Smoking is no different whether a teenager picks up the habit depends on whether he or she has contact with one of those Salesmen who give teenagers "permission" to engage in deviant acts. But whether a teenager likes cigarettes enough to keep using them depends on a very different set of criteria. In a recent University of Michigan study, for example, a large group of people were polled about how they felt when they smoked their first cigarette. "What we found is that for almost everyone their initial experience with tobacco was somewhat aversive," said Ovide Pomerleau, one of the researchers on the project. "But what sorted out the smokers-to-be from the never again smokers is that the smokers-to-be derived some overall pleasure from the experience — like the feeling of a buzz or a heady pleasurable feeling." The numbers are striking. Of the people who experimented with cigarettes a few times and then never smoked again, only about a quarter got any sort of pleasant "high" from their first cigarette. Of the ex-smokers — people who smoked for a while but later managed to quit — about a third got a pleasurable buzz. Of people who were light smokers, about half remembered their first cigarette well. Of the heavy smokers, though, 78 percent remembered getting a good buzz from their first few puffs. The questions of how sticky smoking ends up being to any single person, in other words, depends a great deal on his or her own particular initial reaction to nicotine.

This is a critical point, and one that is often lost in the heated rhetoric of the war on smoking. The tobacco industry, for instance, has been pilloried for years for denying that nicotine is addictive. That position, of course, is ridiculous. But the opposite notion often put forth by antismoking advocates — that nicotine is a deadly taskmaster that enslaves all who come in contact with it — is equally ridiculous. Of all the teenagers who experiment with cigarettes, only about a third ever goes on to smoke regularly. Nicotine may be highly addictive, but it is only addictive in some people, some of the time. More important, it turns out that even among those who smoke regularly, there are enormous differences in the stickiness of their habit. Smoking experts used to think that 90 to 95 percent of all those who smoked were regular smokers. But several years ago, the smoking questions on the federal government's national health survey were made more specific, and researchers discovered, to their astonishment, that a fifth of all smokers don't smoke every day. There are millions of Americans, in other words, who manage to smoke regularly and not be hooked — people for whom smoking is contagious but not sticky. In the past few years, these "chippers" — as they have been dubbed — have been exhaustively studied, with the bulk of the work being done by University of Pittsburgh psychologist Saul Shiftman.

Shiftman's definition of a chipper is someone who smokes no more than five cigarettes a day but who smokes at least four days a week. As Shiftman writes:

Chippers' smoking varies considerably from day to day, and their smoking patterns often include days of complete abstinence. Chippers reported little difficulty maintaining such casual abstinence and reportedly experienced almost no withdrawal symptoms when abstaining from smoking… Unlike regular smokers who smoke soon on waking to replenish the nicotine that has cleared overnight, chippers go several hours before smoking their first cigarette of the day. In short, every indicator examined suggests that chippers are not addicted to nicotine and that their smoking is not driven by withdrawal relief or withdrawal avoidance.

Shiftman calls chippers the equivalent of social drinkers. They are people in control of their habit. He says:

Most of these people had never been heavy smokers. I think of them as developmentally retarded. Every smoker starts out as a chipper, in the early period, but then graduates more heavily into more dependent smoking. When we collected data about the early period of smoking, the chippers look like everyone else when they start out. The difference is that over time, the heavy smokers escalated whereas the chippers stayed where they were.

What distinguishes chippers from hard-core smokers? Probably genetic factors. Allan Collins of the University of Colorado, for example, recently took several groups of different strains of mice and injected each with steadily increasing amounts of nicotine. When nicotine reaches toxic levels in a mouse (nicotine is, after all, a poison) it has a seizure — its tail goes rigid; it begins running wildly around its cage; its head starts to jerk and snap; and eventually it flips over on its back. Collins wanted to see whether different strains of mice could handle different amounts of nicotine. Sure enough, they could. The strain of mice most tolerant of nicotine could handle about two to three times as much of the drug as the strain that had seizures at the lowest dose. "That's about in the same range as alcohol," Collins says. Then he put all the mice into cages and gave them two bottles to drink from: one filled with a simple saccharin solution, one filled with a saccharin solution laced with nicotine. This time he wanted to see whether there was any relationship between each strain's genetic tolerance to nicotine and the amount of nicotine they would voluntarily consume. Once again, there was. In fact, the correlation was almost perfect. The greater a mouse's genetic tolerance for nicotine, the more of the nicotine bottle it would drink. Collins thinks that there are genes in the brains of mice that govern how nicotine is processed — how quickly it causes toxicity, how much pleasure it gives, what kind of buzz it leaves — and that some strains of mice have genes that handle nicotine really well and extract the most pleasure from it and some have genes that treat nicotine like a poison.

Humans, obviously, aren't mice, and drinking nicotine from a bottle in a cage isn't the same as lighting up a Marlboro. But even if there is only a modest correlation between what goes on in mice brains and ours, these findings do seem to square with Pomerleau's study. The people who didn't get a buzz from their first cigarette and who found the whole experience so awful that they never smoked again are probably people whose bodies are acutely sensitive to nicotine, incapable of handling it in even the smallest doses. Chippers may be people who have the genes to derive pleasure from nicotine, but not the genes to handle it in large doses. Heavy smokers, meanwhile, may be people with the genes to do both. This is not to say that genes provide a total explanation for how much people smoke. Since nicotine is known to relieve boredom and stress, for example, people who are in boring or stressful situations are always going to smoke more than people who are not. It is simply to say that what makes smoking sticky is completely different from the kinds of things that make it contagious. If we are looking for Tipping Points in the war on smoking, then, we need to decide which of those sides of the epidemic we will have the most success attacking. Should we try to make smoking less contagious, to stop the Salesmen who spread the smoking virus? Or are we better off trying to make it less sticky, to look for ways to turn all smokers into chippers?

Let's deal with the issue of contagion first. There are two possible strategies for stopping the spread of smoking. The first is to prevent the permission-givers — the Maggies and Billy G.'s — from smoking in the first place. This is; clearly the most difficult path of all: the most independent, precocious, rebellious teens are hardly likely to be the most susceptible to rational health advice. The second possibility is to convince all those who look to people like Maggie and Billy G. for permission that they should look elsewhere, to get their cues as to what is cool, in this instance, from adults.