People are getting dumber. So concludes a new study in the Proceedings of the National Academy of Sciences (PNAS): Using military conscription data from Norwegian males born from 1962 and 1991, the authors find that the secular increase in population intelligence observed throughout the 20th century has peaked and has now gone into reverse.
Average IQs, as measured on standardized intelligence tests, increased for most of the 20th century. This astonishing fact was first reported in 1984 by the New Zealand political scientist James Flynn, when he analyzed the trend in U.S. test scores. This upward trend has since been dubbed the "Flynn effect."...
...The new PNAS study finds that the average IQ score for conscripts rose from 99.5 for the 1962 birth cohort to 102.3 for the 1975 cohort. Following 1975, the average score trended down, reaching 99.4 for the 1989 cohort (then rising slightly to 99.7 for the 1991 cohort). In other words, average IQ rose at about the same decadal rate identified by Flynn in the first sets of conscripts and then fell at about the same rate in the second sets. The researchers restricted their analysis to individuals born in Norway to two Norwegian-born parents.
About a decade ago various researchers reported that the Flynn effect had begun to reverse in some countries, with average IQ scores starting to decline again. More recently, some observers have suggested that average IQs are coming down because of dysgenic fertility—that is, because less intelligent people are having more children than smarter folks—or because of lower-IQ immigrants and their children. These trends, they argue, are now beginning to swamp the IQ-boosting effects that improvements in nutrition, education, and falling pathogen stress had during the 20th century.
...If falling average IQ scores cannot be attributed to dysgenic or immigration effects, they must be the result of some environmental effects. But what? The researchers conclude that "our results remain consistent with a number of proposed hypotheses of IQ decline: changes in educational exposure or quality, changing media exposure, worsening nutrition or health, and social spill-overs from increased immigration."
...As George Mason University economist Tyler Cowan pithily puts it, "We have started building a more stupidity-inducing environment. Or at least the Norwegians have."
On the bright side, a 2018 review article by Flynn and his University of Otago colleague Michael Shayer reports that America continued to show a steady rate of average IQ gain from 1989 to 2014 at about its historic rate of .3 IQ points per year.
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Originally Posted by Chris
