CONTENTS
About the Book
Title Page
Dedication
Acknowledgments
The Male Brain (diagram)
The Cast of Neurohormone Characters
Phases of a Male’s Life
INTRODUCTION: What Makes a Man
ONE: The Boy Brain
TWO: The Teen Boy Brain
THREE: The Mating Brain: Love and Lust
FOUR: The Brain Below the Belt
FIVE: The Daddy Brain
SIX: Manhood: The Emotional Lives of Men
SEVEN: The Mature Male Brain
EPILOGUE: The Future of the Male Brain
APPENDIX: The Male Brain and Sexual Orientation
Notes
References
Index
About the Author
Also by Louann Brizendine, M.D.
Copyright
From the author of the groundbreaking, international bestseller The Female Brain comes this eagerly awaited follow-up.
Did you know that the male brain . . .
Is a lean, mean problem-solving machine that uses analytical brain structures, not emotional ones, to find solutions
Thrives under competition, instinctively plays rough, and is obsessed with rank and hierarchy
Has an area for sexual pursuit that is 2.5 times larger than that of the female brain, consuming him with sexual fantasies about female body parts
As Dr Louann Brizendine’s impeccably researched, irresistible guide follows the male brain from infancy to adulthood, it unlocks many secrets and offers fascinating insights into a range of subjects, including emotional intimacy, anger, aggression, and winning. It also answers many baffling questions and exposes the often shocking gulf that exists between the sexes.
To the men in my life:
My husband, Dr. Samuel Herbert Barondes
My son, John “Whitney” Brizendine
My brother, William “Buzz” Brizendine II
And in memory of my father,
Reverend William Leslie Brizendine
THIS BOOK HAD its beginnings during my educational years at U.C. Berkeley, Yale, Harvard, and U.C. London, so I would like to thank those teachers who most influenced my thinking during those years: Frank Beach, Mina Bissell, Harold Bloom, Marion Diamond, Walter Freeman, Florence Haseltine, Richard Lowenstein, Daniel Mazia, Fred Naftolin, Stanley Jackson, Roy Porter, Carl Salzman, Leon Shapiro, Rick Shelton, Gunter Stent, Frank Thomas, George Valliant, Clyde Willson, Fred Wilt, Richard Wollheim.
During my years on the faculty at Harvard and UCSF, my thinking has been influenced by: Cori Bargman, Samuel Barondes, Sue Carter, Regina Casper, Lee Cohen, Mary Dallman, Allison Doupe, Deborah Grady, Mel Grumbach, Leston Havens, Joel Kramer, Fernand Labrie, Sindy Mellon, Michael Merzenich, Joseph Morales, Kim Norman, Barbara Parry, Victor Reus, Eugene Roberts, Nirao Shah, Carla Shatz, Stephen Stahl, Marc Tessier-Lavigne, Rebecca Turner, Owen Wolkowitz, Chuck Yingling, and Ken Zack.
My colleagues, staff, residents, medical students, and patients in the Women’s Mood and Hormone Clinic. I would especially like to thank my faculty members at the clinic: Lyn Gracie Adams, Steve Hamilton, Dannah Hirsch, Jane Hong, Shana Levy, Faina Novosolov, and Elizabeth Springer.
And for their friendship and support throughout: Lynne Benioff, Marc Benioff, Diane Cirincione, Janet Durant, Adrienne Larkin, Sharon Melodia, Nancy Milliken, Jeanne Robertson, Sandy Robertson, Alla Spivak, and Jodi Yeary.
The work presented in this book has been based on and greatly benefited from the research and writings of: Marty Altemus, Arthur Arnold, Arthur Aron, Simon Baron-Cohen, Andreas Bartels, Frank Beach, Jill Becker, Sherri Berenbaum, Karen Berkley, Jeff Blaustein, Marc Breedlove, Lucy Brown, David Buss, Larry Cahill, Anne Campbell, Sue Carter, David Crews, Susan Davis, Karl Deisseroth, Geert De Vries, Catherine Dulac, Elisa Epel, Helen Fisher, David Geary, Jay Giedd, Jill Goldstein, Louis Gooren, Mel Grumbach, Andy Guay, Elizabeth Hampson, Bob Handa, James Herman, Melissa Hines, Gert Holstege, Sarah Hrdy, Janet Hyde, Tom Insel, Bob Jaffe, Doreen Kimura, Eleanor Maccoby, Dev Manoli, Helen Mayberg, Martha McClintock, Erin McClure, Bruce McEwen, Michael Meaney, Toni Pak, Barbara Parry, Don Pfaff, David Rubinow, Robert Sapolsky, Peter Schmidt, Nirao Shah, Barbara Sherwin, Elizabeth Spelke, Dick Swaab, Jane Taylor, Shelley Taylor, Rebecca Turner, Kristin Uvnas-Moberg, Victor Viau, Myrna Weissman, Sandra Witelson, Sam Yen, Kimberly Yonkers, Elizabeth Young, Larry Young, and the many other scientists whose work I have cited in this book.
