The Pleasure Instinct Part 1

The Pleasure Instinct_ why we crave adventure, chocolate, pheromones, and music.

by Gene Wallenstein.

Acknowledgments.

Whatever good the reader finds in this book can be traced to those who have, in one way or another, taught me over the past couple of decades about human nature. To those who have inspired me (and countless others) through the years with their lectures, conversations, writings, and generous time, I thank John Allman, David Barash, Kent Berridge, T. Berry Brazelton, David Buss, Michael Cabanac, Michael Crawford, Richard Davidson, Richard Dawkins, Terrence Deacon, Irven DeVore, Jared Diamond, Ellen Dissanayake, Robin Dunbar, Paul Ekman, Howard Eichenbaum, Nancy Etcoff, Steven Gangestad, Fred Gage, Elizabeth Gould, Steven Jay Gould, William Greenough, Dean Hamer, William Hamilton, Michael Ha.s.selmo, Marc Hauser, Dee Higley, Sarah Blaffer Hrdy, Nicholas Humphrey, Thomas Insel, Victor Johnston, Jerome Kagan, J.A. Scott Kelso, Ray Kesner, Melvin Konner, Judith Langlois, Joseph LeDoux, Paul MacLean, John Manning, Andrew Meltzoff, Michael Merzenich, Geoffrey Miller, Steven Mithen, Sheri Mizumori, Anders Moller, Allan Nash, Ulric Neisser, Charles Nemeroff, Jaak Panksepp, Steven Pinker, Mark Ridley, Terry Robinson, Norman Rosenthal, Michael Ryan, Robert Sapolsky, Ellen Ruppel Sh.e.l.l, Devandra Singh, Georg Striedter, Donald Symons, Randy Thornhill, Sandra Trehub, Robert Trivers, Leslie Ungerleider, Ann Wallenstein, Greg Wallenstein, Claus Wedekind, George Williams, E. O. Wilson, Roy Wise,Amotz Zahavi, and Robert Zatorre.

I also wish to thank my editor at John Wiley & Sons, Christel Winkler; my literary agent, Jim Hornfischer; and Tom Miller at Wiley for their invaluable encouragement and steadfast commitment to the project.

My dear wife, Melissa, is owed a level of grat.i.tude that is impossible to repay. Her love, companionship, support, and intellectual stimulation have been at the core of my life for the past fifteen years and have provided continual inspiration during the writing of this book. Finally, for teaching me what is most profound about human nature, I wish to thank my beautiful children, to whom this book is dedicated.

Part One

The Pleasure Instinct and Brain Development

Chapter 1.

Foibles and Follies.

If you p.r.i.c.k us, do we not bleed? If you tickle us, do we not laugh? If you poison us, do we not die? And if you wrong us, shall we not revenge?

-William Shakespeare, The Merchant of Venice

Human nature exists.

-Melvin Konner, The Tangled Wing

Why does pleasure exist?

Beyond academic circles one seldom hears this question. In daily life, as we move through the minutiae of meetings, ready the kids for school, manage a household, and take care of the basic necessities, we're more likely to seek new ways to pursue pleasure than ponder its existence. Pleasure, like fear and fire, is a natural force that humans have sought to harness and control since their beginnings. The pleasure instinct-evolution's ancient tool for prodding us in the directions that maximize our reproductive success-has created a staggering panorama of behaviors, pathologies, and cultural idioms in our modern lives that often bewilder and beguile.

This book is a biography of sorts, a chronicle of the relationship between humans and pleasure. As the story is told, we will address some of the deepest questions that have been asked about human nature through recorded history and undoubtedly beyond. To understand pleasure, we must know its history and evolution. How is it that the human mind experiences pleasure in mere shapes and colors, textures and touch, myths and stories? Why does humor relieve tension? Why does music invigorate us-to dance, swoon, make love, or march off to battle-while many other noises leave no mark? Why do social attachments make us feel good? Do other animals experience pleasure? Why do we find babies so darn cute? And how is it possible that pleasurable feelings can be elicited from such an astonishingly wide array of events ranging from the mother's gaze at her newborn to the addict's antic.i.p.ation of his next high?

Philosophers and spiritual leaders have debated the value and nature of pleasure for centuries, often comparing it to its more abiding sibling, happiness.The two are related, of course, but most of us, from saint to sinner, have never doubted which of the pair would make the best honeymoon companion. Happiness is often said to be a "gift for making the most of life" or "enjoying the simple things." Pleasure is a hedonistic reflex, a burning impulse to abandon rational thought altogether and immerse oneself in the moment. Happiness is an abstraction, constructed from our social and moral ident.i.ties-a carefree stroll on the beach, 2.3 children and a white picket fence, a sense of accomplishment. The pleasure instinct, like the survival instinct, is pure biological imperative fueled by an ephemeral reward so fevered and beautiful with desire that it can drive us to extraordinary lengths. Happiness is a Norman Rockwell painting hanging over your fireplace on a cold winter's eve. Pleasure is the warmth and aesthetic beauty of the flames, the heat beating on your skin.

Pleasure is experienced in a mult.i.tude of colorful ways-the ecstasy of a s.e.xual encounter, the epicurean delight of chocolate, the delivery of a punch line.Yet despite this it has a central core of universal features that cuts across all human cultures and historic periods. In this respect, we are all deeply connected by both the gifts and constraints that natural selection and adaptation have afforded us.

