On Modules and Medical Materialism

Something about a recent post on the subjective experience of migraines by Siri Hustvedt got me to thinking about problems in the evolution of the human mind. I suppose this is because I am currently teaching a class on evolutionary theory for graduate students in the the Anthropological Sciences program and we have been thinking a lot about the intellectual legacy of sociobiology and, especially, Evolutionary Psychology (EP). EP is a currently popular school of thought for understanding the human mind. One of the central tenets of contemporary EP is the idea of extensive modularity -- that the brain is a collection of special purpose "organs" designed to deal with problems that our ancestors habitually dealt with in our hunter-gatherer past.

The philosopher, David Buller has leveled what I see as a pretty devastating critique on this fundamental idea in contemporary EP. He suggests that the end product of brain mechanisms cannot, in themselves, be seen as adaptations since the development of these mechanisms is dependent on an environmentally-induced phenotype. Brain ontogeny is characterized by by a variety of additive and subtractive events in which new connections are formed and excess cells are pruned (possibly in a Darwinian fashion) subject to environmental input. In this view, it is the developmental processes, not the final products, that are the object of selection, a perspective that follows Terry Deacon's argument in the Symbolic Species. Buller suggests that it is the brain's plasticity that is the adaptation and not specialized information-processing modules.

There is a lot to ruminate on here, particularly regarding the genetic architecture of putative modules and how selection is likely to be meted out with respect to cognitive traits. But that will need to wait for another day...


Buller, D. J. 2006. Evolutionary psychology: A critique. In Sober, E. (ed.), Conceptual Issues in Evolutionary Biology, 3rd Edition, pp. 197-216. Cambridge: MIT Press.

Tooby, J., and L. Cosmides (1992). The Psychological Foundations of Culture. In Jerome H. Barkow, et al. (eds.), The Adapted Mind: Evolutionary Psychology and the Generation of Culture, pp. 19-136. New York: Oxford University Press.

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