The Rational Animal: How Evolution Made Us Smarter Than We Think

by Kenrick, Douglas T.

  The skateboarders didn’t consciously decide to take more risks when the woman was watching. Instead, unconscious ancestral mechanisms made this decision for them, by flooding their bodies with testosterone specifically when a woman could observe their behavior.

  Evolution has honed male biology to be attuned to reproductive opportunities, like the presence of an attractive woman. From the perspective of a fellow’s genes, though, it would be especially nice if, before he risked his neck, he could somehow ascertain that the woman watching him was currently capable of becoming pregnant. But is that even possible?

  In a laboratory at Florida State University, psychologists Saul Miller and Jon Maner investigated this precise possibility by observing men as they played a game of blackjack. In case you don’t hang out in casinos, blackjack is a card game in which you can choose to play it safe (by declining any new cards once you get to sixteen or higher) or to take risks (by deciding to take a new card and risk the possibility of “busting” by going over twenty-one). As the men played blackjack, the researchers had a young woman observe them.

  Just like the Aussie skateboarders, the Floridian fellows took more risks when the woman was watching. But this study raised the stakes. Over the course of the experiment, the researchers kept track of where the female research assistant was in her ovulatory cycle. Although she had been carefully instructed to dress and act identically every single day, her presence had a different effect on men’s play on the days she was ovulating. When she was most fertile, the fellows took the most risks.

  How did the men know she was ovulating? They didn’t, at least not in any way they could consciously identify. But their bodies knew. In a follow-up study, the researchers found that merely exposing men to the subtle scent of an ovulating woman’s T-shirt instantly caused men’s testosterone levels to shoot up.

  Armed with an understanding of the intimate connections between men’s risk-taking biology and reproductive success, let’s return to the saga of the Kennedys. The family’s penchant for risk occasionally led to bad judgments, unfortunate outcomes, and even a few dead Kennedys. Risk always involves trade-offs. Taking hazardous chances can lead to death, but it can also lead to payoffs like money and status. At a deeper level, though, the Kennedy men’s risk taking paid off in the most valuable currency in the evolutionary realm—reproductive success. Recall that women in all societies around the world are attracted to ambitious men willing to take risks to become successful. Although taking these kinds of risks led some of Joe Kennedy’s descendants to perish, his genes have flourished. In the course of only a few generations, the genes of this one Irishman have thrived—producing twenty-nine grandchildren and over sixty great-grandchildren. And as we noted before, those descendants themselves continue to live rich and successful, if occasionally risky, lives.

  THE ULTIMATE QUESTION

  So, are people rational or irrational? If we look only at the surface, many of our choices appear rather foolish. Most of us would choose to be the person in the movie-ticket line who lucked into $100 instead of the one who won $150 but didn’t win $1,000. It’s not economically rational to say, “No thanks. I prefer not to have an extra free fifty bucks.” The many superficially worrisome tendencies of the human mind lead some of us to seriously doubt whether people are rational Econs and to consider instead that they are all dim-witted morons.

  Well, we beg to differ. Rather than Econs or morons, we are rational animals. Yes, decision making is biased, and yes, individual decisions are sometimes rather moronic. But underneath all those biases and misjudgments is an exceptionally wise ancestral system of decision making. To understand how people make decisions, we must first ask why the brain evolved to make the particular choices that it does. By connecting the story of human behavior with that of the rest of the animal kingdom, we come to see that our brains are designed to make choices in ways that enhanced our ancestors’ fitness.

  BUT THERE’S a twist in the plot! Just because evolutionary forces guide our behavior does not mean that you or I or Joe Kennedy’s newest great-grandson is driven to achieve just one single evolutionary goal of “maximizing fitness.” Just as it is too simple to say that people seek utility, it is too simple to say that people seek fitness. Instead, as we discuss next, human decision making is designed to achieve a set of very different evolutionary goals. In investigating how people meet these evolutionary goals, scientists have discovered something important: solutions to these different problems often require us to make decisions in different—and sometimes completely incompatible—ways. We are, in fact, inconsistent by design. To see why this has profound implications for your decisions, let’s make a stop in Alabama and take a look at several puzzling decisions made by Martin Luther King Jr.