We live in an antidepression era, dominated by a seemingly insatiable appet.i.te for happiness, and it is critically important to our individual and societal health (and happiness) to understand why this is the case.We can't get no satisfaction. We go on spiritual quests, read all the right books, join health spas, travel, buy new cars, eat out, watch cable TV. We all want a piece of it-bliss, elation, cheer, the primrose path, spice, t.i.tillation, glee, exuberance, mirth, joy, and jubilation. How about vice, addiction, l.u.s.t, malfeasance, adultery, a monkey on your back, obsession, and perversion? Our modern brains, forged from the grist of evolution's mill during our stay as hunter-gatherers, must deal with contemporary conditions that are radically different from-and in some cases in direct opposition to-the ancestral environments in which more than 97 percent of our history has been lived. Thus the importance of understanding why pleasure evolved, how the context and selection factors that shaped its evolution differ vastly from the environmental circ.u.mstances we face today, and the personal and societal consequences of these differences cannot be overstated. And certainly not ignored.

Pleasure is not an epiphenomenon, a lucky happenstance of neurons being in the right place and firing at the right time. It has evolved to serve a very specific and adaptive set of functions from our distant past. The genes that encourage the expression and feeling of pleasure are success stories of natural selection-they are still around. Therefore, in our quest to understand the psychological, biological, and cultural foundations of pleasure in the modern world, we must consider what problems pleasure solved for our ancestors. If the pleasures did not provide a functional solution to some selection factors faced by our earlier brethren, the genes that shape their expression and feeling would be long gone, into the dustbin of ecological time like most others.

Darwin without "Social Darwinism"

Understandably, some people twinge when Darwinism and human nature are mentioned in the same breath-Darwin himself made virtually no reference to humans in his great work The Origin of Species The Origin of Species. Our fear, perhaps, lies in what we foresee as a sterile, eugenic existence such as that thrust upon the characters in Aldous Huxley's Brave New World Brave New World. Most of us genuinely resent the notion that our behaviors, thoughts, and feelings-the very ingredients that make humans extraordinary-are shaped, even in part, by biological and genetic factors. We refuse to accept that our genes chain us to a destiny preordained by proteins. But, as we'll see throughout this book, nothing in modern Darwinian theory claims this to be the case. Indeed, understanding why emotions evolved, particularly the pleasure instinct, can have a profound and positive impact on daily life by showing readers how pleasure influences the way we make aesthetic, social, and moral choices, and learn from our mistakes.

Until recently, scientists have concentrated almost exclusively on studying how social and cultural factors shape emotions. Academics have typically shied away from using evolutionary principles to study slippery subjects such as pleasure because they often fear that such an approach leaves little or no room for the role of experience. We've heard it so many times:"People like things because they learn to like them, not because their genes tell them to." We're not programmed with innate preferences, the argument goes; we learn what is pleasurable through trial and error.And this is often the case. Yet studies have shown that rather general biases are present immediately after birth. For example, newborns prefer the taste of sweets to sours; a smile to an expressionless face; symmetrical to asymmetrical objects and scenes; and rhythmic to random sounds. These preferences emerge long before the infant ever encounters a cookie or hears its first joke. This book explores the many innate proclivities that have evolved in humans as a result of our pleasure instinct, and examines how they dramatically shape our brains, behaviors, thoughts, and feelings.

In the last twenty years a scientific revolution has been under way that marks a significant departure from how human behavior has been studied in the past. The new thinking rests on the firm belief that to make sense of human nature, one must consider how the human mind was molded by both natural and s.e.xual selection. Instead of simply asking, How does the mind solve problem X? a better question is,Why was that particular mind/brain mechanism selected for during our earlier history as hunter-gatherers?

Some claim this revolution began with the 1975 publication of E. O. Wilson's now cla.s.sic book Sociobiology Sociobiology, which examined the way selection factors influence reproduction strategies. Rarely has a scientific text produced such a strong sense of political outrage, particularly among social critics who saw it as a scientific justification for patriarchal societies. Posters were placed all over Harvard University inviting students to attend and disrupt Wilson's cla.s.ses with noise-makers, and he was attacked in the press by many of his colleagues.

Yet the revolution has continued to gather steam, finding support and a more solid foundation from such diverse fields as molecular biology, behavioral genetics, cognitive psychology, cultural anthropology, and neuroscience. Sociobiology and its heir apparent, evolutionary psychology, have now grown at an exponential rate, with thousands of researchers using them as the main paradigms through which they investigate human behavior and indeed culture.

For our purposes, we will use both evolutionary and developmental principles to help us navigate the rambling terrain of pleasure-from its ancient landma.s.ses that gave rise to modern landscapes, to its largely unexplored hinterlands. Pleasure, as we shall see, is the "common currency" that regulates the way humans self-stimulate their own brain growth and maturation. Human babies, for instance, are exceedingly discriminating in what they prefer to look at, listen to, feel, taste, and smell. These innate biases-from a love of primary colors, to a fondness for prosody-ensure that infants seek out the best kinds of sensory experiences for promoting normal brain development in their early years of life. Such biases persist well beyond the critical periods that every parent is familiar with, and form a system of positive reinforcers that profoundly impact adult cognition and behavior. In the chapters that follow we will address long-standing questions and learn why pleasure is ultimately a regulator of development. The issues that arise are at the very core of what it means to be human, and give us a glimpse of what we can reasonably expect of human nature. Why did pleasure evolve? What are the evolutionary advantages, biological realities, and consequences of pleasure?

