You hear it everywhere: men and women behave differently because of the way we’re wired. As neuroscientist and writer Christian Jarrett explains in “Great Myths of the Brain,” there are indeed differences between the average male brain and the average female brain, but we’re a long way from knowing what they mean.
For example, men have bigger brains than women do, even after taking account of their bigger bodies, throughout the lifespan, and may have 16 percent more neurons in the neocortex, where much of our thinking occurs. However, women also have a higher ratio of “gray” to “white” matter, and a high gray/white ratio is associated with better cognitive function in the elderly. It would be a big mistake to assume the bigger male brain means men are “smarter” or that the higher gray/white ratio means women are. Perhaps smaller brains have a bigger gray/white ratio, regardless of sex — and we can’t draw conclusions about functioning.
Put a man and a woman in a brain scan and give them certain experiences or tasks and their brains light up differently. But this doesn’t mean that men and women will behave differently or that one sex is superior at the task at hand. People often will behave similarly even when they show contrasting patterns of brain activity, and some argue that the sex-based brain differences serve to even things out rather than the other way around.
Now let’s look at some of the most prevalent stereotypes and how neuroscience has been used to support them. You may have heard of “mirror neurons,” often hypothesized to be the basis of empathy. A book titled “The Female Brain” proposed that women have more mirror neurons or that their mirror neurons are more active. After all, lots of people believe that women are more empathic and generally superior at reading other people’s emotions. According to Jarrett, there is some evidence that women are better at recognizing facial expressions of fear and disgust, but none that they have more active or more mirror neurons.
The human brain consists of two hemispheres. How many times have you heard that some people are more “left-brained” (logical, analytical) and some “right-brained” (intuitive, creative)? In fact, there’s no sign of better hubs on the left side or right side in individuals. This is especially important since many people think women are more “right-brained.” In a widely publicized study that fed this myth, the researchers concluded that from childhood on, boys develop more connectivity within each brain hemisphere compared to girls, who have more connections between the two sides. What might that mean? Some suggested that it explained why men are better map-readers — despite the fact that the study didn’t include experiments in which anyone read a map. Another large study examined the connectivity question and did not find sex differences.
All this said, studying brain sex differences may yet lead to useful discoveries. In an analysis of more than a hundred studies, the researchers concluded that this research may help us better understand depression, autism, schizophrenia, and attention deficit disorder, which are all related to brain development and show up differently in males and females. However, the authors write, “the link between function and structure is still under-explored; no predictions as to how structure may influence physiology or behavior are possible.” Keep that in the forefront of your own brain the next time you hear that women and men are “wired” to behave differently. Also remember that our brains respond to our experiences over time: even “wiring” isn’t fixed. As Shakespeare has Ophelia say in Hamlet: “Lord, we know what we are, but know not what we may be.”
May 20, 2015
Janet O’Dell, RN