I looked at urban/rural differences by birth cohort.---
white's born 1900-1940
white's born 1941-1969
white's born 1970-*
The rural/urban difference has converged from 9 points to 5 points to 3 points across the three cohorts.
Continuing with the rural vs. urban IQ theme, let's consider the gaps among those of (relatively) shared ethnicity by the broadly based type of communities they were raised in. Ron Unz speculates that because urban dwellers outperform their bucolic counterparts on IQ tests and their proxies, groups that are skewed more heavily towards urban living and away from rural living are consequently more intelligent for it. The HBD chickadee poked some holes in Unz' initial assertions, but on net, the conclusion could plausibly follow from the contemporary data.
I wondered, though, if German and Dutch wordsum averages were lower because of a more rural skew than those of Italian and Irish descent, or if the differences were apparent among those of different ethnicities living in similar communities. The following table lists mean IQ values as estimated from wordsum scores by self-identified ethnicity among whites (with the exception of those of African descent) by community type. The last column shows the urban/rural gap. Due to concerns with sample sizes, the selection is somewhat limited. Unfortunately, Dutch numbers aren't high enough on the urban component for useful comparisons to be made:
|Ancestry||Rural IQ||Suburban IQ||Urban IQ||Urban advantage|
With the exception of Mexicans, the trend is remarkably consistent. Rural rustics fare poorly, suburbanites are somewhere in the middle, and urban dwellers come out on top. That those of Mexican descent don't exhibit the same pattern that everyone else does, including blacks, makes Unz' argument that Hispanics will eventually get up to snuff with other Americans appear more than a little tenuous.
While the rural/urban gap is real, the presumption that the relative proportions of ethnics living in different community types accounts for the overall differences in intelligence isn't clear. Excluding Russians, about half of whom are Jewish with a heavy urban skew for Russian Jews and a non-urban skew for non-Jewish Russians, the overall differences between ethnic groups remain at each community level as well.
That is, the English and the Scottish outscore the Germans and the Irish in rural, suburban, and urban settings. It's not just that the Scottish are more urban than the Germans are, rural Scots outperform rural Germans and urban Scots outperform urban Germans. Since we're looking at the environments people grew up in as kids, it shouldn't take multiple generations for the urban premium to confer an advantage over rural living.
If Unz' theory was perfect, there would be no differences among varying ethnicity in rural environments, with the overall ethnic differences instead being accounted for by the fact that higher scoring ethnicities were skewed more heavily towards urban dwelling and less intelligent ethnicities skewed towards rural life. To the contrary, among white European ethnic groups, the correlation between rural mean wordsum scores and urban mean wordsum scores is a statistically significant, vigorous .78. Going from rural to urban helps everyone (except Mexicans!), but underlying differences remain irrespective of what community type is being considered.
Admittedly, this is stretching the suggestive value of wordsum scores as a predictor of intelligence to the maximum, and I'm not attempting to speak with authority about Unz' theory or the refutations of it here. I'm just offering up so more food for thought for those who've been following and thinking about it over the last week.
GSS variables used: ETHNIC, RACE(1)(2), RES16(1-2)(3-5)(6), BORN(1), WORDSUM