No Two Alike

by Judith Rich Harris

  Group warfare evolved in primates and in social insects because the winners of these wars left more descendants than the losers (or than those unwilling to fight at all). Nature has ways of motivating her creatures to do what she wants them to do. Nowadays one hears a lot about the horrors of war, but in the old days one heard mostly about its glories, perhaps because the stories were told mostly by the winners. An American who fought for the North in the Civil War—fought side by side with his comrades against an enemy whose faces they could see—described what it was like in an address he gave many years later. He described the excitement of a “fierce gallop against the enemy, with your blood up and a pace that left no time for fear.” He described what it feels like when a soldier discovers he is “able to lift himself by the might of his own soul.” He was wounded three times in the war and he wasn’t sorry it was over, but he was glad to have had “the incommunicable experience of war…the passion of life at its top.”47

  Okay, what did children have to learn, back in the Paleolithic, to prepare themselves for adulthood? What did they have to do, or know, or know how to do, in order to be successful in their adult lives? By “successful” I mean in the ways that evolutionary psychologists talk about—ways that would increase their genetic contribution, or that of their close relatives, to future generations.

  For social development, the learning tasks that have to be accomplished in childhood fall into three categories. The first involves managing relationships; the second, becoming socialized; and the third has to do with besting one’s rivals—or at least not being bested by them—in Darwinian-style competition.

  I’ll start, as the baby does, with relationships. Before he can do anything else, the baby has to make his mother love him. Then he has to learn how to get along with a variety of other people: his father, his siblings, other children, other adults. He has to be able to tell these people apart, learn what to expect of each of them, and figure out how to behave with each. Crying may cause his mother to offer him milk and comfort, but it doesn’t have that effect on other people and, once he’s past a certain age, it may not work even on his mother.

  As children get older, more people enter their lives and more decisions have to be made. To make wise choices in friendships, alliances, trading partners, and mates, children have to learn to size up people. They have to learn how to tell the trustworthy from the undependable. They have to know whom they can dominate and whom they had better defer to. These things all involve collecting information about people and dealing with them as individuals.48

  The second category of learning tasks are those involved in socialization. This means learning the culture—adapting to one’s group. It means acquiring the skills and knowledge, the language and customs, that people in one’s society are expected to have. Children need to learn how to behave in a way that is deemed appropriate in their society.

  Because the members of a tribe may not all know each other personally, having the right language and accent, the right customs, and the right clothing and hairstyle can be a matter of life or death. There is a good example in the Old Testament:

  And the Gileadites took the passages of Jordan before the Ephraimites: and it was so, that when those Ephraimites which were escaped said, Let me go over, that the men of Gilead said unto him, Art thou an Ephraimite? If he said, Nay; Then said they unto him, Say now Shibboleth: and he said Sibboleth: for he could not frame to pronounce it right. Then they took him, and slew him at the passages of Jordan: and there fell at that time of the Ephraimites forty and two thousand.49

  Forty and two thousand might have been an exaggeration, but however many there were of them, they died because they spoke with the wrong accent.

  Now for the third kind of learning task. Evolution is all about competition, and one of the purposes of childhood is to prepare children to compete successfully in adulthood. But humans have many ways of competing, and what works for one could be a disaster for another. Behaving aggressively, for example, can be a successful strategy for some people but not for others. Big, strong individuals versus puny ones, physically attractive individuals versus unattractive ones—they’re going to have different sets of options. In order to succeed in adult life, children have to work out a long-term strategy of behavior that is tailored to their own particular assets and liabilities.

  These three kinds of jobs—managing relationships, becoming socialized, and working out a long-term strategy for competing—are, I propose, the specialties of three separate departments of the mind. I will call them “systems,” like the visual system, because each receives information from a number of hierarchically arranged, lower-level mechanisms. The three systems are products of evolution; they are organs of the mind. Like other essential organs, they are present in all physically normal humans, and (though the organs themselves will vary somewhat from one individual to another) their function is the same in everyone.

  Leda Cosmides and John Tooby have explained how natural selection has produced a variety of complex mental mechanisms in our species:

  The statistically recurrent conditions encountered during hominid evolutionary history constituted a set of adaptive problems. These conditions selected for a set of cognitive mechanisms that were capable of solving the associated adaptive problems…. The more important the adaptive problem, the more intensely natural selection specializes and improves the performance of the mechanism for solving it. This is because different adaptive problems often require different solutions, and different solutions can, in most cases, be implemented only by different, functionally distinct mechanisms.50

  My proposal is consistent with these principles.

  In the next three chapters I will work out the design specs for the relationship system, the socialization system, and the system that specializes in competing. I’ll explain how they differ and why we need all three to explain how the environment shapes personality. Why we need all three to explain how children learn, and what they learn, from their experiences with other people.

  7

  The Relationship System

  SHERLOCK HOLMES concluded, in the case of “The Five Orange Pips,” that the murders he was investigating must have been committed by more than one perpetrator. In fact, he told Dr. Watson, the responsible entity was a group: members of the secret society known as the Ku Klux Klan. Yes, it was a gang of sinister Americans. They had crossed the Atlantic in a ship named the Lone Star and were trying to regain possession of some incriminating documents that had been taken to England by the first victim.

