Previous studies report that adult height has significant associations with wages even controlling for schooling. But schooling and height are imperfect measures of adult cognitive skills (brains) and strength (brawn); further they are not exogenous. Analysis of rich Guatemalan longitudinal data over 35 years finds that proximate determinantsadult reading comprehension skills and fat-free body masshave significantly positive associations with wages, but only brains, and not brawn, is significant when both human capital measures are treated as endogenous. Even in a poor developing economy in which strength plausibly has rewards, labor market returns are increased by brains, not brawn.
