Lifetime reproductive success in reproductively suppressed female voles

Summary A population of the grey red-backed vole,Clethrionomys rufocanus bedfordiae, was investigated on a 1 ha control grid and a 1 ha grid on which the voles were fed within a 2.1 ha outdoor enclosure in Hokkaido, Japan by live trapping from 1984 to 1986, for testing the Reproductive Suppression Model of Wasser and Barash (1983)-females can optimize their lifetime reproductive success by suppressing reproduction when future conditions for the survival of offspring are likely to be sufficiently better than present ones as to exceed the costs of the suppression itself. Age at the first pregnancy more varied in a higher density population on the experimental grid and females could be classified into the early and the late reproductive type in two generations (A: females born from February to June 1985; B: females born from September to November 1985). Lifetime reproductive success (the number of pregnancies, the number of successful litters, and the number of offspring) was not different between the early and the late reproducing females. The late reproducing females lived for longer periods than the early reproducing females, so that the loss by delayed start of reproduction was compensated for by a longer life span. Life span was not different between offspring of the early and the late reproducing females. These facts supported the Reproductive Suppression Model.     

Population: Past growth and future control

This paper is the opening chapter and demographic context of a forthcoming book onThe World's Food. It offers a summation of the Malthusian perception of food and population, an overview of population growth in history and the role of the demographic transition. The varying experiences of developing countries in bringing down the birth rate are examined and used as a basis for projecting future population growth.     

Fertility in botswana: The recent decline and future prospects

Recent estimates of fertility in Botswana suggest a rapid decline of more than two births per woman between 1981 and 1988. This paper proposes that the baseline fertility was overestimated but that nonetheless fertility declined by about one birth per woman during the 1980s. The decline in fertility was linked to a deterioration in social and economic conditions caused by a major drought in the early 1980s and to the increased availability of family planning services in the same period. Fertility apparently began to rebound in the late 1980s in response to improved conditions, which came about as a result of a successful drought relief program. Future declines in fertility depend on the continued success of the family planning program, particularly in rural areas.     

Fertility in China: An uncertain future

As one of the world’s two population ‘billionaires’, the future of China’s population is truly of global significance. With its very low fertility and a rapidly ageing population, it might appear that the country’s famous (or notorious) family planning restrictions are somewhat anachronistic. Here, we explore the process of reform seen over the past three decades and, most recently, in late 2013. We suggest that the popular notion that the family planning restrictions are acting as a pressure valve suppressing a pent-up demand for childbearing, particularly in rural China, is likely to be inaccurate. We also suggest that further reform of the restrictions will not solve the problems of population ageing or many of the other issues widely associated with the restrictions. We conclude that the prospects for further reform are wide-ranging, but likely to be beset by many challenges.     

Renewable resources and population growth: Past experiences and future prospects

The links between population growth, resource use, and environmental quality are too complex to permit straightforward generalizations about direct causal relationships. Rapid population growth, however, has increased the number of poor people in developing countries, thus contributing to the degradation of the environment and the renewable resources of land, water, and nonhuman species on which humans depend. Demands of the rich industrial countries have also generated environmental pressures and have been foremost in the consumption of the so-called nonrenewable resources: fossil fuels, metals, and minerals. On the other hand, population and economic growth have also stimulated technological and management changes that help supply and use resources more effectively. Wide variations in the possible ultimate size of world population and technological change make future interrelationships of population, resources, and the environment uncertain as well as complex. But those interrelationships are mediated largely by government policies. Responsible governments can bring about a sustainable balance in the population/resource/environment equation by adopting population and development policies that experience has shown could reduce future population numbers in developing countries below the additional five billion indicated in current United Nations medium projections, coupled with proven management programs in both developing and developed countries that could brake and reverse the depletion and degradation of natural resources.This article is adapted from: Robert Repetto, "Population, Resources, Environment; An Uncertain Future,"Population Bulletin, Vol. 42, No. 2 (Washington, D.C.: Population Reference Bureau, 1987).     

