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May 22, 2005

Baron-Cohen on systemizers, empathizers and assortative mating

Simon Baron-Cohen has a new piece over at Edge elaborating on his ideas about systemizers and empathizers. He received many responses and responded to those responses.

I think there are two primary issues that I see here:

  1. In the details Baron-Cohen's theory will probably be wrong because most scientific hypotheses are wrong in terms of the model that they present for a given subset of data.

  2. Over the long term research like Baron-Cohen's will stimulate the generation of counter-hypotheses and concurrent hypotheses by those who take the step beyond critique.

The most accurate model that explains human psychological variation along the axis of sex (and beyond) mixes genetic biases and a developmental arc that is both biologically (hormones, nutrition, etc.) and socially mediated. The scholarly 1 argument is generally over the details. The empirical data on the ground is mixed, and seems (to my eye) be bogged down by semantic cross-talk. For example, Baron-Cohen's systemizer-empthaizer spectrum quickly becomes depicted as a typology by one respondent, to which he replies that he perceives it as a spectrum. But of course verbally he can't simply refer to a numerical point on his spectrum and assume he'll be understood, he has to decompose the range of variation into two categories. This is why Baron-Cohen likely placed spare normal distribution graphs on many pages of his book The Essential Difference, verbally he had to speak in categories not to be bogged down in stat-jibberish, but quite clearly he does not conceive his model in a typological fashion in its essense and wanted to remind his readers of that reality graphically.

Another point, which Helena Cronin's response zooms in on, is that there are a priori considerations as to why human males and females should display a wide range of phenotypic median differences. This is a crucial point that I think many who operate outside the natural sciences, in particular evolutionary biology, miss. Sex is an evolutionary mystery. Any given parthogenetic (asexual, virginal procreation) individual would generate twice as many copies of their genes (two alleles instead of one) with each gestation as a female who exchanges genetic material with a male. Additionally, the existence of the male sex, which itself does not gestate, seems very wasteful. The short of it is that in terms of adaptation sexual reproduction must increase the fitness of said sexual individual by at least a factor of two over asexual reproduction. There have been many explanations of sex, and many hypotheses for why males exist, most of them starting with the position that sex facilitates faster evolutionary response to selection via an increase in variation (recombination and allelic exchange). Additionally, the high possible reproductive variance of males means that they can act to dampen down the genetic load of a population due to a correlation between fitness and fecundity in every generation (so that unfit males with high mutational load act as carriers of deleterious alleles into evolutionary oblivion). Some people appeal to structural constraints, that is, sex exists in higher animals because of the phylogenetic past of these species or genetic competition between cytoplasmic DNA (there are parthogenetic insects and what not, so I am skeptical of this). But even if sex is a structural holdover from our past, it is a background condition against which animals must compete and evolve.

Sexual dimorphism is a reality in human beings. Regardless of the origin of sex, humans have been stuck with the fact ~1/2 of the species can not gestate and bring forth offspring, and this will have evolutionary consequences (though more slowly than usual). This compelling background assumption makes the theories of individuals like Simon Baron-Cohen much more intelligible, and invidious accusations of political motive can take a step back. I suspect this explains two primary forms of response to Baron-Cohen's hypothesis: No, you are wrong, and, probably wrong, but here are other options and possibilities. Some people are aware that something needs to be explained outside of cultural shaping (because sex differences precede the emergence of human culture in other animals, so parsimony suggests that there is a biological aspect to it), while others seem to wish away this reality.

Related: By now you have probably noticed that Steven Pinker and Elizabeth Spelke debated sex differences in the mind, but check out the responses.

1 - There are some on the traditionalist Right who welcome the findings of evolutionary psychologists because it buttresses their own moral normative positions. But the reality is that usually these positions are solid and live without fear from biology because they precede scientific empirical data. Therefore, a mapping of biology -> ideology must always be examined in light of the factors involved in the "->", as opposed to simply assuming that the connection is transparent, as many on the Right do. And, as many on the Left do, for the opposition to biologistic thinking tends to issue from a naive understanding among those who style themselves "progressives" about the possibilities that are constrained by the progress of science. The reality I would argue is that constraint is a condition of human existence, and the constraints suggested by science are more than counteracted by the possibilities and new avenues of exploration opened up.

Posted by razib at 11:25 AM