140 NOTES TO CHAPTER 1
sonality type, and abilities. When comparing by sex, women had larger straight
gyri. However, a different picture emerged when comparing by gender. The
researchers found that regardless of the sex of the subject, more feminine scores
correlated with higher scores on social intelligence tests, as well as larger straight
gyri. For example, males who were judged to be more feminine had a larger
straight gyrus than the male average, as well as better than the average male
scores on social intelligence. Wood et al. see this as evidence that social intelli-
gence is highly gendered (not just sexed), and that gender is linked to the size of
this strip of cortex. Despite having, in theory, the same etiology in prenatal hor-
mones, Wood, Heitmiller, et al. suggest masculinity/femininity in the brain does
not perfectly overlap with the dimorphism of the genitals. Bodies with male re-
productive organs can have more, or less, “male” brains. While in their view gen-
der remains an effect of biology, this research also demonstrates the variability of
gender patterns, as well as the variability of brain morphology, within sexes. The
study is being cited as a welcome challenge to the idea that “brain differences are
a simple product of the Y chromosome” (Eliot 2009, n.p.; Kaiser forthcoming).
But while it pulls apart the conjoined categories of sex/gender, it is also conso-
nant with a long- standing effort by sex difference researchers to locate bifurcated,
universal categories of gender (masculinity and femininity) in the brain and to
position the brain as more significant than the genitals in the development of sex-
ual identity and orientation (Kraus 2012). Here, gender is not conceived as plastic;
instead, like reproductive organs, it is determined by prenatal brain development.
21 This possibility is interesting in light of the follow- up study by Wood, Murko, et
al. (2008), which measured social intelligence and the straight gyrus in seventy-
four children between the ages of seven and seventeen.^ They found that girls, like
women, did better on social intelligence tests than their male counterparts. But
instead of finding larger straight gyri in girls than in boys (what they expected
after finding this pattern in adults), they found the opposite — the boys had
proportionally larger straight gyri than girls. The relative difference of this area,
it seems, reverses over the lifespan. This surprising finding did not lead Wood,
Murko, et al. to question their larger hypothesis or its evolutionary under-
pinning. Instead, they explain this finding by referencing the earlier maturation
of girls’ brains: “for this region females may be ahead on the developmental tra-
jectory, with earlier gray matter pruning. By adult years, boys catch up and com-
plete developmental gray matter changes and straight gyrus size ends smaller
than females.” This explanation, however, does not address why males’ develop-
mental delay is more pronounced in this region than others. Nor does it explain
why male brains in this area have not caught up by adulthood. We are left with a
fuzzy proposition: In girls, a smaller straight gyrus is linked to greater social in-
telligence in youth, and bigger straight gyrus size accounts for their greater social
intelligence when they are older.
22 The concept of performativity derived from Butler’s work (1990, 1993, 2004)
describes how culture shapes embodied experience and creates an historicized