Moreover, alcoholic beverages within human cultures effectively transcend the natural process of fermentation. They have a long and widespread history as superb social lubricators. The great monuments of the human civilization—for example, the Egyptian pyramids and the Incan royal centers and irrigation works—were built by rewarding the workers with vast quantities of alcoholic refreshment. Today, fund-raising and political success can hardly be imagined without a liberal supply of drink. On any night in any part of the world you will find people gathered in bars, pubs, and drinking halls, conversing animatedly and relieving the stresses of the day.
Before modern medicines, alcoholic beverages were the universal palliative. The pharmacopeias of ancient Egypt, Mesopotamia, China, Greece, and Rome depended on fermented beverages for treating every kind of ailment. They were also used as vehicles for dissolving and dispensing medicinal herbs, resins and spices. Past peoples didn’t need science to tell them about alcohol’s antiseptic and antioxidant properties or other benefits that prolonged life and increased reproductive rates. They experienced or observed some of the beneficial effects firsthand.
The psychotropic effects of alcoholic beverages stoked our religious propensities worldwide. Sub-Saharan Africa, where the human odyssey began, is today awash in alcoholic beverages made from honey, sorghum, and millet. Virtually every important religious festival, celebration, or rite of passage—above all, those honoring ancestors—is marked by the presentation and drinking of a fermented beverage. Even in secular Western culture, where drinking alcohol is more of a recreational diversion than a religious passion, people follow distinct protocols in their consumption of the beverages, whether partaking of a favorite beverage at cocktail hour or carefully managing an intake of stimulants to prolong the frenzy of an all-night binge. Every culture has its own formula and terminology for coping with a hangover the morning after, perhaps by drinking more alcohol (the hair of the dog), downing a witch’s concoction of vitamins, herbs and other exotic ingredients, or simply taking in lots of water (alcohol dehydrates the body) and food.
The close association between religious practices and alcohol attests to either firmly entrenched biological tendencies or long-established cultural traditions. In other words, investigating the consumption of alcoholic beverages highlights the classic dilemma in studying human society: are certain behaviors more the result of nature or of nurture? Around the world, the available archaeological, chemical, and botanical evidence attests to the close association between alcoholic beverages and religion. Except where alcohol has been proscribed or access to the divine has been achieved in other ways (e.g., through meditation, as in Hinduism and Buddhism), important religious ceremonies often center on an alcoholic beverage. In the West, the wine of the Eucharist is at the heart of Christian religious observances, and every important Jewish ceremony is marked by the drinking of a specific number of glasses of wine.
Other common cultural threads connecting alcoholic beverages and human culture run through my narrative. Some of these strands likely reflect the fact that our species arose in sub-Saharan Africa and then spread out to the rest of the world only about one hundred thousand years ago. Humans everywhere sought sugar-rich, naturally fermenting fruits, honey, grasses, tubers, and other ingredients for fermented beverages. These resources were often combined to make a stronger grog or a drink with more potent medical or psychotropic effects. The earliest inhabited sites in the Middle East, central Asia, China, Europe, Africa, and the Americas are replete with fermentable natural products. Where artwork and artifacts have survived, they support the idea that the preparation and use of fermented beverages during the Palaeolithic period was focused on an authority figure, the “shaman,” who oversaw a community’s religious and social needs. Even in this early period, tight bonds must have existed between fermented beverages, religion, music, dance, and sex. Ocher pigmentation of burials and bones, probably symbolizing blood and sometimes the fermented beverage itself, is widespread. Musical instruments were made from specific bird bones, probably because of the associations with their mating calls, dances, and other unusual and seemingly otherworldly behaviors. People donned the costume of birds such as the crane and danced to the music.
