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1.
During the past quarter century fertility has dropped below replacement levels in many parts of the world. According to United Nations estimates, in 2005 this was the case in 65 countries, comprising 43 percent of the world's population. In many cases, most notably in Europe and East Asia, the shortfall of fertility from the level that would be necessary in the long run to sustain a stationary population is substantial. In Europe, for example, the average total fertility rate for the period 2000–2005 was 1.4. Indefinite maintenance of such a level implies a shrinkage of the total population by one‐third over a generation–roughly every 30 years. Accompanying that rapid decline of total numbers would be an age structure containing a preponderance of the elderly, posing extreme adjustment difficulties for the economic and social system. Societies that wish to avoid radical depopulation would have to engineer a substantial rise infertility–if not to full replacement level (slightly more than two children per woman), then at least to a level that would moderate the tempo of population decline and make population aging easier to cope with. An additional counter to declining numbers, if not significantly to population aging, could come from net immigration. This is the demographic future assumed in the UN medium‐variant projections for countries and regions currently of very low fertility. Thus, for example, in Europe over the period up to 2050 fertility is assumed to rise to 1.85 and net immigration to amount to some 32 million persons. The UN projections also anticipate further improvement in average life expectancy–from its current level of 74 years to 81 years. This factor slows the decline in population size but accelerates population aging. Under these assumptions, Europe's population would decline from its present 728 million to 653 million by 2050. At that time the proportion of the population over age 65 would be 27.6 percent, nearly double its present share. Demographic change of this nature is not a novel prospect. It was envisioned in a number of European countries and in North America, Australia, and New Zealand in the late 1920s and early 1930s. Concern with the possible economic and social consequences generated much discussion at that time among demographers and social scientists at large and also attracted public attention. Possible policy measures that might reverse the downward trend of fertility were also debated, although resulting in only hesitant and largely inconsequential action. The article by D. V. Glass reproduced below is an especially lucid and concise treatment of demographic changes under conditions of low fertility and their economic and social implications. It appeared in Eugenics Review (vol. 29, no. 1, pp. 39–47) in 1937 when the author was 26 years old. Glass's line of argument is broadly representative of the main focus of demographic analysis in the mid‐1930s on aspects of population dynamics, applying the then still novel analytical tool of the stable population model. It also echoes the work of economists then witnessing the great difficulties capitalist economies faced in adjusting to structural changes in consumer demand and labor supply. While Glass addresses these issues primarily with reference to England and Wales, he sees the issues as affecting all industrialized countries. The Malthusian problem of relentless population growth he persuasively declares to be irrelevant for these countries. The Western world faces the opposite problem: population decline, a trend only temporarily masked by the effects of an age distribution that still has a relatively high proportion of women in the child‐bearing ages, reflecting the higher fertility level of the past. A stationary population, Glass cogently argues, is to be welcomed, and he considers the absolute size at which zero growth would be achieved relatively unimportant. In contrast, a continuous population decline would have “thoroughly disastrous” results in an individualist civilization and in “an unplanned economic system.” And, he concedes, somewhat quaintly, that sustained below‐replacement fertility would pose a great problem “even in a country in which the means of production were owned communally.” Glass's conclusions about the reversibility of low fertility are as pessimistic as those of most informed observers today. Still, he sees hope in a future “rationally planned civilization” that would “produce an environment in which high fertility and a high standard of life will both be possible.” In this context, high fertility means the level necessary to sustain the population in a stationary state. By present‐day standards the level Glass calculates as needed for long‐term zero growth is indeed fairly high: 2.87 children per woman. But that figure reflects the fact that, when he wrote, mortality up to age 50 was still fairly high and fertility occurred almost wholly within marriage; it also assumes zero net immigration. In the last 70 years much has changed in each of these three components of population dynamics, both in England and Wales and in the rest of Europe. Still, Glass's commentary remains highly relevant to the discussion of the problems of low fertility today. David Victor Glass (1911–78) was associated with the London School of Economics throughout much of his scientific career. He followed R. R. Kuczynski as reader in demography in 1945 and became professor of sociology in 1948. His work on demography, population history, and population policy had already made him one of the most influential demographers in pre‐World War II Britain. After the war he rose to international prominence through pioneering work on the Royal Commission of Population; through his research on historical demography, the history of demographic thought, and social mobility; and through founding, in 1947, the journal Population Studies, which he edited until his death.  相似文献   

