Males have greater g: Sex differences in general mental ability from 100,000 17- to 18-year-olds on the Scholastic Assessment Test

Intelligence, hormones, sex, brain size, and biochemistry: It all needs to have equal causal standing before integration is possible

Recent brain imaging points to differences in brain structure that relate to intelligence, but how do we model their causal relationship within a coherent framework that circumvents classic dualist traps? A bottom-level nonlinear, dynamic, multifactor, multiplicative, multidimensional, molecular (ND4M) trait-covariance time-space model may accomplish this better than traditional approaches.

Sex Differences in Childhood Associations between DNA Markers and General Cognitive Ability

Abstract. An association between intelligence at age 7 and a set of five single-nucleotide polymorphisms (SNPs) has been identified and replicated. We used this composite SNP set to investigate whether the associations differ between boys and girls for general cognitive ability at ages 2, 3, 4, 7, 9, and 10 years. In a longitudinal community sample of British twins aged 2-10 (n > 4,000 individuals), we found that the SNP set is more strongly associated with intelligence in males than in females at ages 7, 9, and 10 and the difference is significant at 10. If this finding replicates in other studies, these results will constitute the first evidence of the same autosomal genes acting differently on intelligence in the two sexes.

Sex differences in the development of neuroanatomical functional connectivity underlying intelligence found using Bayesian connectivity analysis

A Bayesian method for functional connectivity analysis was adapted to investigate between-group differences. This method was applied in a large cohort of almost 300 children to investigate differences in boys and girls in the relationship between intelligence and functional connectivity for the task of narrative comprehension. For boys, a greater association was shown between intelligence and the functional connectivity linking Broca's area to auditory processing areas, including Wernicke's areas and the right posterior superior temporal gyrus. For girls, a greater association was shown between intelligence and the functional connectivity linking the left posterior superior temporal gyrus to Wernicke's areas bilaterally. A developmental effect was also seen, with girls displaying a positive correlation with age in the association between intelligence and the functional connectivity linking the right posterior superior temporal gyrus to Wernicke's areas bilaterally. Our results demonstrate a sexual dimorphism in the relationship of functional connectivity to intelligence in children and an increasing reliance on inter-hemispheric connectivity in girls with age.