By the Neolithic period, humans around the globe had developed very similar methods of saccharifying the starches in cereals to sugars by chewing or sprouting. All the most widely planted cereals in the world today—wheat, rice, corn, barley, and sorghum—were processed by these methods, and the available evidence suggests that the initial domestication of these grains in the Middle East, Asia, Mexico, and the Sahel of Africa was motivated by a desire to increase alcoholic-beverage production. The extraordinary transformation of the minuscule teosinte into maize is difficult to explain unless humans were initially attracted to the plant’s sweet stalks, ripe for fermentation, and then, over millennia, bred it selectively for larger and sweeter kernels. The methods for making and drinking cereal brews—including early Mesopotamian barley beer, Chinese rice wine, and American corn chicha—were also broadly similar around the world and remain so in many places: ferment a wort in a large, open-mouthed jar, and then drink from the same vessel with a long straw, usually sharing the brew with a group of family or friends. Alcoholic beverages made from sweet fruits, including grape, fig, date and cacao, probably also prompted the domestication of these plants.
One particularly surprising result from our biomolecular archaeological investigations was the discovery that the earliest-known alcoholic beverages came onto the world scene at about the same time—the early Neolithic period, ca. 7000–5000 B.C.—on either side of Asia. In the west, we find the resinated wines of the northern mountainous region of the Near East; five thousand kilometers away, we find the Jiahu grog of China, made by combining rice, hawthorn fruit, grapes, and honey. I have proposed that ideas and traditions of plant domestication and beverage making must have traveled piecemeal, with other aspects of culture, across the expanses of Central Asia, following a prehistoric predecessor of the Silk Road. But an equally compelling hypothesis that would explain these facts, as well as the emergence of new beverages at so many times and places across the planet, is that humans are by nature both innovative and attracted to fermented drinks. In short, if alcoholic beverages are such an integral part of human life, perhaps we are “programmed” with the urge to make and drink them, without needing to invoke any cultural traditions.
IS DRINKING IN OUR GENES?
It may help to look inside ourselves before tackling the more difficult scientific issues. People’s reactions to alcohol run the gamut of emotions, from euphoria to belligerence and nihilism. Fortunately, most of my own experiences have been benign. I cannot remember ever having an aversion to alcohol, but this may be the Irish in me speaking. When the McGoverns settled in Mitchell, South Dakota, they set up the town’s first bar. The Norwegian side of my ancestry, at least going back several generations, took the opposite tack, railing against the evils of drink. Perhaps one set of genes balanced out the other, but I have been able to maintain a fairly balanced approach to my alcohol intake—more so than many people, including a number of my Irish relatives.
My first excessive experimentation with alcohol came rather late in life, at the age of sixteen. I had, of course, sneaked a few nips of a martini or Manhattan at my parents’ cocktail parties or wangled some crème de menthe in a parfait on the weekend, which seemed vaguely reprobate but adult. It was the flavors of the herbs in these liqueurs that enticed me more than any consciousness-altering effects of the alcohol. All that changed on a two-month cycling trip to the German Alps in 1965.
Before embarking on our adventure, my fellow cyclists and I stopped by the famous Hofbräuhaus in Munich, where the barmaids’ arms were lined with liter-sized beer mugs. Although I joined in the drinking songs, at first, as a good American, I stuck with Coca-Cola. About three weeks into the tour, however, it dawned on me that beer was actually less expensive than Coke, so it made sense to s
tretch my budget by quaffing a brew, or two, at dinner. The problem was that beer was served by the liter, and by the time our Schweinbraten or Knockwurst was served, the first glass was empty, and it was time for a second. This set me up for the challenge at the end of the meal, when I had to recount to the waiter exactly what I had had, so the bill could be tallied. Being three sheets to the wind, I felt great but dreaded a memory lapse. With some prompting, I usually managed to remember. Stumbling out the door and back onto our bikes—speeding through the night while avoiding pedestrians and cars—was equally challenging.
Back home, I returned to my previous abstemious lifestyle. I still felt the occasional hankerings for a beer, but it was never all-compelling. On a lark, while still underage, I once dressed up in my Tyrolean alpine out-fit of Lederhosen and suspenders, along with a green peaked hat adorned with a feather and jewelry, and paid a visit to the neighborhood bar. A few carefully turned German phrases convinced the bartender I deserved a beer.
