Louann Brizendine is a neuropsychiatrist who seems intent on bolstering sex stereotypes with poor science. Presumably in the service of promoting a new book, she has an article on CNN which attempts to explain ‘why men obsess over sex’ but which has lots of odd errors and strange unsubstantiated claims.
The thing that immediately struck me was in the initial paragraphs:
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.
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 rest of the article is full of Brizendine’s usual style which is to take a common stereotype of male or female behaviour and then to ‘explain’ it with a overly-simple, one dimensional and usually not directly tested brain explanation.
For 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.
And there’s plenty more unlikely claims along similar lines. Apparently oxytocin is responsible for ‘nice’ grandpas whereas ‘grumpy’ grandpas can be explained by a drop in testosterone in later life.
Please make it stop.
UPDATE: Thanks to @willoller and Bergen who pointed out that the dorsal premammilliary nuclei have been identified in humans. Interestingly, however, I can only find one study which has ever investigated it in humans and nothing which suggests it is a “defend your turf” area. This conclusion seems entirely drawn from rat studies (e.g. this one) and what Brizendine seems to be doing, in this and other recent articles, is taking findings from rat studies and talking as if they were directly relevant to humans which is dubious to say the least.
Link to awful ‘Why men obsess over sex’ article (via @sarcastic_f)
Mind Hacks 
Those poor dear weak males. Did she
suggest there should be a special
compound for them for their own
protection? Oh well, no, that would
defeat the whole monetary benefit
of feeding social stereotypes with
bogus science. Your comment about the
rats made me laugh btw.
Does she mention gay males? That testosterone would seem to be driving more of a penis-driven trance in them. I have not read her books, nor do I have any desire to. I’ll take Richard Dawkins instead, thanks.
It seems that the real issue here is Brizendine’s extremely poor choice of descriptive language in her book, and not the validity of her research.
Normally, I love the posts on Mind Hacks, but I have to say that this one is disappointing. It seems to be selectively erroneous. For example, a quick google search yields research based verification that dorsal premammillary nuclei are identified as a mammalian trait, and The Dictionary of Human Anatomy (Martin C. Hirsch, 2000)lists dorsal premammilliary nuclei as a human feature.
More disturbingly, however, is the study linked to in the post supposedly supporting the argument that there is no substantial size difference between the male and female amygdala. First of all, take a look at the gender sample distribution in the study: 21 males and 9 females. Nowhere near evenly distributed by gender (not to mention it’s a very small sample). Secondly, the study specifies using cytoarchitectural delineation to define the size of the amygdala. But Neuroscientists, such as Manfred Gahr, point out that amygdala size varies greatly depending on what you measure; cytoarchitecture,cytochemicals, or projection properties. These elements each change in ‘size’ independently of one another. This article details the importance of understanding how ‘size’ is defined in neurological research (http://bjp.rcpsych.org/cgi/content/full/181/3/255).
The point is that most research defining the ‘size’ of the male v. female amygdala can differ greatly depending on what exactly is being measured. We’re not talking about measuring a lump of tissue here. We’re talking about measuring the spiderweb of neuron connections in a quantifiable way. The majority of research on amygdala ‘size’ agrees that there is a gender specific ‘size’ difference. And many of those experiments involve over 100 individuals in a sample with an even gender distribution, as opposed to the questionable numbers and distribution in the article linked to the mind hacks post.
Basically, I think this mind hacks post is reacting more to the terrible terrible word choices by Brizendine and hiding behind an erroneous claim of bad science. Carefully selecting only the research that agrees with your hypothesis doesn’t make your claims correct. You have to take into account all accessible research on the subject.