By late 2011 there will be more than 7 billion people in the world, with 8 billion in 2025 and 9 billion before 2050. New technologies and institutions, and a lot of hard work have enabled us to avoid widespread Malthusian misery. Global income per capita has increased 150% since 1960, outpacing the growth of population. But we cannot be sure that incomes will continue to grow. One major difference is that now the world has a much larger population to support and, more notably, nearly all of the population increase that is projected in the coming decades will occur in the most politically, socially, and economically fragile countries. Fortunately, important insights into this demographic challenge have emerged in the past 10 years. Most important is that the rate of population growth is not the only demographic variable with consequences for economic growth and development: the age structure of the population is also fundamentally important.
