Or does it?

Elaine Aron has an idea about this. She believes that high sensitivity was not itself selected for, but rather the careful, reflective style that tends to accompany it. "The type that is 'sensitive' or 'reactive' would reflect a strategy of observing carefully before acting," she writes, "thus avoiding dangers, failures, and wasted energy, which would require a nervous system specially designed to observe and detect subtle differences. It is a strategy of 'betting on a sure thing' or 'looking before you leap.' In contrast, the active strategy of the [other type] is to be first, without complete information and with the attendant risks-the strategy of 'taking a long shot' because the 'early bird catches the worm' and 'opportunity only knocks once.' "

In truth, many people Aron considers sensitive have some of the twenty-seven attributes a.s.sociated with the trait, but not all of them. Maybe they're sensitive to light and noise, but not to coffee or pain; maybe they're not sensitive to anything sensory, but they're deep thinkers with a rich inner life. Maybe they're not even introverts-only 70 percent of sensitive people are, according to Aron, while the other 30 percent are extroverts (although this group tends to report craving more downtime and solitude than your typical extrovert). This, speculates Aron, is because sensitivity arose as a by-product of survival strategy, and you need only some, not all, of the traits to pull off the strategy effectively.

There's a great deal of evidence for Aron's point of view. Evolutionary biologists once believed that every animal species evolved to fit an ecological niche, that there was one ideal set of behaviors for that niche, and that species members whose behavior deviated from that ideal would die off. But it turns out that it's not only humans that divide into those who "watch and wait" and others who "just do it." More than a hundred species in the animal kingdom are organized in roughly this way.

From fruit flies to house cats to mountain goats, from sunfish to bushbaby primates to Eurasian t.i.t birds, scientists have discovered that approximately 20 percent of the members of many species are "slow to warm up," while the other 80 percent are "fast" types who venture forth boldly without noticing much of what's going on around them. (Intriguingly, the percentage of infants in Kagan's lab who were born high-reactive was also, you'll recall, about twenty.)

If "fast" and "slow" animals had parties, writes the evolutionary biologist David Sloan Wilson, "some of the fasts would bore everyone with their loud conversation, while others would mutter into their beer that they don't get any respect. Slow animals are best described as shy, sensitive types. They don't a.s.sert themselves, but they are observant and notice things that are invisible to the bullies. They are the writers and artists at the party who have interesting conversations out of earshot of the bullies. They are the inventors who figure out new ways to behave, while the bullies steal their patents by copying their behavior."

Once in a while, a newspaper or TV program runs a story about animal personalities, casting shy behavior as unseemly and bold behavior as attractive and admirable. (That's our kind of fruit fly!) But Wilson, like Aron, believes that both types of animals exist because they have radically different survival strategies, each of which pays off differently and at different times. This is what's known as the trade-off theory of evolution, in which a particular trait is neither all good nor all bad, but a mix of pros and cons whose survival value varies according to circ.u.mstance.

"Shy" animals forage less often and widely for food, conserving energy, sticking to the sidelines, and surviving when predators come calling. Bolder animals sally forth, swallowed regularly by those farther up the food chain but surviving when food is scarce and they need to a.s.sume more risk. When Wilson dropped metal traps into a pond full of pumpkinseed fish, an event he says must have seemed to the fish as unsettling as a flying saucer landing on Earth, the bold fish couldn't help but investigate-and rushed headlong into Wilson's traps. The shy fish hovered judiciously at the edge of the pond, making it impossible for Wilson to catch them.

On the other hand, after Wilson succeeded in trapping both types of fish with an elaborate netting system and carrying them back to his lab, the bold fish acclimated quickly to their new environment and started eating a full five days earlier than did their shy brethren. "There is no single best ... [animal] personality," writes Wilson, "but rather a diversity of personalities maintained by natural selection."

Another example of the trade-off theory of evolution is a species known as Trinidadian guppies. These guppies develop personalities-with astonishing speed, in evolutionary terms-to suit the microclimates in which they live. Their natural predators are pike. But some guppy neighborhoods, upstream of a waterfall for example, are pike-free. If you're a guppy who grew up in such a charmed locale, then chances are you have a bold and carefree personality well suited to la dolce vita. In contrast, if your guppy family came from a "bad neighborhood" downstream from the waterfall, where pike cruise the waterways menacingly, then you probably have a much more circ.u.mspect style, just right for avoiding the bad guys.

