Overpopulation - Demographic Transition

Demographic Transition

The theory of demographic transition held that, after the standard of living and life expectancy increase, family sizes and birth rates decline. However, as new data has become available, it has been observed that after a certain level of development the fertility increases again. This means that both the worry that the theory generated about aging populations and the complacency it bred regarding the future environmental impact of population growth are misguided.

Factors cited in the old theory included such social factors as later ages of marriage, the growing desire of many women in such settings to seek careers outside child rearing and domestic work, and the decreased need of children in industrialized settings. The latter factor stems from the fact that children perform a great deal of work in small-scale agricultural societies, and work less in industrial ones; it has been cited to explain the decline in birth rates in industrializing regions.

Another version of demographic transition is proposed by anthropologist Virginia Abernethy in her book Population Politics, where she claims that the demographic transition occurs primarily in nations where women enjoy a special status (see Fertility-opportunity theory). In strongly patriarchal nations, where she claims women enjoy few special rights, a high standard of living tends to result in population growth.

Many countries have high population growth rates but lower total fertility rates because high population growth in the past skewed the age demographic toward a young age, so the population still rises as the more numerous younger generation approaches maturity.

"Demographic entrapment" is a concept developed by Maurice King, Honorary Research Fellow at the University of Leeds, who posits that this phenomenon occurs when a country has a population larger than its carrying capacity, no possibility of migration, and exports too little to be able to import food. This will cause starvation. He claims that for example many sub-Saharan nations are or will become stuck in demographic entrapment, instead of having a demographic transition.

For the world as a whole, the number of children born per woman decreased from 5.02 to 2.65 between 1950 and 2005. A breakdown by region is as follows:

• Europe – 2.66 to 1.41
• North America – 3.47 to 1.99
• Oceania – 3.87 to 2.30
• Central America – 6.38 to 2.66
• South America – 5.75 to 2.49
• Asia (excluding Middle East) – 5.85 to 2.43
• Middle East & North Africa – 6.99 to 3.37
• Sub-Saharan Africa – 6.7 to 5.53

Excluding the observed reversal in fertility decrease for high development, the projected world number of children born per woman for 2050 would be around 2.05. Only the Middle East & North Africa (2.09) and Sub-Saharan Africa (2.61) would then have numbers greater than 2.05.