WHEN 22-YEAR-OLD Charles Darwin set out in1831 to circle the globe onthe HMS Beagle, hismind lay squarely in themainstream. He assumed that life forms were fixed entities, each one handcrafted by God for its special place in nature. But during his travels, Darwin started noticing things that didn't fit the paradigm. Why, he wondered, would finches and iguanas assume distinct but related forms on adjacent islands? And when Darwin proposed a revolutionary solution--that all nature's variety stems from a simple process that preserves useful variations and discards harmful ones--the authorities were appalled. ""A scientific mistake,'' thundered Louis Agassiz, then the world's leading naturalist--""untrue in its facts ... and mischievous in its tendency.''
What drives people like Darwin to stick pins in conventional wisdom? And why do radical innovations so enrage people like Agassiz? To Frank Sulloway, a science historian at MIT, it's no coincidence that Darwin was the fifth of six kids in his family, or that Agassiz was the firstborn in his. Sulloway has spent two decades gathering data on thousands of people involved in historic controversies--from the Copernican revolution to the Protestant Reformation--and running statistical tests to see what sets rebels apart from reactionaries. His findings, due out this month in a new book titled ""Born to Rebel'' (640 pages. Pantheon Books. $30), suggest that ""the foremost engine of historical change'' is not the church, state or economy but family structure. Sulloway makes a compelling case that firstborns, whatever their age, sex, class or nationality, specialize in defending the status quo while later-borns specialize in toppling it. Indeed, he says, people with the same birthranks have more in common with each other than they do with their own siblings.
It's an audacious claim (Sulloway himself is a later-born), and not one that social scientists will flock to embrace. Birth-order research, for all its intuitive appeal, has a reputation for flakiness. ""Both laypeople and experts tend to overinterpret the importance of birth order,'' says Joseph Rodgers, a psychologist at the University of Oklahoma. ""There are very few birth-order effects.'' In a 1983 review of 2,000 studies dating to the 1940s, the Swiss psychologists Cecile Ernst and Jules Angst declared that since most had failed to control for variables like social class and family size, none could be taken seriously. Sulloway agrees that much of the past research has been marred by weak hypotheses and poor methods. But his own study tackles many of the issues left unresolved by earlier ones, and some experts are raving about it. ""It's a monumental work of scholarship,'' says Sarah Blaffer Hrdy, an anthropologist at the University of California, Davis. ""I think it will change the way all of us think about ourselves and our families.''
Most of us already have a seat-of-the-pants sense of how birthrank affects personality. Firstborns are by reputation the listmakers and control freaks. ""Show me a librarian who's not a firstborn,'' says pop psychologist Kevin Leman, author of ""The Birth Order Book'' and ""Growing Up First Born.'' ""They live by the Dewey Decimal System.'' Firstborns are supposedly at home in trades like accounting and architecture--and maybe airline piloting. Walter Cronkite, Peter Jennings and Ted Koppel are all firstborns or only children. Chevy Chase, Danny DeVito and Jay Leno are last-borns. Psychologists have theorized about sibling differences since the 1920s, when Freud's estranged disciple Alfred Adler alleged that firstborns spend their lives getting over their displacement by younger brothers and sisters. But the models have been vague enough to accommodate almost any real-world observation--or its opposite. Adler, for example, argued that last-borns are often spoiled and lazy because they don't have younger siblings challenging them. He also characterized them as go-getters, hardened by incessant competition with their elders. Take your pick.
Sulloway starts not by spinning random hypotheses but by thinking about the Darwinian pressures that foster sibling competition throughout the natural world. Parental support is often the key to a youngster's survival--and siblings are often the primary obstacle. When food is scarce, chicks in a nest may gang up to murder the youngest member of the brood, without a peep of parental protest. Humans harbor similar propensities. Many societies accord firstborns higher status than later-borns, and some still condone killing a newborn in times of scarcity, just to ensure an older child's survival. Sibling competition may take different forms in the New Jersey suburbs than it does among peasants facing starvation. But firstborns and later-borns still confront very different pressures and opportunities. And by Sulloway's reckoning, their experiences should foster very different qualities of character.
How, exactly, should they differ? Firstborns, who grow up knowing they're ""bigger, stronger and smarter than their younger siblings,'' should be more assertive and dominant. They should also be more jealous and status-conscious, having seen their untrammeled turf invaded by newcomers. Their early experience as parents' lieutenants should make them more conscientious than later-borns. And the favoritism they enjoy should leave them more closely wedded to their parents' values and standards. Later-borns, since they can't get their way by force or bluster, should be more sociable and agreeable. And their lesser stake in the established family order should leave them more open to novelty and innovation.