  2

  The Seven Subselves

  ON SEPTEMBER 28, 1962, Martin Luther King Jr. was sitting peacefully on a convention stage in Birmingham, Alabama, when a man in the audience casually walked onstage and approached him. Suddenly, the man began punching Dr. King in the face. King was knocked over by the first blow, but even as the civil rights leader fell, his attacker continued throwing a brutal barrage of punches. Although King had been advocating nonviolent protests against racial discrimination, no one would have blamed him if he had gotten violently angry at his assailant, a white supremacist later revealed to be on a mission from the American Nazi Party. Instead, King chose a different course of action. He stood back up, gazed into his attacker’s face with a look of transcendent calm, and dropped his arms defenselessly, “like a newborn baby,” according to one observer. As others jumped to his defense, King pleaded with them, “Don’t touch him. Don’t touch him. We have to pray for him.”

  This incident is one of many that demonstrated King’s commitment to moral principles. Ordained as a Baptist minister, Reverend King devoted himself to embodying and promoting the ideals of decency, integrity, and virtue. His commitment to nonviolence was steadfast and consistent, extending well beyond issues of civil rights for African Americans. He spoke out against the war in Vietnam, for example, even though it cost him the support of powerful allies such as President Lyndon Johnson. On other occasions, his commitment to nonviolent protests against civil rights landed him in jail.

  Yet Dr. King’s unwavering commitment to moral principles did not extend to the realm of extramarital affairs. King’s friend and fellow civil rights leader Ralph Abernathy admitted that the iconic religious leader, despite being a married man with four young children, was a “womanizer.” Besides having an ongoing affair with a woman he saw frequently, King allegedly also engaged in numerous short-term liaisons with other women while he was traveling. According to biographer David Garrow, King’s promiscuity caused him to feel extreme guilt. But that guilt was not enough to alter his behavior. When faced with temptations of the flesh, Dr. King repeatedly put aside his higher moral values.

  Did King’s moral lapses result from an occasional breakdown in the operation of the otherwise rational man inside his head? Or might there be another explanation for his behavioral inconsistencies? We argue that Martin Luther King Jr. suffered from a common form of multiple personality disorder. Even without reexamining the evidence from his biographies or consulting a single psychiatrist, we believe we can diagnose King as having at least seven personalities.

  In fact, when we say King had a “common” form of multiple personality disorder, we are understating the case. Multiple personalities are not just common; they are universal. Without knowing a single thing about the particulars of your life, we argue that you also have at least seven personalities. Although it feels as if there is just one single self inside your head, at a deeper evolutionary level, you have a multiplicity of selves. And worse yet, each of these selves is like a little dictator who completely changes your priorities and preferences when he or she takes charge. This is important because it means that the same person will make different choices depending on which self is currently at the helm.

  SELVES
WITHIN THE SELF

  A famous clinical case study of multiple personality disorder was turned into the movie The Three Faces of Eve, in which the central character switches between the timid and self-effacing “Eve White” and the dangerously fun-loving and flirtatious “Eve Black.” The real-life character depicted in this movie was Chris Sizemore, whose psychiatrists claimed had not just three but twenty different personalities. While the majority of people do not suffer from the clinical version of multiple personality disorder, each normal person does have multiple selves.