2.
The most salient demographic trend pictured by the influential set of population projections prepared by the Population Division of the United Nations (a unit in the UN's Department of Economic and Social Affairs) is the continuing substantial increase—albeit at a declining rate—of the global population during the coming decades. According to the “medium” variant of the most recent (1998) revision of these projections, between 2000 and 2050 the expected net addition to the size of the world population will be some 2.85 billion, a figure larger than that of the total world population as recently as the mid‐1950s. All of this increase will occur in the countries currently classified as less developed; in fact, as a result of their anticipated persistent below‐replacement levels of fertility, the more developed regions as a whole would experience declining population size beginning about 2020, and would register a net population loss of some 33 million between 2000 and 2050. A report prepared by the UN Population Division and released on 21 March 2000 addresses some of the implications of the changes in population size and age structure that low‐fertility countries will be likely to experience. The 143‐page report, issued under the eyecatching title Replacement Migration: Is It a Solution to Declining and Ageing Populations?, highlights the expected magnitude of these changes by the imaginative device of answering three hypothetical questions. The answer to each of these questions is predicated on the assumption that some specified demographic feature of various country or regional populations would be maintained at the highest level that feature would exhibit, in the absence of international migration, in the United Nations' medium population projections (as revised in 1998) during the period 1995–2050. The selected demographic features are total population size, the size of the working‐age population (15–64 years), and the so‐called potential support ratio: the ratio of the working‐age population to the old‐age population (65 years and older). The illustrative device chosen for accomplishing the specified feats of preserving the selected demographic parameters (i.e., keeping them unchanged up to 2050 once their highest value is attained) is international migration. Hence the term “replacement migration.” Given the low levels of fertility and mortality now prevailing in the more developed world (and specifically in the eight countries and the two overlapping regions for which the numerical answers to the above questions are presented in the report), and given the expected future evolution of fertility and mortality incorporated in the UN population projections, the results are predictably startling. The magnitudes of the requisite compensatory migration streams tend to be huge relative both to current net inmigration flows and to the size of the receiving populations; least so in the case of the migration needed to maintain total population size and most so in the case of migration needed to counterbalance population aging by maintaining the support ratio. Reflecting its relatively high fertility and its past and current record of receiving a large influx of international migrants, the United States is a partial exception to this rule. But even for the US to maintain the support ratio at its highest—year 1995—level of 5.21 would require increasing net inmigration more than tenfold. The country, the report states, would have to receive 593 million immigrants between 1995 and 2050, or a yearly average of 10.8 million. The extreme case is the Republic of Korea, where the exercise calls for maintaining a support ratio of 12.6. To satisfy this requirement, Korea, with a current population of some 47 million, would need 5.1 billion immigrants between 1995 and 2050, or an average of 94 million immigrants per year. (In the calculations, the age and sex distribution of migrants is assumed to be the same as that observed in the past in the main immigration countries. The fertility and mortality of immigrants are assumed to be identical with those of the receiving population.) The “Executive Summary” of the report is reproduced below, with the permission of the United Nations. Chapters of the full report set out the issues that prompted the exercise; provide a selective review of the literature; explain the methodology and the assumptions underlying the calculations; and present the detailed results for the eight countries and two regions selected for illustrative purposes. A brief discussion of the implications of the findings concludes the report. As is evident even from the figures just cited, immigration is shown to be at best a modest potential palliative to whatever problems declining population size and population aging are likely to pose to low‐fertility countries. The calculations, however, vividly illustrate that demographic changes will profoundly affect society and the economy, and will require adjustments that remain inadequately appreciated and assessed. The criteria specified in the UN calculations—maintenance of particular demographic parameters at a peak value—of course do not necessarily have special normative significance. Past demographic changes, with respect notably to the age distribution as well as population size, have been substantial, yet they have been successfully accommodated under circumstances of growing prosperity in many countries. But the past may be an imperfect guide in confronting the evolving dynamics of low‐fertility populations. As the report convincingly states, the new demographic challenges will require comprehensive reassessments of many established economic and social policies and programs.  相似文献   

