The evolution of human intelligence and the coefficient of additive genetic variance in human brain size

Does a fitness factor contribute to the association between intelligence and health outcomes? Evidence from medical abnormality counts among 3654 US Veterans

“…Other recent findings provide convergent support (Miller & Penke, 2007;Posthuma et al, 2003;Prokosch et al, 2005;Silventoinen, Posthuma, van Beijsterveldt, Bartels, & Boomsma, 2006;Sundet, Tambs, Harris, Magnus, & Torjussen, 2005). For example, in a previous analysis of VES data, we reported positive correlations (.14-.19) between intelligence and three measures of semen quality-sperm count, sperm concentration, and sperm motility-which is likely to be a highly fitness-related trait in males (Arden, Gottfredson, Miller, & Pierce, 2009).…”

Quantitative genetic analysis of brain size variation in sticklebacks: support for the mosaic model of brain evolution

“…The low evolvability estimates for brain size could be indicative of it having been subject to history of strong stabilizing selection (cf. [58]). However, in the view that brain size is a high-dimensional composite trait which should accumulate genetic variance through all genes influencing its different parts, this explanation seems unlikely.…”

“…The ellipsoid model [33] we used to estimate the size of the different brain regions is likely to have lower resolution than more sophisticated methods such as magnetic resonance imaging [58] and histology (e.g. [27]) that are increasingly used to characterize variability in brain structures.…”

The more g-loaded, the more heritable, evolvable, and phenotypically variable: Homology with humans in chimpanzee cognitive abilities

“…We also expand on these previous two studies and examine phenomena that are still unexplored in studies of Jensen effects in human intelligence: it is possible to calculate coefficients of additive genetic variance (CVA) using the database from Hopkins et al (2014), which constitute a mean-standardized and scale-invariant index of genetic variance in a trait (Houle, 1992). Unlike heritabilities, CVAs are independent of environmental variation effects upon individuals, and they are evolutionarily informative as high CVAs are typical of fitness-related traits, especially those under directional selection and those influenced by many genes (Miller & Penke, 2007). Thus, we predict that there should also be a Jensen effect on CVA, which would indicate that more g -loaded abilities have been subjected to stronger and more recent selection pressures than more specific and modularized cognitive abilities.…”