I have a confession. When I first moved to New England from Michigan, I said hi to everyone. I waved at police officers. I asked gas station attendants about the weather and talked to or greeted whomever I bumped into. Eventually though, I started to notice that such cordialities were not always returned. Sometimes I got a stare. It wasn’t quite a dirty look, but a kind of squirrel-faced wondering about whether I wasn't from “around here” or was just slow.
Cultures differ in all sorts of ways—their greetings, clothing, expectations about how children should behave, coming-of-age rituals, expressions of sexuality, numbers of husbands or wives, beliefs in god, gods, or lack thereof. People celebrate but also wage wars about these differences. Usually such variety is attributed to the vagaries of history and chance. Some things, like religious expression and differences or, say, the fleeting popularity of tube socks, seem simply beyond the realm of explanation. And yet haven’t you ever wondered whether there is some reason we are all so different, some underlying cause to our great cultural diversity?
Recently a group of biologists has offered a theory that they say explains, if not tube socks, then nearly everything else. In a series of high-profile papers, Corey Fincher and Randy Thornhill, both at the University of New Mexico, and Mark Schaller and Damian Murray of the University of British Columbia argue that one factor, disease, ultimately determines much of who we are and how we behave.
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.
Other researchers have seen links between disease and culture; for example, prohibitions against consuming pork would have protected early societies from swine-borne diseases like trichinosis. But Fincher’s scope is broader. In the story of disease, Fincher sees no less than the sweeping story of humanity.
As a rule, it is good to be skeptical of biologists who, like Fincher and Thornhill, propose to explain a whole bunch of things with one simple theory. More so when those biologists are dabbling in questions long reserved for cultural anthropologists, who devote their careers to documenting and understanding differences among cultures and their great richness of particulars. Biologists, and I am no exception, seem to have a willingness–or even need—to see generalities in particulars. Fincher’s new theory would offer an example of these desires (and a little hubris) run amok, of biologists seeing the entire history of human culture through one narrow lens. It would offer such an example, if it didn’t also seem, quite possibly, right.
Fincher and colleagues tested their theories by simply looking at whether there were consistent patterns in how cultural practices vary among regions of the world, and whether the prevalence of disease varies in a similar way. Are the places with the most diseases also the most xenophobic? Yes, they found.
Consistently, in regions where deadly diseases are more common, people are more xenophobic, more strongly focused on the welfare of their group, and less likely to be nice to strangers. Where diseases are more prevalent, individuals are less open to meeting strangers and to new experiences. Where diseases are more prevalent, cultures and languages differ more from one another. Sure enough, all of the scientists' predictions seem to hold, or at least to not be easily refuted. If you meet someone who is wary or even openly hostile to you, who bows or shake hands rather than kisses and in general keeps their distance, chances are they come from someplace with a terrible prevalence of disease.