I love when I see articles discuss environment/biology in ways that are cutting-edge, instead of “nature versus nurture” or even “nature and nurture are both important”. This one is a good one.
Autism Diva has extensive hypotheses about variation in autism rates within Southern California. This is a good example of how you can start to explain cultural variation: you say could it be this, could it be this, could it be this, and then you move on to asking how to test each of those hypotheses.
Sometimes symptoms we think are the central, causative symptoms of a disorder aren’t. For example, in big chunks of the Western world, anorexia involves a distorted body image and the fear of becoming fat. But in Ghana and China you see anorexia without distorted body image, without the fear of becoming fat – and instead with religious beliefs driving the restricted food intake
This is one of many awesome things about culturally informed research: it can help point out the deeper, broader phenomenon that we’re seeing different facets of in different cultural circumstances. In this case, the theory is that most symptoms of anorexia are triggered, in susceptible people, by dropping below a certain body weight. But not all susceptible people are going to drop below their trigger body weight – just the ones who are sufficiently obsessed with body weight (in cultures that encourage that) or religion (in cultures that encourage that) or whatever.
Anyway, what it turns out looking like is: some people have a tendency to severely restrict calories and exercise a whole lot if their weight drops below a certain (unhealthy) point. Does that not sound totally stupid? Well, it does in the Western world and China and Ghana. But if you’re in and environment like Africa in the Pleistocene era, and the middle of a famine, getting a lot of exercise by migrating would be a very good idea, and not settling down and eating while you’re supposed to be migrating is also a good idea.
For reasons I’ll go into later, this is both a very good explanation and an inadequate one (in addition to being an explanation I’ve misplaced the cite for, but I will try to remedy that if I bring it up again). In the meantime I’ll just say that a phenomenon that was at least a little bit valuable for someone or their kind in an evolutionary environment can be severely detrimental to someone in a modern environment (as anorexia is theorized to be). Saying something served a purpose in a past context does not mean there is anything desirable or preservation-worthy about it outside of that context.
Edit: Found the cite I misplaced! It was a talk Shan Guisinger gave at the Human Behavior and Evolution Society conference in 2004. The American Psychological Association published an <a href=”http://www.apa.org/monitor/apr04/anorexia.html”>article</a> on her <a href=”http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=14599241&dopt=Abstract”>2003 article</a>.
^1: Bennett, Sharpe, Freeman, & Carson, 2004 for Ghana; Lee, 1995 for China.
^2: Thanks to Michael for writing me the script for footnoting!