Liquid Bread
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Liquid Bread

Beer and Brewing in Cross-Cultural Perspective

Wulf Schiefenhövel, Helen Macbeth, Wulf Schiefenhövel, Helen Macbeth

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eBook - ePub

Liquid Bread

Beer and Brewing in Cross-Cultural Perspective

Wulf Schiefenhövel, Helen Macbeth, Wulf Schiefenhövel, Helen Macbeth

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About This Book

"This important volume sheds new light on the social, political, and economic role of beer in society.... Highly Recommended."— Choice

A Choice Outstanding Academic Book of The Year 2011
Winner of the 2011 Gourmand World Cookbook UK Award

Beer is an ancient alcoholic drink which, although produced through a more complex process than wine, was developed by a wide range of cultures to become internationally popular. This book is the first multidisciplinary, cross-cultural collection about beer. It explores the brewing processes used in antiquity and in traditional societies; the social and symbolic roles of beer-drinking; the beliefs and activities associated with it; the health-promoting effects as well as the health-damaging risks; and analyses the modern role of large multinational companies, which own many of the breweries, and the marketing techniques that they employ.

From the introduction:
What made you pick up this book? Was it the thought of that foaming pint while you relaxed in a British pub, a German beer garden, a Czech restaurant, an American or 'Continental' bar, on a beach or ski slope or in front of the television at home? Wherever your beer was purchased, in much of the world you would have been offered choice. The choice might only have been between different brand names of bottled beer, or it might have been between a wide range of ales, lagers, wheat and other beers from a cask, a keg, cans or bottles. Even people who do not drink beer will be aware of this diversity….the editors believe that this collation of perspectives on beer will also intrigue many readers in the general public.

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Year
2011
ISBN
9780857452160

CHAPTER 1

NATURAL INGESTION OF ETHANOL BY ANIMALS: WHY?

W.C. McGrew

Introduction

Why would any organism habitually ingest a toxic substance? If toxins decrease net fitness in terms of lifetime reproductive success, then natural selection should favour individuals that avoid consuming them, versus those that do. Ethanol is such a toxin, e.g. it directly kills nerve cells. Yet, it is naturally consumed by a variety of animal taxa, both invertebrate and vertebrate: Diptera, especially Drosophila spp.; Hymenoptera; Lepidoptera; among birds, Passeriformes, e.g. waxwings, Bombycilla spp.; among mammals, Bovidae, Proboscidae, Suidae (for review of references, see Dudley 2000; Eriksson and Nummi 1982). So, do the benefits outweigh the costs?
Ethanol is produced by fermentation of sugars by yeast (microscopic fungi). In nature, this most commonly involves the simple sugars found in ripe fruit, and so ingestion is associated with facultative or obligate frugivory. Toxicity is said to be an evolved strategy of micro-organisms that allows them to triumph over macro-organisms in competition for these calorific resources (Janzen 1977). Thus, there is an evolutionary ‘arms race’ between yeasts and other fruit-eaters, whether these be other microbes or large-bodied vertebrates. The counter strategy of ethanol consumers is physiological, and is basically the same from butterfly to barfly. Ethanol is metabolised (detoxified) by a two-stage, enzymatic process: alcohol dehydrogenase (ADH) breaks down ethanol into acetaldehyde, then aldehyde dehydrogenase (ALDH) breaks that down into acetate, and acetate is then incorporated into the Krebs cycle.
The yeasts’ strategy is not decisive, however, as ethanol ingestion is commonplace. In fruit flies (Drosophila spp.), all stages of the life cycle consume ethanol and the larvae develop in an alcoholic culture of rotting fruit pulp. Both in humans and nonhumans, ethanol ingestion goes beyond direct consumption of fruit to the liquid form, wine, garnered from monosaccharides in fruit, nectar, sap, honey, etc. For example, seven species of mammals, including three species of primates (pentailed treeshrew, Pitlocercus lowii; common treeshrew, Tupaia glis; slow loris, Nycticebus coucang) regularly consume the fermented nectar of the bertam palm, Eugeissona tristis (Wiens et al. 2008).
However, humans apply simple technology such as heat to complex carbohydrates, such as starch, to break down polysaccharides into simple sugars for fermentation, thus producing beer from cereals or tubers. Finally, humans apply even more impressive technology (distillation) to transform low-concentration alcoholic fluids to high-concentration ones (spirits). Production of ethanol for ingestion seems to be a human universal, found in all societies with access to apt raw materials (Brown, 1991).
Finally, one must explain not only the physiological aspects of ethanol ingestion, but also its behavioural and cognitive aspects. Ethanol-consuming organisms of all types sometimes ingest it to the point of intoxication (as measured by altered motor patterns) and show high appetitive motivation (as measured by response to deprivation or willingness to work for ethanol as a reward) (Fitzgerald 1972).

