Demographic responses and population change.

Most Western societies have gone through a process of population change during the past 100-150 years. One important aspect is the socalled demographic transition: the shift from high to low birth and death rates, and accelerated growth resulting from the lag between falling mortality and falling fertility, in national populations. Equally important has been the "rural-to-urban" transition, which involved the migration of millions of people from rural areas. It is hypothesized, following the suggestion of Davis (Theory of the Multi-Phasic Demographic Response), that the adjustment in reproductive behavior made by a community in response to a rising "strain," such as that resulting from higher natural increase, is likely to differ depending upon the ease with which the community can relieve the strain through out migration. Relationships among such characteristics of modernization as intensity of industrialization, speed of urbanization, structural changes in the agricultural system, and declining fertility are implied. Case studies of England and Sweden lend support to the hypothesis: more rapid urban-industrial development, larger-scale movement from rural areas, and a delayed decline in the rural birth rate distinguish the English transition.