3.
Africa's expanding population: old problems,new policies   总被引:1,自引:0,他引:1  
Sub-Saharan Africa faces an historic challenge: to achieve economic and social progress while experiencing extraordinary population growth. With an estimated 1989 population of 512 million, the 42 countries of sub-Saharan Africa have the highest birth and death rates of any major world region. While death rates have fallen since the 1960s, persistently high birth rates yield annual growth rates above 3% in many countries. The United Nations projects that the region's population will increase 2.7 times by 2025--to 1.4 billion. Throughout the region, population has outstripped economic growth since the mid-1970s. In addition, many African countries are experiencing an epidemic of AIDS (Acquired Immunodeficiency Syndrome). The extent and demographic impact of the epidemic still are unknown, but disturbing social and political effects are already being felt. The region's population growth will slow only when African couples begin to have fewer children. The average number of children per woman ranges from 6 to 8 for most countries. The Africans' preference for large families is deeply rooted in the culture and fed by the perceived economic benefits they receive from their children. Economic stagnation during the 1980s prompted many national governments to recognize that rapid population growth was hindering their socioeconomic development. The political climate has shifted away from pronatalist or laissez-faire attitudes toward official policies to slow population growth. The policy formation process--detailed here for 4 countries (Zambia, Nigeria, Zaire, and Liberia)--is ponderous and beset with political and bureaucratic pitfalls, However, policy shifts in more and more countries combined with evidence of increased contraceptive use and fertility downturns in a few countries give some hope that the region's extraordinary population growth may have peaked and will start a descent. Whatever the case, the decade of the 1990s will be crucial for the future of sub-Saharan Africa.  相似文献   

4.
The uneven timing of the demographic transition in different countries of the world will lead to divergence between countries in ethnic and religious homogeneity. Developed‐country populations that began their fertility transitions relatively early are becoming increasingly diverse with respect to the ethnic origin and religion of their inhabitants, primarily as a result of high recent levels of immigration. Many demographic patterns of the developed world, such as low death and birth rates, are becoming universal. It might be expected that less developed countries will also turn from emigration to experiencing immigration, as their populations age and their economies develop. This essay suggests, however, that future ethnic diversity arising from immigration may be less marked in many of those developing countries than in the West, especially among latecomers to the fertility transition. Five reasons are advanced as impediments to the globalization of ethnic heterogeneity arising from immigration: demographic, economic, political, and factors related to resource constraints, and climate change. The essay considers what social, economic, and political consequences might arise if high levels of ethnic diversity, and possibly ethnic replacement, remained an idiosyncratic peculiarity of today's developed countries, which would therefore diverge in important ways from the rest of the world as the twenty‐first century unfolds.  相似文献   

5.
At its recent Fifth Plenary Session held in Beijing, the Eighteenth Central Committee of the Communist Party of China decided to abolish the one‐child policy and allow all couples to have two children, thus closing an important chapter of China's social and demographic history. Recent fertility trends make it clear why it is urgent to abandon this policy. Census and survey data show that China's TFR had already fallen below replacement in 1991. Since the mid‐1990s, TFRs in most years have been lower than 1.5 children per woman. Since 2010, even lower fertility rates have been recorded by the annual population change surveys. Since the mid‐1990s, fertility decline has been increasingly driven by generalized ideational changes resulting from the social, economic, and cultural transformation of recent decades. In recent years many couples who were entitled to have a second child have chosen not to do so. For this reason, the termination of the one‐child policy is unlikely to lead to a major upturn in fertility, but rather to the continuation of a low‐fertility regime with more diverse fertility patterns across different sub‐populations, a pattern that has been observed in many countries.  相似文献   

6.
The second half of the twentieth century witnessed the development of a crusading spirit and massive technical aid aimed at reducing fertility levels and rates of population growth in developing countries, and also the involvement of demographers in these events. The demographers at Princeton University’s Office of Population Research, Frank Notestein and his colleagues, have been singled out by recent authors as playing a unique role in bringing about these changes, and they have been criticized for encouraging demographers to become involved, so eroding their scientific objectivity. This paper examines the development of relevant population thought and theory in the English-language literature over the first half of the twentieth century. It concludes that in the circumstances of the second half of the twentieth century, it was inevitable that developed countries and their demographers would become involved in controlling fertility levels in developing countries. The OPR story should be seen largely in terms of how the world’s leading demographic center and its demographic transition theory were swept along by global changes. As those developments started, attitudes to population change in densely settled Asia became Malthusian, even as population growth accompanied by mortality decline in Asia demonstrated that, at least in the short term, the positive checks were disappearing.  相似文献   