Hypotheses

Seven hypotheses seem to explain ethanol ingestion. These need not be mutually exclusive, but each can be tested individually, at least in principle. These are presented below in order of increasing complexity:
  1. accident, ingestion may be an inadvertent by-product of frugivory
  2. pathology, ingestion may be anomalous by nature or nurture, in individuals that knowingly or otherwise seek self-injury
  3. nutrition, ingestion may be energy-seeking
  4. medicine, ingestion may be health-enhancing
  5. gustation, ingestion may be taste-rewarding
  6. hedonism, ingestion may be psychologically disinhibiting, leading to enhanced pleasure or to relief of pain
  7. cognition, ingestion may alter intellectual capacity, leading to risk-taking or altered states of consciousness
Below, each of these hypotheses will be examined in terms of what is known in the published literature on ethanol ingestion by nonhuman species.

Results

Accidental ingestion seems likely for ingestion of pulpy, succulent fruits that gradually ripen, especially since ethanol is always present in ripe fruits (Dudley 2002). Fruits need not be ‘rotten’ or overripe before fermentation starts; rather, it is only a matter of sufficient sugar content plus yeast spores, and the latter are ubiquitous. However, ethanol levels in ripe fruit are low, typically of the order of 0.1 per cent, so that their consumption is unlikely to have physiological or behavioural effects on fitness. Higher ethanol levels in rotting fruit are signalled by distinctive odour, taste, and even appearance, with the former often being detectable at a distance before the fruit is handled. This makes accidental ingestion of significant levels of ethanol unlikely.
More conclusive evidence of non-accidental ingestion comes from goal-directed selection of fermented fruit over non-fermented fruit. This is well-known in Drosophila life-history, e.g., egg-laying, but there seem to be no data for vertebrates, except as natural history anecdotes (e.g., Siegel 1989). In unnatural conditions in captivity, preference for ethanol can be developmentally induced in a wide range of vertebrates, but the procedures typically require extreme experimental manipulation (Siegel and Brodie 1984). Again, this suggests that habitual ingestion in nature is accidental.
Finally, when whole clades of insects normally ingest ethanol, it seems unlikely to be happenstance. The same applies to certain passerines, especially long-distance, migratory frugivores, but the situation for mammals remains unclear.
Pathological ingestion of ethanol may explain individual cases by analogy to alcoholism in humans. This explanation is strengthened by studies reporting successful experimental induction of ethanol addiction in nonhumans (e.g. Kornet et al. 1990) and naturalistic accounts (Marais 1969: 98–101, on wild baboons). Furthermore, genetically based variation in ADH and ALDH isozymes across human populations have been implicated in cross-cultural differences in alcohol abuse (see review in Dudley 2002).
However, for the reasons given above, pathology cannot account for obligate ingestion of ethanol in invertebrates and (apparently) birds. Again, the situation for mammals in natural circumstances remains unclear, as anecdotes (that is, accounts of rare or even unique events) may indicate only idiosyncrasy (that is, persistent individual patterns of behaviour, e.g., Carrington, 1959: 68) and may not generalise to widespread habits (Siegel 1989). Even if systematic, comprehensive data showed mammals to be regular consumers of ethanol, and even if short-term studies revealed no ill-effects, longer-term data are needed to test the hypothesis of lifespan pathology.
Nutritional ingestion of ethanol seems straight-forward: it is a better source of calories than unfermented carbohydrates, in terms of direct kcal/g yield. Furthermore, the odour plumes of ethanol may attract frugivores to indirect benefits of available calories from sugars present in patches of both ripe and overripe fruit (Dudley 2000).
However, a diet in which a high proportion of calories come from ethanol (and human alcoholism is sometimes defined accordingly) is malnutritional. Such ‘empty’ calories may be deficient in other nutrients, although this varies from spirits to wine to beer, with the latter sometimes being labelled as ‘liquid bread’ (see editors’ Preface). Finally, the most sensible argument against nutritional ingestion of ethanol by frugivores is dietary selectivity. Why not just eat sugar-rich fruit at peak ripeness so as to get the caloric benefit and to avoid the toxic cost?
Medicinal ingestion of ethanol seemed an unlikely explanation until recently, but recent findings from epidemiological studies on humans (e.g. Cleophas 1999) and on medicinal plant use in non-humans (Huffman 1997) suggest otherwise. Moderate levels of alcohol consumption may lower cardiovascular risk in all vertebrates, although it is unlikely to account for invertebrate ingestion of ethanol, given the latter's very different circulatory systems. Studies of medicinal plant use by mammals, although burgeoning, focus mainly on secondary compounds (e.g. alkaloids) and not on ethanol, and none yet has linked ethanol to symptom relief or improved health. However, this hypothesis is virtually untested for non-humans, so little can be said.
