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Taking the nature vs. nurture debate to a new level, this fascinating, comprehensive journey into the world of genetic research and molecular biology offers a fresh assessment of the work that has been done in this relatively new field during the last half century-work that has demolished common assumptions and overturned existing theories about what determines our personality and behavior.
"...reveals the findings of one researcher who studied the links between genetics and personality."
|1||The Chemistry of Self||3|
|2||Birth of a Study||20|
|3||Desperately Seeking Twins||34|
|4||Cosmic Secrets of Twins||46|
|6||Two Dogs Named Toy||62|
|8||Other Behavioral Genetics Studies||85|
|9||Stars of the New Field||99|
|10||The Other End - Searching the DNA||118|
|11||Moving Right Along the Double Helix||134|
|12||The Ups and Downs of Human Nature||147|
|13||Short and Happy Life of the Tabula Rasa||171|
|14||Surviving the Jensen Furor||183|
|15||Oh So Political Science||197|
|16||Scientists in Denial||216|
|17||Violent Crime in the Maryland Woods||228|
THE CHEMISTRY OF SELF
ON A MONDAY MORNING Of a typical workweek, a single woman in her early thirties is awakened by k.d. lang coming over her clock radio. She switches to a classical station and is pleased to hear a Haydn symphony; the soothing rationality of classical music is her preference for starting the day. After a hot shower, she applies her usual discreet makeup, then selects a beige suit with gold buttons to wear to the office. She wore it only four days ago, but she feels good in it and knows it's becoming.
She brews a pot of Yuban French Roast and drinks a cup--milk but no sugar--while skimming the morning paper, which annoys her for having nothing about a major film star's arrest on drug charges that had been mentioned on the eleven o'clock news. An article on the obstructed relief efforts in Zaire upsets her and she resolves to donate another fifty dollars to Save the Children. On her way to the street, the elevator stops at a lower floor and an unfamiliar man in his forties enters and greets her cheerfully. She grunts and feels a complicated mix of obligatory civility, stranger-fear, violated space, and anger at male sexual presumption. She yearns for the elevator to reach the lobby.
Once outside her building, she resists splurging on a taxi and waits for a bus. Finding a seat next to a teenaged boy with books on his lap, one open to a page of graphs, she feels a rush of satisfaction at her success since leaving college, where her grades were lackluster. But then a pang of regret hits-her about career opportunities missed, missteps taken. The boy indicates he is getting off. She slides into his seat and looks out the window to see an old man carrying a suitcase stumble on the curb and almost fall. An urge to help comes over her.
The empty seat beside the woman is taken by a tall slender man in his forties. From the corner of her eye she sees that he has curly brown hair, a trim mustache, and glasses--three of her favorite attributes in a male. She reads her newspaper, but glances at his pants leg so close to her skirt and wonders if his leg is hairy. She forces down an erotic surge by plunging into an editorial on redistricting. Traffic is moving slowly; she fears she'll be late. A Hispanic man who looks drunk boards the bus and fumbles for the fare as the traffic light turns red. She wants to scream.
All of these reactions, concerns, judgments, and decisions might seem products of conscious thoughts. Or, with more reflection, some might be traced to the woman's experience, upbringing, or social conditioning. They may, in fact, have sprung from none of these, but may have been prompted, wholly or in part, by her genes, those infinitesimal bits of DNA, which thirty years of research tells us influences our personalities, our behavior, and how we respond to the world around us. As the woman goes about her day, she draws on her reasoning power to deal with special situations. Much of the time, however, she is, like most of us, on semiautomatic pilot, reacting to whatever the environment throws at her with ebbs and surges, blips and flashes, of chemical, gene-rooted responses. As with all humans, her behavior is shaped and guided by signals from the biochemical motherboards that genes have created in each of us.