7.
W Hou 《人口研究》1988,(6):32-37
China's population policy has had tremendous effects on the reduction of fertility. The impact of the population policy is manifested in the following aspects. 1) Reducing the size of the total population by 200 million in 17 years. If the population growth rate had remained at its 1970 level of 2.6/1000, the total population would have been 1.28 billion in 1987. 2) The implementation of the population policy accelerated the process of demographic transition. The mortality decline which began in the early 1950s initiated the demographic transition. The Fertility decline began after the birth control policy was implemented and shifted the transition to a low population growth stage even before the socioeconomic conditions which are considered to be the determinants of fertility decline appeared. The fertility decline, in turn, promoted the socioeconomic development of the country. 3) Solving the problem of food; feeding 21.6% of the world's population on 7.1% of the world's farm land is no easy task. The success of population control, no doubt, played an important role in lowering the population growth rate so that the growth of food production could keep pace with the needs of the population. 4) A decline in the dependency ratio is a favorable condition to socioeconomic development. China's dependency ratio of 59.7 is among the lowest in developing countries and is close to the level in developed countries. Therefore, more production output can be used in investment rather than consumption. 5) The fertility decline facilitated a balanced economic growth. The ratio of population growth as compared to the growth of major economic indicators should be considered an important issue in maintaining macroeconomic control. The population policy made it possible for economic growth to surpass population growth.  相似文献   

8.

Over the last one hundred years, there has been, in many developed countries, a demographic convergence towards the two child family. The possible implications for population growth of such a tendency are considered in this paper in terms of both family limitation and also the intergenerational transmission of fertility. These two effects interact so that as the proportion of two‐child families increases, the possible influence of mother‐daughter fertility associations on population growth decreases, though even now it could override otherwise significant changes in either or both of the birth and death intensities. In particular, it is shown that according as to how fertility is transmitted through generations, it is still possible to have zero growth rates consistently with a widely dispersed stable distribution of family size as well as a typical mortality regime.  相似文献   

9.
Over the past 20 years, policy attention has been focused upon the implications of below‐replacement fertility for the aging of populations. This article argues that another potential consequence, a decline in the absolute size of the labor force, may prove to be an equally compelling issue because of its impact on rates of economic growth. Because the United States will experience both increasing labor productivity and an increase in its labor supply, the growth orientation of the global economy is likely to persist. In this circumstance, given relatively comparable changes in the productivity of labor across countries, countries that face major declines in their labor supply will fare less well than countries that are able to maintain their labor supply at least constant. The article examines the labor supply prospects of 16 developed countries for the period 2000–2050, drawing attention to the ways in which countries may be able to influence the future levels of their labor supply.  相似文献   

10.
There have been numerous projections on China's population at the end of century. Their differences are due to different estimations on the effects of fertility determinants. 2 simulation models have been developed, both from micro and macro levels, to estimate the population at the end of the century on the basis of 6 different fertility patterns. 3 possible options for fertility patterns are discussed. 1.) The 1 child per family option means that every couple has 1 child by the year 1989, the population of China will be 1.2 billion in the year 2000. Even if this is a ideal situation, it would not be a feasible policy, as the pressure from the rural population to have more than 1 child has been increasing in recent years. Nevertheless, it is still possible for urban couples to accept having only 1 child. Therefore, encouraging more people to have 1 child should be held as a basic policy. 2.) Under the option of 2 children per family with 2 or 3 years of spacing, the total population in the year 2000 would be 1.2 - 1.4 billion, which is unacceptable in terms of the development situation. 3.) Following a differential fertility policy towards urban, rural, and minority populations would mean that urban couples would have 1 child, rural couples whose first child is a girl or those who are in special circumstance would have 2 children. Minorities would have 2 or 3 children. AMong the above options, number 3 is more likely to be achieved in view of current socioeconomic, cultural, and demographic factors.  相似文献   

11.
This article compares five currently debated scenarios for fertility policy transition in China, in terms of their implications for future population growth and population aging, the proportions of elderly living alone, labor force trends, pension deficits, economic costs, the marriage squeeze, and other socioeconomic outcomes. Based on these comparative analyses, the author concludes that China needs to begin a gradual modification of its fertility policy as soon as possible. He proposes a three‐stage “soft‐landing” strategy for fertility policy transition: (1) a 7‐year initial smooth transition period; (2) from approximately 2014‐15 to 2032‐35 a universal two‐child policy combined with late childbearing in both rural and urban areas; (3) after 2032‐35 all Chinese citizens would be free to choose family size and fertility timing. This strategy will enable China to have much more favorable demographic conditions and socioeconomic outcomes, as compared to keeping the current policy unchanged.  相似文献   