Epidemics in the Americas: major issues and future research

The author discusses the problems associated with the study of epidemics in the Americas. He indicates that "study of the history of the epidemics in the Americas faces peculiar difficulties inherent in any topic which covers the New World from pole to pole in a widely interdisciplinary range.... The interdisciplinary nature of the theme exposes the inadequacies of our bibliographies and indexes, especially those by field of study. The topic apparently falls between the interstices of anthropological, historical, and even medical indexes, including the international medical index." He then proposes new avenues of research that may prove helpful.     

Australian primary maternity units: Past,present and future

Primary maternity units are commonly those run by midwives who provide care to women with low-risk pregnancies with no obstetric, anaesthetic, laboratory or paediatric support available on-site. In some other countries, primary level maternity units play an important role in offering equitable and accessible maternity care to women with low-risk pregnancies, particularly in rural and remote areas. However there are very few primary maternity units in Australia, largely due to the fact that over the past 200 years, the concept of safety has become inherently linked with the immediate on-site availability of specialist medical support.The purpose if this paper is to explore the various drivers and barriers to the sustainability of primary maternity units in Australia. It firstly looks at the historical antecedents that shaped primary level maternity services in Australia, from the time of colonisation to now. During this period the space and management of childbirth moved from home and midwifery-led settings to obstetric-led hospitals. Following on from this an analysis of recent political events shows how Australian government policy both supports and undermines the potential of primary maternity units. It is important that researchers, clinicians and policy makers understand the past in order to manage the challenges facing the development and maintenance of midwifery-led maternity services, in particular primary maternity units, in Australia today.     

Vitality and malaise in demography: outlook and strategies for the future

"When dealing with age structures...the question could be posed...whether in the age structure such pronounced 'distortions' already exist as to make a major contribution to plotting the course of demography and then, as a more or less inevitable consequence, to shaping the social and economic context. In other words, whether conditions of 'demographic malaise' exist linked, on the one hand, to an extraordinarily young age structure and a consequent 'excess' population growth...and, on the other, to an extraordinarily old age structure and a subsequent 'excess' population decline.... This study proposes to focus particularly on this second instance, which pertains to contemporary western populations or sub-populations, [using the example of Italy]."     

现行城市外来人口管理方式的弊端及其对策

现行城市社会对外来人口的管理方式存在着三种明显的弊端 :(1)计划式的管理方式导致了管理的低效性 ;(2 )防范式的管理方式把外来人口当作了对立面 ;(3)“只管手脚、不管头脑”式的管理方式使外来人口的思想品行放任自流。因此 ,完善现行外来人口管理制度的关键在于转变管理方式 ,使旧的管理方式逐渐被新型的管理方式所取代。新型的外来人口管理方式的基本原则是 :(1)以市场化为目标取向 ;(2 )以为外来人口服务为基本宗旨 ;(3)以教育外来人口为重要环节。我们认为 ,“政府引导的外来人口自我管理模式”是一种可供城市政府选择的新型的外来人口管理方式     

Demographic Trends in Ukraine: Past,Present, and Future

Ukraine, during the first half of the twentieth century, underwent a series of man‐made demographic catastrophes—World War I, the Bolshevik Revolution, the 1932/33 famine linked to land collectivization, the massive deportations and executions of Stalin's Great Terror, and World War II. This article assembles estimates of the demographic impact of these deadly events. In their absence, it is estimated that Ukraine's hypothetical population would have been 87 million on the eve of independence in 1991, instead of its actual 52 million. Pre‐independence demographic losses were episodic and driven by external forces. By contrast, since independence in 1991, Ukraine has experienced a sustained demographic crisis of its own making. Ukraine's population declined from 52 million in 1990 to 45 million by 2013. Fertility, while it has recovered from its lowest point, remains at a TFR of about 1.5—far below replacement. Emigration, although the greatest hemorrhage of young people in the 1990s is over, is still of concern. The loss of Crimea and the unsettled state of affairs in Southeastern Ukraine give further cause for concern.     

