Are Gender Differences a Product of Nature - or of Nurture?
In her book, PINK BRAIN, BLUE BRAIN, Dr. Lise Eliot shatters the myths about gender differences, arguing that the brains of boys and girls are largely shaped by how they spend their time.
CommitmentNow.com: The title of your book is Pink Brain, Blue Brain, Are there actual differences between boy’s brains and girl’s brains?
Lise Eliot: There must be. However, I was surprised to find very little evidence of them in the existing research on children’s brain structure and function, even using very sensitive measures like EEG. The reason I say there must be differences is because there are clear differences in behavior, such as the different toy preference that starts showing up around 1 year of age. Also, boys are more physically active, while girls talk earlier. But most of these behavioral differences are small—with lots of overlap between boys and girls—so finding the neurologic basis for them is extremely difficult.
CommitmentNow.com: What is plasticity and what role does it have in gender differences?
Dr. Eliot: Neuroplasticity is the term that scientists have adopted to describe the incredible malleability of the brain. We are not born with all our software installed. It is gradually loaded as children explore and interact with the world around them. Even simple abilities, like vision, are critically shaped by babies’ encounters with their environment. Considering how different the experience of boys and girls are—from parents’ different expectations and interaction styles to the clothes, toys, role models, and especially, peer interactions—their brains are immersed in essentially two different cultures, which potently impact the way they wire up.
CommitmentNow.com: Other books indicate that scientists have discovered differences between girl’s and boy’s brains that result in, for example, greater communication skills in boys and more aggressive behavior in boy’s. What is your opinion of these theories?
Dr. Eliot: My response is: “Show me the data!” I agree that such differences should be apparent in neuroscientific findings, but they aren’t thus far. And the reason is presumably because the communication and aggression differences, while real, are not as large as our stereotypes portray. So the neurologic differences are similarly going to be subtle, making them difficult for scientists to detect.
CommitmentNow.com: You state that parents begin to treat their sons and daughters differently in infancy. Can you give us one or two examples of this?
Dr. Eliot: To estimate such gender bias, researchers use gender disguise experiments, in which baby boys are dressed like girls and vice-versa. When adults interact with a child they believe is a boy, they are likelier to call him “big,” “strong,” and “alert,” while if they believe the child is a girl, are likelier to call her things like “delicate” and “sweet.” I also cite a study done at NYU, where moms brought in their 11 month old babies to try crawling down a carpeted ramp. The mom actually had to adjust the angle of the slope to the steepest they thought their babies would be willing to try crawling down. Moms of girls underestimated their courage by a significant degree, while moms of boys were accurate. The same greater cautiousness is found when parents interact with older daughters at the playground, compared to sons.
CommitmentNow.com: We all know of girls who forgo playing with trucks in favor of dolls, despite their parents’ best efforts and their desire not to reinforce gender stereotypes. Are boys and girls hard-wired for “gender typical” play?
Dr. Eliot: To some degree, yes. The sex difference in toy preference is just about the largest of all psychological sex differences, and has been proven to be enhanced by prenatal testosterone. However, the truck/doll divide also grows larger through the preschool years due to learning, as parents have been found to bristle when sons try on Mom’s high heels or show too much interest in Sister’s Barbies. While parents tend to be fairly egalitarian in our discipline and affection, we do subtly encourage “gender-appropriate” play, especially in boys. In fact, by age 5, girls have opened up and play about equally with “boy” and “girl” toys, while boys (who have more social restrictions from both adults and peers) avoid anything pink or girly like the plague.
CommitmentNow.com: What is the “boy code” and how does it affect boys' expression of emotions?
Dr. Eliot: This refers to the powerful socialization boys exert on each other, to be tough both physically and emotionally. It may originate from boys’ greater propensity for physical aggression, but is also reinforced by fathers, media role models, and most cultural definitions of “masculinity.” It’s a great example of how small innate differences become magnified through social learning, to produce the familiar masculine stereotype. Little boys cry just as much as girls, but quickly learn it’s not manly.
The issue is, does the “boy code” shut down male emotion too much? Some would say yes, and say it contributes to later violence, poor fathering, and the lack of social connection among many men and their families. On the other hand, there is real value in learning to contain your emotions, which may make it easier for men to compete in the workplace, advocate for their own interests, and resist depression. So my conclusion is that boys could use some tempering of the “boy code,” while girls could use a bit more of it in their development.
CommitmentNow.com: You state that boys' and girls' social experiences actually change the brain, often permanently. Can you explain how that works?
Dr. Eliot: This is the neuroplasticity we’ve been talking about. Our best understanding comes from studies of visual development. Babies have to see in order for their visual cortex to wire up properly. A child born with a visual problem, such as a congenital cataract, can end up permanently blind in that eye if the problem is not corrected within the first couple months of life (Fortunately, it is very easily corrected.) The problem isn’t actually in the eye itself, but in the brain, which can’t wire up properly in the absence of normal vision. Adults, by contrast, can suffer from a cataract for decades, but it won’t impair their vision once the cloudy lens is removed and replaced with an artificial lens. That’s because their visual cortex already developed properly in the first place.
For social learning, the neural circuits are less well understood. However, there is now lots of evidence from studies of rodents that different styles of parenting permanently alter pups’ brains and behavior. Rat pups that are licked and groomed more by their mothers end up less anxious, better able to handle stress, and with a healthier hippocampus than less well-nurtured rats. What’s more, certain motor neurons that control male sexual behavior depend on the mother’s licking and grooming in order to survive and produce permit sexual function. So parenting behavior is quite important for social development, including gender-typical behavior, and scientists are even identifying the permanent changes in DNA structure that underlie these lifelong effects of early nurturing.
CommitmentNow.com: What is the most important thing for parents to know about brain differences in their sons and daughters?
Dr. Eliot: Very simply, that nothing about human brain development is fixed or “hardwired.” Children do have different propensities, which vary by sex, personality, family culture, and many other factors. I think it is important to be aware of average sex differences, so we can try to “cross-train” children in the areas they may not be inclined to pursue (words, literacy, and emotional sensitivity for boys; competitiveness, risk-taking, and spatial skills for girls). However, we need to be ever-vigilant about stereotyping children, and assuming that they will learn or respond in a certain way, based only on their gender.
Each gender has its strength and weaknesses, but in today’s world, kids need it all, so let’s stop pigeon-holing them.
Lise Eliot is Associate Professor of Neuroscience at The Chicago Medical School of Rosalind Franklin University of Medicine & Science. A Chicago native, she received an A.B. degree from Harvard University, a Ph.D. from Columbia University, and did post-doctoral research at Baylor College of Medicine in Houston. In addition to teaching and writing, Dr. Eliot lectures widely on children’s brain and mental development. She lives in Lake Bluff, Illinois with her husband and their 15-year-old daughter and 13- and 10-year-old sons.
To purchase Pink Brain, Blue Brain, click here.
