Drunk

People like to masturbate. They also like to get drunk and eat Twinkies. Not typically all at the same time, but that’s a matter of personal preference.

From a scientific perspective, we have long been told that these otherwise variegated pleasures have one thing in common: They are evolutionary mistakes, sneaky ways humans have figured out how to get something for nothing. Evolution gives us little shots of pleasure for doing things that advance its plan, like nourishing our bodies or passing on our genes. Clever primates, though, have been gaming this system for eons—inventing porn, birth control, and junk food, and seeking out or creating substances that will flood their brains with dopamine with callous disregard for evolution’s original design goals. We are inveterate pleasure seekers, promiscuously grabbing little jolts of ecstasy whenever and wherever we can. When someone gets an endorphin hit from devouring a Twinkie, downing a shot of Jägermeister, and then pleasuring themselves to Swingers Getaway IV, they are getting an undeserved reward. Evolution must be furious.

One type of evolutionary mistake can be thought of as an evolutionary “hangover,” where we are plagued by behaviors and drives that were once adaptive, but are no longer. Our desire for Twinkies is a classic example of an evolutionary hangover. Junk food is appealing because evolution built us to like sugar and fat. This was a sensible strategy for our ancestors, hunter-gatherers haunted by the constant specter of hunger and starvation. It goes seriously off the rails, however, in modern environments, where most people have easy access to cheap sweets, carbs, and processed meats, sometimes helpfully delivered in a single, heart attack–inducing package. Evolution can also be subverted by “hijacks.” These are cases where we’ve figured out an illicit way to tap into a pleasure system originally designed to reward other, more adaptive behavior. Masturbation is an exemplary hijack. Orgasms are meant to reward us for having reproductive sex, thereby helping our genes get into the next generation. We can, however, trick our bodies into giving us that same reward in any number of entirely, wildly non-reproductive ways.

In scientific circles, there is debate about whether our mistaken taste for alcohol is of the hijack or hangover variety. Proponents of hijack theories claim that alcoholic beverages make us feel good because their active ingredient, ethanol, happens to trigger the release of reward chemicals in our brain. This is a design glitch: These chemicals are actually intended by evolution to reward genuinely adaptive behavior, like eating nutritious things or pushing a hated enemy into a tar pit. But the brain can be tricked, and ethanol is one of the easiest ways to do so.

Proponents of the hangover theory see various ways in which a desire for getting at least mildly drunk might have been adaptive for our evolutionary ancestors, but argue that this drive has become extremely maladaptive in any kind of modern environment.

Whether of the hangover or hijack variety, evolutionary mistakes persist because natural selection hasn’t bothered to deal with them yet. This is typically because whatever costs they involve are either relatively minor or have only become problematic quite recently. Evolution can afford to turn a blind eye to masturbation as long as our drive for orgasms still results in enough genes getting passed on to the next generation. Junk food is a modern problem mostly confined to the developed world. Alcohol is also something evolution could afford to ignore, at least until relatively recently. This is because alcohol, like sugar, occurs only in small quantities in the natural world. It takes some serious work to get a buzz off naturally fermenting fruit. It is only with the advent of agriculture and organized, large-scale fermentation—maybe 9,000 years ago, a blink of an eye in evolutionary terms—that serious booze became available to lots of people, pushing susceptible humans onto the slippery slide to widespread drunkenness, lost weekends, and ruined livers.

A crucial but often unacknowledged feature of any sort of evolutionary mistake view of alcohol or other chemical intoxicant use is that it sees getting drunk or high, like masturbation or stuffing your face with junk food, as an unmitigated vice. A vice is a habitual practice that gives fleeting pleasure, but that is ultimately harmful to oneself and others, or at best a waste of time. Indeed, even the most ardent fan of masturbation would have to admit that, all else being equal, there are probably more productive ways to spend a weekend afternoon. Indulging in these practices may feel good, but it is not doing us—or anyone else—any good.