Gustatory ingestion of ethanol is the simplest explanation of all: Like humans, other animals may consume alcohol because it tastes good. The gustatory sense of chimpanzees closely resembles that of humans (Kalmus 1970) and wild chimpanzees favour tastes that signal calories (Nishida et al. 2000). Natural history accounts (e.g., Sikes 1971: 242) suggest that wild animals such as elephants cannot resist overdoing their ingestion of fermented fruit, even to the point of inebriation. Anecdotes from home-reared apes suggest the same: a female chimpanzee used to mix herself martini cocktails (Temerlin 1975). These reports are suspect on grounds of anthropomorphism, but could be easily tested by taste tests on ‘enculturated’ apes who typically favour a diet of processed cultivars.
The real problem with the gustatory hypothesis, however, is its proximate nature. Even if it holds, it merely pushes back the question to the ultimate (i.e. fitness) level. Why would natural selection shape a sensory system that makes a toxin taste good? Why would evolution produce an appetitive drive for substance that would appear to reduce lifetime reproductive success?
Hedonic ingestion of ethanol is based on its psychoactive properties of disinhibition, assuming that disinhibition may increase pleasure or decrease pain. Such emotional-motivational processes in the central nervous system of vertebrates are complex but well-studied. In humans, ingestion of ethanol produces a short-term effect of enhanced well-being that is manifest in playfulness, or of analgesia. By homology, given similar cerebral functioning, one might expect similar processes in large-brained mammals, especially anthropoids. Again, natural history and companion animal anecdotes suggest such effects. But for an invertebrate, lacking even a brain, much less a complex cerebral cortex, it is hard to know how to test such an hypothesis. Even if butterflies or wasps appear to be tipsy in their actions (and who can know of their motives?), their behaviour is not attributed with the capacity for play.
The potential costs of hedonism are obvious, in terms of increased vulnerability to predation, competition, or other hazards, or of potentially greater injury incurred by ignoring painful stimuli. This would seem to be especially acute for arboreal or volant creatures, where a single instance of motor dysfunction could be fatal. Captive chimpanzees and orangutans who voluntarily consume large amounts of ethanol show all the symptoms of human drunkenness, from locomotor ataxia, to hyper-excitability, to stupor (Fitzgerald 1972). Even a hangover could be a handicap, in competition with a teetotalling rival. However, the potential benefits of disinhibition should not be ignored. If playfulness enhances inventiveness and inventiveness leads to behavioural adaptation, then ethanol ingestion may facilitate more efficient foraging or more creative social strategising. These are difficult ideas to test, as are all hypotheses related to play (Spinka et al. 2001).
The cognitive hypothesis for ethanol ingestion suggests that it may enhance or safeguard intellectual functioning. Being cortically based, this hypothesis may be inseparable from the hedonic hypothesis, but there may be a distinction between functioning neural modules for emotion and for cognition. Ruitenberg et al. (2002) recently showed for humans that light-to-moderate alcohol consumption is associated with a reduced risk of dementia.
Disinhibited brains may differently calculate probabilities or risks, or may even reconstitute their perceptual worlds, as in altered states of consciousness. One can imagine a socially subordinate individual emboldened by ethanol surprising its superiors and so improving its social status. Similarly, a normally shy individual may benefit socially by initiating new social affiliations. High risks may lead to high payoffs. However, when squirrel monkeys ingest ethanol, it is the dominant individuals who become more aggressive, not the subordinates (Winslow and Miczek 1988).
By the same token, high risks may lead to high, even fatal or disastrous costs. For every envisioned reward, there is an equally costly punishment. The key is relative probability of outcomes, as calculated by a strategising, rational brain. In the long run (for chronic as opposed to acute problems to be solved), it seems intuitively unlikely that an ethanol-disinhibited individual is likely to out-think a more temperate one. However, this is an empirical question, in which the effects of ethanol ingestion dosage on everything from reaction time to Machiavellian deception need to be tested, in a range of vertebrates. However, again, one assumes that this hypothesis will be of little use in understanding hard-wired invertebrates.