The interaction between genes and environment is, we now know, essential to the developing child--and for psychologists the term "environment" means every influence on an organism that is not genetic. Not only in children, but in adults too, the environment can have powerful effects. But to a greater degree than ever before realized, the genetic influences on behavior, barring an extraordinary childhood (malnutrition, social deprivation, prolonged abuse), express themselves pretty much as configured before birth.
Scholars have traditionally divvied up the human into an array of discrete vantage points--anatomy, psychology, anthropology, sociology, economics, political science, history. We now see these disciplines converging on a component of our physical selves that mounting evidence indicates is the underlying basis of it all: the twenty-three pairs of chromosomes, containing approximately 100,000 genes, that exist in every human cell. Whatever the term--chromosomes, genes, DNA, the double helix, nucleic acids, ribosomes, alleles--all refer to our biochemical blueprints.
Genetic discoveries have been receiving so much press that non-scientists can be forgiven for seeing the DNA furor as a fad, a New Thing steamroller, this year's channeling or biorhythms. The world appears so in the grip of a double-helix dither that less excitable types shrug it off as a hyped-up media ploy to make the news of the day appear different from the news of last week. Unfortunately for people already bored with gene palaver, the ramifications of this scientific earthquake will continue unfolding, and making news, well into the next century. And the possibilities this knowledge opens up are vast.
Many of the most riveting findings have been of a high-priority medical nature, the genetic roots of birth defects and diseases that, throughout time, have plagued humanity. Because of the widespread suffering caused by these genetic mishaps--British geneticist Steve Jones states that one child in thirty is born with a genetic irregularity of one sort or other--the excitement over genetic therapies is understandable. More recently, the sensational news about cloning a sheep from a mature cell has seized the spotlight from even the landmark medical breakthroughs.
Important as these advances are, they have overshadowed a concurrent, and in some ways more momentous, revolution--the burgeoning understanding of genetic links to personality and behavior. A mass of research that has been building over the past two decades has forced most psychologists and other social scientists to acknowledge what they had long denied: Genes influence not just physical characteristics such as hair color and susceptibility to cancer but our personalities, temperaments, behavioral patterns--even personal idiosyncrasies, the quirks and foibles that make each person unique.
Since behavior is the subject of this book, and the term is broad enough to glaze the eyes of nonprofessionals, it might be a good idea to consider what the word means to scientists. For them, behavior is everything the organism does and thinks--from crying for its mother to delivering a Nobel acceptance speech. Ambition is behavior; so are laziness, rebellion, and compassion. Patriotism, sexism, hating your boss, and loving the Lakers--all are forms of behavior. Virtually anything the individual does, any product of the brain, any action, any mood, emotion, mannerism, or tic, is lumped under the umbrella word "behavior."
From the beginning of the brief hundred years that the mechanics of inheritance have been unfolding, science understood that genes were the building plans for our bodies and brains, the human machine that seemed to be able to think and behave in unlimited numbers of ways. Patterns and constraints were imposed on behavior from the external world, especially from the culture and its primary agents, parents. Now we see that this picture is not accurate. Many patterns and constraints are imposed by culture, but many others, the new evidence shows--along with batteries of impulses, leanings, attitudes, susceptibilities, aptitudes--are born with us.
It is hard enough for nonscientists to conceive or a few microscopic specks of nucleic acid containing the instructions for growing an arm, an ear, or a kidney. Now research says we must grasp as well that similar specks can also go far toward determining if we are to be happy or morose, passive or aggressive, bright or dim, liberal or conservative, religious or atheistic. "Phenotype" is the word scientists use for each genetic manifestation. (Genotype refers to an organism's entire complement of genes, the overall blueprint for each species.) A leg is a phenotype; so are arms, ears, and kidneys. Geneticists have come to consider behavior (or behavioral propensities) just another phenotype.