  Sherlock never nabbed the culprits. “Very long and very severe were the equinoctial gales that year,” Dr. Watson recorded in his chronicle. The Lone Star, by then on its way back to America, was never seen again: only the shattered sternpost of a boat with the letters L.S. carved on it, spotted far out in the Atlantic.1

  A convenient solution. An equinoctial gale can wipe out an entire group in a single blow: no need to convince a jury that each individual member was a co-conspirator in the crime.2 The judicial systems of Great Britain and the United States were designed to assess the guilt or innocence of specific individuals, rather than groups. We hold each individual responsible for his or her own actions. If someone is convicted of a crime and it turns out to have been a case of “mistaken identity”—he was mistaken for the perpetrator—the conviction is rightly seen as a miscarriage of justice. It would be a miscarriage of justice even if the mistake was understandable: if, for instance, they were identical twins. Consider this case:

  On March 10, 1988, someone bit off half the ear of Officer David J. Storton. No one doubts who did it: either Shawn Blick, a twenty-one-year-old man living in Palo Alto, California, or Jonathan Blick, his identical twin brother. Both were scuffling with the officer, and one of them bit off part of his ear…. Officer Storton testified that one of the twins had short hair and the other long, and it was the long-haired man who bit him. Unfortunately, by the time the men surrendered three days later they sported id
entical crew cuts and weren’t talking.

  Their lawyers argued that neither twin could be convicted of biting off half the ear of Officer Storton.

  For each brother there is a reasonable doubt as to whether he did it, because it could have been the other. The argument is compelling because our sense of justice picks out the individual who did a deed, not the characteristics of that individual.3

  Our minds go to a great deal of trouble to prevent us from making errors of mistaken identity. Officer Storton made an effort to distinguish the twins but unfortunately he chose a marker—hair length—that could easily be changed. He must have realized too late that he should have looked for something that couldn’t be modified so readily, such as a scar or a mole.

  There’s a paradox here. We are willing to convict people of crimes only if we’re certain, beyond a reasonable doubt, of their personal culpability; and yet for thousands of years the members of our species have been engaging in group warfare,4 the goal of which is to kill off the members of other groups solely on the basis of their group membership. “Thou shalt not kill” is one of the Ten Commandments; yet hardly had the message been delivered than Joshua embarked upon his wholesale slaughter of the inhabitants of Jericho, Makkedah, Libnah, Lachish, Eglon, and Ai. It apparently never occurred to Joshua that God might have meant that he shouldn’t kill them. On the contrary, he believed he was carrying out God’s will.5

  “Why,” asked the psychologist William James in 1890, “are we unable to talk to a crowd as we talk to a single friend?”6 Why do we shrug when we hear of hundreds of people killed in an earthquake but weep when we see a photo of one injured child? Why is it that getting to know and like someone doesn’t necessarily cause us to think well of the group to which he or she belongs—a disjunction revealed by the ineffectiveness of the protest, “Some of my best friends are Jews”?

  The answer is that there are multiple systems in the mind for processing information. We have, I propose, two different mental mechanisms designed to process and store information about people. One collects data on individuals, the other on groups or social categories—types or classes of people. Criminal justice and law enforcement are (or should be) based on information processed by the first mechanism; war and bigotry are outcomes of the second. These mechanisms belong to different mental systems. The one that specializes in individuals is part of the relationship system, the topic of this chapter.

  The relationship system is the source of many of the things evolutionary psychologists love to write about, including mate selection and romantic love, reciprocal altruism, favoritism toward kin, dominance hierarchies, cheater detection, coalition formation, and gossip. It is responsible for the illusion called the fundamental attribution error. Its function is to furnish answers to evolutionarily important questions like these: Will this person help me if I am in need? Does this person repay favors? Can this person be relied upon to be a fair partner in trade? Is this person a close relative? Would this person have sex with me? Would this person be a good long-term mate? Can this person beat me up? Will this person take my side if someone else tries to beat me up? Does this person like me?

  In the first chapter of this book I marveled at the vast storage capacity and tireless energy of what I named the people-information acquisition device. “Unlike the language acquisition device,” I said, “which did its best work before your twelfth birthday and then rested on its laurels, your people-information acquisition device will keep chugging away all through your life.” Perhaps I was a bit unfair to the language acquisition device: it’s true that it did its best work before your twelfth birthday, but it hasn’t closed up shop by any means. You can still learn new words.

  Children start learning words around their first birthday. By the time they start school they know around 13,000 words, which averages out to a new word every two hours. Then, according to Steven Pinker, “the pace picks up, because new words rain down on them from both speech and print.” A typical high school graduate has a vocabulary of about 60,000 words; double that number for readers of books like this one.7 That’s 120,000 words you have in your head!—more, I’d guess, than the number of people whose names or faces you recognize, but perhaps not vastly more.