- How does pleasure fine-tune the brain? Why are certain sensory experiences more pleasurable than others?- What evolutionary/developmental factors govern our attraction and attachment to friends, lovers, relatives, and offspring?- What makes sinning so much fun? How did addictive behaviors evolve and what can natural selection and developmental principles tell us about treatment?- Why is laughter contagious? How is it related to aggression? Are mice ticklish? Do animals experience love and joy? Why do we smile when pleased?- Is there such a thing as a universal set of aesthetics? Why do some of us see art while others see only squiggly lines? What is it that makes some people more physically attractive than others? Why do we like the sounds of wind, thunder, and flowing streams? Why do we find certain environmental landscapes so aesthetically pleasing?- Why do so many of us take pleasure in thrills and chills-from parachuting out of airplanes to riding roller coasters to watching horror flicks? How are phobias related to thrill-seeking?- And perhaps most important of all-how can we use what science is now learning about the pleasure instinct to improve our quality of life?

This is but a small sampling of the questions that arise naturally when we ask: Why does pleasure exist? Fundamental answers to these questions will not be found by generating a hodgepodge of disjointed theories, each tied to a particular issue. Instead, when asked against the backdrop of evolution, they reveal the framework of a new worldview that is beginning to change the way we think about human nature.The story of how the pleasure instinct evolved and continues to function today begins with our first steps into the cognitive niche.

The next two chapters of this book are dedicated to exploring these initial steps into the cognitive niche and provide a conceptual foundation for understanding the role of pleasure in the evolution of our species. Chapters 4 through 8 detail how the pleasure instinct facilitates normal brain growth and development in each of the five primary senses-touch, taste, smell, audition, and vision. Chapters 9 through 11 provide three examples of how the pleasure instinct impacts our everyday lives, including how we choose mates and why we love rhythm so much, and provides a new perspective on addictive behaviors. Finally, chapter 12 summarizes this material and considers the open questions that await answers from future research.

Chapter 2.

How to Win Friends and Influence People "I think therefore I am" is the statement of an intellectual who underrates toothaches.

-Milan Kundera, Immortality

h.o.m.o sapiens . . . can rightfully be called the babbling ape.

-Edward O. Wilson, Consilience

In most families there is nothing more exciting than the appearance of a new baby. In ours, the latest addition is my little niece Kathleen, who now in her fourteenth month can do so many amazing things, most of which we take for granted but are really miracles of development. A few months ago she joined the ranks of fellow bipeds and meanders about the house awkwardly, resembling a slightly inebriated little sailor making her way home after last call. She can recognize objects as being unique and distinct from others, no longer labeling everything uniformly as "daht." And she has an amazingly complex palate of emotional expressions, the full range of which, I have come to realize, can be displayed with little or no notice. But this is just the beginning.

It's been clear for many weeks that Kathleen can understand far more than she is able to verbalize. Sitting next to her at dinner the other night, I noticed she was trying to catch a balloon tied to the back of her chair. "Do you want me to get that for you, sweetie?" I asked. And then, all of a sudden, it happened-she said, "Yeah . . ." At last, contact! There was a real person inside that little body. Our brief exchange didn't grab the interest of those around us, but I was astonished by the unexpected exactness of her answer. For the first time, I truly felt we had made a connection.

Later that evening while talking with a friend about my dinner conversation, I tried to explain why I was so taken aback by my niece. Surely it is to be expected that she'll begin to talk sooner or later, but my surprise arose from two levels of awareness. On the first level, it's staggering to think of the mechanistic and computational achievement it is to extract meaning from mere acoustic energy-sound waves thrust in your direction from the peculiar manner in which people modulate their breath as they exhale. The biological and psychological capacities that support the many processes in between auditory sensation and language interpretation can (and do) fill volumes in university libraries. Then there is the other side, language production. After Kathleen has interpreted my question and decided on an answer, she must mold her young articulators into the correct spatial arrangement, which varies over time, to create the proper sound waves that will have meaning for me, the listener. And finally, there is all that fancy neural processing in between language interpretation and production that is made evident when we realize that Kathleen's answer does not result from some simple stimulus-response pairing, a monosynaptic reflex, or a bit of cla.s.sical conditioning. Rather, a conscious, self-referential decision was made.

In his book The Language Instinct The Language Instinct, cognitive scientist Steven Pinker marvels at this peculiar trick humans have evolved for communication: As you are reading these words, you are taking part in one of the wonders of the natural world. For you and I belong to a species with a remarkable ability: we can shape events in each other's brains with exquisite precision. . . . Simply by making noises with our mouths, we can reliably cause precise new combinations of ideas to arise in each other's minds. As you are reading these words, you are taking part in one of the wonders of the natural world. For you and I belong to a species with a remarkable ability: we can shape events in each other's brains with exquisite precision. . . . Simply by making noises with our mouths, we can reliably cause precise new combinations of ideas to arise in each other's minds.