Most of us have our own vivid memories of our first taste of alcohol and drinking derring-do. Yet we are generally ignorant of the mechanisms by which this drug unleashes such powerful emotions and whether its effects are due more to nature or to nurture. Brain research, molecular biology, and epidemiological studies have begun to provide some answers.
Controlled scientific studies of large families (e.g., the Collaborative Study on the Genetics of Alcoholism), twins, and adopted children show that more than half of an individual’s susceptibility to excessive drinking has a genetic basis. The other half is due to our environment, like the opposing principles that were conveyed to me by my parents or the influence of my fellow bicyclists exerted on me as we frequented the beer halls and restaurants of Germany.
Scientists have also made considerable progress in unraveling the neurological and genetic bases of the effects of alcohol on the brain, especially with respect to addiction, a major medical and social problem. This is no simple matter, in part because of alcohol’s pervasiveness from the beginning of life on Earth, but also because it involves the human brain—the most complex known biological structure, with more than 10 billion interconnected and interacting cells.
Medical ethics prohibits inserting probes into the human brain to measure the effects of alcohol. (Monkeys and rats, as I learned to my chagrin while sharing an office with a fellow grad student at the University of Rochester’s Brain Research Center, are less fortunate.) In lieu of probes, neuroscientists have devised innovative indirect measurement techniques. Electroencephalographs can record the overall activity of brain waves. Radioactive markers can be injected into volunteers under the influence to trace the physical path of alcohol as it courses through the body and crosses the blood-brain barrier into the brain. Using f-MRI (functional magnetic resonance imaging), PET (positron emission tomography), or SPECT (single photon emission computed tomography), researchers can observe real-time changes as chemical signals activate and deactivate different brain regions. An individual’s cellular and molecular peculiarities can be defined through biopsies of cadaver tissue samples.
The major neural pathways affected by alcohol are the emotional centers, in particular the brain stem and the limbic system deep within our brains, comprising the hypothalamus, thalamus, amygdala, hippocampus, and other structures. These areas are connected by pathways of nerve cells, or neurons. The brain stem and limbic system are often referred to as the “primitive brain,” as similar structures are present in animals which appeared earlier on the Earth. In humans, this primitive brain is encased within a large cortex of gray matter, the locus of our peculiarly human traits of language acquisition, music making, religious symbolism, and consciousness of self. Dense neural connectivity with the limbic system assures that no thought or sense memory, perhaps the taste of the legendary 1982 Pétrus or the award-winning Midas Touch, goes unrecorded: it may arouse powerful emotions and be remembered years later.
Other organisms attracted to sugar and alcohol, including the slug and the fruit fly, lack cortices and must have an entirely different experience. Nevertheless, in keeping with the continuity of all life on this planet, the genes that determine the structures of their more primitive nerve centers and account for their responsiveness to alcohol (which scientists have identified by such evocative names as barfly, tipsy, cheapdate, and amnesiac) are essentially the same as those of humans. The responses of a roundworm (Caenorhabditis elegans) or fruit fly (Drosophila melanogaster) as it consumes progressively more alcohol are familiar to anyone who can recall having had too much to drink—agitated movement, followed by incoordination, lethargy, sedation, and finally paralysis. And, like humans, these lower animals, whatever they “think” about the experience, can become habituated or addicted to alcohol.
The neurons in our brains communicate via chemical messengers, or neurotransmitters. Alcohol coursing through the blood prompts the release of these compounds into the synapse, or the gap between the neurons. The neurotransmitters travel across the synapses and attach to receptors on the next neuron, triggering an electrical impulse. As we sip that drink, neurons fire at high speed seemingly ad infinitum. Different types and quantities of neurotransmitters activate specific pathways of neurons in our emotional and higher-thought centers. More alcohol leads to more activation, which we experience as the conscious or not-so-conscious feelings of elation or sadness, dizziness, and eventually stupor.