  Each word, and each person, has to be given its own mental storage space; it wouldn’t do to mix up words, any more than it would do to mix up people. If it was Shawn who bit you, you don’t want to punch Jonathan in the nose the next time you see him. If you want someone to hand you the hammer, you don’t want to ask for the ax.

  Words are stored in what Pinker calls a “mental lexicon.” Each word has its own entry in the mental lexicon, just as in a real dictionary (except that they aren’t in alphabetical order or in any fixed order at all). The mental entry for a word gives its meaning, pronunciation, and part of speech—noun, verb, and so on. Though we aren’t ordinarily aware of knowing a word’s part of speech, this largely unconscious knowledge is what enables us to put it together with other words to form grammatical sentences. Even very young children possess unconscious knowledge about parts of speech. When four-year-olds are shown a picture of a fictitious creature and told “This is a wug,” they refer to a pair of the creatures as “wugs,” showing that they classify the word as a noun and that they know how to form plurals of nouns. When shown a picture of “a man who knows how to rick,” they say that yesterday he ricked, showing that they know how to form past tenses of verbs.8

  Actually, there are two ways to form past tenses of verbs. As Pinker explained in his book Words and Rules, the two ways are by words and by rules. “Words” is how we have to do it for irregular verbs like go–went, buy–bought, and hold–held; each form of these verbs has its own separate listing in the mental lexicon. They have to be memorized one by one; there isn’t any shortcut. What makes the job easier is that irregular verbs tend to be the ones used most often (this is true in all languages), and most of them are monosyllables.

  The other way of forming past tenses, “rules,” is illustrated by the children who said that yesterday the man ricked. Since there isn’t such a verb, they couldn’t have heard it before; and yet they knew how to form its past tense: just add -ed. Many of the errors young children make in speech are misapplications of general rules; sometimes they add -ed incorrectly and come out with words like “goed,” “buyed,” and “holded.”

  So here we have two separate mechanisms doing the same job—producing the same sort of output—and sometimes they give conflicting results. The mind solves such conflicts in different ways: sometimes by compromising, sometimes by giving one mechanism precedence over the other. In the case of verbs, the language system gives precedence to the list in the mental lexicon. First, look to see if the verb has a past tense listed there. If it doesn’t, or if you can’t find it quickly enough, go by the general rule. Can’t find a past tense for “rick” in your lexicon? Okay, then add -ed. Children make errors for a while because the entries for went, bought, and held are not yet strong enough (they haven’t been stamped in by enough repetition) to suppress the rule mechanism. The irregular past tense form doesn’t pop up quickly enough to fill in the blank in the sentence.9

  There is neurological evidence for these two systems, based in part on observations of patients with various types of brain injuries. Damage to the anterior portions of the language area (located around the Sylvian fissure) sometimes produces patients with a disability called agrammatism: they remember words (though not as well as people with neurologically intact brains do) but have great difficulty with grammatical suffixes and are almost incapable of thinking up a past tense for a made-up word like “rick.” Damage to the posterior part of the language area, on the other hand, can produce a disability called anomia—difficulty in retrieving words. You know how frustrating it is when you can’t think of someone’s name and it’s right on the tip of your tongue? Patients with anomia can’t think of words like “clock”:

  Of course, I know that. It’s the thing you use, for c
ounting, for telling the time, you know, one of those, it’s a…I just can’t think of it. Let me look in my notebook.10

  But these patients know how to form plurals and past tenses. Sometimes they will make up a word if they can’t think of the one they’re looking for, and they’ll put the correct suffixes on these made-up words: “I believe they’re zandicks.” “She wikses a zen from me.” These patients commit the same kind of errors we hear from children: words like “holded” and “digged.” Such errors also occur in the speech of people with Alzheimer’s disease. A typical pattern in victims of Alzheimer’s is that they can’t think of words but, for a while, can still speak in grammatical sentences. They use fillers like “thing” and “you know” as substitutes for the missing words.11

  With evidence from a variety of sources, Pinker supported his theory that the language system consists of two distinguishable components: a lexicon of memorized words plus a set of rules for combining and inflecting them. The part of this theory that is relevant here is the mental lexicon. I believe the evidence is equally good that the neurologically normal human mind contains a mental lexicon for people, with a separate entry for each individual we know anything about.12 This lexicon is the product of the people-information acquisition device. Aided by the face-recognition module, which I mentioned earlier in the book, it distinguishes finely among individuals, just the way the language lexicon distinguishes finely among words.

  One of the remarkable things about mental systems is that many of them provide their own incentives. That’s part of their job: to motivate their owners to use them. Children are eager to learn the language; they don’t have to be encouraged or rewarded. Nor do adults have to be paid for learning and using new words. But perhaps the urge to do so diminishes over the course of a lifetime. In contrast, the urge to collect and share information about people remains strong; grownups love to gossip, and to listen to gossip, just as much as kids do. It is this urge that makes people read biographies and novels and watch movies and plays, and that makes sports fans want to see the faces of the players and hear them interviewed. We follow the careers of famous people and are fascinated by revelations about their lives. We wouldn’t think of voting for someone for president until we felt we knew a lot about him. Even though we will probably never meet him, we want to know: Can this person be relied upon to play fair?