Stabilization of human population through economic increasing returns

The assumptions of declining fertility with rising income and rising per-ca pita output with rising population imply the existence of a stable demograp hic equilibrium with a high standard of living and relatively low total pop ulation. This Smithian equilibrium differs from the well-known Malthusian e quilibrium in its comparative statics: technical progress lowers the Smithi an equilibrium population, while it raises the Malthusian equilibrium popul ation; a fall in fertility lowers the Smithian equilibrium income, but rais es the Malthusian equilibrium income. Economic data show strong support for the hypotheses of increasing economic returns to population and declining fertility with income, and suggest that the human population of the world a nd per-capita output will stabilize at about 25-30% above their current siz e, that is, at 7 - 8.5 billion people, with a per-capital output of 6500-75 00 1990 dollars. (C) 2000 Elsevier Science S.A. All rights reserved. JEL cl assification: J1; O4.