Louann's Brizendine's The Male Brain has just come out. I haven't read it yet — for some reason, the publisher didn't send me a review copy — and so I'll reserve judgment until my copy arrives. But Vaughan Bell at Mind Hacks has an evaluation ("Brizendine, true to stereotype", 3/24/2010) based on an Opinion piece by Brizendine on CNN 's web site ("Love, sex, and the male brain", 3/24/2010).
Judging by that Op-Ed, Dr. Brizendine's new book is cut from the same cloth as her earlier one, The Female Brain. (See here, here and here for links to previous LL discussion.) Vaughan quotes this passage from the CNN piece
Our brains are mostly alike. We are the same species, after all. But the differences can sometimes make it seem like we are worlds apart.
The "defend your turf" area — dorsal premammillary nucleus — is larger in the male brain and contains special circuits to detect territorial challenges by other males. And his amygdala, the alarm system for threats, fear and danger is also larger in men. These brain differences make men more alert than women to potential turf threats.
and notes that
Male and female humans are indeed the same species, but we are not a species which has a dorsal premammillary nucleus because it's only been identified in the rat.
Furthermore, there is no reliable evidence that amygdala size differs between the sexes in humans and a recent study that looked specifically at this issue found no difference.
The reference to sex (non-)differences in amygdala size is specific and telling (J. Brabec et al., "Volumetry of the human amygdala – An anatomical study", Psychiatry Res 2010). Dr. Brizendine is clearly up to her old tricks here, confidently setting out "scientific facts" that are unsupported (or even contradicted) by the scientific literature.
But the issue about the dorsal premammillary nucleus is less clear to me — Vaughan bases his debunking on a PubMed search, which does turn up only references to work in rodents. But maybe Brizendine has found some work that measures this small and obscure piece of the brain in male and female humans — I'll take a look at the footnote(s) provided for this point in her book. (I don't expect to find anything relevant, alas, but fair is fair.)
Overall, as Vaughan points out,
The rest of the article is full of Brizendine's usual style which is to take a common stereotype of male or female behaviour and than to 'explain' it with a overly-simple, one dimensional and usually not directly tested brain explanation.
He cites this specific example:
All that testosterone drives the "Man Trance"– that glazed-eye look a man gets when he sees breasts. As a woman who was among the ranks of the early feminists, I wish I could say that men can stop themselves from entering this trance. But the truth is, they can't. Their visual brain circuits are always on the lookout for fertile mates. Whether or not they intend to pursue a visual enticement, they have to check out the goods.
Got that? Testosterone is responsible for men looking at breasts, perhaps even falling into an irresistible tit-driven trance, and we can't help it. Are there any scientific studies on whether hooter staring is related to testosterone levels? (Sadly) No.
In general, this new book certainly looks like another collection of what I've called scientific bible stories:
As I've watched the reaction to Louann Brizendine's book over the past few months, I've concluded that "scientific studies" like these have taken over the place that bible stories used to occupy. It's only fundamentalists like me who worry about whether they're true. For most people, it's only important that they're morally instructive.
What would the producers of CNN Headline News, NPR's "Wait, wait, don't tell me" or the BBC's "Have I got news for you" say, if presented with evidence that they've been peddling falsehoods? I imagine that their reaction would be roughly like that of an Episcopalian Sunday-school teacher, confronted with evidence from DNA phylogeny that the animals of the world could not possibly have gone through the genetic bottleneck required by the story of Noah's ark. I mean, lighten up, man, it's just a story.