Not all vices are created equal, however. When it comes to our Swingers Getaway IV scenario, it’s actually the Jäger shots that should keep evolution up at night. A bit of work time lost to masturbation is no big deal. Alcohol, on the other hand, can be truly dangerous. Alcoholic intoxication is an abnormal mental state, characterized by reduced self-control and degrees of either euphoria or depression, brought about by the temporary impairment of a big chunk of the brain. As the term suggests, it involves the ingestion of a toxin, a substance so harmful to the human body that we possess elaborate, multi-layered physiological machinery dedicated to breaking it down and getting it out of our systems as quickly as possible. Our bodies, at least, clearly see alcohol as a serious threat.

An alcoholic beverage typically provides calories but little nutritional value, and is made from otherwise valuable, and historically scarce, grains or fruit. Its consumption impairs cognition and motor skills, damages the liver, kills off brain cells, and fuels ill-advised dancing, flirting, fighting, and even more louche behaviors. In small doses, it can make us happy and more sociable. But increased consumption quickly leads to slurred speech, violent arguments, maudlin expressions of love, inappropriate touching, or even karaoke. While getting completely wasted can induce ecstatic experiences of selflessness and group bonding, it also often leads to vomiting, injuries, blackouts, ill-advised tattoos, and serious property damage. And let’s not even get started on hangovers.

From an evolutionary perspective, the use of certain drugs makes sense. Coffee, nicotine, and other stimulants are basically performance enhancers, allowing us to pursue our normal evolutionary goals with an extra spring in our step, our motor functions unimpaired, and our grip on reality firm.1 It is the use of intoxicants, primarily alcohol, that is truly puzzling. This is because intoxicants, from the minute they hit our bloodstream, begin to impair us, slowing our reflexes, dulling our senses, and blurring our focus. They do this primarily by targeting the prefrontal cortex (PFC) in the brain, our center of cognitive control and goal-directed behavior. “Intoxication,” as we’ll be using the term in this book, thus includes not only the more dramatic states of inebriation—what we’d consider legally “drunk”—but also the mellow, happy buzz produced by those first couple sips of wine. As innocuous as a mild social high might seem, it is already undermining the capacity that arguably makes us human: our ability to consciously govern our own behavior, stay focused on task, and maintain a clear sense of self.

Given that the PFC is a key to our success as a species, consuming any amount of alcohol or other intoxicant seems really stupid. It takes well over twenty years to fully develop the PFC, a physiologically expensive part of the brain, and the last to reach maturity. It is therefore odd that one typical way to celebrate a twenty-first birthday is to chemically knock it down a few pegs. Given the potentially enormous costs, and apparent lack of benefits, to impairing our cognitive control, why do humans still like to get intoxicated? Why is the labor-intensive practice of converting wholesome grains and delicious fruit into bitter, low-dose neurotoxins, or seeking out intoxicating plants in the local biome, so ubiquitous across cultures and geographic regions?

It should puzzle us more than it does that one of the greatest foci of human ingenuity and concentrated effort over the past millennia has been the problem of how to get drunk. Even small-scale societies on the brink of starvation will set aside a good portion of their precious grain or fruit for alcohol production. In pre-colonial Mexico, tribes that otherwise had no organized agriculture traveled great distances to make liquor from cacti fruit during the brief periods when they were in season. Migrants whose alcohol supplies have run dry have desperately fermented shoe leather, grasses, local insects, whatever they could get their hands on. Nomads of Central Asia, with little access to starch or sugars, go so far as to make booze out of fermented mare’s milk. In contemporary societies, people spend an alarming proportion of their household budgets on alcohol and other intoxicants. Even in legally dry nations, huge numbers of people suffer painful deaths trying to get drunk on cleaning products or perfumes.