Among those pursuing this research, some focus on specieswide traits, seeking out the evolved behavioral template shared by everyone. These are the evolutionary psychologists and sociobiologists who try to identify the broad traits that have evolved to make up human nature--aggression, competitiveness, sociality, and altruism would be a few. Behavioral geneticists, on the other hand, are more interested in individual differences. They are ferreting out the genetic influences, if any, that make one person fearful, another bold, one optimistic, one pessimistic, one placid, one fretful. They are also seeking the specific genetic configurations that abundant evidence indicates interact with the environment to produce such common behavioral problems as depression, addiction, obesity, and autism.
An unexpected product of this research is the ever-narrower behavioral nooks and crannies that reveal a genetic component. For most of us it is not difficult to accept at least partial genetic orchestration of broad categories of temperament such as shyness, pessimism, and boldness, among others. Narrower traits, however, such as compassion, extravagance, rule-flouting, and risk-taking, can, without too great an effort of the imagination, also be nominated for biochemical underpinnings. But our minds rebel at the news that genes can induce such behavioral minutiae as hand gestures, pet-naming, and nervous giggles. According to recent research, this appears to be the case. Whether aimed at individual differences or specieswide traits, both behavioral genetics and evolutionary biology are in the business of seeking genetic paths to behavior, and both are bringing about a new perspective on the human complex.
Therapeutic promise is not the only reason the news about gene therapy and cloning has overshadowed the news concerning behavior. The genetic insights about physical defects and dysfunctions are filling a void of knowledge or deepening existing understanding. This sort of information is welcomed by everyone. Findings about the gene-behavior dynamic, on the other hand, are overturning existing truths and demolishing assumptions upon which fifty years of psychological theory has been based. Totally different answers are emerging to questions many experts were confident had long been answered. It is this apostate cast to the behavioral findings that has caused turmoil in the academic community and provoked angry debate. It has also contributed to the early media caution in announcing the discoveries.
THE LARGEST BODY of hard data to establish the genetic roots of behavior has come from comparisons of fraternal with identical twins and comparisons of adopted with biological siblings. For thirty years these investigations have been progressing quietly in scores of kinship studies in the United States and abroad and building a mountain of evidence of the gene-behavior relationship. Of all this research, the most persuasive as well as the most dramatic has been an eighteen-year examination at the University of Minnesota of identical twins who were separated shortly after birth and raised in different homes. The study has examined over seventy sets of separated identical twins and more than fifty sets of fraternals. The telling results startled not only the scientific world but the Minnesota researchers themselves. This was not so much for the degree of genetic influence on traits, which has already been established by other studies, but by the highly specific nature of some genetic expressions. Some of these stories are astounding and dramatically extend the possibilities of genetic string-pulling.
Conclusive as these overall twin findings were for many of the extensive gene-personality links, even harder scientific evidence corroborating this data is just now beginning to emerge from molecular biologists who are tracking the DNA itself to locate explicit chromosomal segments that lead to particular behaviors. While twin and adoption studies measure and compare individuals to establish genetic influence, molecular biologists can be seen as approaching human behavior "from the other end," seeking out the individual genes that might contribute to a particular trait. Such gene pinpointing brings us much closer to interventions--enhancing, fixing, blocking. The possibilities are endless.
After a disheartening series of near misses--studies that appeared to have located culprit genes for specific behaviors but that could not be replicated--success appeared to have arrived in January 1996. Researchers in two different research groups (one in the U.S., another in Israel) isolated a DNA fragment that was consistently longer in subjects who showed a taste for risk-taking. This appeared to be the first time a precise strand of nucleic acid was linked to a particular personality trait. The discovery was reported on the front page of the New York Times. It looked as if science had at last "seen" the bouquet of molecules that causes certain people to shoot rapids and bungee jump. As so often has happened with efforts to pinpoint behavioral genes, this finding was cast into doubt by a third study in Finland, but few in the field doubted that such specific pairings of genes and behavior were far off.