I would also like to thank the foundations and supporters of my work: the Lynne and Marc Benioff Family, the Lawrence Ellison Medical Foundation, National Center for Excellence in Women’s Health at UCSF, the Osher Foundation, the Staglin Family Music Festival for Mental Health, the Salesforce.com Foundation, the Stanley Foundation, and the UCSF Department of Psychiatry.
This book was written and rewritten with the assistance of Toni Robino. I owe her the greatest debt of gratitude.
I would especially like to thank Diane Middlebrook and the Literary Salon. Diane set the stage for me to begin writing; she read many drafts of my work and was, and is, an inspiration even past her untimely death.
Amy Hertz believed in this book from day one and deserves special thanks for helping shape my thinking and writing over the years.
I am very thankful to those who worked to make this book happen: Julie Sills, Stephanie Bowen, Elizabeth Rendfleisch, Mark Birkey, Gary Stimeling, Lorraine Glennon, Diane Salvatore, my ever encouraging agent, Lisa Queen of Queen Literary, and my dedicated publicity manager at Random House, Rachel Rokicki.
I am grateful to my editor at Random House, Kris Puopolo, who supported me with intelligence, skill, and dedication through many years of writing, rewriting, starts, and stops.
I also want to thank my son, John “Whitney,” for graciously allowing me to use many of his personal stories and whose help in understanding the world of boys, teens, and young men has been invaluable. His sense of humor and determination continue to inspire me.
Most of all I thank my husband and soul mate, Sam Barondes, for everything—his insights into the world of men, his wisdom, levity, intelligence, critiques, editorial advice, scientific acumen, tolerance, empathy, and love.
Scientists think of brain areas like the ACC, TPJ, and RCZ as being “hubs” of brain activation, sending electrical signals to other areas of the brain, causing behaviors to occur or not occur.
(how hormones affect a man’s brain)
TESTOSTERONE—Zeus. King of the male hormones, he is dominant, aggressive, and all-powerful. Focused and goal-oriented, he feverishly builds all that is male, including the compulsion to outrank other males in the pecking order. He drives the masculine sweat glands to produce the come-hither smell of manhood—androstenedione. He activates the sex and aggression circuits, and he’s single-minded in his dogged pursuit of his desired mate. Prized for his confidence and bravery, he can be a convincing seducer, but when he’s irritable, he can be the grouchiest of bears.
VASOPRESSIN—The White Knight. Vasopressin is the hormone of gallantry and monogamy, aggressively protecting and defending turf, mate, and children. Along with testosterone, he runs the male brain circuits and enhances masculinity.
MÜLLERIAN INHIBITING SUBSTANCE (MIS)—Hercules. He’s strong, tough, and fearless. Also known as the Defeminizer, he ruthlessly strips away all that is feminine from the male. MIS builds brain circuits for exploratory behavior, suppresses brain circuits for female-type behaviors, destroys the female reproductive organs, and helps build the male reproductive organs and brain circuits.
OXYTOCIN—The Lion Tamer. With just a few cuddles and strokes, this “down, boy” hormone settles and calms even the fiercest of beasts. He increases empathic ability and builds trust circuits, romantic-love circuits, and attachment circuits in the brain. He reduces stress hormones, lowers men’s blood pressure, and plays a major role in fathers’ bonding with their infants. He promotes feelings of safety and security and is to blame for a man’s “postcoital narcolepsy.”
PROLACTIN—Mr. Mom. He causes sympathetic pregnancy (couvade syndrome) in fathers-to-be and increases dads’ ability to hear their babies cry. He stimulates connections in the male brain for paternal behavior and decreases sex drive.
CORTISOL—The Gladiator. When threatened, he is angry, fired up, and willing to fight for life and limb.
ANDROSTENEDIONE—Romeo. The charming seducer of women. When released by the skin as a pheromone he does more for a man’s sex appeal than any aftershave or cologne.
DOPAMINE—The Energizer. The intoxicating life of the party, he’s all about feeling good, having fun, and going for the gusto. Excited and highly motivated, he’s pumped up to win and driven to hit the jackpot again and again. But watch out—he is addictively rewarding, particularly in the rough-and-tumble play of boyhood and the sexual play of manhood, where dopamine increases ecstasy during orgasm.
ESTROGEN—The Queen. Although she doesn’t have the same power over a man as Zeus, she may be the true force behind the throne, running most of the male brain circuits. She has the ability to increase his desire to cuddle and relate by stimulating his oxytocin.