He makes the important point that the miracle of language is not just in its mechanics-sound waves bouncing off a cochlear, larynx, and pharyngeal openings constricted just so-but in the functional properties that emerge with its usage, namely the exchange of information that may come in any number of forms, such as those relating to nature, technology, social ident.i.ty, physical health, emotions, and so on.

This brings me to the second reason I was so surprised by Kathleen. When she answered, "yeah," I was impressed by her response on an intellectual level, yet at the same time, I felt an inexplicably strong emotional reaction, an attachment that formed instantly with this single syllable. I had heard her say words before, so it was not the mere occurrence of recognizable speech, but rather the context of the social connection that bound us that was so engaging. Just as the emergence of language has been shaped, in both the species and the individual, by the compet.i.tive forces of natural selection, so too has the appearance of emotions such as pleasure. The manner in which pleasure drives our biological need for social attachment and communication is the subject of this chapter, and it is an amazing story.

Precocious Primates Ask an archaeologist what factors gave h.o.m.o sapiens h.o.m.o sapiens the compet.i.tive edge over our neighbors- the compet.i.tive edge over our neighbors-h.o.m.o erectus in Asia and Neanderthals in Europe-and they will likely describe the impressive transition from Oldowan stone tool use found at sites dating 2 million to 1.5 million years ago to the more sophisticated Levallois flake technology for making sharp blades.They will further comment on the explosion in variety and specificity of tools for different functions that appear in the archaeological record: elegant wood-carved spears used for hunting game; blades shaped into projectile points, end sc.r.a.pers, chisels, and burins, all custom-made to match a particular task; and tools born from bone such as awls and needles. Ask anthropologists the same question and they will use the same archaeological data to remind us that earlier hominids tended to segregate their daily lives into different locations according to task.Tools were constructed in one location, food preparation in another, and so forth. in Asia and Neanderthals in Europe-and they will likely describe the impressive transition from Oldowan stone tool use found at sites dating 2 million to 1.5 million years ago to the more sophisticated Levallois flake technology for making sharp blades.They will further comment on the explosion in variety and specificity of tools for different functions that appear in the archaeological record: elegant wood-carved spears used for hunting game; blades shaped into projectile points, end sc.r.a.pers, chisels, and burins, all custom-made to match a particular task; and tools born from bone such as awls and needles. Ask anthropologists the same question and they will use the same archaeological data to remind us that earlier hominids tended to segregate their daily lives into different locations according to task.Tools were constructed in one location, food preparation in another, and so forth. h.o.m.o sapiens h.o.m.o sapiens, on the other hand, are believed to have used a centralized location where all of these activities were performed together, providing an integrative and highly social aspect to everyday life.

But we are left with this daunting question:Why did this shift in social behavior occur? Put simply, why did our ancestors enter the "cognitive niche"? The survival of typical h.o.m.o sapiens h.o.m.o sapiens depended critically on the possession of very basic factual knowledge and skilled techniques for managing their place in the habitat. They had to be able to locate food and know how to extract and prepare it for consumption. They had to learn where their predators were and how to avoid or defend against them. They needed to be familiar with the terrain and, at the very least, possess rudimentary navigation skills. The list goes on and on-just for basic survival. Such increasingly complicated knowledge can most effectively be learned in the context of a social community. In the words of British psychologist Nicholas Humphrey, such a community "provides both a medium for the cultural transmission of information and a protective environment in which individual learning can occur." In this sense, the primary role of intelligence in higher primates is not to produce great works of art or advance scientific achievement, but simply to hold society together. depended critically on the possession of very basic factual knowledge and skilled techniques for managing their place in the habitat. They had to be able to locate food and know how to extract and prepare it for consumption. They had to learn where their predators were and how to avoid or defend against them. They needed to be familiar with the terrain and, at the very least, possess rudimentary navigation skills. The list goes on and on-just for basic survival. Such increasingly complicated knowledge can most effectively be learned in the context of a social community. In the words of British psychologist Nicholas Humphrey, such a community "provides both a medium for the cultural transmission of information and a protective environment in which individual learning can occur." In this sense, the primary role of intelligence in higher primates is not to produce great works of art or advance scientific achievement, but simply to hold society together.

Once a species begins on the path toward socialization, it is as if they were thrown on an evolutionary treadmill, and there is no going back.The emergence of social interactions ultimately leads to ever-increasingly complex social behaviors, social emotions, and group conduct that in turn develop a need for yet more complex social skills. This process is known in evolutionary biology as a "ratchet effect," somewhat akin to a gear that is only capable of moving in a single direction. The limiting factor, of course, is determined by the extent to which the adaptive consequences of social behavior outweigh its burden and eventual cost on successful reproduction. Those individuals who place too great an emphasis on socialization while neglecting other subsistence factors will have a reduced chance of survival into reproductive age and attracting a suitable mate.

Social interaction brings with it enormous potential for changing the way individual members of a group go about their day-today survival. Though basic subsistence is always challenging, life in complex societies such as those constructed by many primates is demanding in a very different way. There are clear benefits to be had for those members of the group who can manipulate the social structure of the clan by outmaneuvering their peers. Individuals must be adroit at reading the social cues of the group; predicting the consequences of their own behavior and that of others; and tallying the complicated balance sheet of advantages and losses that revolve around these myriad social transactions. Hence, social primates are required to be calculating beings by the very nature of the system they create and maintain. In such a system, social skill, communication, and intellect are inseparable.