Confusion has resulted from the two different methods of linking genes to behavior when misfires of one were mistakenly seen to negate the successes of the other. A typical example of the misunderstanding appeared in a 1994 Time magazine cover story, "Genetics, the Future Is Now." The piece was an authoritative overview of the medical discoveries and a discussion of the social and ethical issues they evoke. The article stumbled, however, when it touched on behavior. "Studies claiming to have found genes for alcoholism," it read, "... have not held up under scrutiny, but many people still assume such complex behaviors may be predetermined by heredity." With the word "assume," Time renders a belief in a genetic component to traits such as alcoholism little more than a hunch. And by the use of the word "predetermined" rather than "predisposed," Time sets up a straw-man theory of all-powerful genes held by no behavioral geneticist.
Twin and kinship studies have for decades established genetic components to some forms of alcoholism, depression, and many other behavioral irregularities. To accurately sum up the state of behavioral genetics research at that time, they could say that, no, scientists had not yet found the specific genes, but, yes, they knew that genes were involved. But that was knowing plenty, enough certainly to justify the millions of research dollars that have been spent in the years since seeking out specific genes. The failure to pinpoint gene-behavior tie-ups in no way weakened the hard statistical evidence of inherited predispositions from somewhere in the genome.
In the two years since the Time article appeared, there have been major advances in gene-behavior understanding, and specific genes for specific behaviors have now been isolated. But the confusion lingers on. Reviewing Philip Kitcher's book The Lives to Come in The New Yorker of February 12, 1996, John Seabrook wrote: "What if it turns out that there really are genes that influence intelligence, along with a variety of behavioral characteristics. . .?"
To write such a sentence in a respected publication in 1996 is akin to someone writing in the New York Times, "What if it turns out the sun really is the center of the solar system. . .?" Although the conclusion of genetic influence over behavior has been, to a degree, inferential, the abundance of data has long since removed the issue from what-if-land.
It is understandable that the DNA scanners have created greater excitement than the observational studies of twins and adoptees. The main reason for this preference is that zooming in on trouble-causing genes brings science much closer to therapies and remedies. But those of us rooting for broad acceptance of the new knowledge about genes and behavior see a public relations advantage as well. Astronomers might prove mathematically that Pluto is out there circling the sun, but for most people, it is much more convincing to see a photo of the elusive planet, however fuzzy.
When scientists hold a news conference to show on a screen the gene that causes alcoholism--or depression or violence or nail-biting or child abuse--the impact on the public is sure to be far greater than the hardworking psychologist, who may have examined thousands of twins pairs, holding up charts, saying, "See, my statistics prove a genetic influence." However powerful the numbers, this is still an abstract, circumstantial case; juries always prefer concrete, eyewitness cases.
In animals a number of genes have been located that govern specific behaviors. Most recently a gene in female rodents was found that when blocked, turned mothers from busy nurturers into indifferent loll-abouts. The experiment had clearly isolated a good-mother gene. (Don't have kids without it.) In humans, similar tie-ups are imminent. Since late 1994, several genetic mechanisms that cause obesity have been revealed, and many more gene-behavior couplings are sure to follow.
As the spotlight is turning from the kinship studies with their dry statistics to the sexier molecular biologists with their promise of behavioral-gene snapshots, it should be pointed out that the searches would not have been undertaken in the first place if it were not for the psychologists who for the past thirty years, in bold defiance of their field's prevailing orthodoxy, have been following their intuitions and searching out genetic links to behavior using the only tools at their disposal, the statistical comparisons of genetically related individuals.
Just as Gregor Mendel only inferred the existence of genes but nonetheless developed his on-target laws in the 1860s by merely observing patterns of inheritance, so the behavioral geneticists have drawn conclusions from their studies of twins and adoptees with no idea which genes brought about the all-too-evident behavioral effects and little idea how they functioned. They pushed ahead, making no secret of their ignorance of the workings in "the black box" that sat between a gene and a trait. Although much mystery still obscures the chemical path from genes to behavior, molecular biologists have joined behavioral geneticists to demonstrate beyond any doubt that the genes-behavior paths are there.
