The historical reductions in mortality and fertility are driven by, and help to reinforce, other defining aspects of sustainable development, including expanded access to education, improvements in sexual and reproductive health, and greater gender equality. Collectively, these changes promote an increased productivity of workers, a larger workforce especially as women take on new social roles, and a higher standard of living.
Changing population age structures also present a substantial challenge, especially to countries that are unprepared for them. The failure to account for and adapt to changes in a population’s age structure can exacerbate existing gaps in development, especially when the shift in population over time is toward age groups that lack access to essential services and social protection. Countries with growing populations of young people must find ways to provide education and employment opportunities for youth or risk forfeiting some of their potential contribution toward sustainable development.This is an important example of the concept that demography underlies almost everything in the world. And, of course, it underscores a point made by Richard Smith, former editor of the British Medical Journal, who recently argued that: "Demography is ultimately more powerful than economics, yet we hear constantly from economists and hardly ever from demographers. We need to hear more from demographers".