The interesting thing is that these differences are heritable, not learned, so that the offspring of bold guppies who move into bad neighborhoods inherit their parents' boldness-even though this puts them at a severe disadvantage compared to their vigilant peers. It doesn't take long for their genes to mutate, though, and descendants who manage to survive tend to be careful types. The same thing happens to vigilant guppies when the pike suddenly disappear; it takes about twenty years for their descendants to evolve into fish who act as if they haven't a care in the world.

The trade-off theory seems to apply equally to humans. Scientists have found that nomads who inherited the form of a particular gene linked to extroversion (specifically, to novelty-seeking) are better nourished than those without this version of the gene. But in settled populations, people with this same gene form have poorer nutrition. The same traits that make a nomad fierce enough to hunt and to defend livestock against raiders may hinder more sedentary activities like farming, selling goods at the market, or focusing at school.

Or consider this trade-off: human extroverts have more s.e.x partners than introverts do-a boon to any species wanting to reproduce itself-but they commit more adultery and divorce more frequently, which is not a good thing for the children of all those couplings. Extroverts exercise more, but introverts suffer fewer accidents and traumatic injuries. Extroverts enjoy wider networks of social support, but commit more crimes. As Jung speculated almost a century ago about the two types, "the one [extroversion] consists in a high rate of fertility, with low powers of defense and short duration of life for the single individual; the other [introversion] consists in equipping the individual with numerous means of self-preservation plus a low fertility rate."

The trade-off theory may even apply to entire species. Among evolutionary biologists, who tend to subscribe to the vision of lone individuals h.e.l.l-bent on reproducing their own DNA, the idea that species include individuals whose traits promote group survival is hotly debated and, not long ago, could practically get you kicked out of the academy. But this view is slowly gaining acceptance. Some scientists even speculate that the evolutionary basis for traits like sensitivity is heightened compa.s.sion for the suffering of other members of one's species, especially one's family.

But you don't have to go that far. As Aron explains, it makes sense that animal groups depend on their sensitive members for survival. "Suppose a herd of antelope ... has a few members who are constantly stopping their grazing to use their keen senses to watch for predators," she writes. "Herds with such sensitive, watchful individuals would survive better, and so continue to breed, and so continue to have some sensitive individuals born in the group."

And why should it be any different for humans? We need our Eleanor Roosevelts as surely as grazing herds depend on their sensitive antelopes.

In addition to "shy" and "bold" animals, and to "fast" and "slow" ones, biologists sometimes speak of the "hawk" and "dove" members of a given species. Great t.i.t birds, for example, some of whom are much more aggressive than others, often act like case studies in an international relations cla.s.s. These birds feed on beech tree nuts, and in years when nuts are scarce, the hawkish female birds do better, just as you'd expect, because they're quick to challenge nut-eating compet.i.tors to a duel. But in seasons when there are plenty of beech nuts to go around, the female "doves"-who, incidentally, tend to make more attentive mothers-do better than the "hawks," because the hawks waste time and bodily health getting into fights for no good reason.

Male great t.i.ts, on the other hand, have the opposite pattern. This is because their main role in life is not to find food but to defend territory. In years when food is scarce, so many of their fellow t.i.t birds die of hunger that there's enough s.p.a.ce for all. The hawkish males then fall into the same trap as their female comrades during nutty seasons-they brawl, squandering precious resources with each b.l.o.o.d.y battle. But in good years, when compet.i.tion for nesting territory heats up, aggression pays for the hawkish male t.i.t bird.

During times of war or fear-the human equivalent of a bad nut season for female t.i.t birds-it might seem that what we need most are aggressive heroic types. But if our entire population consisted of warriors, there would be no one to notice, let alone battle, potentially deadly but far quieter threats like viral disease or climate change.