ON THE FACE of it, all of this may not seem too revolutionary. Everyday chitchat abounds in behavioral geneticist thinking. "She got her extravagance from her mother." Or, "the musical talent comes from his father's side." Or, "he's a crook just like his granddaddy." Whether consciously or not, such remarks suggest DNA strings that lead to spending sprees, piano-playing, and crookedness. While we may have gut feelings of genetic transmission of personality traits--animal breeders have known about it for centuries--such thinking has been abhorrent to prevailing scientific thought for much of this century. Back-porch philosophers and animal breeders could believe whatever they wished; science knew we humans were creatures of our rearing environments. Experience and learning determined who we are, nothing else.
This is no minor artifact of intellectual history to be tossed quickly into the bin marked "Earlier Mistakes." The behaviorist belief in an all-powerful environment has for many decades dominated enlightened thinking and been the basis of our society's approaches to child-rearing, education, social dysfunctions--and, of course, psychological problems. All the leading psychotherapists, from Freud to Joyce Brothers, might have disagreed about which environmental influences made you wet your bed, bite your nails, expose yourself--but none had any doubts that it was something in the environment. Always the environment. And this view is still very much with us, if more as a habit of thought than a conscious idea.
Psychiatrist Peter Neubauer, who did his own study of reared-apart twins, tells a story of identical brothers that vividly illustrates the degree to which the environmental assumption dominated our thinking. The brothers, who were in their early thirties, had been separated at birth and raised in different countries. Both were neat and clean to a compulsive degree. When asked to explain how they had become this way, each twin traced his idiosyncrasy to his adoptive mother. One explained that his mother had also been obsessively fastidious, constantly cleaning the house, doing laundry, straightening things. He had no doubt that his tidiness came from her. The other brother, not knowing his twin's explanation, replied without hesitation that he knew exactly why he was so neat: His mother had been a complete slob as a housekeeper. He was reacting against her.
The men did not need training in the day's psychology to have absorbed the behaviorist truth that the key to unusual adult behavior lay somewhere in childhood experience, in the rearing environment. There was no other possibility. Armed with that assumption, explanations were easy to come by, even if they contradicted each other.
In the days when such behaviorist certitude prevailed, countless research projects examined how and to what degree the environment, acting alone, determined behavior. Those skewed psychological studies, which remarkably still go on, were based on the premise that one newborn was pretty much like another; the environment stamped the infants with distinctive personalities. For behaviorists, unraveling the puzzle of a particular human was simply a matter of discovering which environmental elements were the most relevant during the formative years. No one found genetic influences because no one was looking for them. Now that many are looking, they've found them in spades.
The new information about genes is not just a matter of fresh dogma replacing old. The discoveries of behavioral genetics have shown the earlier environment-is-everything model to be half true, but a view of human functioning so myopic, so lopsided as to invalidate most of the findings based on it. It also caused considerable harm. A prime example would be the psychodynamic "cures" imposed on sufferers of conditions we now know can have genetic roots--calamities like schizophrenia, autism, obesity, and an array of neurotic symptoms. Harm was also inflicted when parents were blamed for childhood problems that stemmed from genetic irregularities. In addition to the injustice involved, placing blame in the wrong place moved practitioners further from remedies. For nailing down the cause of psychological problems, genetic knowledge now provides an additional suspect: pesky bits of nucleic acid contained in the genes that the parents may have provided but over which they have little or no control.
A PRINCIPAL REASON the extreme behaviorist, antigenes view dominated psychology for so many years was its strong political appeal. The liberal movements that flourished in the first half of the century based much of their theory on the concept of an infinitely malleable human. The world could be made better by making people better. Talk of genetic influences suggested unchangeable humans and was seen as justification for such societal brutalities as racism and slavery. Not only was a belief in gene-based behavior seen as an obstacle to improving the world, but it was also viewed as an excuse for not trying.