SULLOWAY HAS FOUND INGENIOUS ways of testing these hypotheses. By sifting through the 2,000 studies that Ernst and Angst discarded in 1983, he found 196 in which researchers had factored out differences in social class and family size before looking for birth-order effects. And those studies, which included nearly 121,000 participants, supported his predictions about each of the five personality dimensions that psychological tests look for. Birth order was a lousy predictor of extroversion, a category so broad that it could encompass both a firstborn's assertiveness and a later-born's backslapping sociability. But most studies found that firstborns were more neurotic than were later-borns, and more conscientious (as in responsible, organized and achievement-oriented). Later-borns were consistently deemed more agreeable, and they were overwhelmingly more open to experience. People without siblings fell somewhere between firstborns and later-borns on most personality measures, but they were no more open to experience than were firstborns.
So far, so good. But did these psychological tests say anything about how people would behave out in the world? That's where Sulloway's historical surveys come into play. To get at the roots of real-life radicalism, he compiled biographical data on 6,566 people who have played public roles in scientific or political controversies over the past five centuries. By having panels of historians rate these players on their resistance or receptivity to the innovations they confronted, he was able to plot their ""openness to experience'' in relation to everything from birth order to age, sex, race, temperament, social class, family size and even the tenor of their family relationships.
In one case after another, the influence of birth order is remarkable. Later-borns were more likely than firstborns were to support each of the 61 liberal causes Sulloway surveyed, from the Protestant Reformation to the American civil-rights movement. Indeed birth order rivaled race as a predictor of who would support the abolition of slavery during the mid-1800s. Firstborns and later-borns differ more in their styles of thought than in their core beliefs--liberals can be rigidly doctrinaire and conservatives can be open to new ways of thinking. But the last-borns in Sulloway's survey were 18 times more likely to take up left-wing causes than to get involved in conservative ones, such as the temperance movement. Not surprisingly, Mahatma Gandhi and Martin Luther King Jr. were all later-borns, as were Leon Trotsky, Fidel Castro, Yasir Arafat and Ho Chi Minh. Rush Limbaugh, George Wallace and Newt Gingrich are all firstborns.
The pattern was just as clear when Sulloway examined 28 scientific controversies. Later-borns were five times more likely than firstborns were to support the Copernican and Darwinian revolutions--and nine times more likely to embrace phrenology, a wacky 19th-century fad that involved divining character from the shape of a person's skull. By contrast, Sulloway found that ""conservative innovations,'' such as the eugenics movement, have consistently been spearheaded by firstborns and opposed by later-borns.
This isn't to say that birth order is all that counts in life, or even in the contentious worlds of science and politics. ""These are statistical patterns, not physical laws,'' says Harvard evolutionist Ernst Mayr. ""There are always exceptions.'' Isaac Newton was a firstborn, for example, and Adolf Hitler wasn't. Sulloway is the first to admit that the effects of birth order can be offset, exaggerated or even overridden by other factors. Indeed, he devotes much of the new book to plotting the ways in which different influences interact. Gender has a huge and obvious impact on personality. But studies have found that firstborn girls are typically more confident, assertive and verbally aggressive than their younger brothers or sisters are. By the same token, age makes most people less open-minded, regardless of their birthrank. Within Sulloway's sample, young later-borns were more than twice as likely as elderly ones were to embrace the idea of evolution during the 19th century. But 80-year-old later-borns were still more receptive than 30-year-old firstborns.
Like age, certain features of a person's innate temperament can mask the effects of birth order. Congenital shyness, for example, tends to minimize birth-order differences. By placing a damper on other aspects of character, it makes firstborns less arch and later-borns less outwardly subversive. Likewise, extroversion tends to magnify the contrast. It might lead a firstborn to become a drill sergeant instead of a bank teller, and a last-born to do stand-up comedy instead of writing poems. Conflict with a parent can also offset a firstborn's conformist ways. Once estranged from the familial status quo and pushed into the underdog role, says Sulloway, anyone becomes more radical.
Sulloway's findings are sure to strike a chord with lay readers, but social scientists may not appreciate his chutzpah. In the years since Ernst and Angst declared birth order meaningless, few researchers have bothered to look at it, and many of those who have tried have been disappointed. In a recent book titled ""Birth Order and Political Behavior,'' Alfred University political scientist Steven Peterson and two colleagues describe how they analyzed a huge list of eminent figures to see if it was dominated by firstborns. When they came up dry, they assumed there was nothing left to study. ""There are always some people who are going to say, "Gee, you just didn't look at enough variables','' says Peterson's collaborator Alan Arwine. ""It's like trying to kill a vampire.'' But Arwine and Peterson's findings don't contradict Sulloway's. They merely answer a less interesting question. ""The question isn't whether firstborns are more eminent than later-borns,'' Sulloway insists. ""Eminence isn't even a personality trait. It's an outcome. What's interesting is that firstborns and later-borns become eminent in different ways.''