Consider Vice President Al Gore's decades-long crusade to raise awareness of global warming. Gore is, by many accounts, an introvert. "If you send an introvert into a reception or an event with a hundred other people he will emerge with less energy than he had going in," says a former aide. "Gore needs a rest after an event." Gore acknowledges that his skills are not conducive to stumping and speechmaking. "Most people in politics draw energy from backslapping and shaking hands and all that," he has said. "I draw energy from discussing ideas."

But combine that pa.s.sion for thought with attention to subtlety-both common characteristics of introverts-and you get a very powerful mix. In 1968, when Gore was a college student at Harvard, he took a cla.s.s with an influential oceanographer who presented early evidence linking the burning of fossil fuels with the greenhouse effect. Gore's ears perked up.

He tried to tell others what he knew. But he found that people wouldn't listen. It was as if they couldn't hear the alarm bells that rang so loudly in his ears.

"When I went to Congress in the middle of the 1970s, I helped organize the first hearings on global warming," he recalls in the Oscar-winning movie An Inconvenient Truth-a film whose most stirring action scenes involve the solitary figure of Gore wheeling his suitcase through a midnight airport. Gore seems genuinely puzzled that no one paid attention: "I actually thought and believed that the story would be compelling enough to cause a real sea change in the way Congress reacted to that issue. I thought they would be startled, too. And they weren't."

But if Gore had known then what we know now about Kagan's research, and Aron's, he might have been less surprised by his colleagues' reactions. He might even have used his insight into personality psychology to get them to listen. Congress, he could have safely a.s.sumed, is made up of some of the least sensitive people in the country-people who, if they'd been kids in one of Kagan's experiments, would have marched up to oddly attired clowns and strange ladies wearing gas masks without so much as a backward glance at their mothers. Remember Kagan's introverted Tom and extroverted Ralph? Well, Congress is full of Ralphs-it was designed for people like Ralph. Most of the Toms of the world do not want to spend their days planning campaigns and schmoozing with lobbyists.

These Ralph-like Congressmen can be wonderful people-exuberant, fearless, persuasive-but they're unlikely to feel alarmed by a photograph of a tiny crack in a distant glacier. They need more intense stimulation to get them to listen. Which is why Gore finally got his message across when he teamed up with whiz-bang Hollywood types who could package his warning into the special-effects-laden show that became An Inconvenient Truth.

Gore also drew on his own strengths, using his natural focus and diligence to tirelessly promote the movie. He visited dozens of movie theaters across the country to meet with viewers, and gave innumerable TV and radio interviews. On the subject of global warming, Gore has a clarity of voice that eluded him as a politician. For Gore, immersing himself in a complicated scientific puzzle comes naturally. Focusing on a single pa.s.sion rather than tap dancing from subject to subject comes naturally. Even talking to crowds comes naturally when the topic is climate change: Gore on global warming has an easy charisma and connection with audience members that eluded him as a political candidate. That's because this mission, for him, is not about politics or personality. It's about the call of his conscience. "It's about the survival of the planet," he says. "n.o.body is going to care who won or lost any election when the earth is uninhabitable."

If you're a sensitive sort, then you may be in the habit of pretending to be more of a politician and less cautious or single-mindedly focused than you actually are. But in this chapter I'm asking you to rethink this view. Without people like you, we will, quite literally, drown.

Back here at Walker Creek Ranch and the gathering for sensitive people, the Extrovert Ideal and its primacy of cool is turned upside down. If "cool" is low reactivity that predisposes a person to boldness or nonchalance, then the crowd that has come to meet Elaine Aron is deeply uncool.

The atmosphere is startling simply because it's so unusual. It's something you might find at a yoga cla.s.s or in a Buddhist monastery, except that here there's no unifying religion or worldview, only a shared temperament. It's easy to see this when Aron delivers her speech. She has long observed that when she speaks to groups of highly sensitive people the room is more hushed and respectful than would be usual in a public gathering place, and this is true throughout her presentation. But it carries over all weekend.

I've never heard so many "after you's" and "thank you's" as I do here. During meals, which are held at long communal tables in a summer-camp style, open-air cafeteria, people plunge hungrily into searching conversations. There's a lot of one-on-one discussion about intimate topics like childhood experiences and adult love lives, and social issues like health care and climate change; there's not much in the way of storytelling intended to entertain. People listen carefully to each other and respond thoughtfully; Aron has noted that sensitive people tend to speak softly because that's how they prefer others to communicate with them.

