“Intelligence and Semen Quality Are Positively Correlated”, 2008-11-28 (; backlinks):
Human cognitive abilities inter-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 fitness-related trait has not been tested directly, let alone answered.
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 statistically-significant positive correlations between intelligence and 3 key indices of semen quality: log sperm concentration (r = 0.15, p = 0.002), log sperm count (r = 0.19, p < 0.001), and sperm motility (r = 0.14, p = 0.002) in a large sample of US Army Veterans [Vietnam Experience Study]. 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 [J] fitness factor may contribute to the association between intelligence and health. Clarifying whether a fitness 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.
[Keywords: intelligence, fitness, g, semen quality, sperm, fertility]
See Also:
No Evidence for a Relationship between Intelligence and Ejaculate Quality
How cognitive genetic factors influence fertility outcomes: A mediational SEM analysis
Embryo Selection For Intelligence § Sperm Phenotype Selection
Intelligence in youth and all-cause-mortality: systematic review with meta-analysis