MCDB 150 - Lecture 10 - Quantitative Aspects
Lecture 10 - Quantitative Aspects
Census data is often politically influenced and hence inaccurate. The birthrate in developing countries is nearly twice that in developed countries. Most humans live in less developed countries, so the world birthrate is near the higher number. The world birthrate is two and a half times the death rate; we are not close to population stabilization. Almost everywhere, the death rate has been drastically reduced; further changes will not massively affect demographic trends. Changes in fertility rate now control population. Demographic data must be corrected for age structure. A young population in a poor country will have a lower death rate than an older population in a richer country. Countries with high birthrates and exploding populations will have a high proportion of children. There are more people in each younger age bracket than in older ones. Many more adolescents will come into reproductive ages than older women will leave fertile ages. Fertility per woman is falling in the world, but, since there are ever more childbearers, the number of children born does not drop. Because of this 'momentum,' it can take over 100 years from when fertility falls to replacement level (approximately 2 children per woman) to when population stabilizes. In developing countries, even though fertility has been reduced, population growth often outstrips economic growth. People may give up on modernization and instead, idealize a return to some imagined past that was glorious.
"Family Portrait: A Clan Keeps on Growing."
Weeks, Population, pp. 40-45, 53-57