The Determinants of Mortality

The pleasures of life are worth nothing if one is not alive to experience them. Through the twentieth century in the United States and other high-income countries, growth in real incomes was accompanied by a historically unprecedented decline in mortality rates that caused life expectancy at birth to grow by nearly 30 years. In the years just after World War II, life expectancy gaps between countries were falling across the world. Poor countries enjoyed rapid increases in life-expectancy through the 1970s, with the gains in some cases exceeding an additional year of life expectancy per year, though the HIV/AIDS epidemic and the transition in Russia and Eastern Europe have changed that situation. We investigate the determinants of the historical decline in mortality, of differences in mortality across countries, and of differences in mortality across groups within countries. A good theory of mortality should explain all of the facts we will outline. No such theory exists at present, but at the end of the paper we will sketch a tentative synthesis.