The argument
The reasoning has two parts. The first, sometimes called the savanna principle, holds that the human brain has difficulty dealing with things that did not exist in the ancestral environment. The second is Kanazawa's proposal that general intelligence evolved to solve novel problems. Together they suggest that intelligence should make the most difference in dealing with evolutionarily new situations.
Claimed predictions
Kanazawa's analyses of survey data reported associations between higher measured intelligence and attitudes he regarded as novel, including liberalism and atheism. The associations between intelligence and particular social attitudes have been reported by other researchers, too, though those researchers do not necessarily accept this explanation for them.
Why it is controversial
The hypothesis has been heavily criticized on several grounds. The classification of what is evolutionarily novel can look arbitrary, and little is known directly about the preferences of ancestral humans. Many psychometricians doubt that general intelligence is a specialized module for novelty, since it predicts performance on familiar as well as novel tasks. Correlations also leave ample room for other explanations, such as education, upbringing, and social environment. Kanazawa has been involved in further public controversies over his writing on race and intelligence. Readers should treat the hypothesis as a speculative proposal that lacks broad acceptance.
Further reading
- Kanazawa, S. (2010). Evolutionary psychology and intelligence research. American Psychologist, 65(4).
- Kanazawa, S. (2010). Why liberals and atheists are more intelligent. Social Psychology Quarterly, 73(1).