Sunday, September 6, 2009

A few anthropological notes, or, why we're fearful and rude

Here are two stories involving recent psychological/anthropological/biological research:
As to the first, while describing an interesting study, the story itself is characteristically media. We can pinpoint the amygdala as being the "source" of the flight-or-fight (ie, fear) response, and we have now learned that as we (or, at least, as rats) grow, a "protective molecular sheath" coats the cells of the amygdala, which seems to also "protect" the memories contained within. So baby rats can forget "traumatic" experiences which would otherwise elicit the fear response. This doesn't mean, however, that chemically (or otherwise) removing this molecular cell coating would actually "erase" memories. Baby rats forget past fears, adult rats do not; adult rats with the molecular coating removed recover "their early ability to erase fearful memories." This is not the same as actually erasing the memories themselves. Current phobia and post-traumatic stress disorder therapies aim to "reprogram" the person's fear response - such that, as the story says, a soldier who survived being in a car bomb can "learn to believe that a car ride doesn't have to end in violence." The advent of drug therapies which would dissolve this chemical sheath on amygdala cells would still need to be applied in tandem with psychological treatment. This, of course, also assumes that human beings would react as rats do to the removal of this molecular layer. Though we are similar, we are not the same. And, in the end, is it so bad that fearful memories are "erasure-resistant," as the study itself (ref 1) says? We may not wish to remember, but is that cause enough to warrant forgetting?

The second story is also quite interesting. Several biologists from the University of New Mexico and UBC in Vancouver argue that one thing - disease - basically shapes who we are and how we behave, anthropologically speaking (ref 2). The article in Smithsonian Magazine does an excellent job of explaining the main points; to quote the author, Rob Dunn's, summary:
Their theory is simple. Where diseases are common, individuals are mean to strangers. Strangers may carry new diseases and so one would do best to avoid them. When people avoid strangers—those outside the tribe—communication among tribes breaks down. That breakdown allows peoples, through time, to become more different.
Differences accumulate until in places with more diseases, for example Nigeria or Brazil, there are more cultures and languages. Sweden, for example, has few diseases and only 15 languages; Ghana, which is a similar size, has many diseases and 89 languages. Cultural diversity is, in this view, a consequence of disease.
Then Fincher and colleagues go even further. Where people are more xenophobic and cultures more differentiated from one another, wars are more likely. Democratic governments are less likely because the tribe or group comes first; the nation and individuals in other tribes within the nation come second. And finally, poverty becomes nearly inevitable as a consequence of poor governance, hostility between groups, and the factor that triggered this cascade in the first place—disease.
It's a rather convincing argument, but, as we all know, everything looks like a nail when one has a spiffy new hammer. First and foremost, correlation does not necessarily imply causation. Many of those who commented on the article pointed out weaknesses in the study's theory, in addition to citing counter-examples:
"Wouldn't this behavior eventually prove maladaptive? While disease-induced xenophobia might ensure a group's survival over the course of a few generations, wouldn't that group eventually become inbred if its members cannot curb their distrust of outsiders?" - Matthew Graybosch
"The only way this theory works is if the researchers can demonstrate that indigenous theories of death and disease act identically to the modern germ theory they are using in this model." - heteromeles
"Much as we are an animal, our society is far more complex and our behavior is, biologically looking, often times irrational and likely governed by more than biological factors, at least as we understand them now (although they do provide neurological and hormonal framework)." - Marko Pecarevic
"...a small, genetically-homogeneous population may have particular reason to fear stranger's diseases, since these may wipe them out. The way out of this trap is to outbreed. But this exposes you to more diseases." - Peter H. Proctor
While "rudeness" specifically isn't actually explained by the theory (but who reads articles titled "Pathogen prevalence predicts human cross-cultural variability in individualism/collectivism" anyway?), it would seem that, in the end, biology cannot alone explain the behavior of human beings, no matter how pretty a theory might appear (biology isn't like physics, sorry boys!). There has been, and perhaps always will be, a continuing argument over nature versus nurture (as Dunn eloquently wrote, "Somewhere, probably, a cultural anthropologist is writing and rewriting a thorough and vehement response."). Perhaps this is somewhere "true" religion can help - not the xenophobic, cultish religion, but the "love your neighbor as yourself," good-Samaritan, "heal the sick" kind of religion. We are taught to always extend our hand, even to the sick and leprous, and in light of the theory, this encouragement of sociological "mixing" would, in the end, bolster our immunity, both to disease and to fear of cultural diversity.

Gogolla N, Caroni P, L├╝thi A, & Herry C (2009). Perineuronal nets protect fear memories from erasure. Science (New York, N.Y.), 325 (5945), 1258-61 PMID: 19729657

Fincher CL, Thornhill R, Murray DR, & Schaller M (2008). Pathogen prevalence predicts human cross-cultural variability in individualism/collectivism. Proceedings. Biological sciences / The Royal Society, 275 (1640), 1279-85 PMID: 18302996

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