The rise and fall of the third chimpanzee

among many possible ones, and as if a lion or a female decides on reflection whether it is really a valid indicator of speed or good genes. In practice, of course, those 'choices' are the result °f evolution and become specified by genes. Those females who select males on the basis of indicators that really denote good male genes, and those males that use unambiguous indicators of good genes for self-advertisement, tend to leave the most offspring, as do those gazelles and lions that spare themselves unnecessary chases. As it turns out, many of the advertising signals evolved by animals pose a paradox similar to that posed by cigarette advertisements. The indicators often seem to be ones that do not suggest speed or good genes but instead constitute handicaps, expenses, or sources of risk. For example, a gazelle's signal to a lion that it sees approaching consists of a peculiar form of behaviour termed 'slotting'. Instead of running away as fast as possible, the gazelle runs slowly while repeatedly jumping high into the air with stiff-legged leaps. Why on earth should the gazelle indulge in this seemingly self-destructive display, which wastes time and energy and gives the lion a chance to catch up? Or think of the males of many animal species which sport large structures, such as a peacock's tail or a bird of paradise's plumes, that make movement difficult. Males of many more species have bright colours, loud songs, or conspicuous displays that attract predators. Why should a male advertise such an impediment, and why should a female like it? These paradoxes remain an important unsolved problem in animal behaviour today.

Zahavi's theory, which remains controversial among biologists, goes to the heart of this paradox. According to his theory, those deleterious structures and forms of behaviour constitute valid indicators that the signalling animal is being honest in its claim of superiority, precisely because those traits themselves impose handicaps. A signal that entails no cost lends itself to cheating, since even a slow or inferior animal can afford to give the signal. Only costly or deleterious signals are guarantees of honesty. For example, a slow gazelle that slotted at an approaching lion would seal its fate, whereas a fast gazelle could still outrun the lion after slotting. By slotting, the gazelle boasts lo the lion, 'I'm so fasl that I can escape you even after giving you this head slarl. The lion ihereby has grounds for believing in ihe gazelle's honesty, and both ihe lion and ihe gazelle profit by nol wasling lime and energy on a chase whose outcome is cerlain. Similarly, as applied lo males displaying towards females, Zahavi's iheory reasons lhal any male lhal has managed lo survive despite ihe handicap of a big lail or conspicuous song musl have terrific genes in other respects. He has proved thai he musl be especially good al escaping predalors, finding food, and resisling disease. The bigger ihe handicap, ihe more rigorous ihe lest lhal he has passed. The female who selects such a male is like the medieval damsel testing her knighl suilors by walching ihem slay dragons. When she sees a one-armed knighl who can slill slay a dragon, she knows lhal she has finally found a knighl wilh greal genes. Thai knighl, by flaunting his handicap, is aclually flaunting his superiority.

Il seems lo me lhal Zahavi's iheory applies to much cosily or dangerous human behaviour aimed at achieving stalus in general or al sexual benefils in particular. For inslance, men who woo women wilh cosily gifts and olher displays of weallh are in effecl saying, 'I have plenty of money lo support you and children, and you can believe my boast because you see how much money I'm spending now withoul blanching. People who show off expensive jewels, sports cars, or works of art gain slalus because ihe signal cannol be faked; everyone else knows whal those oslentatious objecls cosl. American Indians of ihe Pacific Norlh-wesl used lo seek slalus by competing lo give away as much weallh as possible in ceremonies known as pollalch riluals. In ihe days before modern medicine, lallooing was not only painful bul dangerous because of ihe risk of infection; hence lallooed people in effecl were advertising two facels of iheir slrenglh, resistance lo disease plus tolerance of pain. Men on ihe Pacific island of Malekula show off by the insanely dangerous practice of building a high tower and jumping off it head first, after lying one end of some sloul vines lo iheir ankles and ihe olher end lo ihe lop of the tower. The length of ihe vines is calculaled to slop ihe braggart's plunge while his head is still a few feel above ihe ground. Survival guaranlees lhal ihe jumper is courageous, carefully calculating, and a good builder. Zahavi's iheory can also be exlended lo human abuse of chemicals. Especially in adolescence and early adullhood, ihe age when drug abuse is mosl likely lo begin, we are devoting much energy to asserting our stalus. I suggesl lhal we share ihe same unconscious inslincl lhal leads birds lo indulge in dangerous displays. Ten ihousand years ago, we 'displayed' by challenging a lion or a Iribal enemy. Today, we do it in olher ways, such as by fast driving or by consuming dangerous drugs.

