The relationship between cross-national genetic distances and IQ-differences David Becker ⁎, Heiner Rindermann Department of Psychology, Chemnitz University of Technology, Wilhelm-Raabe-Str. 43, D-09107 Chemnitz, Germany abstract article info Article history: Received 18 February 2016 Received in revised form 9 March 2016 Accepted 12 March 2016 Available online xxxx The study analyzes whether genetic differences (“genetic distances”) help to explain cross-national IQ differ- ences being controlled for environmental factors. Genetic distances are an indicator of evolutionary history and of difference or similarity between populations. Controlled for environmental determinants the relationship between genetic distances and intelligence differences can be interpreted as an effect of genetic factors. Genetic distances were calculated in Y-chromosomal haplogroup frequencies between N = 101 national populations based on k = 27 genetic studies. Correlations and path-analyses with differences in geographical coordinates and the Human Development Index (HDI) as background and control factors revealed a positive impact of genetic distances on cross-national IQ-differences (r = .37, β = .22 to .40). The strongest impact was found for HDI (r = .67, β = .58). Longitudinal differences have no positive effect (r = -.09, β = -.13 to -.26), latitudinal differ- ences have a positive one (r = .37, β = .07 to .21). The positive relationship to latitudinal differences underpins an evolutionary explanation. Chances and limits of this approach (e.g. no intelligence coding genes detected) un- derstanding national differences in cognitive ability and the role of environmental factors are discussed. © 2016 Elsevier Ltd. All rights reserved. Keywords: Genetic distances Haplogroups Geography Cranial capacity HDI Evolution Cold winter theory 1. Introduction In a widely discussed paper the economists Spolaore and Wacziarg (2009) found that genetic distances have an effect on in- come differences across nations, even when controlling for measures of geographic distance, climatic factors, transportation costs and measures of religious, historical and linguistic differences. However, missing in their analysis was recognizing the mediator effect of genes via cognitive human capital on productivity and income. Many studies done with different methods by different researchers have shown a positive impact of cognitive factors on economy end- ing in higher income (e.g. Hanushek & Woessmann, 2015; Lynn & Vanhanen, 2012; Rindermann, Kodila-Tedika, & Christainsen, 2015). “Cognitive human capital”, cognitive ability, competence or skills are understood as the ability to think (intelligence), the dispo- sition of knowledge (the store of true and relevant knowledge) and the intelligent use of this knowledge. We further use interchange- ably the terms “cognitive ability” and the abbreviation “IQ”. Cross- national differences in cognitive ability based on student assessment tests or psychometric IQ have been reported by Lynn and Vanhanen (2012), Hanushek and Woessmann (2015) or Rindermann, Sailer, and Thompson (2009) (to name only the most recent ones). Given the established association between national cognitive abilities and markers of genetic ancestry (such as Y chromosomal haplogroups; Rindermann, Woodley, & Stratford, 2012), it is reasonable to suppose that the association between genetic distance and income observed by Spolaore and Wacziarg (2009) may be mediated by cross-national differences in IQ. Possible genetic effects on cross- national differences in IQ may work directly or indirectly and are sup- ported by evolutionary theories (e.g. Hart, 2007; Kanazawa, 2004; Lynn, 1987; Rushton, 2004; Woodley, Rindermann, Bell, Stratford, & Piffer, 2014). While they are seen by many researchers as being contro- versial (e.g. Gould, 1981) or scientifically not enough supported (e.g. Wicherts, Borsboom, & Dolan, 2010) a recent opinion survey among in- telligence researchers showed that experts at least favorably consider genes as one explanatory variable for international differences in cogni- tive ability (Rindermann, Becker, & Coyle, 2016). Furthermore, genetic distances were taken into account to explain cross-national differences in another psychological variable, happiness and well-being (Proto & Oswald, 2014). Finally, a recent study of León and Burga-León (2015) used the method of F ST distances to analyze as- sociations between genetic distance from South Africa and latitude, lon- gitudinal distance from South Africa, absolute latitude, fertility, human development index (HDI) and cognitive ability. They found a robust positive effect on cognitive ability, however, they did not relate genetic distance to cognitive difference itself. Evolutionary theory predicts positive relations between genetic dis- tances (proximity) and differences (similarity) in national cognitive ability levels: Genetic diversification into geographically diverse Personality and Individual Differences 98 (2016) 300–310 ⁎ Corresponding author. E-mail addresses: david.becker@s2009.tu-chemnitz.de (D. Becker), heiner.rindermann@psychologie.tu-chemnitz.de (H. Rindermann). http://dx.doi.org/10.1016/j.paid.2016.03.050 0191-8869/© 2016 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid