Population ageing among non-Maori New Zealanders in later Victorian times: a quirk of immigrant settlement history?

AT THIS TIME, the cusp of the twenty-first century, age profiles in many countries are being fundamentally reshaped by population ageing or greying, a process apparently unique in world demographic history and one expected to be sustained well into the future.' Most evident in Europe and elsewhere in the developed world, including Japan, ageing is a global trend, with its symptoms appearing in a growing number of developing countries as far apart culturally if not geographically as Sri Lanka, parts of India, Thailand, China and Cuba. Population greying is arguably the most conspicuous longer term structural consequence of the shift from high to low vital rates that lies at the core of the 'theory of demographic transition', the paradigm that has been a central preoccupation of population studies for many decades. Neither Frank Notestein's original statement of the theory in 1945, however, or later variants of it, elaborate on causally interlinked, equally momentous longer term shifts in the spatial distribution and composition of population. Nevertheless a number of such parallel transformations have been codified in recent times. Perhaps best known of these is Wilbur Zelinsky's 'hypothesis of the mobility transition' but several other components of population have also received attention, among them age and gender. These have been considered from several contrasting perspectives, either empirically (e.g. Ansley Coale using historical data for Sweden); in broad-brush theory building, notably by Donald Cowgill and, writing a decade later, by Abdel Omran; or as an exercise in intuitive reasoning supported by case study evidence, as in New Zealand by myself and Andrew Trlin. As Coale cogently demonstrates and as other writers argue, however, fertility rather than mortality transformation is the prime catalyst of metamorphosis in age distribution. Thus the trajectory of sustained fertility decline that precipitates the process of change within the closed population assumed in the conventional model of 'the demographic transition' also initiates a long-term process of age structure maturation. It does so by progressively diminishing, in wave-like sequence, the relative importance of younger then older children while enhancing that of successive cohorts or groupings of adults to ultimately take in the elderly. In contrast, the impact of mortality decline on age structure is at once weaker and more subtle. In the early stages it tends to be localized toward the start of the life span, that is among infants and young children, but as the decline deepens over time it is elders who become major beneficiaries. Among populations at an advanced stage of both 'the demographic transition' and Omran's