Asia's demographic future: the next 20 years

Even with the decline of fertility rates in most of Asia, the problem of population growth is still very serious. It is important to stress to Asian leaders and Western researchers that the problem is by no means solved just because fertility rates have declined. In many countries the number of young people is quite substantial and when they increase their numbers, certain problems will develop. Over the next 20 years, urban areas will see a marked increase in population and the resultant problems. Unemployment, increased pollution, and overcrowding will greatly decrease the quality of life for millions of people. This will happen because of natural increases and from the migration of the rural communities. In the rural areas, because of high fertility rates, population will continue to grow in spite of the large numbers of peoples moving to the city. Asia has some of the most densely populated agricultural communities and as their numbers increase, poverty and its associated problem will follow. The solutions to these problems include continued efforts in family planning, maternal and child health, and the improvement of the status of women.     

Mortality,past and future

The study of mortality in previous centuries and of the trends in recent decades helps to elucidate some present-day medical problems and to contribute to their solution. The author considers, from a historical and socio-economic point of view, the factors which, during the last 200 years, have influenced the trends of mortality. This analysis indicates the lines along which present research, aimed at reducing mortality and extending expectation of life, should be directed.

Infancy (0–1 year): In backward countries, the whole of infancy is a period of high mortality. In progressive countries, on the other hand, the main reproductive wastage is in the ‘perinatal’ period, that is to say, covering stillbirths and deaths during the first week of life. For example, even in New Zealand, the death risk per day is more than eighty times as high during the first week of life than in the following 358 days.

Historical studies and social class comparisons suggest that further reduction of perinatal mortality is likely to depend on socio-economic, housing and cultural factors rather than on improvements in obstetric skill. Evidence cited by the author indicates that a crucial factor may be to provide expectant mothers with adequate rest during the weeks immediately prior to delivery. In general, research into mortality in infancy is too much bounded by a purely medical point of view whereas a socio-medical approach is needed.

Childhood (1–14 years): There has been an immense reduction in childhood mortality during the last 200 years. Less than 200 years ago the mortality among children aged 1–4 and 5–9 years was thirty-three times, and among those aged 10–14 years twelve times, that of the present day. Future reduction of mortality among children will be primarily a function of social factors and trends.

Adolescence and maturity (15–49 years): One of the outstanding trends of the last 200 years has been a relative increase in tuberculosis mortality among those aged 15–49 years, whereas among children tuberculosis has become relatively less important

as a cause of death. Recently, however, there has been a decline in the relative importance of tuberculosis as a cause of death among the adolescent and mature and, among New York males, it now takes second place to the cardiovascular

diseases. The total mortality of people in this age group has fallen, since the sixteenth century, by 77% for men and 81% for women. No spectacular discoveries are needed to reduce the mortality of this group by a further third; in doing this, control of environment will be the important factor.

Later maturity and old age (50 years and over): In the four centuries since the Renaissance the mortality of people over 50 years of age has been reduced by half. Among the factors contributing to this reduction is a fall in mortality due to tuberculosis. But even cancer, which is popularly supposed to have increased, used to be more common in the eighteenth century than it is now and to appear at an earlier. age. Moreover, there has been a change in the organs most commonly affected. The distribution of the greater proportion of cancer in a given population is a function of living conditions in the broadest sense of the term. Studies of groups exposed to carcinorelevant factors suggest that a high incidence of cancer in one organ is associated with a low incidence in other organs. But on many other causes of death at the older ages far more research is required, especially on the cardio-vascular-renal complex, and on the degenerative joint and bone diseases.     

Chronic movers and the future redistribution of population: A longitudinal analysis

This research has two purposes. First, it examines individual- and household-level factors related to the propensity to move. The findings reveal that mobility is largely a matter of habitual movers changing residence repeatedly and frequently. The second objective is concerned with strengthening the foundation for projecting aggregate levels of mobility: (1) how does repeated movement manifest itself at the metropolitan scale? and (2) for predictive purposes, which aggregate indices capture the most important features of local population composition? Mobility rates were found to vary principally with the prevalence of chronic movers in an SMSA. These findings have several implications for policies designed to guide future population distribution. First, an SMSA’s capacity to correct local manpower imbalances by exchanging human capital with other areas may depend partially on its relative abundance of habitual movers. Second, the likelihood that new cities would attract disproportionate numbers of hypermobile persons might enhance their role within the framework of a broader distribution policy. The question posed here is whether high intrinsic levels of population turnover in some cities might fit into a larger strategy for realigning population growth and distribution nationally.