12.
The world's population growth rate peaked at slightly over 2%/year in the late 1960s and in 1986 is down to 1.7% and falling. Annual numbers added continue to rise because these rates apply to a very large base, 4.9 billion in 1986. According to UN medium variant projections, world population growth will peak at 89 million/year in the late 1990s and then taper off until world population stabilizes in the late decade of the 21st century at about 10.2 billion. Close to 95% of this growth is occurring in less developed countries (LDCs) of Africa, Asia (minus Japan), and Latin America. LDC fertility rates are declining, except in sub-Saharan Africa and parts of Latin America and South Asia, but most have far to go to reach the replacement level of 2.1 births/woman. Fertility is below replacement in virtually all more developed countries. For LDCs, large numbers will be added before stabilization even after attainment of replacement level fertility because of the demographic momentum built into their large and young population bases. This complicates efforts to bridge gaps between living standards in LDCs and industrialized countries. From a new debate about whether rapid population growth deters or stimulates economic growth, a more integrated view has emerged. This view recognizes the complementary relationship between efforts to slow population growth and other development efforts; e.g., to improve health and education, upgrade women's status, increase productivity. Most effective in the increased contraceptive prevalence and fertility declines seen in many LDCs has been the combination of organized programs to increase access to family planning information and supplies with socioeconomic development that enhances the desire for smaller families.  相似文献   

13.
Recent long‐term demographic projections suggest a fast deceleration of global population growth and the eventual peaking of world population later in this century at about 9.2 billion, roughly 50 percent above the present level. Some low‐income and food‐insecure countries, however, have projected populations in 2050 that are multiples of present ones. In some of these countries agriculture must play a leading role in their development efforts because they have high economic dependence on that sector. For those among them that have scarce agricultural resources, a prima facie case can be made that the high population growth rates projected may not be compatible with the development potential offered by such resources. Their demographic projections may need to be revisited, taking into account such inadequate potential. The global demographic slowdown notwithstanding, the “population explosion”‐related issues pertaining to food and agriculture will not become irrelevant but will be become increasingly localized.  相似文献   

14.
Thailand reached replacement-level fertility almost a decade ago, although there has been a lag in measuring and recognising the implications of this benchmark event. Fertility could well sink still lower. The momentum of population growth will ensure substantial further increase before the population levels off, but this is not true in all regions. For example, earlier and faster fertility decline in the North, and net outmigration, have led to a situation where some geographical and age segments of the North's population are decreasing. Population policy in Thailand since 1970 has had two major planks: to reduce fertility through an active family planning program, and to distribute population away from the large primate city of Bangkok. The paper discusses whether these policies may need to be modified as a result of the major demographic and socio economic changes that have been taking place. It also discusses the limits to population policy in terms of the likely efficacy of various measures that could be adopted, based on both an assessment of the Thailand situation and the experience of other low-fertility countries.  相似文献   

15.
Total fertility rates fell to previously unseen levels in a large number of countries beginning in the early 1990s. The persistence of TFRs below 1.3 raised the possibility of rapid population aging and decline. We discuss the recent widespread turnaround in so‐called lowest‐low‐fertility countries in Europe and East Asia. The number of countries with TFRs below 1.3 fell from 21 in 2003 to five in 2008. Moreover, the upturn in the TFR was not confined to lowest‐fertility countries, but affected the whole developed world. We explore the demographic explanations for the recent rise in TFRs stemming from fertility timing effects as well as economic, policy, and social factors. Although the current economic downturn may suppress TFRs in the short run, we conclude that formerly lowest‐low‐fertility countries will continue to see increases in fertility as the transitory effects of shifts to later childbearing become less important.  相似文献   

16.
Family size preferences are strongly affected by parents' perceptions of the value, economic contributions, and costs of children. Better understanding of these factors can help policy-makers to improve the effectiveness of population IEC campaigns, design strategies to persuade couples to have smaller families, assess the relationship between economic development and family size preferences, and devise national population policies and family planning programs that reflect individual choices. Parents in high-fertility countries are more likely to perceive children as productive investments than those in low-fertility countries. Parents in the former countries maintain children are an economic advantage or provide practical assistance in the household; they are less likely to emphasize the psychological advantages of children. As economic development occurs, and parents no longer value children for their economic contributions, psychological and social reasons become more important. Changing fertility preferences is more complex than providing couples with family planning services. Similarly, efforts to persuade families that large families are a burden are successful only when families are already interested in reducing their family size. Efforts to persuade couples to have smaller families are likely to be more successful if there are alternative sources of old-age support available, for example, from increased household savings, public or private pensions, or greater contributions from 1st and 2nd children. Investments in education and training, especially for women and children, would also support these goals.  相似文献   

