A systematic review of the state of literature relating parental general cognitive ability and number of offspring

How Intelligence Affects Fertility 30 Years On: Retherford and Sewell Revisited — With Polygenic Scores and Numbers of Grandchildren

“…Furthermore, consistent with the results of a recent large-scale meta-analysis of the phenotypic association between IQ and fertility (Reeve et al, 2018), the use of restricted multi-group path models indicates the presence of a sex difference, characterized by a significantly larger impact of cognitive ability on fertility characteristics among the female relative to male subsample. The finding that age at first birth mediates the impact of cognitive ability on number of children, which in turn predicts number of grandchildren, in addition to the presence of negative correlations between educational attainment, IQ, and number of children, is also inconsistent with the findings of Mededović's (2017) study of a Serbian population, which failed to find effects of IQ on age at first birth, but identified direct effects of IQ on number of children and grandchildren, with the effect of the former being positive and the effect on the latter being negative.…”

“…There is considerable interest in the causes and consequences of associations between cognitive ability and fertility. A recent meta-analysis found that these two variables have typically been negatively correlated in the United States in the 20th and 21st centuries, with some (albeit far more limited) evidence of such a negative relationship in a small number of other areas of the world for which data were available (Reeve et al, 2018). The identification of genetic variants that predict cognitive ability and educational attainment (in the form of polygenic scores, PGSs) has enabled analyses that indicate that these variants are under direct negative directional selection in contemporary populations (Beauchamp, 2016;Conley et al, 2016;Kong et al, 2017), effectively confirming predictions made by Galton 140 years ago (Galton, 1869).…”

Stability and change in male fertility patterns by cognitive ability across 32 birth cohorts

“…While test items remained unchanged throughout, a renorming of the test in 1980 shifted scores by one stanine, reducing the number of time-invariant score categories to 8. 1 Descriptive statistical models are used to smooth random variation in the data. Model 1 estimates the average probability of childbirths within cells defined by the father's birth cohort, age and stanine score using a logit specification.…”

Slowing life history (K) can account for increasing micro-innovation rates and GDP growth, but not macro-innovation rates, which declined following the end of the Industrial Revolution

“…Among individuals within Western populations, there are only weak correlations between g and K measured using psychometric instruments, indicating that they relate to largely distinct neurological systems (Woodley of Menie & Madison 2015). This is further evidenced by the observation that in modernized Western populations, as was mentioned, K is under positive directional selection (Woodley of Menie et al 2017b), whereas in those same populations, g is under negative directional selection (hence the long-term decline; Reeve et al 2018). The opposing phenotypic trajectories (rising K and decreasing g ) can hence account for the rise in micro-innovation rates (as tracked by rising GDP per capita) and the decline in macro-innovation rates following the end of industrialization in Western nations.…”