The selection pressures that led to early hominids' growing need for more sophisticated subsistence technology contributed to two important changes in their social behavior: (1) they granted offspring a longer grace period of dependence on adults, free to learn about their habitat through play, exploration, and experimentation; and (2) they encouraged greater interaction across generations whereby the young learn about subsistence technologies from elder, more experienced teachers. These shifts markedly widened the age range of the communal setting, and brought the very young into contact with the very old, resulting in particularly difficult social challenges. Both the older and the younger members of a community tend to be most dependent on the core adults of the group; thus an evolutionary mechanism must exist to facilitate or encourage the adults to cater to the whims, desires, and needs of these two groups. There must be some adaptive benefit for the adults that outweighs the cost to them in caring for the young, old, sick, and infirm. That adaptive benefit, of course, is mediated by the pleasure derived from social bonding-the pleasure I found in the exchange with my niece.

Many scholars agree that two behaviors probably provided the survival edge that benefited h.o.m.o sapiens h.o.m.o sapiens over their contemporaries: the evolution of social attachment and language. I believe that both social attachment and language evolved from selection factors I call proto-emotions. These are basic, instinctual emotions that are exhibited by many primates: pleasure, fear, anger, disgust, sadness, surprise, and the various hungers. Proto-emotions have a very quick onset and are short-lived, almost like a reflex. The social emotions-for instance, happiness, maternal love, s.e.xual love, infatuation, pride, and admiration-differ from proto-emotions in that they consist of long-lasting behavioral and mood states that typically outlast precipitating conditions and increasingly depend on a capacity for self-reference and reflection. These are the modern emotions we experience today that evolved from conditions in our ancestral past, remnants of a prior age where life was lived as hunter-gatherers on the open plains of the savanna. In the pages that follow, we'll explore how pleasure led to the evolution of social attachment and language, and most importantly, how it shaped the positive social emotions that reverberate through our lives so profoundly today. Why did our instinct for pleasure drive us to become such loquacious, social creatures? And how did this newfound love of gabbing, gossip, and group affiliation result in modern emotions such as love, l.u.s.t, happiness, and joy? over their contemporaries: the evolution of social attachment and language. I believe that both social attachment and language evolved from selection factors I call proto-emotions. These are basic, instinctual emotions that are exhibited by many primates: pleasure, fear, anger, disgust, sadness, surprise, and the various hungers. Proto-emotions have a very quick onset and are short-lived, almost like a reflex. The social emotions-for instance, happiness, maternal love, s.e.xual love, infatuation, pride, and admiration-differ from proto-emotions in that they consist of long-lasting behavioral and mood states that typically outlast precipitating conditions and increasingly depend on a capacity for self-reference and reflection. These are the modern emotions we experience today that evolved from conditions in our ancestral past, remnants of a prior age where life was lived as hunter-gatherers on the open plains of the savanna. In the pages that follow, we'll explore how pleasure led to the evolution of social attachment and language, and most importantly, how it shaped the positive social emotions that reverberate through our lives so profoundly today. Why did our instinct for pleasure drive us to become such loquacious, social creatures? And how did this newfound love of gabbing, gossip, and group affiliation result in modern emotions such as love, l.u.s.t, happiness, and joy?

The Language Link We take for granted that language can illuminate what is subjective, the amorphous yet innumerable feelings, thoughts, and inklings that mix through our minds like hot and cold currents every moment of the day. We like to think that other humans share this dizzying internal menagerie, or at least some parts of it. But what would a dog say if it could speak a human language? Would a dog's inner emotional experiences be close enough to a human's so that a common lexicon might emerge? Could we really learn more about the thoughts and feelings of animals-what is in their hearts and minds-if we could decode their vocalizations?

The linguistic philosopher Ludwig Wittgenstein argued that all truths, be they emotional, moral, aesthetic, or intellectual, are known only through experience. He suggested that they lose their real value and meaning in the telling, and that language is merely a form of depiction, a representational system that inevitably fails to characterize our genuine nature since it can only work through a.n.a.logy. Thus, even if we successfully decode an animal's sounds, we could not truly understand them because language is but a mirror of reality rather than the genuine object, and an animal's reality, as the argument goes, is too far removed from our own. Language is the finger pointing at the moon, not the moon itself. In cognitive science circles, this is known as the representation problem-deciphering how symbols, such as language, map onto subjective experiences, such as feelings and thoughts. The representation problem, of course, extends to all symbol-using species, and we will revisit it throughout this book.