17.
20 ESCAP member countries responded to the "Third Population Inquiry among Governments: Population policies in the context of development in 1976." The questionnaire sent to the member countries covered economic and social development and population growth, mortality, fertility and family formation, population distribution and internal migration, international migration, population data collection and research, training, and institutional arrangements for the formulation of population policies within development. Most of the governments in the ESCAP region that responded indicate that the present rate of population growth constrains their social and economic development. Among the governments that consider the present rate of population growth to constrain economic and social development, 13 countries regarded the most appropriate response to the constraint would include an adjustment of both socioeconomic and demographic factors. 11 of the governments regarded their present levels of average life expectancy at birth "acceptable" and 7 identified their levels as "unacceptable." Most of the governments who responded consider that, in general, their present level of fertility is too high and constrains family well-being. Internal migration and population distribution are coming to be seen as concerns for government population policy. The most popular approaches to distributing economic and social activities are rural development, urban and regional development and industrial dispersion. There was much less concern among the governments returning the questionnaire about the effect of international migration than internal migration on social and economic development.  相似文献   

18.
Despite the existence of a national family planning program that dates to 1965 Pakistan has not seen a reduction in the fertility rate. One of the poorest countries in the world, Pakistan has 1 of the highest population growth rates in the world at about 3.0% annually. For over 2 decades, the average woman in Pakistan has given birth to more than 6 children. At the current fertility rate, the country's current population of 120 million will increase to over 150 million by the year 2000, and it will increase to 280 million by 2020. And even if today every woman were to begin having only 2 children, the population would still reach 160 million before leveling off. But reducing fertility in Pakistan will prove difficult. One of the leading obstacles is the low status of women. Few women in Pakistan have advanced education or professional jobs. Only 1/4 of those women without education or who are not working have any knowledge concerning contraception. Family size and composition also fuel the high rate of fertility. On the average, women desire 5 children (the fact that women average more than 5 suggests an unmet need for contraception). And due to social, cultural, and economic conditions, Pakistanis generally prefer male offsprings. Islamic opposition to family planning has also contributed to the continued high rates of fertility. Finally, administrative and management weaknesses have hindered Pakistan's family planning program. In order to overcome these obstacles, Pakistan will have to enlist the commitment of political, religious, and community leaders. The status of women will have to be improved, and the attitudes of people will need to change.  相似文献   

19.
The Population Division of the United Nations biennially issues detailed population estimates and projections covering the period 1950–2050. The most recent revision of these estimates and projections, the 2002 assessment, was released in February 2003. At irregular intervals, the Population Division also publishes long‐range projections. The most recent of these, covering the period up to 2150, was issued in 2000, based on the 1998 assessment. On 9 December 2003, the Population Division released the preliminary report on a new set of long‐range projections, dovetailing with the 2002 assessment, that extend over a much longer time span: up to 2300 ( http://www.un.org/esa/population/publications/longrange2/longrange2.htm ). Unlike previous long‐range projections, which, apart from China and In‐dia, were prepared for large regional groupings only, the new projections are elaborated separately for 192 countries. Given the enormous uncertainties of the character of demographic trends over such an extended period, the information content of these projections is somewhat elusive. However, they are expected to be used to provide the demographic input for long‐range models of global climate change. Long‐range population projections also serve to demonstrate the unsustainability of certain seemingly plausible assumptions as to the future course of particular demographic parameters. In the present case, for example, the high‐fertility projection, reflecting a sustained total fertility rate at the relatively modest level of 2.35, by 2300 would yield a population of some 32 billion in the countries now classified as less developed. Or, in a yet more extreme exercise 0/reductio ad absurdum, maintaining constant fertility at present rates would result in a population size of some 120 trillion in the countries now classified as least developed. Apart from the “high fertility” and “constant fertility” models just cited, the projections are calculated for three additional instructive variants: “low fertility,”“medium fertility,” and “zero growth.” Underlying each of the five variants is a single assumption on mortality change: expectation of life at birth creeping up, country‐by‐country, to a 2300 level ranging between 88 and 106 years. International migration is set at zero throughout the period 2050‐2300 in each variant. Thus the projections are unabashedly stylized and surprise‐free, providing a simple demonstration of the consequences, in terms of population size and age structure, of clearly stated assumptions on the future course of demographic variables. Reproduced below is the Executive Summary of the preliminary report on the UN long‐range projections presented to a UN technical working group on long‐range projections at its December 2003 meeting in New York and slightly revised afterward. A full final report on this topic by the Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat will be published later in 2004.  相似文献   

20.
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