Quiet (26 page)

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 assert 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 circumstance.

“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 assume 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 circumspect 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 sex 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 hell-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 compassion 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 tit birds, for example, some of whom are much more aggressive than others, often act like case studies in an international relations class. 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 competitors 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 tits, 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 tit birds die of hunger that there's enough space 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 bloody battle. But in good years, when competition for nesting territory heats up, aggression pays for the hawkish male tit bird.

During times of war or fear—the human equivalent of a bad nut season for female tit 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 passion 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 class 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 assumed, 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 passion 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. “Nobody 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.