  At first blush, it might seem shockingly counterintuitive to claim that there is not one single you running the show inside your head. But an overwhelming body of scientific evidence supports the idea of multiple selves. Some of the earliest research came from a classic series of studies on “split-brain” patients, conducted in the 1960s by Michael Gazzaniga and Roger W. Sperry. Gazzaniga and Sperry studied people whose left and right cerebral hemispheres had been surgically separated (as a treatment for epilepsy). For these people the verbal left side of the brain could not communicate with the nonverbal right side. If the researchers showed an image (a picture of a spoon, for example) to the subject’s verbal left brain (by flashing it into the right half of the visual field), the person was able to name it. But if the same image was flashed into the left half of the visual field (thus appearing only to the nonverbal right brain), the person could point to a spoon to indicate that it was the object in the image, but was unable to name it. This work, which became a cornerstone of modern neuroscience and eventually won a Nobel Prize, began to challenge the idea of a unified consciousness. It showed that our conscious experiences can be very different depending on which part of the brain is currently active and processing incoming information.

  In the intervening fifty years, many other findings—from human and animal neuropsychology, biology, and studies of learning and memory—have revealed that there is not one single executive system inside your head but a conglomeration of separate systems, running different subprograms to deal with different problems. Reviewing the evidence in his book Why Everyone (Else) Is a Hypocrite, University of Pennsylvania psychologist Rob Kurzban points out that the mind’s different systems (or modules) sometimes disagree with each other, which can lead us to behave inconsistently. This means that it’s not just Martin Luther King Jr. who’s a hypocrite—you, your neighbors, and the guy with the split brain pointing at a spoon are all hypocrites. According to Kurzban, the nature of our divided mind suggests that there is no “I”; instead, each of us is a “we.”

  Despite the mounting evidence for multiple selves, the idea that each one of us has a single unitary self remains intuitively compelling and widespread. For rational economists, the number-crunching business whizzes we met in the last chapter, a cornerstone assumption about human behavior is that people have stable preferences. If you choose to put cream and sugar in your coffee on Tuesday in Birmingham, Alabama, you are also likely to choose cream and sugar with your coffee in Memphis, Tennessee, on Wednesday.

  This assumption about stable preferences is pervasive in business and psychology. Advertisers, for instance, look to pitch particular products to matching market segments. They don’t place ads for Harley-Davidson motorcycles in church periodicals. Financial advisors categorize their clients according to various investment risk-tolerance profiles and avoid recommending highly risky and volatile stock opportunities to librarians. Personnel officers try to match the right person for the right job and steer clear of placing artistic coffeehouse types in the accounting department. In all of this, there is a presumption that a given consumer, investor, or job applicant will be the same tomorrow as today, the same in an hour as now, and the same in another building as in this one.

  But what if each one of us is really several different people?

  If each of us actually has multiple people living in our heads, this has radical implications for the way we think about behavior. Instead of having just one self, we are really a collection of selves—a group of subselves. Like different personalities, each of your subselves has peculiar quirks and preferences. And each comes out only when you are in a particular situation. At any one time, only one subself is in charge, which is the current you at that moment.

  If we are a multiplicity of subselves, this suggests that even though we feel like we are the same person all the time, we might actually change who we are depending on where we are, what we’re doing, and who else is around. To see how this might work, let’s take a closer look at a study showing how the same person will respond very differently to an advertisement, depending on which subself is currently in the driver’s seat. After that, we’ll more formally introduce whichever one of your subselves is reading this book to the other people living inside your head.

  PRIMED FOR PERSUASION

  Before proceeding with our program, we’d like to take a moment for a brief word from our sponsor—the Nouvelle Breton Café. The Nouvelle Breton provides a completely unique experience, as noted by a reviewer for the Los Angeles Times: “It is truly a one-of-a-kind place that has yet to be discovered by others.” Gina Polizzi from Pacific Food News calls it “a unique place off the beaten path.” If you’re looking for a great dining experience different from any other, look no further than the Nouvelle Breton Café.

  Given that description, would you go out of your way to dine at the Nouvelle Breton Café?

  What if you’d instead seen an ad emphasizing that this café was the most popular restaurant in the area, noting that over 1 million people have eaten there, and stating that “if you want to know why everyone gathers here for a great dining experience, come join them at the Nouvelle Breton Café.”