Discussion

It seems clear that no single hypothesis explains ethanol ingestion by all animal taxa, from fruit fly to elephant. For Drosophila, it seems likely that all but Hypothesis 3 are irrelevant, and not even worth trying to test. (For Homo sapiens it seems likely that none of them could be falsified, at least for all cases). Furthermore, it is clear that for none of the hypotheses are there adequate data, certainly not in print, and probably not even envisioned. Targeted testing of these ideas is underway, but it is sporadic (Eriksson and Nummi 1982; Dudley 2002). Most of what we think we know about mammalian ethanol ingestion is no more than natural history notes. This means that humans may be the only mammalian species to use alcohol in any real way, and if so, it can be added to the short list of derived traits that are both unique and universal to the species (Brown 1991). But the fact that many organisms have ADH and ALDH (Prinzinger and Hakimi 1996) suggests that there is more to the story than this.
Given all these caveats, what can be said however tentatively? Dudley's (2000) masterly treatment in principle supports Hypothesis 3 for normative cases. Animals ingest ethanol to get energy, and this works fine in environments of evolutionary adaptedness. That is, at the low levels of ethanol available in nature, the catabolisation of ethanol from fruits is straightforward. But what to make of over-indulgence, of drunken pachyderms or tipsy waxwings? It seems that non-humans in nature have access only to ‘wine’, but usually in solid, not liquid, form. Carrington's (1959) description of a wild African elephant addicted to fermented millet raided from a village seems to be the only case of non-human ‘beer’ consumption. Similarly, at various places in West Africa where villagers tap palm trees (e.g., Elaeis guineensis) for natural fermented palm wine, wild chimpanzees pilfer the containers and drink the contents (Carvalho, personal communication).
Dudley (2000) invokes the principle of hormesis, which entails a nutrient–-toxin continuum. That is, chemical compounds that are beneficial in low dosages may be harmful at high dosages. In human beings, this may apply to ethanol and alcoholism, just as over-consumption of salt links to hypertension, sucrose to diabetes, and saturated fats to coronary disease. In all cases, a substance that is rare in nature has become readily accessible in unnat...

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