled from their environments. Thus was ushered in humankind’s first biotechnology, based on empirical observation—with the help of a microscopic organism, the yeast Saccharomyces cerevisiae (still used in modern fermented-beverage making). Lacking the means to preserve fruit and other natural products in season, people likely used fermentation as a way to increase the shelf life of food and drink.

Ancient experimentation in making alcoholic beverages was spurred on by a number of physiological factors, too, including our sensory awareness of alcohol and the aromatic and taste compounds produced by fermentation; our liver, which efficiently converts the compound into energy using alcohol dehydrogenase (which makes up about 10 percent of this organ’s metabolic enzymes); and perhaps most important, the pleasure cascade of neurotransmitters unleashed by alcohol in our brain. Fermented beverages clearly eased the difficulties of everyday life—the workers who built the pyramids of ancient Egypt and Mesoamerica were paid in beer. Alcohol also knitted together, or “lubricated,” the social fabric of cultures by bringing humans together and warming them up to one another.

Many of the articles in this collection take a medical view of alcohol, demonstrating how scientific knowledge of alcohol in relation to human physiology has advanced during the past century. Indeed, alcoholic beverages were a kind of universal medicine before modern synthetic drugs became available. Botanical compounds with medicinal properties could also be dissolved in an alcoholic medium to be applied to the skin or imbibed. The world’s ancient pharmacopoeias—Chinese, Indian, Egyptian and Greco-Roman—are dominated by such recipes. Additionally, because of alcohol’s antiseptic properties, those who drank distilled beverages rather than raw water, which could be tainted with harmful microorgan- isms and parasites, had a longer life expectancy.

The articles here highlight the modern versions of drinks with very ancient pedigrees, including grape wine and barley and wheat beers. Human innovation also eventually led to the discovery of how to make highly carbonated beverages (such as champagne) and to concentrate alcohol by distillation, sometimes with an herbal twist of wormwood, anise or other additives (such as absinthe). As a reminder to the reader that science does not stand still, recent findings have shown that, contrary to an article included in this volume, absinthe does not pose a particularly potent health threat. Its production in the U.S. has again been approved by the Food and Drug Administration.

The debate over the pros and cons of alcohol shows little sign of abating. I would add another confounding ingredient to the mix: it is quite possible that much of what we consider uniquely human—music, dance, theater, religious storytelling and worship, language, and a thought process that would eventually become science—were stimulated by the creation and consumption of alcoholic beverages during the Paleolithic period, which encompasses some 95 percent of our largely unknown hominin history. Our ancestors must have been astounded by the process of fermentation itself, as the liquid mysteriously churned and was transformed into another substance with psychoactive properties. And much more surely remains to be discovered.

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