The results of a recently published study suggest that there has been a substantial drop in IQ in Western countries—a whopping decline of 14 points from 1889 to 2004.
A couple of caveats are in order. First, the researchers weren’t actually measuring intelligence. The study looked at changes in simple reaction time from the Victorian era until now. Simple reaction time is just that: how fast a person can react to a single limited stimulus (a flash of light, a tone, the sudden appearance of symbol on an otherwise blank computer screen). It turns out that simple reaction time is highly correlated with general measures of intelligence. Second, the study was correlational; there may be other things besides intelligence that are correlated with reaction time that have also changed since 1889 (the ability to direct attention to a single limited stimulus, for example).
But let’s take the data at face value, and assume that the researcher’s conclusions are correct, that people in Western society 124 years ago were on average a standard deviation more intelligent than they are today. What does that mean? What has changed since then that has dumbed people down? The authors of the article blame it on the fact that smart women have fewer children relative to less intelligent women: across generations dumbness proliferates while smartness becomes rarified.
Maybe that explains Alabama. But what about nonwestern countries? Surely the smart-women have-fewer-kids theory applies equally in an indigenous tribe. What else has changed in the Western world since the late 1800s?
To what extent is the increased dependence on technology to blame?
To what extent is the increased domestication of the human mind to blame?