Other critics will dismiss Sulloway's whole approach. ""From what I read, it's not scientific,'' says Toni Falbo, a professor of educational psychology at the University of Texas at Austin. ""He looks at special cases. If you're looking at special cases, particularly in history, you can find a case that fits almost any hypothesis you want.'' By her logic, history is just an endless series of special cases, not a lawful process that can be illuminated through hypothesis testing. Sulloway's real accomplishment is to show that's not the case. His ""special cases'' span five centuries and many countries, yet they repeatedly confirm his predictions. ""Frank attacks questions that could not be more contingent,'' says John Tooby, an anthropologist at the University of California, Santa Barbara--""why some countries ended up Protestant, why France resisted Darwinism, who ended up in which faction in the French National Assembly--and shows that they fit into larger patterns.''
Sulloway doesn't claim to have solved any ultimate questions. He plans to expand his database, test new predictions and publish a revised edition of the book every five years or so. ""The publisher put that in my contract,'' he says. ""It was the only way I could make myself stop and publish this.'' Anyone who can stomach a revolution should be glad that he did.
In the world of the family, sibling competition is dog-eat-dog and the oldest seldom goes to bed hungry.
STEVE FORBES: Conservative in polotics and demeanor, Forbes is the inheritor firstborn, presiding over the family empire. His Harley-riding, hot-air-ballooning dad was, naturally, a later-born.
SADDAM HUSSEIN: A human monument to the less delicate firstborn traits, he's aggresive, ambitious, dominating, vengeful and covetous. Firstborns may not play nicely with others, but they make excellent dictators.
OPRAH WINFREY: Firstborns from disrupted families and mionrity groups tend to wind up more like later-borns. Oprah fits the mold--a rebellious teen, a social liberal and empathy personified.
CLINT EASTWOOD: When an actor is hired to go shoot everybody in town, he's a firstborn," jokes author Frank Sulloway. Eastwood, Sly Stallone and Bruce Willis are all firstborns. So was John Wayne. It could be coincidence. Feel lucky, punk?
MARCIA CLARK: Firstborn overconfidence and an inability to empathize with other views may have cost her the Simpson case.
HILLARY CLINTON: A classic firstborn. "She knows what she wants and knows how to get it," says Frank Sulloway. Was conservative, like her dad, in high school.
They can't beat 'em, so they don't join 'em. Later-born siblings excel by choosing different paths.
MADONNA: The third of six children in a conservative, Roman Catholic family, Madonna is a natural rule-breaker. But what about her eagerly awaited baby? Firstborns tend to emulate their parents, so Madonna Jr. ought to keep fingers wagging well int o the next millennium.
MICHAEL JORDAN: Later-borns are more likely to have mutiple interests, so Air Jordan's golf mania and foray into pro baseball make sense. And only a later-born would drop a hoops career like his for a stint on a White Sox farm team.
BILL GATES: Since later-borns are more open to radical new ideas, it's a no-brainer that the techno-revoluntionary behind Microsoft has an older sibling.
DAVID LETTERMAN: Comedians tend to be later-borns. Clowning can attract parental attention in a crowded family, and wit is a weapon against older, larger siblings. Jay Leno and Conan O'Brien also are later-borns.
JACK KEVORKIAN: The suicide doc's crusade is socially radical, and since it's ostensibly motivated by compassion, it perfectly suits Kevorkian's status as the second child of three. Middle children are generally the most empathetic, says Sulloway.
GLORIA STEINEM: Feminism's famous proponent shares her later-born status with social reformers Susan B. Anthony, Martin Luther King and Malcolm X.
Later-borns are said to be more receptive to unconventional thinking. How do you match up? In section one, find the description closest to yours and enter the numerical value in the box. For each item in section two, enter the numerical value indic ated, then add or subtract. The resulting score suggests your receptivity to unorthodox ideas.
SECTION ONE FIRSTBORNS MIDDLE LAST-BORNS Under age 30 Social conservatives 14 40 49 Social moderates 48 77 84 Social liberals 75 92 96 Age 30 to 59 Social conservatives 6 22 26 Social moderates 25 58 66 Social liberals 52 82 86 Age 60 or over Social conservatives 3 12 15 Social moderates 15 44 50 Social liberals 36 72 76 Enter Your Score Here: SECTION TWO 1 Pronounced conflict with parent: Firstborns add 30; later-borns add 10 2 Gender: Women add 5; men no adjustment 3 Pronounced shyness: Firstborns add 20; middle-borns no adjustment; last-borns subtract 15 4 Early loss of a parent: Firstborn who acted as surrogate subtract 15; later-born raised by surrogate add 15 5 Race: Minorities add 10 Add all entries: this is your final score: Your rebel score: -12 to 24 = intolerant of new ideas; 25 to 61 = resistant; 62 to 99 = supportive; 100 to 136 = entusiastic.
Source: "Born to Rebel" by Frank J. Sulloway