  Here’s a more general question for your inner marketing consultant: Which of the two ads do you think would be more effective, the first (emphasizing that the restaurant is unique) or the second (emphasizing that the restaurant is popular)? If you considered this question from a traditional market-segmentation perspective, you might guess that the answer would depend on the type of person seeing the ad. One type of person—the conforming, yes-man sort—might be attracted to going where millions have gone before, eagerly following the masses. But another type of person—the rebellious, independent sort—might be turned off by lemminglike conformity, preferring something unique and off the beaten path. Different people are, well, different. Some people have one set of preferences, while others have another.

  But the idea of multiple subselves suggests something radically different: that the same ad might be effective or ineffective depending on which person inside your head is currently viewing the ad. This means that even for the same individual, an ad might be appealing to one subself and repulsive to another.

  Working with our colleagues Noah Goldstein, Chad Mortensen, Bob Cialdini, and Jill Sundie, we initially tested this idea by asking people to view advertisements promoting products ranging from restaurants and museums to the city of Las Vegas. Before anyone saw the ads, however, we first activated, or primed, one of two different subselves inside people’s heads. The idea was to put people in a situation they might experience when watching television. Ads on TV don’t just appear at random; they pop up during particular programs, perhaps an uplifting romantic comedy or a frightening police crime drama. The type of program a person is watching might naturally bring out one of his or her different subselves. Is it possible that the you watching a romantic comedy depicting flirtatious, sexy characters might be different from the you watching a thriller depicting violent killers in our midst? If so, these two yous might have entirely different responses to the exact same marketing appeal.

  To test this possibility, some people in the study viewed a clip from the hair-raising classic The Shining, in which Jack Nicholson plays a madman chasing his family members around an isolated and deserted hotel with an ax. A few minutes into the clip, at an especially scary moment, we went to commercial, showing people several ads. Some of the ads included a message
informing viewers about the popularity and high demand for each product (for example, “visited by over a million people a year”). Other times people saw the same ads, but the ads didn’t mention anything about popularity or high demand.

  When people viewed the ads in between segments of a scary program, they found the products more attractive when the ad emphasized the product’s popularity. Adding the message “visited by over a million people a year” to a museum ad, for example, boosted people’s desire to visit that museum. People became especially receptive to messages about following the crowd after watching a frightening movie clip. Like wildebeests in the presence of a leopard, people who are feeling threatened want to be part of a larger group.

  In fact, the people who had been viewing the scary film weren’t simply drawn to follow the masses; they actively avoided products and experiences that would make them stand out from the crowd. We know this because some of the ads in the study included a message emphasizing the uniqueness of the product (think “limited edition”). After watching the scary movie, people rated unique products as less attractive. Adding a message about standing out from the crowd to the museum ad actually led people to avoid the museum. Despite its being the exact same museum as shown in the other versions of the ad, an art gallery presented as unique and different wasn’t the kind of place people wanted to visit while they were feeling defensive. When people watched a scary movie, then, they were attracted to products that were common and popular and avoided those that were different and unique.

  But people’s preferences changed drastically if they instead watched a romantic movie. Before seeing the same commercials, a second group of people watched a clip from the romantic film Before Sunrise, which portrays an attractive man and woman (Ethan Hawke and Julie Delpy) falling in love as they travel by train through the most picturesque cities in Europe. This film clip brought out a very different subself, leading viewers to experience erotic and loving feelings. Unlike people who saw the scary movie clip, the people in a romantic frame of mind were most affected by ads that emphasized a product’s uniqueness. Now, when they saw the message about standing out from the crowd in the museum advertisement, they were especially drawn to it. Like animals on the prowl for a mate, people primed for romance want to stick out from the crowd. By contrast, including information about the popularity of the product repelled the romance-minded subjects. Adding the message “visited by over a million people” made the museum seem blasé and commonplace, leading people with a romantic mind-set to avoid the destination.