A kissing cousin to this line of argument is the cla.s.sic linguistic problem of induction-how one infers the referent of a word from a speaker's vocalizations and behavior. Imagine you are a linguist encountering a newly discovered human population. One of the clan members shouts "agovi" as a turtle saunters by.Your first guess, probably, is that agovi agovi means "turtle." This is a perfectly reasonable inference, since at least in English, comments elicited by an object typically refer to the object itself. But this is premature because agovi may also refer to animals or objects that move slowly, have sh.e.l.ls, are hard and spherically shaped, are smaller than a house but larger than a breadbox, or are the most important ingredient for soup.The induction problem shows that any attempt to determine word meaning strictly from behavior is in deep trouble, since there are simply too many possible interpretations for any specific action. How did the first language emerge, then, if we can't even get past single words? I believe a reasonable alternative is that hominids' initial foray into semantics, and perhaps the genesis of structured language, were driven not by their desire to label everything in sight, but rather by their common need to exchange emotional information. means "turtle." This is a perfectly reasonable inference, since at least in English, comments elicited by an object typically refer to the object itself. But this is premature because agovi may also refer to animals or objects that move slowly, have sh.e.l.ls, are hard and spherically shaped, are smaller than a house but larger than a breadbox, or are the most important ingredient for soup.The induction problem shows that any attempt to determine word meaning strictly from behavior is in deep trouble, since there are simply too many possible interpretations for any specific action. How did the first language emerge, then, if we can't even get past single words? I believe a reasonable alternative is that hominids' initial foray into semantics, and perhaps the genesis of structured language, were driven not by their desire to label everything in sight, but rather by their common need to exchange emotional information.

How did proto-emotions, particularly pleasure, foster the evolution of modern language? There are many theories that are fun to consider. Did language develop in response to the increasingly complicated social lives our ancestors lived, or is it perhaps the other way around, a new tool that evolved for other reasons-a spandrel-that facilitated greater socialization? What did the first languages sound like and how did they facilitate social attachment and the development of modern emotions?

Although it's impossible to jump in a time machine and listen in on a prehistoric town meeting, we can adopt a different strategy. We can look to a source of information that will help us decipher how the pleasure instinct may have shaped social attachment and linguistic life for hominids-the emergence of spoken language in children. This is not an attempt to resuscitate the old Haekelian idea that ontogeny (the development of an individual) recapitulates phylogeny (the development of a species).This notion is based on the a.s.sumption that the ontogenetic form being considered develops through a series of stages that are essentially re-creations of the adult forms of its evolutionary predecessors.We will employ a more modern view that has emerged recently, which instead emphasizes studying the embryological and developmental commonalities and differences among genetically similar species. This theoretical approach never arose in Haekel's day because it depends on the modern science of genetics. We will use it here because learning how an infant becomes linguistic can tell us a great deal about how language arose in our species as an important tool for emotional expression. "The human race began to talk as babies begin to talk," noted the psychologist Carl Johnston, ". . . in the prattle of every baby, we have a repet.i.tion in a minor key of the voice of the earliest man . . . by watching the first movements of speech in a baby, we see once more the first steps in articulate language, which the whole world of man took in dim ages long ago."

The Trouble with Tribbles In ninth grade I remember reading a novel set in the distant future where a highly sophisticated artificial intelligence program is implanted into robots, eventually giving them enough brainpower to take over the world from humans, outthinking our every move. If you want a more probable scenario, one that at least makes sense from an evolutionary perspective, our mechanized subjugators are most likely to be adorably cute little creatures-perhaps puppylike-that gain power over us by tapping into our emotions rather than our rational components of mind. For primates, cuteness is more than simply a disarming factor. In our robots, cuteness would ensure that humans promote their survival by taking care of them, pampering them as one might an infant, working for the benefit of their continued comfort. In short, we would develop many of the behaviors and feelings toward them that go along with social attachment. The process is reminiscent of an old Star Trek Star Trek episode in which the away team that has beamed down to the planet below encounters a species of hamsterlike critters known only as Tribbles. Going against Spock's counsel, the team brings the harmless creatures on board the episode in which the away team that has beamed down to the planet below encounters a species of hamsterlike critters known only as Tribbles. Going against Spock's counsel, the team brings the harmless creatures on board the Enterprise Enterprise, to the delight of the crew, who notice that when petted, Tribbles sing a beautiful cooing song. Before long, playing with Tribbles becomes the primary recreation of the shipmates, who are unable to resist their fuzzy appearance and soothing sounds. Meanwhile, the captain and Dr. McCoy begin to realize that petting Tribbles stimulates them to reproduce, and before long the Enterprise Enterprise is in a desperate state, about to be overwhelmed by the exponential growth of these little fur b.a.l.l.s. Soon Tribbles are everywhere, popping out of the food replicators, cooing from inside the ship's main computer consoles; they have reached every nook and cranny of the vessel. Only Spock, devoid of emotions, seems immune to their charms and quickly takes control of the situation by isolating these dangerously lovable creatures from the rest of the crew. is in a desperate state, about to be overwhelmed by the exponential growth of these little fur b.a.l.l.s. Soon Tribbles are everywhere, popping out of the food replicators, cooing from inside the ship's main computer consoles; they have reached every nook and cranny of the vessel. Only Spock, devoid of emotions, seems immune to their charms and quickly takes control of the situation by isolating these dangerously lovable creatures from the rest of the crew.

The survival of all mammals, particularly the social primates, depends critically on their ability to secure attachment and nurturance from those around them. In most primates this dependence is aimed directly at the mother, who becomes involved in a complicated species-specific exchange with her offspring, employing whatever version of "motherese" phylogeny has given her. In humans and other mammals, the exchange between parent and offspring that leads to bonding and attachment can be likened to a conversation. Even though structured language may be entirely absent in the species, a turn-taking of sorts occurs, with certain physical and behavioral characteristics of the newborn eliciting a nurturing response from the parent, which then evokes yet more stimulation from the newborn, continuing the cycle. In humans this exchange is partly composed of prelinguistic vocalizations at first, with rapid phonological development that mirrors emotional expression in the first twenty-four months.