HORMONES CAN DETERMINE what the brain is interested in doing. Their purpose is to help guide social, sexual, mating, parenting, protective, and aggressive behaviors. They can affect being rough-and-tumble, competing in sports or attending sporting events, solving problems, interpreting facial expressions and others’ emotions, male-male bonding, dating and mating, ogling attractive females, forming sexual and pair-bond relationships, protecting family and turf, fantasizing, masturbating, and pursuing sex.
YOU COULD SAY that my whole career prepared me to write my first book, The Female Brain. As a medical student I had been shocked to discover that major scientific research frequently excluded women because it was believed that their menstrual cycles would ruin the data. That meant that large areas of science and medicine used the male as the “default” model for understanding human biology and behavior, and only in the past few years has that really begun to change. My early discovery of this basic inequity led me to base my career at Harvard and the University of California–San Francisco (UCSF) around understanding how hormones affect the female and male brains differently and to found the Women’s Mood and Hormone Clinic. Ultimately that work led me to write The Female Brain, which addressed the brain structures and hormonal biology that create a uniquely female reality at every stage of life.
The distinct brain structures and hormonal biology in the male similarly produce a uniquely male reality. But as I considered writing The Male Brain, nearly everyone I consulted made the same joke: “That will be a short book! Maybe more of a pamphlet.” I realized that the idea that the male is the default-model human still deeply pervades our culture. The male is considered simple; the female, complex.
Yet my clinical work and the research in many fields, from neuroscience to evolutionary biology, show a different picture. Simplifying the entire male brain to just the “brain below the belt” is a good setup for jokes, but it hardly represents the totality of a man’s brain. There are also the seek-and-pursue baby boy brain; the must-move-or-I-will-die toddler brain; the sleep-deprived, deeply bored, risk-taking teen brain; the passionately bonded mating brain; the besotted daddy brain; the obsessed-with-hierarchy aggressive brain; and the fix-it-fast emotional brain. In reality, the male brain is a lean, mean problem-solving machine.
The vast new body of brain science together with the work I’ve done with my male patients have convinced me that through every phase of life, the unique brain structures and hormones of boys and men create a male reality that is fundamentally different from the female one and all too frequently oversimplified and misunderstood.
Male and female brains are different from the moment of conception. It seems obvious to say that all the cells in a man’s brain and body are male. Yet this means that there are deep differences, at the level of every cell, between the male and female brain. A male cell has a Y chromosome and the female does not. That small but significant difference begins to play out early in the brain as genes set the stage for later amplification by hormones. By eight weeks after conception, the tiny male testicles begin to produce enough testosterone to marinate the brain and fundamentally alter its structure.
Over the course of a man’s life, the brain will be formed and re-formed according to a blueprint drafted both by genes and male sex hormones. And this male brain biology produces his distinctly male behaviors.
The Male Brain draws on my twenty-five years of clinical experience as a neuropsychiatrist. It presents research findings from the advances over the past decade in our understanding of developmental neuroendocrinology, genetics, and molecular neuroscience. It offers samplings from neuropsychology, cognitive neuroscience, child development, brain imaging, and psychoneuroendocrinology. It explores primatology, animal studies, and observation of infants, children, and teens, seeking insights into how particular behaviors are programmed into the male brain by a combination of nature and nurture.
During this time, advances in genetics, electrophysiology, and noninvasive brain-mapping technology have ignited a revolution in neuroscientific research and theory. Powerful new scientific tools, such as genetic and chemical tracers, positron-emission tomography (PET) and functional magnetic resonance imaging (fMRI), now allow us to see inside the working human brain while it’s solving problems, producing words, retrieving memories, making decisions, noticing facial expression, falling in love, listening to babies cry, and feeling anger, sadness, or fear. As a result, scientists have recorded a catalog of genetic, structural, chemical, hormonal, and brain-processing differences between women and men.
In the female brain, the hormones estrogen, progesterone, and oxytocin predispose brain circuits toward female-typical behaviors. In the male brain, it’s testosterone, vasopressin, and a hormone called MIS (Müllerian inhibiting substance) that have the earliest and most enduring effects. The behavioral influences of male and female hormones on the brain are major. We have learned that men use different brain circuits to process spatial information and solve emotional problems. Their brain circuits and nervous system are wired to their muscles differently—especially in the face. The female and male brains hear, see, intuit, and gauge what others are feeling in their own special ways. Overall, the brain circuits in male and female brains are very similar, but men and women can arrive at and accomplish the same goals and tasks using different circuits.
We also know that men have two and a half times the brain space devoted to sexual drive in their hypothalamus. Sexual thoughts flicker in the background of a man’s visual cortex all day and night, making him always at the ready for seizing sexual opportunity. Women don’t always realize that the penis has a mind of its own—for neurological reasons. And mating is as important to men as it is to women. Once a man’s love and lust circuits are in sync, he falls just as head over heels in love as a woman—perhaps even more so. When a baby is on the way, the male brain changes in specific and dramatic ways to form the daddy brain.
