Genética y conducta

INTELL-00490; No of Pages 6

ARTICLE IN PRESS
Intelligence xxx (2008) xxx–xxx

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Intelligence
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Intelligence and semen quality are positively correlated
Rosalind Arden a,⁎, Linda S. Gottfredson b, Geoffrey Miller c, Arand Pierce d
a b c d

Social, Genetic, Developmental & Psychiatry Centre, Institute of Psychiatry, King'sCollege London, London SE5 8AF, United Kingdom School of Education, University of Delaware, Newark, DE 19716 USA Psychology Department, Logan Hall 160, University of New Mexico, MSC03 2220 Albuquerque, NM 87131 USA Department of Pathology, School of Medicine, University of New Mexico, MSCO8 4640, Albuquerque, NM 87131 USA

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Human cognitive abilitiesinter-correlate to form a positive matrix, from which a large first factor, called ‘Spearman's g’ or general intelligence, can be extracted. General intelligence itself is correlated with many important health outcomes including cardio-vascular function and longevity. However, the important evolutionary question of whether intelligence is a fitnessrelated trait has not been tested directly, let aloneanswered. If the correlations among cognitive abilities are part of a larger matrix of positive associations among fitness-related traits, then intelligence ought to correlate with seemingly unrelated traits that affect fitness—such as semen quality. We found significant positive correlations between intelligence and 3 key indices of semen quality: log sperm concentration (r = .15, p = .002), log spermcount (r = .19, p b .001), and sperm motility (r = .14, p = .002) in a large sample of US Army Veterans. None was mediated by age, body mass index, days of sexual abstinence, service in Vietnam, or use of alcohol, tobacco, marijuana, or hard drugs. These results suggest that a phenotype-wide fitness factor may contribute to the association between intelligence and health. Clarifying whether afitness factor exists is important theoretically for understanding the genomic architecture of fitness-related traits, and practically for understanding patterns of human physical and psychological health. © 2008 Published by Elsevier Inc.

Article history: Received 3 July 2008 Revised 10 September 2008 Accepted 1 November 2008 Available online xxxx Keywords: Intelligence Fitness g Semen quality SpermFertility

1. Introduction The new field of ‘cognitive epidemiology’ is emerging from the surprising discovery that intelligence correlates with many important health outcomes, even longevity (Batty, Deary, & Gottfredson, 2007). These correlations may be mediated by lifestyle factors such as eating well, exercising, avoiding cigarettes, working in safer, less stressful jobs, and having betteraccess to health care. However, there is a further possibility, suggested by the nature of intelligence itself: all cognitive abilities, no matter how diverse, inter-correlate positively, forming a matrix (or ‘manifold’). This commonality depends primarily on a single underlying factor called Spearman's g, named for its discoverer—the British psychologist Charles Spearman (1863–1945). Spearman's gusually accounts
⁎ Corresponding author. E-mail address: arden.rosalind@gmail.com (R. Arden). 0160-2896/$ – see front matter © 2008 Published by Elsevier Inc. doi:10.1016/j.intell.2008.11.001

for around half the total variance in any broad battery of tests (Carroll, 1993). The term ‘intelligence’ is often used interchangeably with ‘g’ (as here) because the behavioural manifestations of g fit wellwith popular conceptions of intelligence: “the faculty of understanding, quickness of mental apprehension” (Little, Fowler, & Coulson, 1984). Could the positive manifold among cognitive abilities be part of a larger manifold among all fitness-related traits? (By ‘fitness’ we mean the statistical propensity to survival and reproductive success, given ancestrally typical conditions: fitness-related...