On the cellular scale, it is very difficult, if not impossible, to tell the brains of men and women apart. That is, if you zoom in on a part of the brain (like the hippocampus, cortex or striatum) and look at the morphology of a single neuron or the electrical characteristics of that neuron, you would be hard pressed to tell if the neuron you are looking at belongs to a male or a female. This is not very surprising since it is also difficult to tell if the neuron you are looking at is from a human, ape, or elephant. That is a cellular introduction to the non-cellular book that I am reviewing today: Delusions of Gender: How our minds, society, and neurosexism create difference by Cordelia Fine.
My friend from undergrad who is now a philosophy professor recommend this book to me and described it in such a way that I suspected I would hate it. Upon actually reading it however, I was quite surprised at how informative and entertaining it was.
Let's get to it!
Delusions of Gender is a book written in response to the idea that there are inherent differences between men and women that are hard-wired into the brain by evolution and that make women naturally suited for certain activities and men naturally suited for others.
In other words, Cordelia Fine claims that this is NOT the case, or at least that it is not nearly as much the case as people currently believe. This is a difficult claim to make. It's so easy to see that men and women are different in body, so why wouldn't their brains be different? And doesn't evolution make the sexes of many species 'inherently' different? For examples, look at the praying mantis, the zebra finch, and the stickleback.
So what I found amazing is that Cordelia Fine argued this impossible claim so well that I was thoroughly convinced that everything I had heard about the differences between male and female brains and abilities was at best uncertain, and at worst completely wrong.
Let me summarize some of the exact points that she makes:
- You are bound to find differences when you are looking for them.
- Differences are more likely to be reported and publicized than similarities.
- There are glaring flaws in many neuroscience studies showing brain differences between men and women.
- Even if all the studies showing brain differences between men and women were taken as true, that still wouldn't mean that the differences are 'hard wired' or 'inherent' or 'because of evolution'
- Even if all the brain differences are real, and even if they are 'hard wired', that still doesn't mean that women and men actually think differently.
To explain a little further:
Claim 1 says that when there is one difference between two groups, it is easy to think of a scientific study to determine if something else is different between these two groups. This is important because of the 'obvious' differences between men and women (yeah, they have different junk). Since everyone knows men and women are different re: genitalia, let's test whether they are different in brain or behavior. This may seem totally reasonable, but a counter example is finger-print pattern. People can be grouped by their fingerprint pattern into 'loop-shape' or 'swirl-shape' people. This fingerprint pattern is determined genetically, but since it is not an obvious difference (you probably don't even know which group you belong to), no one has ever tested whether 'loop-shape' people have bigger hippocampi than 'swirl-shape' people.
Claim 2 says that for every newspaper headline shouting "Women are inherently totally whacked" (see also this post) there might be several studies quietly showing "Women and men are pretty similar" This problem, research showing differences getting published and hyped, while research showing 'no difference' getting ignored or not even published to begin with is not a problem new to science, nor is it specific to gender issues. It is always more exciting and always has a 'higher impact' as they say, to show that two things are different.
A recent paper by De Liberto et al., (2012) shows that male and female mice show no difference in the amount of DAT (dopamine transporter) in the striatum.
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| De Liberto et al., 2012 figure1C |
Let's do a quick thought experiment: Imagine that the researchers had found a difference here, say "male mice have less DAT than female mice." This could have 'meant' that men have more dopamine at the synapse (as the DAT is responsible for cleaning up excess dopamine there), and this could have been 'translated' into the idea that men are happier or women are more moody and prone to depression (Dopamine levels are implicated in moodiness and depression). Wow! what an exciting finding! Front cover of Time magazine: "The Secret Science Behind Moody Women." However, here in reality, these results showed no difference, so they became just a small figure panel in paper about the effects of estrogen.
Claim 3 is the one I had the hardest time reading. It is true that there is a lot of sloppy science out there, but I think she goes a little too far in her distrust of science. For example, she brings up the dead fish in an MRI study as evidence for fMRI studies being flawed. It is true that in all scientific studies there is a risk of falsely identifying a difference when there is none, but that is exactly what the correction for multiple comparisons is for. This is a statistical correction that all scientist should know about and apply, but sometimes (maybe even often) they don't. However, there are plenty of fMRI studies that do correct for this multiple testing problem and are scientifically sound.
Claims 4 and 5 are my favorite. I thought I would hate this book when I thought that her claim was going to be 'men and women are not different, and neuroscience is flawed and stupid.' However, when I saw that she was actually claiming 'we don't know enough about the brain to draw the conclusions people are drawing' I got right on board. There is way too much "the amygdala lit up therefore the person was frightened" and "the hippocampus is bigger so the person must navigate space better" going around. These claims can get ridiculous and most are just not supported. We don't have a full understanding of the brain, or even of any part of the brain. We don't even have a full understanding of the single neurons that make up the brain (as you well know from reading The Cellular Scale).
In conclusion, there may be (and probably are) brain differences between men and women, some of these differences might be 'hard wired' and 'inherent' and some of them might develop as a child grows up in a gender-difference driven culture. (By the time you get a kid into an MRI machine, s/he has done a lot of developing.) These (possible/probable) brain differences might mean that men and women think differently, or they might not.
We just don't know enough about it, yet.
© TheCellularScale
There are many excellent reviews of this book out there, here are just a few:
SevenDeadlySynapses
NeuroSkeptic (who is actually cited in this book)
TheThinkingMeatProject
GenderAccrossBorders
Di Liberto V, Mäkelä J, Korhonen L, Olivieri M, Tselykh T, Mälkiä A, Do Thi H, Belluardo N, Lindholm D, & Mudò G (2012). Involvement of estrogen receptors in the resveratrol-mediated increase in dopamine transporter in human dopaminergic neurons and in striatum of female mice. Neuropharmacology, 62 (2), 1011-8 PMID: 22041555
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