Demographic Change: How, why and consequences

Abstract

Change is inherent to demography because demography is the study of how and why populations change. Without change, demography does not exist as a discipline. In its simplest definition, demography is the scientific study of human populations. According to Landry (1945), the term demography was first used by the Belgian statistician Achille Guillard, in his 1855 publication Éléments de statistique humaine, ou démographie comparée. However, John Graunt's Natural and political observations mentioned in a following index, and made upon the bills of mortality, published in 1662 in London, is generally acknowledged to be the first published study in the field of demography. The book demonstrated the usefulness of compilations of information relating to the population of London by presenting statistics on a wide range of characteristics such as employment, age and sex composition, health and environment. Graunt also published an early version of the life table which, having been further developed by Edmund Halley and Joshua Milne, led to the publication in 1840 of the first official life table by William Farr, compiler of scientific abstracts in the General Register Office of England and Wales. The statistical concepts of the life table remain today the fundamental elements of demographic method. The life table, perhaps better termed a death table, is a description of how the number in a population, all born on the same day, falls with age until all have died. This chapter begins with a more detailed description of demography in terms of life transitions before moving on to a discussion of the measurement of these transitions. Next, it addresses the theory of how and why transitions occur and the association of demography with the theoretical approaches of other disciplines.