The rare cultures that do not produce alcohol inevitably substitute some other intoxicating substance, such as kava, hallucinogen-laced tobacco, or cannabis, in its place. Among traditional societies, if there is something in the biome that has psychoactive properties, you can be sure that the locals have been using it for millennia. More often than not, it tastes horrible and has vicious side effects. For instance, ayahuasca, a hallucinogenic brew made from Amazonian vines, is painfully bitter and quickly brings on brutal diarrhea and vomiting. In some South American cultures, people go so far as to lick poisonous toads. All over the world, wherever you find people, you find them doing disgusting things, incurring incredible costs, and expending ridiculous amounts of resources and effort for the sole purpose of getting high.2 Given how central the intoxication drive is to human existence, the archaeologist Patrick McGovern has only semi-facetiously suggested that our species be referred to as Homo imbibens.3

This desire to get mentally altered has ancient roots, ones that can be traced to the very beginnings of civilization.4 At sites in eastern Turkey, dating to perhaps 12,000 years ago, the remains of what appear to be brewing vats, combined with images of festivals and dancing, suggest that people were gathering in groups, fermenting grain or grapes, playing music, and then getting truly hammered before we’d even figured out agriculture. In fact, archaeologists have begun to suggest that various forms of alcohol were not merely a by-product of the invention of agriculture, but actually a motivation for it—that the first farmers were driven by a desire for beer, not bread.5 It is no accident that the earliest human archaeological finds from around the world always include huge numbers of specialized, elaborate vessels used solely for the production and consumption of beer and wine.

Sumerian myths go so far as to link the origins of human civilization to drinking (and good sex). In the epic Gilgamesh (ca. 2000 BCE), probably our oldest surviving literary document, the wild man Enkidu, who roams as one with the animals, is tamed and made human by a temple prostitute. Before offering him a full week of mind-blowing sex, she first sates him with the two great pillars of civilization: bread and beer. He particularly likes the beer, drinking seven jugs that cause him to “become expansive and sing with joy.” Then, and only then, do they move on to the main event.6 The ancient Aryans, who sometime between 1600 and 1200 BCE moved from the steppes of Central Asia into the Indian subcontinent, built their religious system around a mysterious intoxicant called “soma.” Scholarly debate continues to rage about what soma actually was—the current dominant theory is that it was a liquid made from the fly agaric hallucinogenic mushroom7—but it clearly packed a punch. A hymn from the Rig Veda, dating to perhaps 1200 BCE, records the god Indra’s words as the soma high starts to kick in and his thoughts begin to race, leaving him wildly out of his mind but also imbued with universe-shattering power:

Why is one of the most important of Vedic gods imagined as not merely getting supremely lit up, but actually drawing his power from a concoction of magic mushrooms? This is particularly puzzling when the literal drug in question is more likely to leave one prostrate and helpless, pupils dilated and motor coordination shot, hardly in any kind of shape to “thrash the earth soundly.” Would it not make more sense to portray Indra as having enjoyed a solid meal and nutritious milk before heading off to order the universe or dispatch his enemies?

The great power of adopting a scientific approach to human behavior is the ability to unmask deep puzzles about human existence that otherwise hide in plain sight. Once we begin to think deeply and systematically about the antiquity, ubiquity, and power of our taste for intoxicants, the standard stories suggesting it’s some sort of evolutionary accident become difficult to take seriously. Considering the enormous costs of intoxication, which humans have been paying for many thousands of years, we would expect genetic evolution to work toward eliminating any accidental taste for alcohol from our motivational system as quickly as possible. If ethanol happens to pick our neurological pleasure lock, evolution should call in a locksmith. If our taste for drink is an evolutionary hangover, evolution should have long ago stocked up on aspirin. It hasn’t, and explaining why it hasn’t is of more than merely academic interest. Without understanding the evolutionary dynamics of intoxicant use, we cannot even begin to think clearly or effectively about the role intoxicants can and should play in our lives today.

