poisons voluntarily, even eagerly. It is as if unconscious programmes were driving us to do something we know to be dangerous. What could those programmes be?
Naturally, there is no single explanation: different motives carry different weight with different people or in different societies. For instance, some people drink to overcome their inhibitions, others to deaden their feelings or drown their sorrows, still others because they like the taste of alcoholic beverages. Naturally, too, differences among human populations and social classes in their options for achieving satisfying lives largely account for geographic and class differences in chemical abuse. It is not surprising that self-destructive alcoholism is a bigger problem in high-unemployment areas of Ireland than in Southeast England, or that cocaine and heroin addiction is commoner in Harlem than in affluent suburbs. Hence it is tempting to dismiss drug abuse as a human hallmark with obvious social and cultural causes, and in no need of a search for animal precedents.
However, none of the motives that I have just mentioned goes to the heart of the paradox of our actively seeking what we know to be harmful. In this chapter I shall propose one other contributing motive which does address that paradox. It relates our chemical self-assaults to a wide range of seemingly self-destructive traits in animals, and to a general theory of animal signalling. It unifies a wide range of phenomena in our culture, from smoking and alcoholism to drug abuse. It has potential cross-cultural validity, for it may explain not just phenomena of the Western world but also some otherwise mystifying customs elsewhere, such as kerosene drinking by Indonesian kung-fu experts. I will also reach into the past and apply the theory to the seemingly bizarre practice of ceremonial enemas in ancient Mayan civilization.
Let me begin by relating how I arrived at this idea. One day, I was abruptly struck by the puzzle that companies manufacturing toxic chemicals for human use advertise their use explicitly. This business practice would seem a sure route to bankruptcy. Yet, while we do not tolerate advertisements for cocaine, advertisements for tobacco and alcohol are so widespread that we cease to regard their existence as puzzling. It hit me only after I had been living with New Guinea hunters in the jungle for many months, far from any advertising.
Day after day, my New Guinea friends had been asking me about Western customs, and I had come to realize through their astonished responses how senseless many of our customs are. Then the months of fieldwork ended with one of those sudden transitions that modern transportation has made possible. On 25 June I was still in the jungle, watching a brilliantly coloured male bird of paradise flap awkwardly across a clearing, dragging its 3- foot-long tail behind it. On 26 June I was sitting in a Boeing 747 jet, reading the magazines and catching up on the wonders of Western civilization.
I leafed through the first magazine. It fell open to a page with a photograph of a tough-looking man on horseback chasing cows, and the name of a brand of cigarette in large letters below. The American in me knew what the photograph was about, but part of me was still in the jungle, looking at that photo naively. Perhaps my reaction will not seem so strange to you if you try to imagine yourself completely unfamiliar with Western society, seeing the advertisement for the first time, and trying to fathom the connection between chasing cows and smoking (or not smoking) cigarettes.
The naive part of me, fresh out of the jungle, thought: such a brilliant anti-smoking ad! It is well known that smoking impairs athletic ability and causes cancer and early death. Cowboys are widely regarded as athletic and admirable. This advertisement must be a devastating new appeal by the anti-smoking forces, telling us that if we smoke that particular brand of cigarette, we will not be fit to be cowboys. What an effective message to our youth!