Men also have larger brain centers for muscular action and aggression. His brain circuits for mate protection and territorial defense are hormonally primed for action starting at puberty. Pecking order and hierarchy matter more deeply to men than most women realize. Men also have larger processors in the core of the most primitive area of the brain, which registers fear and triggers protective aggression—the amygdala. This is why some men will fight to the death defending their loved ones. What’s more, when faced with a loved one’s emotional distress, his brain area for problem solving and fixing the situation will immediately spark.
I must have been dimly aware of this long catalog of distinctive male behaviors when I first found out, twenty-one years ago, that the baby I was carrying had a Y chromosome. I immediately thought, Oh dear. What am I going to do with a boy? Up until that moment, I realized, I had unconsciously been thinking It’s a girl! and feeling confident that my own female life experiences could guide me in raising a daughter. I was right to be nervous. My lack of boy-smarts was about to matter more than I imagined. I now know from my twenty-five years of research and clinical work that both men and women have a deep misunderstanding of the biological and social instincts that drive the other sex. As women, we may love men, live with men, and bear sons, but we have yet to understand men and boys. They are more than their gender and sexuality, and yet it is intrinsic to who they are. And it further complicates matters that neither women nor men have a good sense of what the others’ brains or bodies are doing from one moment to the next. We are mostly oblivious to the underlying work performed by different genes, neurochemicals, and hormones.
Our understanding of essential gender differences is crucial because biology does not tell the whole story. While the distinction between boy and girl brains begins biologically, recent research shows that this is only the beginning. The brain’s architecture is not set in stone at birth or by the end of childhood, as was once believed, but continues to change throughout life. Rather than being immutable, our brains are much more plastic and changeable than scientists believed a decade ago. The human brain is also the most talented learning machine we know. So our culture and how we are taught to behave play a big role in shaping and reshaping our brains. If a boy is raised to “be a man,” then by the time he becomes an adult, his brain’s architecture and circuitry, already predisposed that way, are further contoured for “manhood.”
Once he reaches manhood, he will likely find himself pondering an age-old question: What do women want? While no one has a definitive answer to that question, men do know what women and society in general want and expect from them. Men must be strong, brave, and independent. They grow up with the pressure to suppress their fear and pain, to hide their softer emotions, to stand confidently in the face of challenge. New research shows that their brain circuits will architecturally change to reflect this emotional suppression. Although they crave closeness and cuddling as much or perhaps even more than women, if they show these desires, they are misjudged as soft or weak by other men and by women, too.
We humans are first and foremost social creatures, with brains that quickly learn to perform in socially acceptable ways. By adulthood, most men and women have learned to behave in a gender-appropriate manner. But how much of this gendered behavior is innate and how much is learned? Are the miscommunications between men and women biologically based? This book aims to answer these questions. And the answers may surprise you. If men and women, parents and teachers, start out with a deeper understanding of the male brain, how it forms, how it is shaped in boyhood, and the way it comes to see reality during and after the teen years, we can create more realistic expectations for boys and men. Gaining a deeper understanding of biological gender differences can also help to dispel the simplified and negative stereotypes of masculinity that both women and men have come to accept.
This book provides a behind-the-scenes brain’s-eye view of little boys, tumultuous teens, men on the mating hunt, fathers, and grandfathers. As I take readers through the phases of the male brain’s life, my hope is that men will gain a greater understanding of their deepest drives and women will catch a glimpse of the world through male-colored glasses. We are entering an era, finally, when both men and women can begin to understand their distinct biology and how it affects their lives. If we know how a biological brain state is guiding our impulses, we can choose how to act, or to not act, rather than merely following our compulsions. If you’re a man, this knowledge can not only help you understand and harness your unique male brain power, but it can also help you understand your sons, your father, and other men in your life. If you’re a woman, this book will help you interpret and comprehend the intricacies of the male brain. With that new information, you can help your sons and husbands to be truer to their nature and feel more compassionate toward your father.
Over the years, as I have been writing this book, I have come to see the men I love most—my son, my husband, my brother, and my father—in a new light. It is my hope that this book will help the male brain to be seen and understood as the fine-tuned and complex instrument that it actually is.
DAVID RACED PAST the swing set and zoomed around the tool-shed in the backyard with his preschool buddies Matt and Craig hot on his heels. Determined to maintain his lead, he took a shortcut through the sandbox, sending sand and shovels flying as he made a beeline for the coveted Big Wheel tricycle. Matt pushed Craig aside and dived for the wheeled wonder, but David was already sliding into the driver’s seat. With pedals churning, David screeched off down the sidewalk and into the driveway, where he victoriously spun doughnut after doughnut.
