More on the brain size debate: Part I

Okay, I know I promised the next entry would be devoted to Temple Grandin's views on language -- a subject well worth exploring -- but I've found myself distracted by some of my other reading this week. (So much to read, so little time.) Be assured, we'll delve into "Grandin on Language" at a later date. Today, I find my thoughts once again turning to the teaspoon of gray matter separating the male and female brain. ("When it comes to brains, does size really matter?) I revisited this entry after the Tangled Bank Carnival and found myself no less irate over Terence Kealey's pseudoscientific theory of female domestication.

(For those who have neither the time nor inclination to read "Does size really matter?" Kealey argues that women have smaller brains -- and therefore less intellectual brawn -- because they've been successfully domesticated by men. To buttress his point, he draws on evidence presented in a long-term study of foxes showing that the brains of domesticated fox pups shrank over successive generations. While it's true that the female human's brain has shrunk by something like 10 percent over the millennia, Kealey neglects that the male brain has as well.)

As is often the case when I'm preoccupied with a topic, the synchronicities started proliferating. Everywhere I looked, I found more information on the unique processing abilities of the female brain.

I happened to be reading Katherine Ellison's fascinating book on the intellectual benefits of motherhood, The Mommy Brain, when I stumbled on the following passage.

There are a few intriguing differences between men's and women's cerebral equipment that some scientists are convinced lead to differences in the way the two genders think. The most notable difference is overall size: The female brain, on average, is about 15 percent smaller than the average male brain. This is a particularly incendiary topic; a few modern scientists have suggested that brain size is related to intelligence, implying that women, in general, are dumber. Other experts have challenged the larger-is-better view by pointing out that women's brains are more tightly packed with neurons, ergo, more efficient machines.

But here's where it starts to get really interesting . . .

Recent fMRI scans have established that women do seem to use more of their brains at once, compared to men, in response to some stimuli. In one study, researchers looked at the brain activity in ten men and ten women who were listening to an audiotape of a John Grisham novel. In all cases, the men's brains showed activity exclusively in the left temporal lobe, but women's brains were active in both the right and left temporal lobes.

One other physical difference that is often cited in comparisons of male and female brains has to do with a highway of nerve fibers connecting the left and right hemispheres. Called the corpus callosum, the "calloused body," it's an arched structure running midline from the back to the front of the head. Some studies have found that a female human's corpus callosum is on average slightly thicker on one end than a male's, in proportion to total brain size. (Another smaller connecting bridge is called the anterior commissure, found to be on average about 12 percent larger in women.) Size does now seem to matter, as many expert's suspect that women's more generously equipped brain is more efficient at relaying information back and forth between the intuitive right hemisphere and the businesslike left. Helen Fisher, a Rutgers University anthropologist . . . writes that "women's well-connected brains facilitate their ability to gather, integrate and analyze more diverse kinds of information, an aspect of what she calls "web thinking."

(The Mommy Brain, 73-74)

Put that in your pipe and smoke it Mr. Kealey.

In all seriousness, I'm not trying to add fuel to the proverbial fire here. My goal isn't to argue that the female brain is superior. The female brain is simply specialized to perform certain tasks, as is the male brain. This makes perfect evolutionary sense. The idea that the gender charged with propagating species has been engineered to be "dumber," on the other hand, does not.

I find brain size debate ludicrous and fervently hope that it will soon be put to rest, immortalized in the annals of misguided scientific detours, alongside eugenics and creationism.