The Brains of Women and Men Are More Alike Than You May Think
A recent study surveyed the size of the brain's emotional center in scans of men and women and found no significant differences.
We all know the cliches: Men are from Mars, women are from Venus. Women are quicker to cry. Men don't show their emotions.
But research that looked at differences in the brain - specifically in the brain's emotion center - suggests that may all be bunk.
"That belief that there's a male-type brain and female-type brain is just not true," said Lise Eliot, an associate professor of neuroscience at the Chicago Medical School of Rosalind Franklin University of Medicine and Science. "It's not true for the amygdala. It is turning out to be not true for the hippocampus, for the corpus callosum, for left-right dominance. There's just not an attribute of the brain that reliably marks it as male or female."
Eliot, whose 2009 book "Pink Brain, Blue Brain" explained how gender stereotypes are reinforced on young brains, led recent research that analyzed 6,726 MRIs taken from 58 separate studies. Her team scrutinized the brain scans of men and women, and measured the volume of the amygdala in each subject. Previous research using animal models and MRIs had suggested that the amygdala may be larger in males than in females.
The amygdala (of which there are two in the brain) is known as the center for emotion, social behavior, aggression and sexual drive. If men's amygdalae are, in fact, larger, it could be evidence of one way that men and women are wired differently.
The researchers did find that amygdala volumes were in fact about 10 percent larger in male brains. But, Eliot says that corresponds to men's larger body size, including the 10-12 percent overall larger volume of men's brains.
"The difference in amygdala volume is just in proportion to their size difference - it's 10-12 percent larger, which makes sense because men are 10 to 12 percent larger than women," Eliot said. "But if you control for individual head size, there's no difference."
The Franklin University team's finding, which was published in the journal NeuroImage, is the latest in a series of studies that have looked for differences in male and female brains - and found none.
Eliot's team found in a 2015 study that there is no discernible difference in the size of men's and women's hippocampus. The hippocampus plays a key role in the consolidation of learning from short-term memory to long-term memory and in spatial navigation.
A 1997 study from the University of Alberta analyzed scans from 49 studies published since 1980 and found no significant sex difference in the size or shape of the brain's corpus callosum. This bundle of nerves is the part of the mind that allows communication between the two hemispheres of the brain.
Then there is the common belief that people are either "right-brained" or "left-brained," and that women tend to be more right-brained and associated with creativity rather than the calculating, analytical characteristics commonly linked with the left brain. That notion, too, has been challenged.
A 2014 University of Utah Health Sciences study asserted that there is no evidence within brain imaging that indicates some people are right-brained or left-brained.
"It's absolutely true that some brain functions occur in one or the other side of the brain. Language tends to be on the left, attention more on the right," Jeff Anderson, the study's lead author, said at the time. "But people don't tend to have a stronger left- or right-sided brain network. It seems to be determined more connection by connection."
One of the most comprehensive surveys looked at several areas of the brain and analyzed the volume of gray matter and white matter in the brains of more than 1,400 individuals. The researchers from Tel Aviv University in Israel concluded in the 2015 research that all of our brains seem to share a patchwork of forms that crossed gender lines.
Finally, one might wonder if hormones are at play in the brain, leading men and women to think differently.
Again, Eliot says, the research just doesn't show it.
"The studies that have tried to find effects of estrogen and testosterone on thinking skills or emotional skills have been very sketchy," she remarked. "About the only thing we know for sure is that testosterone increases sex drive in both sexes. Other than that, estrogen and testosterone, it's the same thing - they appear to have no effect on any cognitive skills."
The bottom line is while there is obviously variation among human brains and corresponding human behavior, these differences just can't be drawn along gender lines.
"Much of the idea that men's and women's brains are different is just stereotype," said Eliot. "The fact is there are sensitive men and there are callous women. There are aggressive women and there are deeply emotional men. We're all across the spectrum and the most successful people usually have a mix of traits."
Photo: MRI coronal view of the amygdala. Credit: Amber Rieder, Jenna Traynor, Geoffrey B Hall WATCH: Men vs. Women: Who Really Gets Sicker?