Disappointed but not to be outdone, Matt and Craig headed for the open garage to see what else they could find to ride. Craig spotted it first: a large plastic trash can. “Let’s use this!” he shouted. And without another word, the boys were running headlong for the hill in the backyard, dragging the can behind them. “C’mon. Gimme a push!” Craig commanded as he slid into the can. “Harder!” he said, as Matt’s first shove barely budged it. Matt rammed the can with his shoulder as hard as he could, and the green vehicle tumbled down the hill with Craig inside whooping and hollering.
You don’t have to study brain science to know that little boys are all about action and adventure. Go to a playground and you’ll see boys like David and his friends in perpetual motion. Boys are programmed to move, make things move, and watch things move. Scientists used to think this stereotypical boy behavior was the result of socialization, but we now know that the greater motivation for movement is biologically wired into the male brain.
If you watched the fetal development of a male and a female brain with a miniature time-lapse brain scanner, you’d see these critical movement circuits being laid down from the blueprint of their genes and sex hormones. Scientists agree that when cells in various areas of the male and female brains are stimulated by hormones like testosterone and estrogen, they turn on and off different genes. For a boy, the genes that turn on will trigger the urge to track and chase moving objects, hit targets, test his own strength, and play at fighting off enemies.
David and his friends weren’t taught to be action-oriented; they were following their biological impulses. David’s mother said that his love affair with movement was obvious from day one. “When I put him in his bassinet, I thought he’d cry and look beseechingly at me the way Grace did when she was a baby,” she said. “But as soon as he spotted the moving mobile, he forgot I was there.”
David was only twenty-four hours old, and without encouragement or instruction from anyone, he stared at the rotating triangles and squares on the mobile and seemed to find them fascinating. Nobody taught David to follow the movements of the dangling triangles and squares with his eyes. He just did it. A boy’s superior ability to track moving objects isn’t the result of being conditioned by his environment. It’s the result of having a male brain. Every brain is either male or female and, while they are mostly alike, scientists have discovered some profound differences. Certain behaviors and skills are wired and programmed innately in boys’ brains, while others are wired innately in girls’. Scientists have even found that male-specific neurons may be directly linked to stereotypical male behaviors like roughhousing. And studies show that from an early age, boys are interested in different activities than girls. These differences are reinforced by culture and upbringing, but they begin in the brain.
I met David’s mother, Jessica, a few months after he was born. Her daughter, Grace, was three years old, and Jessica and her husband, Paul, were thrilled to have a beautiful baby boy. But Jessica was worried because things weren’t going quite as smoothly with David as they had with Grace. Jessica said, “He’s sweet and cuddly one minute, and the next minute he’s squirming out of my arms. If I don’t put him down, he shrieks like I’m killing him.”
Jessica was afraid that David might be hyperactive. But her pediatrician told her David was just fine and developing normally. Researchers at Harvard found that baby boys get emotionally worked up faster than girls, and once they’re upset, they’re harder to soothe. So, early on, parents spend more time trying to dial down their sons’ emotions than their daughters’.
She said, “Grace was easier to calm. David keeps us constantly on our toes!”
Jessica also told me that David didn’t make eye contact with her the way Grace did when she was a baby. She said that he’d only look at her for a couple of seconds and then go right back to staring at the mobile. I couldn’t help but smile, because I had this same concern with my own son. At that time, psychologists believed the key to developing a bond with your baby was what they called mutual gazing—looking into each other’s eyes. Whereas that’s true for baby girls, it turns out that baby boys bond without as much mutual gazing. And unlike girls, who are inclined to look long and hard at faces, boys’ visual circuits pay more attention to movement, geometric shapes, and the edges and angles of objects from the get-go.
I said to Jessica, “By the time they’re six months old, baby girls are looking at faces longer and making eye contact with just about everyone. But baby boys are looking away from faces and breaking eye contact much more than girls. There’s nothing wrong with David. His brain just doesn’t find eyes and faces as interesting as toy airplanes and other moving objects.”
David’s male brain was prompting him to visually explore animated objects. We now know that genes on the Y chromosome are the reason. Like other boys, David’s fascination with movement was the result of circuitry that started to form in his brain just eight weeks after he was conceived. During fetal development, David’s brain was built in two stages. First, during weeks eight to eighteen, testosterone from his tiny testicles masculinized his body and brain, forming the brain circuits that control male behaviors. As his brain was marinating in testosterone, this hormone began to make some of his brain circuits grow and to make others wither and die.
Next, during the remaining months of pregnancy another hormone, MIS, or Müllerian inhibiting substance, joined with testosterone and defeminized David’s brain and body. They suppressed his brain circuits for female-type behaviors and killed off the female reproductive organs. His male reproductive organs, the penis and testicles, grew larger. Then, together with testosterone, MIS may have helped form David’s larger male brain circuits for exploratory behavior, muscular and motor control, spatial skills, and rough play. Scientists discovered that when they bred male mice to lack the MIS hormone, they did not develop male-typical exploratory behavior. Instead, they behaved and played more like females. The female brain circuits that make a girl a girl are laid down and develop without the effects of testosterone or MIS.