The messages of our old and new displays nevertheless remain ihe same: I'm strong and superior. Even lo lake drugs only once or Iwice, I musl be slrong enough lo gel pasl ihe burning, choking sensation of my firsl puff on a cigarette, or to gel pasl ihe misery of my firsl hangover. To do ii chronically and remain alive and heallhy, I musl be superior (so I imagine). Il is a message to our rivals, our peers, our prospective males—and lo ourselves. The smoker's kiss may lasle awful, and the drinker may be impotenl in bed, bul he or she slill hopes lo impress peers or allracl mates by the implicil message of superiorily.

Alas, ihe message may be valid for birds, bul for us il is a false one. Like so many animal instincts in us, this one has become maladaptive in modern human society. If you can still walk after drinking a bottle of whisky, it may prove thai you have high levels of liver alcohol dehydrogenase, bul il implies no superiority in olher respects. If you have not developed lung cancer after chronically smoking several packs of cigarettes daily, you may have a gene for resistance to lung cancer, but thai gene does nol convey intelligence, business acumen, or the ability to creale happiness for your spouse and children.

It is true that animals with only brief lives and courtships have no alternative except to develop quick indicators, since prospective mates don't have enough time to measure each other's real quality. But we, with our long lives and courtships and business associations, have ample time to scrutinize each other's worth. We need not rely on superficial, misleading indicators. Drug abuse is a classic instance of a once-useful instinct—the reliance on handicap signals—that has turned foul in us. It is that old instinct to which the tobacco and whisky companies are directing their clever, obscene advertisements. If we legalized cocaine, the drug lords too would soon have advertisements appealing to the same instinct. You can easily picture it: the photo of the cowboy on his horse, or the suave man and the attractive maiden, above the tastefully displayed packet of white powder.

Now, let's test my theory by jumping from Western Industrialized Society to the other side of the world. Drug abuse did not begin with the Industrial Revolution. Tobacco was a native American Indian crop, native alcoholic beverages are widespread in the world, and cocaine and opium came to us from other societies. The oldest preserved code of laws, that of the Babylonian king Hammurabi (1792-50 BC), already contained a section regulating drinking houses. Hence my theory, if it is valid, should apply to other societies as well. As an instance of its cross-cultural explanatory power, I shall cite a practice you may not have heard of- kung-fu kerosene drinking. I learned of this practice when I was working in Indonesia with a wonderful young biologist named Ardy Irwanto. Ardy and I had come to like and admire each other, and to look out for each other's well-being. At one point, when we reached a troubled area and I expressed concern about dangerous people we might encounter, Ardy assured me, 'No problem, Jared. I have kung-fu grade eight. He explained that he practised the Oriental martial art of kung-fu and had reached a high level of proficiency, such that he could single-handedly fight off a group of eight attackers. To illustrate, Ardy showed me a scar in his back stemming from an attack by eight ruffians. One had knifed him, whereupon Ardy broke the arms of two and the skull of a third and the remainder fled. I had nothing to fear in Ardy's company, he told me.

One evening at our campsite, Ardy walked with his drinking cup up to our jerrycans. As usual, we had two cans: a blue one for water, and a red one for kerosene for our pressure lamp. To my horror, I watched Ardy pour from the red jerry can and raise the cup to his lips. Remembering an awful moment during a mountaineering expedition when I had taken a sip of kerosene by mistake and spent all the next day coughing it back up, I screamed to Ardy to stop. But he raised his hand and said calmly, 'No problem, Jared. I have kung-fu grade eight.

Ardy explained that kung-fu gave him strength, which he and his fellow kung-fu masters tested each month by drinking a cup of kerosene. Without kung-fu, of course, kerosene would make a weaker person sick. Heaven forbid that I, Jared, for instance, should try it. But it did him, Ardy, no harm, because he had kung-fu. He calmly retired to his tent to sip his kerosene and emerged the next morning, happy and healthy as usual.

I cannot believe that kerosene did Ardy no harm. I wish that he could have found a less damaging way to make periodic tests of his preparedness. But for him and his kung-fu associates, it served as an indicator of their strength and their advanced level of kung-fu. Only a really robust person could get through that test. Kerosene drinking illustrates the handicap theory of toxic chemical use, in a form as startlingly repellent to us as our cigarettes and alcohol horrified Ardy. In my last example, I shall generalize my theory further by extending its application to the past—in this case, to the civilization of Mayan Indians that flourished in Central America one or