Infants enter the world displaying a clear preference for the language spoken by their mother. For instance, studies have demonstrated that French babies as young as four days old suck a nipple more diligently when hearing French than when hearing Russian or English. Likewise, Russian newborns prefer to hear Russian rather than French or English or Italian. Detailed experiments following up on these observations showed that babies tune into the prosody (timing, stress, and inflection) of speech patterns, since playing tapes of the languages backward-which preserves most of the vowels and consonants but alters the melody-eliminates the preference. Hence, newborns are predisposed to pay attention to prosodic features of their mother's voice. Indeed, infants instinctually take such pleasure from these melodic elements of speech that they can be conditioned using prosody as a positive reinforcer (a reward) in the same way as can be done using other pleasurable experiences, such as access to its mother's milk.

These findings are less surprising when we remember that prosody conveys the emotional tone of a message. "Communication is successful," it is said, "not when hearers recognize the linguistic meaning of the utterances, but when they infer the speaker's 'meaning' from them." Many of the linguistic cues used to express intention are nonverbal. Systematic variation in pitch, tone, and duration of sounds-the music of language-is the primary venue for the infant, and it is in these signals that babies generally show the greatest interest. The newborn is naturally attracted to prosodic cues precisely because they contain the emotional meaning of speech, the very part of the message that is both critical to its social attachment with caregivers and accessible to its preverbal mind.

Interestingly, mothers across the globe-from culture to culture-speak practically identical versions of "motherese" to their infants: a complex blend of exaggerated tonal variation, eyes widened with expressive facial postures, and prodigious use of the high-toned "Hmm?" Wherever there are infants, we encounter baby talk, and it would be naive to consider this a form of linguistic instruction; the baby is certainly not enduring grammar drills. Rather, it is the innate social and emotional responsiveness of these inquisitive Lilliputian bundles that compels adults-mothers, fathers, brothers, sisters, and the rest-to speak motherese. The tiny linguophile naturally searches the faces and emotional expressions of nearby adults, an effort in identification and novelty-seeking that promotes further stimulation from parents."The development of linguistic communication is a story about the preoccupation among the human young with things that move-faces that wrinkle, eyes that dance, voices that undulate, and hands that wiggle through the air," wrote child psychologist John Locke."Parents obviously understand this and, correctly believing that more is better, exaggerate their facial and vocal movements when addressing their young.And to good developmental effect, for the cues to phrase boundaries are prosodic, and the cues to vocal turn taking include variations in pitch and gaze."

Why does the infant pay attention to speech? It is surely not to learn the rules of syntax, widen its semantic base, or because it thinks language is an important mode of communication. No, the process of gazing into the eyes of those around it and eliciting motherese stems rather from the child's basic, biological imperative to interact and connect emotionally with the people who nurture it. Infants orient toward the human voice, especially Mama's, and lock on to her face, studying it with deep concentration. Why should they do this? What are the biological and psychological reasons for such persistent behaviors? Surely they are adaptive in that they draw the caretaker closer to the infant, allowing it to identify those who are most likely to offer affection and nurturance.

Babies continue to learn the sounds of their mother tongue during the first year of life, all the while maintaining their innate fondness for prosody and the other features of motherese. We will see in later chapters that the infant's pleasure instinct for prosody has surprisingly long-term consequences, particularly for the evolution of aesthetic and musical preferences in the adult. For instance, synthesized sounds that have extreme pitch variations reminiscent of motherese evoke a feeling of pleasure in adults, who often a.s.sociate them with happiness, interest, and surprise. Sounds that have a falling-pitch contour (high frequency decreasing to lower frequencies) elicit feelings of calm and relaxation. Imagine a parent who soothes a crying child with "Aahh," or the meditation pract.i.tioner chanting "Ohmm."Vocalizations that have a rising pitch contour have a very different effect; they tend to excite and grab our attention-"Hey!" From cross-cultural studies, it is clear that both natural and synthetic exaggerations in pitch have a universal appeal, whether they are embedded in music, speech, or song, presumably as a result of the same underlying biological mechanisms that have evolved to promote social attachment through our attraction to prosody.

An infant's face also conveys emotional information directly to the caregiver, and they are incredibly talented mimics even at birth. Developmental psychologist Andrew Meltzoff was the first to demonstrate that newborns as young as forty-five minutes old are able to reproduce facial gestures corresponding to primary emotional conditions such as disgust (tongue protrusion), surprise (mouth opening), and sadness (lip protrusion)-even before they have seen their own face! Thus from the very beginning of life, human infants are busy employing and refining their methods of communication, and the primary topic of discourse is that of emotions.

While it is true that infants enter a linguistic babbling stage, a visual a.n.a.log of this behavior is seen in their tendency to produce varied facial postures shortly after birth-another sort of babbling. Through trial and error, they learn quickly which expressions evoke an emotional response in adult observers. Adults, of course, learn the same lesson, and generate a number of facial postures and behaviors, eventually stumbling on the ones that elicit facial expressions in the infant that correspond to positive emotions. Emotions, then, are the first language we use. When an adult or an infant sees an emotional expression, it instantly gains information about the displayer's current state. These talents translate to the linguistic domain, where squeaks, gurgles, and coos-the vocabulary of motherese-feed the emotional palate as well.

