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.

Evolution of a Bourgeois Temperment?

So, I'm teaching a graduate-level class in evolutionary theory this quarter. Given my druthers, I would have run a rather technical class in which we would discuss quantitative genetics, optimality models, game theory, multi-level evolution... Stuff like that. Well, we've done a bit of that but, due to popular demand, I actually took out two weeks on game theory and optimality models, and instead we are reading Gregory Clark's new book, A Farewell to Alms, in which argues that the Industrial Revolution may have its roots in quite recent biological evolution. Nicholas Wade wrote a review of the book in the New York Times that a number of students and I found intriguing. In this review, Wade quotes Clark as saying,

Through the long agrarian passage leading up to the Industrial Revolution, man was becoming biologically more adapted to the modern economic world.

We'll see... Regardless of what I think of the book (which I've not yet read, but will do so along side the students starting next week), it seemed like an interesting case on which to bring to bear our new-found analytical skills in evolutionary theory. More later...

Emerging Screwworm Myiasis

Screwworm myiasis, a disease in which blowflies lay their eggs around wounds or mucous membranes of mammalian (including human) hosts and the developing maggots eat the flesh of their living host, has recently emerged in Yemen.  First reports in Yemen come from December 2007.  The screwworm larvae are very sensitive to cold temperatures so one wonders if this emergence may be related to global warming.  The disease used to be endemic in the  southern United States but was eliminated some time ago. If the emergence of this infection on the Arabian Peninsula is indeed related to changing (probably nighttime) temperatures, then one also has to wonder about the possibility for re-emergence in North America...

Declines in Nature-Based Recreation

A paper by Pergams and Zaradic in the most recent issue of Proceedings of the National Academy of Sciences suggests that we are experiencing "a fundamental and pervasive shift away from nature-based recreation." Using a variety of time series measurements of nature-based recreation (e.g., national park visitations, hunting licenses issued, survey-based estimates of camping participation), Pergams and Zaradic find that per capita participation in such activities has decreased since 1987 at a rate of more than 1% annually. Does this portend dark times for future environmentalism? Maybe. There is evidence (cited in the paper) that people become more environmentally responsible from direct contact with nature and that for adults to care about natural areas, they must be exposed to them as children. It doesn't take a whole lot of imagination to guess what types of recreational activities are competing with national-park going to cause this decline. Indeed, the authors have coined the term "videophilia" to describe "the new human tendency to focus on sedentary activities involving electronic media."


Pergams, O.R.W. and P. A. Zaradic. (2008) Evidence for a fundamental and pervasive shift away from nature-based recreation PNAS 2008 105: 2295-2300. doi:10.1073/pnas.0709893105

Multi-Species Outbreak of Yellow Fever

There is a troubling outbreak of yellow fever currently affecting a number of South American countries, including Brazil and Paraguay.  Yellow fever is a multi-host infection that can be transmitted between monkeys and humans.  It is almost always fatal for species in the genera Alouatta and Ateles (howler and spider monkeys respectively).  The Wildlife Conservation Society (WCS) has taken note of the real conservation concerns that arise for small populations of these monkeys in the context of the continuing yellow fever outbreak.  In a world of increasingly fragmented local wildlife populations, where human-wildlife contact increases from human intrusion of forests and other ecosystems, control multi-host epidemics is likely to become an integral part of the conservation ecologist's portfolio.

Why We Pack Our Kids' Lunches

The New York Times reported the largest recall of ground beef ever (143 million pounds) this week.  The recall happened because a California slaughterhouse was caught using downer cows. According to the article:

Of the 143 million pounds that were recalled, 37 million went to make hamburgers, chili and tacos for school lunches and other federal nutrition programs, officials said.

Makes you feel good about these public programs, no?

notes on human ecology, population, and infectious disease