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Intelligence and Group Differences in Preference for Breasts over Buttocks

George Francis and Emil O. W. Kirkegaard


Published: 2023/12/01


Permanent adipose breasts are unique to humans among primates. We propose that permanent breasts, and a preference for them, are an adaptation for pair bonding and a slow life history strategy. This theory predicts that races with a slower life history strategy will prefer breasts to buttocks. To test our hypothesis, we predict preferences for breasts over buttocks from racial admixture and both national and regional average IQ, which we use as an indicator of differences in life history. Measures of Breast-Buttock preference are constructed for nations and subnational regions using the relative frequencies of internet searches on Google, Pornhub and YouPorn for terms related to breasts versus those related to buttocks. Average IQ correlates with Breast-Buttock preference at the national level (r = .76, p < .001), within regions of American countries (r = .85, p < .001), US States (r = .54, p < .001) and US Metro areas (r = .57, p < .001). Controlling for racial ancestry substantially moderated the effect size of intelligence. We consistently found African ancestry to negatively predict breast preference: across countries (r = −.80, p < .001), within US states (r = −.91, p < .001), and US Metro areas (r = −.91, p < .001). These results replicated when using Spanish language search terms within Spanish-speaking countries, suggesting our findings are not peculiar to the English language. Only for US Metro areas did we find a significant effect size for socioeconomic controls. Keywords: Sex, Breasts, Intelligence, Life history, Race, Ethnicity

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