While plenty of entertaining books have been written about the history of alcohol and other intoxicants, there has yet to be one that offers a comprehensive, convincing answer to the basic question of why we want to get high in the first place.9 The sheer popularity, persistence, and importance of intoxicants throughout human history begs explanation. In the pages that follow, I aim to provide one. Cutting through the tangle of urban legends and anecdotal impressions that surround our notions of intoxication, I draw on evidence from archaeology, history, cognitive neuroscience, psychopharmacology, social psychology, literature, poetry, and genetics to provide a rigorous, scientifically grounded explanation for our drive to get drunk. My central argument is that getting drunk, high, or otherwise cognitively altered must have, over evolutionary time, helped individuals to survive and flourish, and cultures to endure and expand. When it comes to intoxication, the mistake story cannot be correct. There are very good evolutionary reasons why we get drunk.10 What this means is that most of what we think we know about intoxication is wrong, incoherent, incomplete, or all of the above.

Let’s begin with the first point. Evolution is not stupid, and works much faster than most people realize. Pastoralists have genetically adapted to drinking milk as adults, Tibetans to living at high elevations, and boat-dwelling Southeast Asian peoples to diving and holding their breath underwater within the space of a few generations.11 If alcohol or drugs were merely hijacking pleasure centers in the brain, or were once adaptive millennia ago but are purely vices now, evolution should have figured this out pretty quickly and put a firm end to the nonsense. This is because, unlike porn or junk food, alcohol and other intoxicants are extremely costly, both physiologically and socially. Our genes face only a marginal cost when they allow us to waste a few moments masturbating or gain a few pounds eating Twinkies. Drunkenly plowing our car into a telephone pole, perishing from liver damage, or losing our livelihood and family to alcoholism are much more serious and direct threats to our genetic well-being. Similarly, cultures can afford to wink at harmless vices, especially ones that might keep people more docile and obedient. Marx never called pornography the opium of the people, but might have if he’d ever gotten a glimpse of the internet. Literal opium, though, is potentially terribly disruptive to cultures, as is any chemical intoxicant.

The fact that our supposedly accidental taste for intoxicants has not been eradicated by genetic or cultural evolution—even when perfectly good “solutions” exist, as I will explain below—means that something else must be going on. The cost of indulgence has to be balanced by specific, targeted benefits. This book argues that, far from being an evolutionary mistake, chemical intoxication helps solve a number of distinctively human challenges: enhancing creativity, alleviating stress, building trust, and pulling off the miracle of getting fiercely tribal primates to cooperate with strangers. The desire to get drunk, along with the individual and social benefits provided by drunkenness, played a crucial role in sparking the rise of the first large-scale societies. We could not have civilization without intoxication.

This leads to a second point. The fact that drinking facilitates social bonding may not sound like a world-shaking revelation. Without an understanding of the specific cooperation problems that confront humans in civilization, however, we have no way of explaining why, throughout history and across the world, alcohol and similar substances have been the almost universal go-to solution. Why bond over a toxic, organ-destroying, mind-numbing chemical when a rousing game of Parcheesi might suffice? Without an answer to this question, we have no way to intelligently weigh arguments for or against replacing after-work pub sessions with escape room competitions or laser tag outings. Many of us deliberately seek out a glass or two of wine to relax after a hard day at work. Would an afternoon bike ride work just as well? How about fifteen minutes of meditation? None of these questions can be answered without an understanding of the relevant biochemistry, genetics, and neuroscience.

Similarly, an ancient trope holds that poetic inspiration is found at the bottom of a bottle. Why is the bottle full of alcohol, not tea? What are the specific effects of alcohol consumption, how could it possibly help with creativity, and what is the right dosage for maximum effect? (Hint: well before you see the bottom of the bottle.) How does alcohol as muse compare to psilocybin or LSD, or simply a walk in the park? There are myriad puzzles surrounding intoxicant consumption that cry out for explanation, and there are currently no truly comprehensive ones on offer. Some people can (and do) drink like fish, others flush and get nauseous after a few sips of weak beer. Most people successfully integrate intoxicants into their daily lives, while others become dangerously addicted and disabled. What are the genes responsible for these reactions, and how can we explain their distribution across the world? All things considered, cultural norms forbidding intoxicant consumption seem like a pretty good idea. Why are they, in fact, relatively rare, and widely circumvented in practice? What are the implications for contemporary issues, such as the role of alcohol in the workplace and drinking age legislation? It should trouble us that our musings on such matters generally occur in complete ignorance of the relevant science. At best, we base our thinking on disconnected facts or snippets of scientific knowledge uninformed by a broader evolutionary perspective.

