| 释义 |
demographic transition
 Fig. 9 Demographic theory of transition. Changes in rates of fertility and mortality accompanying industrialization in which, after a phase of rapid population increase, a previous pattern of population equilibrium involving high birth rates and high death rates is replaced by a different equilibrium involving low birth rates and low death rates. demographic transition the changes in levels of fertility (see FERTILITY RATE) and mortality (see DEATH RATE) accompanying INDUSTRIALIZATION, which lead one pattern of population equilibrium, characteristic of preindustrial societies, to be replaced by a different equilibrium, characteristic of mature industrial societies. This transition is held to involve three phases (see Fig. 9): - a preindustrial phase, a situation in which high birth rates are balanced by high death rates, a position of rough equilibrium;
- an intermediate phase, in which death rates fall but birth rates remain high, a phase of rapid population growth;
- a concluding phase, in which birth rates fall, leading to a new equilibrium.
Explanations usually advanced for this pattern of population change are: improvements in public health in phase (b), followed by changes in economic and cultural orientations in phase (c), leading to a reduction in preferred family size. If this pattern of demographic change can be taken as characterizing the classic historical process of industrialization, the question that today arises is whether the pattern is likely to be repeated in newly industrializing societies, or other contemporary societies undergoing MODERNIZATION. In many of these societies rates of population growth, and levels of social disruption, have been greater than in the middle phase in earlier European patterns of demographic transition. In some societies significant economic growth has been difficult to achieve, and population growth has not been associated with improvements in living standards. It remains to be seen whether a new equilibrium will be established under these very different circumstances. demographic transition
demographic transition a theory of demography which states that, as a nation industrializes, it goes through a series of populational changes, starting with a decline in infant and adult mortality and followed later by a reduction in birth rate. The time lag between the decline in deaths and births produces a rapid population growth in ‘developing’ nations. In ‘developed’ nations births and deaths become approximately equal, giving a stable population structure.demographic transition
 Fig. 42 Demographic transition. The levelling-off of the rate of population growth during a country's economic development. demographic transition a POPULATION cycle that is associated with the ECONOMIC DEVELOPMENT of a country. In underdeveloped countries (i.e. subsistence agrarian economies), BIRTH RATES and DEATH RATES are both high, so there is very little change in the overall size of the population. With economic development (i.e. INDUSTRIALIZATION), INCOME PER HEAD begins to rise and there is a fall in the DEATH RATE (through better nutrition, sanitation, medical care, etc.), which brings about a period of rapid population growth. Provided ECONOMIC GROWTH is consistently greater than the increase in population, income per head continues to expand and eventually serves to reduce the BIRTH RATE (small families become the ‘norm’ in society as people seek to preserve their growing affluence). At this point, population growth slows down and may eventually level off. Most advanced industrial countries have gone through a demographic transition of the kind described above and are today characterized by both low birth and death rates and slow-growing populations. See POPULATION TRAP, DEVELOPING COUNTRY. |