Abstract
IQ predicts many measures of life success, as well as trajectories of brain development. Prolonged cortical thickening observed in individuals with high IQ might reflect an extended period of synaptogenesis and high environmental sensitivity or plasticity. We tested this hypothesis by examining the timing of changes in the magnitude of genetic and environmental influences on IQ as a function of IQ score. We found that individuals with high IQ show high environmental influence on IQ into adolescence (resembling younger children), whereas individuals with low IQ show high heritability of IQ in adolescence (resembling adults), a pattern consistent with an extended sensitive period for intellectual development in more-intelligent individuals. The pattern held across a cross-sectional sample of almost 11,000 twin pairs and a longitudinal sample of twins, biological siblings, and adoptive siblings.
Geniuses have often been noted to be especially childlike, signaling the relationship between g and neoteny. Perhaps neoteny also related to curiosity.
https://en.wikipedia.org/wiki/Neoteny
East Asians have been noted to be especially neotenous. East Asians are higher g.
Humans are especially neotenous compared with other primates. Humans are much higher g than other primates.
Neoteny is related to a great ability to learn. Children are insanely good at learning, especially language. This is also a characteristic of high g.
Head/brain size relative to body size is a neotenous feature. Brain size is known to differ between populations as does g.
What is needed:
- integrate the above findings from behavior genetics, differential psychology, developmental biology and physical anthropology
- find measurements of neoteny from physical anthropology and correlate them with national IQs.
- find measurements of neoteny and correlate with individual g
Wikipedia mentions the following:
These are neotenic traits in humans: flattened face,[5] broadened face,[13] large brain,[5] hairless body,[5] hairless face,[14] small nose,[14] reduction of brow ridge,[5] small teeth,[5] small upper jaw (maxilla),[5] small lower jaw (mandible),[5] thinness of skull bones,[13] limbs proportionately short compared to torso length,[13] longer leg than arm length,[15] larger eyes,[16] and upright stance.[10][17]
These would be very interesting to correlate with individual measurements. For instance, if there is a correlation of g and eye size it would be a good prediction from the model, or between g and body hair (within sex), which might also have some relationship to hormone levels.
