Tuesday, March 18, 2008

An interesting connection

Just something that caught my attention, that I wanted to share. An article in the New York Times magazine this week about the Democratic election noted that Obama seems to win states that either have smaller minority populations or where the Democratic electorate is largely African-American, but loses in states that are most racially mixed.
The assumption has always been that a black candidate should perform worse among white voters in states with less racial diversity because those voters are supposedly less enlightened. In fact, the reverse has been true for Obama: in the overwhelmingly white states of Wisconsin and Vermont, for instance, he carried 54 and 60 percent of the white voters respectively, according to exit polls, while in New Jersey he won 31 percent and in Tennessee he won 26 percent.
What this suggests, perhaps, is that living in close proximity to other races — sharing industries and schools and sports arenas — actually makes Americans less sanguine about racial harmony rather than more so. The growing counties an hour’s drive from Cleveland and St. Louis are filled with white voters whose parents fled the industrial cities of their youth before a wave of African-Americans and for whom social friction and economic competition, especially in an age of declining opportunity, are as much a part of daily life as traffic and mortgage payments. As Erica Goode wrote in these pages last year, Robert Putnam and other sociologists have, in fact, found that people living in more diverse areas evince less trust for others — no matter what their race. Maybe it shouldn’t surprise us that while white Democrats in rural states are apparently willing to accept the notion of a racially transcendent candidate, those living in the shadow of postindustrial atrophy seem to have a harder time detaching from enduring stereotypes, and they may be less optimistic that the country as a whole would actually elect a black candidate.
I was reminded of this paper in Science (subscription or access from subscribing campus required) that came out in September from May Lim, Richard Metzler, and Yaneer Bar-Yam, a group of "complex systems" scientists at Brandeis and M.I.T. They decided to treat the basis of ethnic violence as a type separation problem.
Here, we focus on an aspect of spatial population structure that has been neglected so far; we analyze the global pattern of violence and propose that many instances are consistent with the natural dynamics of type separation (1518), a form of pattern formation (19) also seen in physical or chemical phase separation. Violence arises due to the structure of boundaries between groups rather than as a result of inherent conflicts between the groups themselves. In this approach, diverse social and economic causal factors trigger violence when the spatial population structure creates a propensity to conflict, so that spatial heterogeneity itself is predictive of local violence....The dynamics of this model assume that individuals preferentially move to areas where more individuals of the same type reside (14). The resulting dynamics lead to progressively larger patches ("islands" or "peninsulas") of each type.
Then they go on to figure out, or rather, to propose where violence will occur.
To model violence, we assume that highly mixed regions do not engage in violence, and neither do well-segregated groups, an intuitive hypothesis with empirical support (7). The analysis is applicable to communal violence and not to criminal activity or interstate warfare. In highly mixed regions, groups of the same type are not large enough to develop strong collective identities, or to identify public spaces as associated with one or another cultural group. They are neither imposed upon nor impose upon other groups, and are not perceived as a threat to the cultural values or social/political self-determination of other groups. Partial separation with poorly defined boundaries fosters conflict. Violence arises when groups are of a size that they are able to impose cultural norms on public spaces, but where there are still intermittent violations of these rules due to the overlap of cultural domains. When groups are larger than the critical size, they typically form self-sufficient entities that enjoy local sovereignty. Hence, we expect violence to arise when groups of a certain characteristic size are formed, and not when groups are much smaller or larger than this size.
A bunch of mathematical modeling follows. Then they apply their model to census data from Yugoslavia from the early 1990s, before the start of the violence that broke the country apart and compared the results to news reports of where violence had occurred. To use their understated scientific language, "overlaying the locations of reported and predicted violence...demonstrates a significant ability of our simple model to identify regions of reported violence." They did the same analysis with Indian census data from 2001, looking at religious groups. Again, their model was able to predict where conflicts had occurred with a high degree of accuracy.

So, maybe we shouldn't be surprised about Obama's troubles in the "big states", which have racial distributions described well by the phrase "partial separation with poorly defined boundaries".

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I'm a biochemist at a small college.