There were valid reasons for fearing a backward thrust to the genetic perspective. Charles Darwin had barely enunciated his theory of natural selection before it was brandished by conservatives as proof of the inevitability of social injustice. His monumental insight about evolution with its encapsulation, "survival of the fittest" (which referred only to procreational prowess), was wrenched into the service of reactionary systems such as Social Darwinism (if you are poor it is because you were born to be poor), eugenics (stop the unfit from propagating), and Nazism (eliminate the unfit already here).
Because of these bogus and preemptive applications of inheritance theories, the entire subject of genes and human behavior was stigmatized with ugly ramifications that linger today. In a look at this history further on, I hope to demonstrate that behavioral genetics knowledge, like all knowledge, is neutral and can be used to bolster any political position, left or right. To reject this fundamental information because of previous right-wing applications makes as much sense as rejecting electricity because of daytime television.
Today, however, the genetic evidence is too powerful for whimsical selection on political grounds of one behavioral theory over another. The abundant data now on the table is forcing both liberals and conservatives to grapple with the genes-environment-behavior nexus. The cumulative evidence from evolutionary psychologists, sociobiologists, and behavioral geneticists has established a new reality with which everyone must deal. Because this revised view of the human is gaining acceptance from people of all ideologies, it is highly unlikely that one group will succeed in commandeering it, at least not without a fight from the others.
The shrinking band who still oppose behavioral genetics on political grounds console themselves with fantasies that it is a passing phase. Prominent psychologist Leon Kamin of Northeastern University, who is one of the most bellicose critics, told me in an interview early in my research that genes-behavior theories make sporadic appearances on the intellectual landscape. With weary exasperation he added that these outbreaks lofted him and other alert champions of environmental determinism to beat them back like so many brush fires--writing debunking articles and angry letters to editors. After my five years of research, which I summarize in this book, I feel his remark is akin to saying the spherical-earth theory is an idea that crops up with irritating frequency and must be repeatedly dispatched by scientists of sounder bent.
Political fears are not the only reason for resistance to the genes-behavior findings. Because of broadly held misconceptions about genes' power, many people feel that awarding them a degree of control over our actions means we are no longer masters of ourselves. By admitting that genes influence our behavior, we will be admitting that we are not in charge, that we are operating on chemical remote-control.
The obvious power of genes to dictate physical traits like hair color and foot size has led many nonscientists to assume that if such dictatorial entities also affect behavior, their influence must ipso facto be equally strong in this area. The fear seems to be that if we yield to DNA a degree of sovereignty over our conscious thought, if we permit genes through the behavioral door, we will be acquiescing to the same genetic determination governing our body parts. An individual's chronic pessimism, overeating, or fear of flying would become as unchangeable as eye color.
Behavioral genes don't work that way. None of the data turned up by behavioral geneticists shows genes to be tyrannical commands, but rather nudges, sometimes strong, but more often weak. None of the research has found a single genetic influence on behavior that could be called "all-powerful," even though the critics pin this belief on behavioral geneticists and stigmatize them with the frightening label "genetic determinists."
A lot has been learned in the past year or so about the weakness of some genetic influence. As for the more powerful genetic triggers to behavior-particularly to negative behaviors like addiction and violence--we can now foresee interventions to reduce or alter the effects. It is as though in order to soften the jarring news of how pervasive and meddlesome genes can be, Mother Nature is providing us with calming insights into their uneven power and potential adjustability. With good-news-bad-news timing, we are learning of genes' broad influence over our behavior at the same time we are learning that they are not as powerful as we feared.
Genetic impulses are overruled all the time--when a fat person diets, for instance. As British geneticist Richard Dawkins puts it, when humans use contraception, they are defying their genes, which are bent on reproduction. Nuns and monks take rebellion to the limit and renounce sex altogether. Although the gene-based sex drive is as powerful as any genetic command, it can be disobeyed. However difficult or uninteresting, celibacy is still an option.
