I am not so sure about that. I am thinking back to the Minnesota Twin Study here, and the related fact that heritability of IQ increases with age (up until age 20, at least). Now, it might be that we’re just not great at measuring childhood IQ, or that childhood IQ and adult IQ are two subtly different things.
But it certainly looks as if there’s factors related to adult brain plasticity, motivation (curiosity, love of reading, something) that continue to affect IQ development at least until the age of 18.
heritability of IQ increases with age (up until age 20, at least)
Straight forward result of how the brain learns. Cortical/cerebellar modules start out empty and mature inwards out—starting with the lowest sensory/motor levels closest to the world and proceeding up the hierarchy ending with the highest/deepest modules like prefrontal and associative cortex. Maturation is physically irreversible as it involves pruning most long-range connections and myelinating&strengthening the select few survivors. Your intelligence potential is constrained prenatally by genes influencing synaptic density/connectivity/efficiency in these higher regions, but those higher regions aren’t (mostly) finishing training until ~20 years age.
I am not so sure about that. I am thinking back to the Minnesota Twin Study here, and the related fact that heritability of IQ increases with age (up until age 20, at least). Now, it might be that we’re just not great at measuring childhood IQ, or that childhood IQ and adult IQ are two subtly different things.
But it certainly looks as if there’s factors related to adult brain plasticity, motivation (curiosity, love of reading, something) that continue to affect IQ development at least until the age of 18.
Straight forward result of how the brain learns. Cortical/cerebellar modules start out empty and mature inwards out—starting with the lowest sensory/motor levels closest to the world and proceeding up the hierarchy ending with the highest/deepest modules like prefrontal and associative cortex. Maturation is physically irreversible as it involves pruning most long-range connections and myelinating&strengthening the select few survivors. Your intelligence potential is constrained prenatally by genes influencing synaptic density/connectivity/efficiency in these higher regions, but those higher regions aren’t (mostly) finishing training until ~20 years age.