Studies have also shown that infants are born with a predisposition toward preferring abstract visual stimuli that look like human faces. Neonates a mere nine minutes old were shown different drawings before having ever seen a face-any face. They looked significantly longer (a common measure of preference) at a stylized pictogram of a normal human face, than at pictograms with exactly the same features but scrambled (a nose, mouth, eyes, and brows situated randomly on a circular "face"), suggesting they enter the world searching for kith and kin.

Just as prosody can be used as a pleasurable reward to condition infants, so too can the appearance of a human face. Newborns as young as two days old learn to alter their behavior (sucking and gazing) in order to maximize exposure to human faces. In fact, they master this task with astonishing efficiency, which tells us two very interesting things. First, neonates must be equipped with something that approaches single-trial learning, particularly when the task involves an evolutionarily significant variable such as the face. And second, the infant's capacity for extracting emotional and intentional information from facial features has such critical importance for survival that the pleasure instinct has made the human face a most attractive and rewarding visual stimulus for babies (and, of course, adults).

We will find in later chapters that the human face has physical properties-such as lateral symmetry and exaggerated contrasts-in common with other stimuli that infants find naturally rewarding. Our evolved pleasure instinct for these visual features has lifelong repercussions for the development of aesthetics and physical attraction in the adult. Discovering which physical features the pleasure instinct nudges us toward during our first steps as neonates will help shed light on why certain aesthetic qualities, whether they are in faces, bodies, paintings, or landscapes, are universally appealing for humans. All of these inborn talents provide the neonate with tools for establishing an emotional communion with potential caregivers. One can hardly imagine the survival benefit to an infant who routinely engages inanimate objects (either through vocal or facial expressions) with no obvious human features, to the exclusion of their brethren. Nature is unwilling to take any chances with this most critical of objectives, the biological imperative to become attached to a caregiver, receive nurturance, and eventually become enmeshed into a broader social community. In the next few chapters, we will learn how this fundamental biological rule combines with embryological and developmental processes that regulate the growth and maturation of the human brain.

Chapter 3.

What Makes Sammy Dance?

There seems to be a continuing realization by psychologists that perhaps the white rat cannot reveal everything there is to know about behavior.

-Keller and Marian Breland, The Misbehavior of Organisms

The mind of the thoroughly well-informed man is a dreadful thing. It is like a bric-a-brac shop, all monsters and dust, with everything priced above its proper value.

-Oscar Wilde, The Picture of Dorian Gray

One morning in 1970 a tortured twenty-four-year-old man with a history of drug abuse and severe depression walked into Dr. Robert Heath's office at Tulane Medical School in New Orleans. By then Heath was a well-known, albeit controversial, figure who founded the Department of Psychiatry and Neurology at Tulane in 1948 after being recruited from Columbia University. Within a year of joining the faculty, Heath and his coworkers were conducting experimental studies in humans that would forever change the way psychiatrists think about emotions and at the same time provide enough source material to keep biomedical ethicists busy for decades to come.

By the time he was twenty-four years old, the patient known as B-19 had a diagnosis of temporal lobe epilepsy compounded by a history of chronic drug abuse and depression."I live with the idea of suicide daily," he is quoted as saying, and it is reported that he made several "abortive attempts."We also learn that B-19 was h.o.m.os.e.xual and that "one aspect for the total treatment program for this patient was to explore the possibility of altering his s.e.xual orientation through electrical stimulation of pleasure sites of the brain."

During the early years of his tenure, Heath pioneered the therapeutic use of electrical stimulation of the brain (ESB) to treat epilepsy. Impressed by the work of Olds and Milner, who had just discovered "pleasure centers" in the brains of rats, Heath adapted their approach to recondition the brains of patients suffering from affective disorders and particularly schizophrenia."The primary symptom of schizophrenia isn't hallucinations or delusions," he told a reporter years later."It's a defect in the pleasure response. Schizophrenics have a predominance of painful emotions. They function in an almost continuous state of fear or rage, fight or flight, because they don't have the pleasure to neutralize it." The idea was tantalizing-just stimulate the neural pleasure centers of a schizophrenic and this might rekindle damaged circuits affected by the disease and enable the patient to once again experience positive emotions.

Electrodes and cannulas (needle-thin tubes through which drugs may be delivered directly into the brain) were placed in fourteen subcortical structures of B-19's brain, including the septal region, hippocampus, amygdala, and hypothalamus-areas that were hypothesized to regulate emotions in humans and had previously been identified as locations where rats "self-stimulate."

Prior to the study, B-19's "interests, contacts, and fantasies were exclusively h.o.m.os.e.xual; heteros.e.xual activities were repugnant to him."After B-19 recovered from the surgery, Heath and his coworkers stimulated each electrode briefly and asked their patient to report what he felt. Stimulation at most brain regions produced only mild or "neutral" feelings, and in some cases actually induced anxiety or other aversive sensations. But one electrode positioned in the septal region consistently produced an intense pleasurable response. "The patient reported feelings of pleasure, alertness, and warmth (goodwill); he had feelings of s.e.xual arousal and described a compulsion to m.a.s.t.u.r.b.a.t.e."