Population growth, age structure, and age-specific productivity

Motivated by empirical evidence that fluctuations in age structure affect relative wages across age groups, this paper asks whether there is a steady-state age distribution that maximizes the lifetime wages of a representative worker. The paper proves the surprising result that in a pure labor economy with any constant returns technology, a uniform age distribution minimizes lifetime wages. Skewed age distributions, generated by either positive or negative population growth rates, generate unambiguously higher lifetime wages than a stationary population, in spite of possible reductions in per capita output in every period. The presence of non-labor factors complicates, but does not necessarily reverse, this result. The paper relates the beneficial effects of higher rates of population growth on lifetime wages in a pure labor economy with imperfect substitutability across age groups to the benefits of population growth that appear in overlapping-generation consumption loan models with intergenerational transfers.