While genes are not all-powerful with behavior, evidence mounts they are all-pervasive in that they appear to influence, to however small a degree, our every thought and action. This sweeping claim is not just a verbal trick based on the physiological fact that genes have fashioned the brain with which we think and act. It is said in the more specific sense that human impulses, reactions, dispositions, desires, aversions--most facets of our personalities--are colored directly, if only to a minor degree, by each individual's genetic makeup. In countless studies aimed at sorting out genetic from environmental effects, not one of the numerous traits examined failed to show at least some degree of genetic influence.
I have my own hunch why the loss-of-sovereignty fear may linger longer than the evidence should allow. The people most likely to reject the notion of a behaviorally programmed human brain are the brightest people among us, the brain-proud, those most disposed to believe their every thought flows from pure reason, nothing more. They are also the people who evaluate intellectual trends--writers, academics, and other opinion shapers. It is ironic that those who probably see themselves as having the most to lose by admitting that their behavior has genetic strings attached are the very ones we look to for a thumbs-up or thumbs-down on new visions of human makeup. You might not be upset to learn that genes are manipulating us humans, but Harvard's Stephen Jay Gould hates the idea.
All of these perceived threats--to progressive politics, to scientific orthodoxy, and to self-esteem--have combined to hinder acceptance of the genes-behavioral revolution and to mute, sometimes to a whisper, the announcements of its remarkable findings. Of course, the validity of the new science in no way depends on our enthusiasm for its implications, but its acceptance, to a large degree, does. Even though the resistance is weakening, the result is that much of the public remains unaware of this landmark change in our understanding of the human or at best perceives the genes-behavior perspective as just one of a parade of fads in psychological truth.
Even worse, the old belief that the roots of all human behavior could be found in the rearing environment permeates much of our thinking and hobbles our quest for solutions to a broad range of problems--from individual quirks to societywide scourges like addiction and violence. Some argue that it's only natural we look to the environment for solving problems because environments can be altered, genes cannot. While both points are untrue, the logic is skewed as well. To use behavioral geneticist Robert Plomin's analogy, this is like the man who lost his wallet in an alley but looked for it in the street because the light was better.
The appealing notion that environments are always adjustable is turning out to be just as false as the notion that genes issue orders we can't refuse. An example of an influential environment that is difficult, if not impossible, to adjust would be the womb conditions that can have lasting behavioral impact on the child to be. Also, the air we breathe and the water we drink--and here the two uses of the word "environment" converge--have elements that can affect behavior surreptitiously, as shown by recent findings about the devastating effects of lead pollution on children. Other troublemaking environmental conditions cannot be repaired because we don't know they're out there making trouble.
In spite of much scientific evidence to the contrary, the two fallacies--immutable genes and malleable environments--linger on. It is, I believe, the shadow of these misconceptions that explains why so many informed people accept in principle a genes-behavior dynamic but have yet to incorporate the new view into their cognitive data banks.
And behind all the pragmatic fears of genetic influence lies an emotional resistance. Will an understanding of the biochemical mechanics of behavior make us less interesting? Throughout history our fascination with ourselves has proved endless. Not only is all of world literature and drama evidence of this, we now have scores of satellites circling the globe, beaming hundreds of channels into millions of living rooms. Except for George Page on PBS and a few other animal programs, all of it is taken up with the rich variations of human behavior. Will an unraveling of behavioral biochemistry, a grasp of the black box, make us less intriguing? I suspect a deep-seated dread that reducing such worthy qualities as friendship, loyalty, ambition, and love to molecular interactions will dispel the mystery, diminish the glory. The resistance to knowledge about behavioral genes may not stem so much from what is implied about politics or self-command but from what it might do to our self-absorption. I like to think it will make us even more interesting, but in a different, more enlightened way. We might even net a few new plots in the human saga.
