In The Essential Difference, before getting to his extreme-male-brain theory of autism, Baron-Cohen combs the psychological literature for evidence that normal sex differences in empathizing and systemizing are real and rooted in biology. He expected this claim to be controversial and was surprised and a little irritated when he read, "Didn't we always know this? Didn't our grandmothers tell us this?" Proving with scientific data that sex differences in behavior are innate is notoriously difficult. But Baron-Cohen, understandably enough, spares his popular audience the data. Indeed, the conclusions alone do have a familiar ring. Girls like dolls, boys like trucks. Girls like to gossip, boys like to roughhouse. Girls are more verbal, boys are more spatial, right through the SATs. Girls attack one another indirectly and verbally (which requires them to know how their victim feels). Boys are direct and physical, and when they reach manhood they are far more likely to commit murder—the ultimate in lack of empathy," as Baron-Cohen puts it.
On the other hand, men are also far more likely to be mathematicians, physicists or engineers, as well as to be better at throwing or catching balls. Those things are all examples of systemizing, according to Baron-Cohen, by which he means "the drive to understand a system and to build one." He defines a system as anything that takes an input and transforms it into an output according to some rule. For instance, a baseball's trajectory depends in a predictable way on where the pitcher places his fingers—so it's a system. Baron-Cohen's empathizing-systemizing dichotomy is far broader than the spatial-verbal one that has long been a feature of sex-difference research.
He has done as much as anyone lately to push the evidence for sex differences in behavior right back to the womb. In one study, for example, his graduate student Jennifer Connellan gave 1-day-old babies a chance to show a preference for looking at Connellan's face, at a distance of eight inches, or at a ball of the same size mounted on a stick. Connellan's face moved naturally, the ball more mechanically.
She found that 19 of 44 boys looked at least 10 seconds longer at the ball than at the face, while 11 preferred the face and 14 had no preference. In contrast, 21 of 58 girls preferred the face, while only 10 preferred the ball and 27—the largest group—had no preference. Earlier studies had suggested that women tend to make more eye contact and are better at decoding the language of the eyes. This study, Connellan and Baron-Cohen concluded rather daringly, demonstrates "beyond reasonable doubt" that "female superiority in social ability" is "in part, biological in origin."
What's more, says Baron-Cohen, that superiority may have something to do with how much testosterone a female fetus is exposed to—which is much less than a male fetus with functioning testes. At a Cambridge hospital, Baron-Cohen and his colleagues have access to a bank of frozen amniotic fluid samples, taken from women who, in 1996 and 1997, underwent amniocentesis before giving birth. When the children were 12 months old, Baron-Cohen and Svetlana Lutchmaya videotaped 70 of them (1 at a time) as they played on the floor of his tiny office and counted how many times in 20 minutes each child looked up at Mom. Later, when the kids reached 18 and 24 months of age, the researchers mailed questionnaires to their parents, asking them to evaluate their child's vocabulary. Meanwhile, the amniotic fluid revealed how much testosterone each child had been exposed to late in the first trimester, a critical time for brain development.
"When we got these results, I had one of those strange feelings, like a shiver down my spine," Baron-Cohen writes in his book. "A few drops more of this little chemical could affect your sociability or your language ability. I found it extraordinary." It would indeed be extraordinary if it were that simple. But to prove that more fetal testosterone (FT) is what makes boys less verbal and less interested in faces, you need to exclude the possibility that some other biological difference between the sexes is responsible. You need to show, for instance, not just that male fetuses have more testosterone than female fetuses and that boys turn out less verbal than girls but that the correlation holds within a single sex—that a boy with more testosterone will tend to have a less-evolved vocabulary than a boy with less. Baron-Cohen doesn't yet have that evidence. In their research papers, he and Lutchmaya state that they found a within-sex correlation with fetal testosterone only in one case: Boys with less FT—but not girls—were more apt to look up at Mom.
Mild-mannered and understated as he is in person, Baron-Cohen is willing in print to draw big conclusions from small studies—but he knows he needs larger studies to confirm the findings. One of his current graduate students, Rebecca Knickmeyer, is now laboriously tracking down 3,000 children who correspond to 3,000 amniotic fluid samples in that Cambridge hospital freezer. If she succeeds, she'll have a large enough group to say something firmer about fetal testosterone and social development—and in particular, about fetal testosterone and autism. A group that large should include around 15 children with autism. Baron-Cohen's working hypothesis is that they will have had the highest exposure to fetal testosterone of all.
Tags:
autism spectrum,
autistic person,
british history,
fib,
hottest day,
lack empathy,
mathematician,
mild form of autism,
sense of the world,
sidelong glances,
simon baron cohen,
spite,
surfeit,
tape recorder,
train schedules,
university of cambridge,
veins
