Genetics and Society

Everything’s Heritable First Law. All human behavioral traits are heritable Second Law. The effect of being raised in the same family is smaller than the effect of genes Third Law. A substantial portion of the variation in complex human behavioral traits is not accounted for by the (additive) effects of genes or families.

Genetic Architecture Fourth Law: Genetic variants that are common in a population have very small individual effects on behavioral traits Not always like this in other species Can be different in subpopulations Strong selection can change architecture

The twin studies are all right According to GCAT

Selection Every society selects for something Usually unintended

Breeder’s Equation R = h 2 S R = response h 2 = narrow-sense heritability S = selection differential

Selection can be fast or slow Interesting changes can happen in less than 1000 years Maximum time available for human differentiation, ~100,000 years

Dan Freedman’s babies Behavioral differences at birth

Populations, Classes, Jobs Selection changes populations Classes change by selection and differential recruitment Jobs, differential recruitment

Distributions Modest differences in the mean imply big differences at the extremes

Genetic Isolation Geographic Separation Endogamy

Epigenetic Inheritance Trendy Rare Hard to imagine adaptive mechanism fuhgeddaboudit

Human Capital Formation Usual Model: Parents invest in human capital Fewer kids is better Not true for genetic contribution