About a decade ago, I documented an impressive rise in the mean IQ of Mexican-Americans born in the US. Using GSS data, what is the trend in this decade? Look at the graph (N = 609):
The mean was only 85.0 in the 1970s and 84.7 in the 1980s, but it rose all the way to 94.7 by the 2000s. From this trend, one might get the hope that Mex-Ams might someday converge with the white average of 100.
But it was not to be. The trend has reversed in this decade, and the mean has fallen back down to 91.5.
I don't know how we explain these trends. Dysgenic trends would manifest themselves slowly. We have seen a recent downward turn among several European populations.
The samples sizes for each decade are not large (this decade included 217 people) so some of the trend might be noise.
Assuming the 91.5 average is more or less correct, this is a bad sign for America. A person with an IQ in the low 90s will be unable to do many of the jobs that we need done. Such a population will have more social problems and little high-level achievement.
UPDATE: I looked at all Americans born in the US (N = 25,116) and found a seven-tenths of a point drop in IQ from the last decade to this one.
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