After I shared this information with Jessica, she raised her eyebrows and asked, “Are you saying that if Grace’s brain had been exposed to these male hormones when I was pregnant, she’d act more like David?”
“That’s right,” I said, smiling as her face lit up with recognition. It’s always rewarding to me when I see this kind of relief on a mother’s face. Suddenly, instead of thinking that she’s doing something wrong or that there’s something wrong with her child, she can relax and begin to appreciate her son’s maleness.
She said, “It’s just so different with David. He’s so much more active than Grace was, even at this age. But he can be the very essence of sweetness, too.
“The other day when I was having a hard time getting him down for his nap, Paul took him and played with him on our bed, hoping he’d calm down. I had my doubts about whether it would work, but when I peeked in to check on them a little later, David was lying with his tiny hand inside of Paul’s big one, and they were both fast asleep.”
From birth until a boy is a year old, a period that scientists call infantile puberty, his brain is being marinated in the same high levels of testosterone as in an adult man. And it’s this testosterone that helps stimulate a boy’s muscles to grow larger and improves his motor skills, preparing him for rough-and-tumble play. After the year of infantile-puberty, a boy’s testosterone drops, but his MIS hormone remains high. Scientists call this period, from age one to ten, the juvenile pause. They believe that the MIS hormone may form and fuel his male-specific brain circuits during this ten-year period, increasing his exploratory behavior and rough play. This meant it wouldn’t be long before Jessica would have more reason to worry as David started testing his limits, as I well remember with my own son.
When he was a toddler and we were out walking on Baker Beach in San Francisco, he took off running after a sandpiper toward the water. I shouted and waved my arms like a madwoman to signal danger. He completely ignored me. I had to run after him and grab his shoulders to pull him back from the surf, just as a huge wave was rolling in. That was the first day in what would be years of his ignoring my signals of danger—stop, don’t do that—requiring me to keep a firm hold on him.
Researchers have found that by the time a boy is seven months old, he can tell by his mother’s face when she’s angry or afraid. But by the time he’s twelve months old, he’s built up an immunity to her expressions and can easily ignore them. For girls, the opposite happens. A subtle expression of fear on Jessica’s face would stop Grace in her tracks. But not David.
By the age of one, David seemed oblivious to the look of warning on Jessica’s face. Researchers asked mothers of one-year-old boys and girls to participate in an experiment in which an interesting but forbidden toy was placed on a small table in the room with them. Each mother was told to signal fear and danger with only her facial expressions, indicating that her child should not touch it. Most of the girls heeded their mother’s facial warning, but the boys seemed not to care, acting like they were magnetically pulled toward the forbidden object. Their young male brains may have been more driven than the girls’ by the thrill and reward of grabbing the desired object, even at the risk of punishment. And this also happens with fathers. In another study, with dads and their one-year-olds, the boys tried to reach forbidden objects more often than the girls. The fathers had to give twice as many verbal warnings to their sons as to their daughters. And researchers found that by the age of twenty-seven months, boys more often than girls will go behind their parents’ backs to take risks and break rules. By this age, the urge to pursue and grab items that are off-limits can become a hair-raising game of hide-and-seek—with parents hiding the danger their sons will inevitably seek.
When David was three and a half, Jessica told me that he never ceased to amaze her, both for better and for worse. “He picks me flowers, tells me he loves me, and showers me with kisses and hugs. But when he gets the urge to do something, the rules we’ve taught him vanish from his mind.” She told me that David and his friend Craig were in the bathroom washing up for dinner when she heard Craig yell, “Stop it, David. I’m peeing.” Then she heard the distinct sound of the hair dryer. Danger flashed through Jessica’s brain. Racing down the hall, she flung open the bathroom door just in time to get a splash of urine on her legs. David had turned the blow-dryer on his friend’s stream—just to see what would happen. But being sprayed with urine didn’t upset her nearly as much as David’s disregarding the “no electrical appliances without adult supervision” rule. For the next couple years, she had to keep all electrical appliances well out of David’s reach. But, she told me with a slight blush, “There’s one thing I can’t keep out of his reach, even in public.”
David thought nothing of grabbing and playing with his penis—anytime, anywhere. A boy’s public relationship with his penis is something that has made many mothers wince, including me. But the male brain’s reward center gets such a huge surge of pleasure from penis stimulation that it’s nearly impossible for boys to resist, no matter what their parents threaten. So rather than trying to stop David, I suggested Jessica start teaching him to explore this compelling pleasure in the privacy of his room.