But then it became obvious that the advertisement had been put there by the cigarette company itself, which somehow hoped that readers would draw exactly the opposite message from the advertisement. How on earth did the company let its public relations department talk it into such a disastrous miscalculation? Surely, that advertisement would dissuade any person concerned about his/her strength and self-image from starting to smoke. Still half immersed in the jungle, I turned to another page. There I saw a photo of a whisky bottle on a table, a man sipping presumably the bottle's contents from a glass, and an obviously fertile young woman gazing at him admiringly as if she were on the verge of sexual surrender. How can that be, I asked myself? Everyone knows that alcohol interferes with sexual function, tends to make men impotent, makes one likely to stumble, impairs judgement, and predisposes to cirrhosis of the liver and other debilitating conditions. In the immortal words of the porter in Shakespeare's
Page after page of advertisements flaunted the use of cigarettes or strong alcohol, and hinted at their benefits. There were even pictures of young people smoking in the presence of attractive members of the opposite sex, as if to imply that smoking too brought sexual opportunities. Yet any non-smoker who has ever been kissed by (or tried to kiss) a smoker knows how severely the smoker's bad breath compromises his or her sex appeal. The advertisement paradoxically implied not just sexual benefits but also platonic friendships, business opportunities, vigour, health, and happiness, when the direct conclusion to be drawn from the advertisements was actually the reverse.
As the days passed and I reimmersed myself in Western civilization, I gradually stopped noticing its apparently self-defeating advertisements. I retreated into analysing my field data and wondering instead about an entirely different paradox, involving bird evolution. That paradox was what led me finally to understand one rationale behind cigarette and whisky advertisements. The new paradox concerned the reason that male bird of paradise I had been watching on 25 June had evolved the impediment of a tail 3 feet long. Males of other bird of paradise species evolved other bizarre impediments, such as long plumes growing out of their eyebrows, the habit of hanging upside-down, and brilliant colours and loud calls likely to attract hawks. All those features must impair male survival, yet they also serve as the advertisements by which male birds of paradise woo female birds of paradise. Like many other biologists, I found myself wondering why male birds of paradise use such handicaps as advertisements, and why females find the handicaps attractive.
At that point I came across a remarkable paper by an Israeli biologist, Amotz Zahavi, who had conceived a novel general theory about the role of costly or self-destructive signals in animal behaviour. For example, Zahavi attempted to explain how deleterious male traits might attract a female precisely because they constitute handicaps. On reflection, I decided that Zahavi's hypothesis might apply to the birds of paradise I studied. Suddenly I realized, with growing excitement, that his theory perhaps could also be extended to explain the paradox of our use of toxic chemicals, and our touting it in advertisements.
Zahavi's theory as he proposed it concerned the broad problem of animal communication. All animals need to devise quick, easily understood signals for conveying messages to their mates, potential mates, offspring, parents, rivals, and would-be predators. For example, consider a gazelle that notices a lion stalking it. It would be in the gazelle's interests to give a signal that the lion would interpret to mean, 'I am a superior, fast gazelle! You'll never succeed in catching me, so don't waste your time and energy on trying. Even if that gazelle really is able to outrun a lion, giving a signal that dissuades the lion from trying would save time and energy for the gazelle too. But what signal will unequivocally tell the lion that it is hopeless? The gazelle cannot take the time to run a demonstration 100-yard dash in front of every lion that shows up. Perhaps gazelles could agree on some quick arbitrary signal that lions learn to understand, such as that pawing the ground with the left hind foot means 'I claim that I'm fast! However, such a purely arbitrary signal opens the door to cheating; any gazelle can easily give the signal regardless of its speed. Lions will then catch on that many slow gazelles giving the signal are lying, and lions will learn to ignore the signal. It is in the interests both of lions and of fast gazelles that the signal be believable. What type of signal could convince a lion of the gazelle's honesty? The same dilemma arises in the problem of sexual selection and mate choice that I discussed in Chapters Five, Six, and Nine. This is especially a problem of how females pick males, since females invest more in reproduction, have more to lose, and have to be choosier. Ideally, a female should pick a male for his good genes to pass on to her offspring. Since genes themselves are hard to assess, a female should look for quick indicators of good genes in a male, and a superior male should provide such indicators. In practice, male traits such as plumage, songs, and displays usually serve as indicators. Why do males 'choose' to advertise with those particular indicators, why should females trust a male's honesty and find those indicators attractive, and why do they imply good genes?
I have described the problem as if a gazelle or courting male voluntarily picks out some indicator from
