Demographic transition • The term “demographic transition” refers to the transition from high to low fertility rates (birth rates) and from high to low mortality rates (death rates). • In a pre-industrial society, fertility rates are high since many children are needed to work in agriculture and there is no family planning; death rates are high because of disease, famine, and poor knowledge of medicine.
Demographic transition • As medical knowledge and sanitation improve, the death rate falls, both for older people and for children. • Over time, the birth rate also falls; since child mortality is lower, fewer children are needed in order to ensure a proper number of farm workers. • In a modern industrial society, the birth rate and death rate are both low. The birth rate is low because of family planning, later marriage, and the improved status of women; the death rate is low because of improved health, improved medical care, and a reliable food supply.
Demographic transition • The rate of population growth increases in the middle of the demographic transition, and then falls at the end of the transition. • The number of workers in the labour force also grows, with a lag. • During the demographic transition, there is a change in the age structure of the population: the ratio of the economically-active (i.e., working-age) population to the total population will first fall (as more children and elderly survive), then rise (as the birth rate falls), then fall. • There may therefore be a transitional effect on growth.
Demographic transition • The transition in Europe and other now-industrial countries occurred during the 19th century. By now, in some countries, the birth rate has fallen below the death rate. • The transition in Asia did not start until the mid-20th century but it has been a faster transition process than in Europe, as Asia has been able to import health practices (e.g., sanitation) and health technologies (e.g., penicillin).
Demographic transition • Government intervention also plays a role, as with the one-child policy in China. • The one-child policy, introduced in 1978, restricts couples to having only one child. • Exceptions: • Rural residents, if the first child is a girl. • Ethnic minorities. • Parents who are only children. • The rationale for the policy was to reduce the birth rate. It is controversial due to reportedly draconian enforcement measures, such as infanticide and forced abortion. It is possible for parents to pay fines upon the birth of a second child; the fines vary by province.
"It is forbidden to discriminate against, mistreat or abandon baby girls."
Bloom, David E. and Jeffrey G. Williamson, “Demographic Transitions and Economic Miracles in Emerging Asia,” World Bank Economic Review 12:3 (1998), 419-455.
Sen, Amartya, “More than 100 Million Women are Missing,” New York Review of Books 37:20 (1990). • The fall in the birth rate in China and India has not been experienced equally between boys and girls; rather, the birth rate has fallen more for girls. • If parents want to have fewer children (either due to economic reasons or to government pressure), they often would prefer to have a boy rather than a girl. • The availability of ultrasound technology has made sex-selective abortion more common (even though it is illegal in both China and India). • The result is a higher ratio at birth of boys to girls than would be found in nature.
Sen (1990) • Worldwide, the ratio of boys to girls at birth is 1.06, that is, around 106 boys for every 100 girls. • According to the UN, in 2005, the ratio was: • 117 in China • 108.5 in India
Sen (1990) • How can we estimate the number of missing women? • Differences in the ratio of men to women are the result of differences in the ratio at birth and differences in mortality rates. With unbiased health conditions and equal nutrition, male mortality rates are higher at every age. • In a stationary population, the ratio should be close to 1, although it will be different for countries with different age structures.
Sen (1990) • Even if the sex ratio at birth is unbiased, there could be higher female than male child mortality if girls are not given the same nutrition or health care as boys. • Sen estimates that 100 million women are missing; these estimates are based on ratios of men to women that exist in Europe and North America (1.05 women per man). • Coale (1991) uses a ratio based on past fertility and mortality, and comes up with a lower number of 60 million.
Das Gupta, Monica, Jiang Zhenghua, Li Bohua, XieZhenming, Woojin Chung and BaeHwa-Ok, “Why is Son Preference So Persistent in East and South Asia?,” Journal of Development Studies 40:2 (2003), 153-187.
Qian, Nancy, “Missing Women and the Price of Tea in China,” Quarterly Journal of Economics 123:3 (2008), 1251-1285.
Edlund, Lena, Hongbin Li, Junjian Yi and Junsen Zhang, “Sex Ratios and Crime: Evidence from China,” mimeo (2012) (forthcoming in Review of Economics and Statistics).