Although other forms of intoxication play a role in this story, there are good reasons for focusing primarily on alcohol in particular. Alcohol is the unchallenged king of intoxicants. It can be found almost anywhere people can. If you tasked a cultural engineering team with designing a substance that would satisfy specs aimed at maximizing individual creativity and group cooperation, they would come up with something very much like alcohol. A simple molecule. Easy to make out of almost any carbohydrate. Easy to consume. Storable. Precisely doseable. Complex but predictable and moderate cognitive effects. Quickly eliminated from the body. Easily influenced by social norms. Can be packaged in a tasty delivery system. Pairs nicely with food. Whatever the benefits and functions of cannabis, soma, or dance-induced ecstasy, none of these intoxication technologies display this full range of features, and most also have significantly greater downsides. It’s challenging to negotiate a treaty while high on mushrooms; the cognitive effects of cannabis show a high degree of variability between people; and dancing all night without food or sleep makes it really hard to show up for work in the morning. A two-cocktail hangover is, in contrast, a relatively minor burden to bear. This is why alcohol tends to displace other intoxicants when introduced into a new cultural environment, and has gradually become “the world’s most popular drug.”12

Chemical intoxication is clearly dangerous. Alcohol has ruined many lives, and continues to ravage individuals and communities across the globe. Beyond our vague cultural queasiness about celebrating pleasure for pleasure’s sake, defending the benefits of alcohol risks provoking a strong backlash from those who rightly worry about the profound costs of intoxicant use. But understanding the evolutionary rationales for our drive to get high will help to inform conversations where we have hitherto—in our scientific and anthropological ignorance—been flying blind.

Our analysis will turn up some clear and easy-to-implement advice for everyday life, but also raise more complicated or contentious policy issues, such as the best role for alcohol in the workplace or university. In an age where we are growing rightly concerned about facilitating inappropriate behavior, we might very well decide that the answer is none, but this is not a foregone conclusion. We also have to reevaluate the historic benefits of intoxication, at both the individual and group level, in light of the unprecedented threats that intoxicants pose in the modern world. The relatively recent innovations of distillation and social isolation entirely change intoxicants’ balance on the razor’s edge between order and chaos, creating novel dangers that we only dimly appreciate.

To have survived this long, and remained so central to human social life, intoxication’s advantages must have—over the course of human history—outweighed the more obvious negative consequences. What this calculus recommends in our modern world, massively complex and changing at an unprecedented rate, is something we can only evaluate properly when we take a broad historical, psychological, and evolutionary perspective. It’s pretty clear that Twinkies are bad for you. Masturbation doesn’t make you go blind, but has limited social benefits.

Making the case for alcohol is more complicated. Explaining the human thirst for intoxication is indeed, as the early modern French gastronome Brillat-Savarin put it, “well worth the attention of the philosophical mind.” The answer to the question of why we get drunk—for what problems or challenges intoxicants provide a solution—is, however, of much more than merely philosophical or scientific interest. Understanding the functional role of our drive to get drunk will give us a better sense of the proper role of alcohol and other intoxicants in our lives today. Given the potential costs of getting it wrong, the stakes are too high for us to stumble along as we have, guided only by folk notions, dimly understood policies, or Puritanical prejudices. History can tell us when and with what we have gotten drunk. But it is only when we couple history with science that we can finally begin to understand not only why we desire to get drunk in the first place, but also how it might actually be good for us to tie one on now and then.

People love to drink. As the anthropologist Michael Dietler notes, “Alcohol is by far the most widely and abundantly consumed psychoactive agent in the world. Current estimates place the number of active consumers at over 2.4 billion people worldwide (or roughly one third of the Earth’s population).”1 And this is not a recent development: humans have been getting drunk for a really long time.2