A few weeks after Jessica started trying to get David to play with his penis in “privacy,” the family went on vacation. As they were walking down the hallway in their hotel, David saw a sign hanging on the doorknob of the room next-door and asked, “Mom, what does P-R-I-V-A-C-Y say?” When Jessica said the word out loud for him, he said, “Oh, that man must be doing his privacy in there.” From then on, he’d refer to playing with his penis as “doing my privacy.”
Later that year, when David came into the office with Jessica, I handed him a lavender toy car from an assortment I had in a shoe-box. He frowned as he said, “That’s a girl car.” Tossing the car back into the box, he grabbed the bright red car with black racing stripes, saying, “This is a boy one!” Researchers have found that boys and girls both prefer the toys of their own sex, but girls will play with boys’ toys, while boys—by the age of four—reject girl toys and even toys that are “girl colors” like pink.
I didn’t know this when my own son was born, so I gave him lots of unisex toys. When he was three and a half years old, in addition to buying him one of the action combat figures he was begging for, I bought him a Barbie doll. I thought it would be good for him to have some practice playing out nonaggressive, cooperative scenarios. I was delighted by how eagerly he ripped open the box. Once he freed her from the packaging, he grabbed her around the torso and thrust her long legs into midair like a sword, shouting, “Eeeehhhg, take that!” toward some imaginary enemy. I was a little taken aback, as I was part of the generation of second-wave feminists who had decided that we were going to raise emotionally sensitive boys who weren’t aggressive or obsessed with weapons and competition. Giving our children toys for both genders was part of our new child-rearing plan. We prided ourselves on how our future daughters-in-law would thank us for the emotionally sensitive men we raised. Until we had our own sons, this sounded perfectly plausible.
Scientists have since learned that no matter how much we adults try to influence our children, girls will play house and dress up their dollies, and boys will race around fighting imaginary foes, building and destroying, and seeking new thrills. Regardless of how we think children should play, boys are more interested in competitive games, and girls are more interested in cooperative games. This innate brain wiring is apparently different enough that behavioral studies show that boys spend 65 percent of their free time in competitive games, while girls spend only 35 percent. And when girls are playing, they take turns twenty times more often than boys.
It is commonly said that “boys will be boys,” and it’s true. My son didn’t turn Barbie into a sword because his environment promoted the use of weapons. He was practicing the instincts of his male brain to aggressively protect and defend. Those stereotypically girl toys I gave him in his first few years of life did not make his brain more feminine any more than giving boy toys to a girl would make her more masculine.
I later found out that my son had plenty of masculine company when it came to turning Barbie into a weapon. In an Irish nursery school, researchers observed that boys raided the girls’ kitchen toys and even unscrewed the faucet handles in the miniature sink to use as toy guns. In another nursery-school study, researchers found that preschool boys were six times more likely than girls to use domestic objects as equipment or weapons. They used a spoon as a flashlight to explore a make-believe cave, turned spatulas into swords to battle the “bad guys,” and used beans as bullets.
The next time I talked to Jessica, she told me David came home from kindergarten one day with a black eye. His teacher said he had called Craig a sissy for playing with the girls, and Craig hauled off and hit him. Jessica said, “I felt so bad for him that I took him out for ice cream, and out of the blue, he turned to me and said, ‘I love you, Mommy. I’m gonna marry you when I grow up.’ Seeing him with that black eye and hearing him say that to me just about broke my heart. Why would his best friend hit him like that, just for calling him a name?”
I told Jessica that by the time a boy is just three and a half, the greatest insult is being called a girl. Boys tease and reject other boys who like girls’ games and toys. And after the age of four, if a boy plays with girls, the other boys soon reject him. Studies show that beginning in the toddler years, boys develop a shared understanding about which toys, games, and activities are “not male” and must therefore be avoided. Boys applaud their male playmates for male-typical behavior while they condemn everything else as “girly.”
Curiosity about the origins of boys’ strong preference for masculine toys led researchers to explore this further with young rhesus monkeys. Because monkeys are not gender socialized as to which toys are masculine or feminine, they made good subjects for this study. Researchers gave the young male and female monkeys a choice between a wheeled vehicle, the “masculine” toy, and a plush doll figure, the “feminine” toy. The males almost exclusively spent time playing with the wheeled toy. But the females played equal amounts of time with the doll and the wheeled toy. The scientists concluded that gender-specific toy preferences have roots in the male brain circuitry in both boys and male monkeys. And there is further evidence that this toy preference has its origins in fetal brain development. In human girls, a prenatal exposure to high testosterone, due to a disorder called CAH (congenital adrenal hyperplasia), has been found to influence later toy preferences. By the time these CAH girls are three or four, they prefer boy-typical toys more than other girls do.
Scientists believe that boys’ toys reflect their preference for using big muscle groups when they play. A related preference for action shows up even in art class. Researchers found that elementary-school boys preferred to draw action scenes like car and plane crashes. Nearly all their drawings captured a dynamic movement, and they used only a few colors. The girls in the study drew people, pets, flowers, and trees and used many more colors than the boys did.
