Mankind Quarterly, Vol. 46, No. 2 (Winter 2005)
pp. 139-164

"Genes for Intelligence:" A Review of Recent Progress
Gerhard Meisenberg

Between 40% and 80% of the variability in test intelligence among adults in modern societies is accounted for by genetic factors. Therefore there must be "genes for intelligence" that are responsible for this genetic contribution. In this review I survey the results about the molecular genetics of intelligence up to October 2005, including (1) direct association studies of cognitive ability with functional polymorphisms in brain-expressed "candidate genes"; (2) indirect association studies that have identified chromosomal regions in which quantitative trait loci for intelligence appear to be located; and (3) polymorphisms and recent evolutionary trends in two genes that are related to brain size. Since general intelligence is correlated with brain size, these latter polymorphisms are likely to affect mental development. Rapid progress in the field has been possible only recently in the wake of the human genome project. Further advances have to be expected in the near future.