Demographic transition

Developed by demographer Frank Notestein in 1945, this concept describes the typical pattern of falling death and birth rates in response to better living conditions associated with economic development. This idea is important, for it offers the hope that developing countries will follow the same pathway to population stability as have industrialized countries. In response to the Industrial Revolution, for example, Europe experienced a population explosion during the nineteenth century. Emigration helped alleviate overpopulation, but European couples clearly decided on their own to limit family size.

Notestein identified three phases of demographic transition: preindustrial, developing, and modern industrialized societies. Many authors add a fourth phase, postindustrial. In phase one, birth rates and death rates are both high with stable populations. As development provides a better food supply and sanitation , death rates begin to plummet, marking the onset of phase two. However, birth rates remain high, as families follow the pattern of preceding generations. The gap between high birth rates and falling death rates produces a population explosion, sometimes doubling in less than 25 years.

After one or two generations of large, surviving families, birth rates begin to taper off, and as the population ages, death rates rise. Finally a new balance is established, phase three, with low birth and death rates. The population is now much larger yet stable. The experience of some European countries, especially in Central Europe and Russia, suggests a fourth phase where populations actually decline. This may be a response to past hardships and oppressive political systems there, however.

Historically, birth rates have always been high. With few exceptions population explosions are linked to declining death rates, not rising birth rates. Infants and young children are especially vulnerable; sanitation and proper food are vital. Infant survival is seen by some as a threat because of the builtin momentum for population growth . However, history reveals that there has been no decline in birth rates which has not been preceded by a drop in infant mortality . In a burgeoning world this makes infant survival a matter of top priority. To this end, in 1986 the United Nations adopted a program with the acronym GOBI: Growth monitoring, Oral rehydration therapy (to combat killer diarrhea), Breast feeding, and Immunization against major communicable diseases .

See also Child survival revolution; Population Council

[Nathan H. Meleen ]

RESOURCES

BOOKS

Cunningham, W. P., and B. W. Saigo. Environmental Science: A Global Concern. 2nd ed. Dubuque, IA: William C. Brown, 1992.

Maddox, J. The Doomsday Syndrome. New York: McGraw-Hill, 1972.

PERIODICALS

Keyfitz, N. "The Growing Human Population." Scientific American 261 (September 1989): 7-16.