David not only liked drawing action scenes and playing with boy toys, but by the age of five, his favorite board game was Chutes and Ladders. He would do anything to win, including cheat. He’d slyly move his marker the wrong number of spaces so he could climb up a ladder or avoid having to slide down a chute. And he was devastated when he lost. Jessica said, “Every time Craig and David play this game, they end up fighting.” I could relate. When my son was in kindergarten, we had to remove all the win-lose board games and put them in the closet for a while. Victory is critically important to boys because, for them, play’s real purpose is to determine social ranking. At an early age, the male brain is raring for play-fighting, defending turf, and competing. Losing is unacceptable. To a young male brain, the victory cry is everything.
“Aarghhh!” David shouted as he charged forward, thrusting and jabbing his new laser sword at Craig. Not to be outdone, Craig snatched the sword out of David’s hands and took off running with it. But he made it only a few yards before David caught up and grabbed the back of his mud-caked shirt. Within seconds they were on the ground wrestling for possession of the sword. To someone not familiar with the ways of young boys, this would look like a fight. But David and Craig were having a blast.
Boys wrestle and pummel each other with gusto, competing for toys and trying to overpower each other. They play this way up to six times more than girls do, a reality that Jessica now found highly entertaining, although she hadn’t always seen the humor in it. Boys discover their place in the world by pushing all of their body’s physical limits, so it’s not just fighting but also being able to fart or burp the loudest or the longest that gives a boy bragging rights. Jessica said, “I’ll never understand why David and Craig think farting on each other is so funny. But they think it’s hilarious, and Paul laughs as hard as they do.”
For David and Craig, every day was filled with a series of serious physical contests. How fast can you run? How high can you climb? How far can you jump? A boy’s success or failure in sports and other contests can make or break his sense of self. Even though Jessica could appreciate that males are naturally driven to test their physical abilities, she still worried that David would get hurt. But Paul—who grew up with three brothers—knew that the bumps and bruises were a normal part of boyhood.
During the juvenile pause, boys imitate their dads, uncles, and older male cousins, and they’re particularly intrigued with the men who stand out as alpha males. Go to the zoo and watch the primates, and you’ll see the most powerful male sitting by himself chewing grass and the little guys running up and attacking him from behind. The little guys are playing at things they’ll be required to do in their future. When the alpha male has had enough, he’ll shoo away the juveniles. Undaunted, they will continue to wrestle with each other, literally tumbling across the ground. This rough-and-tumble play is also observed in groups of human boys everywhere.
By the time boys are in first grade, they get a brain high when they show their strength and aggression. Using physical force together with insults is even better. As child researcher Eleanor Maccoby says, “These boys are just trying to have their kind of fun.” This way of playing gives their brain a massive feel-good reward in the form of a dopamine rush. The neurochemical dopamine is addictively rewarding—the brain likes it and wants more—so boys are always seeking the thrill of the next high. That’s why they love scary movies, haunted houses, and daring each other to take risks. Boys don’t necessarily want to get hurt, but they usually think the excitement is worth it. Jessica said, “I’m just happy to get through a day without putting ice or Band-Aids on somebody.”
By grade school, the play styles of boys and girls in groups have diverged, and children self-impose sex segregation. Observational studies found that, worldwide, boys on playgrounds wrestle, roughhouse, and mock-fight frequently; girls do not. In addition to their different play styles, boys and girls may also dislike playing together because, as research shows, by the time boys are in first grade, they’re no longer paying much attention to girls or listening to what they say. A study of boys in a first-grade classroom in Oregon found that boys paid the most attention first and foremost to what other boys said. The teachers placed second, and the girls placed a distant third—if they placed at all. As a matter of fact, ignoring girls altogether was the most common. David and most of the other boys in his first-grade class had already sworn off playing with girls, and their female classmates were just fine with that. They didn’t like playing with the boys either.
A study on an Irish kindergarten playground may shed even more light on the girls’ and boys’ interactions with each other. The researchers noted that the boys monopolized the tricycles and bicycles and played ramming games, while girls—on the few occasions they got a turn to ride—were very careful not to hit other kids’ bikes or anything else. The boys even became territorial and possessive of their bikes, showing a willingness to fight for them that the girls did not show.
Jessica said she couldn’t understand it when David’s teacher wrote on his report card that he was always fighting to be the first in line for recess and lunch. Since Grace never seemed to mind waiting her turn in line, the importance David placed on being first took Jessica by surprise.
The pecking order clearly matters more to boys. Studies show that by age two, a boy’s brain is driving him to establish physical and social dominance. And by the age of six, boys tell researchers that real fighting is the “most important thing to be good at.” Scientists have also learned that boys are remarkably fast at establishing dominance in a group through rough-and-tumble play.