"In the rest of the world," observes Mich.e.l.le, a web designer who leans forward as if bracing herself against an imaginary blast of wind, "you make a statement and people may or may not discuss it. Here you make a statement and someone says, 'What does that mean?' And if you ask that question of someone else, they actually answer."

It's not that there's no small talk, observes Strickland, the leader of the gathering. It's that it comes not at the beginning of conversations but at the end. In most settings, people use small talk as a way of relaxing into a new relationship, and only once they're comfortable do they connect more seriously. Sensitive people seem to do the reverse. They "enjoy small talk only after they've gone deep," says Strickland. "When sensitive people are in environments that nurture their authenticity, they laugh and chitchat just as much as anyone else."

On the first night we drift to our bedrooms, housed in a dormlike building. I brace myself instinctively: now's the time when I'll want to read or sleep, but will instead be called upon to have a pillow fight (summer camp) or play a loud and boring drinking game (college). But at Walker Creek Ranch, my roommate, a twenty-seven-year-old secretary with huge, doe-like eyes and the ambition to become an author, is happy to spend the evening writing peacefully in her journal. I do the same.

Of course, the weekend is not completely without tension. Some people are reserved to the point of appearing sullen. Sometimes the do-your-own-thing policy threatens to devolve into mutual loneliness as everyone goes their own separate ways. In fact, there is such a deficit of the social behavior we call "cool" that I begin thinking someone should be cracking jokes, stirring things up, handing out rum-and-c.o.kes. Shouldn't they?

The truth is, as much as I crave breathing room for sensitive types, I enjoy hail-fellows-well-met, too. I'm glad for the "cool" among us, and I miss them this weekend. I'm starting to speak so softly that I feel like I'm putting myself to sleep. I wonder if deep down the others feel this way, too.

Tom, the software engineer and Abraham Lincoln look-alike, tells me of a former girlfriend who was always throwing open the doors of her house to friends and strangers. She was adventurous in every way: she loved new food, new s.e.xual experiences, new people. It didn't work out between them-Tom eventually craved the company of a partner who would focus more on their relationship and less on the outside world, and he's happily married now to just such a woman-but he's glad for the time with his ex-girlfriend.

As Tom talks, I think of how much I miss my husband, Ken, who's back home in New York and not a sensitive type either, far from it. Sometimes this is frustrating: if something moves me to tears of empathy or anxiety, he'll be touched, but grow impatient if I stay that way too long. But I also know that his tougher att.i.tude is good for me, and I find his company endlessly delightful. I love his effortless charm. I love that he never runs out of interesting things to say. I love how he pours his heart and soul into everything he does, and everyone he loves, especially our family.

But most of all I love his way of expressing compa.s.sion. Ken may be aggressive, more aggressive in a week than I'll be in a lifetime, but he uses it on behalf of others. Before we met, he worked for the UN in war zones all over the world, where, among other things, he conducted prisoner-of-war and detainee release negotiations. He would march into fetid jails and face down camp commanders with machine guns strapped to their chests until they agreed to release young girls who'd committed no crime other than to be female and victims of rape. After many years on the job, he went home and wrote down what he'd witnessed, in books and articles that bristled with rage. He didn't write in the style of a sensitive person, and he made a lot of people angry. But he wrote like a person who cares, desperately.

I thought that Walker Creek Ranch would make me long for a world of the highly sensitive, a world in which everyone speaks softly and no one carries a big stick. But instead it reinforced my deeper yearning for balance. This balance, I think, is what Elaine Aron would say is our natural state of being, at least in Indo-European cultures like ours, which she observes have long been divided into "warrior kings" and "priestly advisers," into the executive branch and the judicial branch, into bold and easy FDRs and sensitive, conscientious Eleanor Roosevelts.

CHAPTER 7

WHY DID WALL STREET CRASH AND WARREN BUFFETT PROSPER?

How Introverts and Extroverts Think (and Process Dopamine) Differently