Human capital, aggregation, and growth

The famous Mincer equation regressing log earnings on years of schooling is derived from a linear human capital accumulation equation at the individual level. Even if the cross-sectional Mincer equation holds at the level of individuals, it does not hold at the macro level of countries because aggregation of human capital has to take into account its vintage structure: human capital is embodied in people of different generations whose lifespan is finite. Finiteness of people's lives imposes also a limit on the potential of human capital accumulation to drive aggregate economic growth. Aggregate human capital accumulation may however become an engine of growth thanks to human capital externalities (knowledge spillovers). We use these findings to revisit the assumptions of the well-known Uzawa-Lucas growth model from an aggregation perspective.