The genetic predictor commonly labeled 'years of schooling' or intelligence actually reflects a broader life-history trade-off — such as the toggle between having more children with less investment versus fewer children with more investment — which is why its selection direction reverses across different times and populations rather than moving consistently toward 'more intelligence.'

Reich speculates that the genetic score linked to years of schooling is entangled with traits like age at first childbirth, obesity, and walking pace, and may really capture a life-history toggle between quantity and quality of offspring — explaining why its selection direction flips depending on the environment. ✦ AI generated

David Reich · Dwarkesh Podcast · 2026-05-08 · original ↗

There’s a toggle between having more kids and investing less in them, and having fewer kids and investing more in excelling in various ways. You can imagine that at different times and in different places… In ecology, there are different ways. Mammals often invest a lot with a pregnancy and a small number of children, whereas fish will spawn huge numbers of offspring into the river, the great majority of whom will be eaten.

verbatim transcript · starts at 35:02