Among the neurotransmitters responsible for our varied responses to alcohol, the most important compounds are dopamine, serotonin, the opioids, acetylcholine, γ-aminobutyric acid (GABA), and glutamate. In particular, many neuroscientists have focused on dopamine, which initiates a “reward cascade” in our brains when we drink. The gene DRD2, on chromosome 11, appears to regulate the dopamine receptor and the availability of this so-called pleasure compound. It is believed that dopamine helps to mellow us out by relieving anxiety and depression. By reducing risky behavior, it causes us to cut back on the amount of alcohol we need to get “high,” and curtails our impulse to drink. Although the verdict on the role of dopamine is still out, it is clearly one of the main compounds that controls our impulse to drink.
Of the other neurotransmitters, I have a special interest in serotonin, because my laboratory analyzed the earliest sample of royal or Tyrian purple, the famous dye of the Phoenicians (see chapter 6). The core of this molecule, which occurs naturally only in certain mollusks, is shared by serotonin. It has been hypothesized that the purple molecule serves to anaesthetize potential predators, much as cuttlefish chase off their enemies with their ink. When our articles on purple started appearing, I unexpectedly began receiving inquiries from drug companies. I had never considered that the dye might have a mind-altering effect or other medicinal benefit. Now I am much more open to the possibility that ancient peoples over thousands of years might have accidentally stumbled upon unique natural resources in their environments that turned out to have medicinal effects. We plan to put purple to the test in our drug-discovery project (see chapter 2). Who knows—we may discover another drug, like aspirin (from willow bark) or the anticancer drug taxol (from yew bark).
Serotonin resides in the nervous system, where it is released when we take a sip of an alcoholic beverage. Like dopamine, it calms the frayed emotions of depression, anger, and mood disorders. It and other related compounds also occur naturally in a wide range of plants, animal venoms, and fungi, such as the psychedelic psilocybin mushroom that played an important role in the religious and social life of some early Mexican groups. As we have seen, ancient peoples often administered these additives in fermented beverages, thus making for a double whammy. Monoamine oxidase (MAO) inhibitors to treat depression and designer drugs are the latest in a long line of concoctions that have been used to boost our natural stores of serotonin. Drinking alcohol, like sexual activity, a long-distance run, or a nasty cut, also releases opioids (including the β-endorphins and enkephalins) in our brains. These compounds can elate us or give us temporary relie
f from pain. In nature, they are most famously found in poppies (Papaver somniferum), the source of opium. By administering this drug in a fermented beverage, ancient peoples of central Asia and Europe probably were able to mimic and accentuate the effects of our own neurotransmitters.
Acetylcholine bears mentioning because one variant of its receptor (M2), traced to the gene on chromosome 7, is also sensitive to a related compound found in the fly agaric mushroom. The mushroom has been proposed, probably incorrectly, as the basis for Zoroastrian haoma and Vedic soma and is still a popular drug among Siberian shamans. Carriers of the CHRM2 gene, which directs the production of the M2 receptor, appear to be more subject to depression in adolescence and therefore more prone to self-medicating with alcohol later in life.
Many other genes, unrelated to the neurotransmitters and their receptors, play roles in our decision to drink alcohol. Pure visual delight, perhaps induced by a deep red or translucent yellow color or bright, effervescent bubbles, might draw us to take a sip of a fermented beverage, but if the liquid tastes or smells repugnant, we recoil. When a bad smell is not enough to send us running, our taste buds—bundles of receptors on our tongues and other mouth parts for sweet and sour, bitter and salt, fat, and the meaty- cheesy umami taste—take over. Bitterness especially signals a potentially dangerous substance, and we are a thousand times more sensitive to compounds triggering this receptor than those of much-preferred sugary substances. Researchers have found that one variant of the bitter taste receptor (hTAS2R16), traced back to a gene on chromosome 7, causes decreased sensitivity to bitter tastes in nearly half the African-American population. This genetic predisposition makes the hops in a beer or the tannins of a grape wine less of a turnoff and possibly more of a turn-on.
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