For all the advances in understanding of genes' power over behavior, no geneticist denies that the environment still plays an important role. Researchers of twins are quick to point out that with separated identical twins, in spite of similarities that so vividly demonstrate genetic effects, their many differences are eloquent testimony to the environment's power to mold.
The evidence we are about to examine leads to the conclusion that while the environment can have a major effect on forming personality and guiding behavior, much of the time it doesn't. But the simple acknowledgment that, with any human behavior, genes may be involved is a momentous change in our species' self-view, and a change with major ramifications for our approach to parenting, education, psychotherapy, and a host of other self-directed human enterprises.
ALTHOUGH SOME ACADEMICS continue to fight for the blank-slate view of the human, the biological-genetic perspective has now established itself in universities throughout the country and, more and more, with the public. Young academic disciplines such as sociobiology and evolutionary psychology are totally rooted in this gene-based view. Increasingly, the traditional social sciences are introducing genes into their grab bags of variables on almost any aspect of human activity. Serious writers are doing the same.
Major behavioral genetics research projects involving teams of scientists are under way at the universities of Minnesota, Texas, Virginia, Colorado, and Louisville, and at Penn State and the Medical College of Virginia. Individual scientists are pursuing smaller studies at Harvard, California State University, and the University of Pennsylvania, as well as at Northwestern and Boston universities. Research at many U.S. hospitals on such medical problems as alcoholism and obesity fall under the category of behavioral genetics. Important research is also in progress in Sweden, Denmark, England, Australia, and Canada.
Increasingly there are signs of gene-behavior awareness seeping into the national consciousness. A New York Times crossword puzzle--perhaps as good a bellwether as any other of mainstream acceptance of controversial knowledge--not long ago required a four-letter word that meant "personality determinant." The word was "gene." During a television interview, author Russell Baker was asked by Charlie Rose his opinion about the source of a sense of humor. Without hesitation Baker replied, "It's genetic." Only a few years earlier, few educated people would have held such an opinion, or if they had, would have let it fall so casually from the tongue in front of a large audience.
Now, however, the genes-behavior link has been accepted to such a degree, in both academia and with the public, that opponents are shifting their field to a pose of "what else is new?" While I was talking with Professor Kamin, he launched into a slash-and-burn diatribe against the most prominent behavioral genetics studies. Did he then, I asked, believe human behavior was without genetic influence? With no hesitation Kamin replied, "Of course there's a genetic component to behavior." You would never detect this view by reading Kamin's many attacks or those of his allies.
Other members of the opposition, the stop-genes group some term the "radical environmentalists" and I term the "genophobes," slip similar admissions into their antigene screeds. But these offhand capitulations have a false resonance, akin to a chorus of fifteenth-century bishops after learning of Columbus's voyage, saying, "Of course the world is round. We knew that. Let's get on to something more interesting." To that, one could only say, "Not so fast, gentlemen. For one thing, you'll have to change all your maps."
Whether we welcome or resist a genes-behavior link and whether or not the link is seen to be compatible with this or that political vision, the evidence is now overwhelming that our nature is as much a product of evolution as our physiques, that each of us is born with an array of behavioral dispositions--some noble, some ruthless, some specieswide, some individual, some general, some of a birth-mark specificity--and that the more we know about these internal givens, the more effective we will be at dealing with ourselves, with others, and with the psychological and societal problems that, till now, have proved intractable.
The research that brought us to this new view of the human is fascinating and eye-opening enough to make every one of us see ourselves differently. The nature-nurture war is over, but the way it played out says volumes about political visions' ability to block scientific advances. It also says much about how easily hopes for the way we would like things to be can blind the best intentioned of us to the way things are. Finally, a retracing of this exciting and epoch-defining transformation will illustrate that improving the world will happen not by bending our view of the human to fit our solutions but by understanding the givens we have inherited from our evolutionary past and basing solutions upon them.