Longevity Among Hunter‐ Gatherers: A Cross‐Cultural Examination

Post‐reproductive longevity is a robust feature of human life and not only a recent phenomenon caused by improvements in sanitation, public health, and medical advances. We argue for an adaptive life span of 68‐78 years for modern Homo sapiens based on our analysis of mortality profiles obtained from small‐scale hunter‐gatherer and horticultural populations from around the world. We compare patterns of survivorship across the life span, rates of senescence, modal ages at adult death, and causes of death. We attempt to reconcile our results with those derived from paleodemographic studies that characterize prehistoric human lives as “nasty, brutish, and short,” and with observations of recent acculturation among contemporary subsistence populations. We integrate information on age‐specific dependency and resource production to help explain the adaptive utility of longevity in humans from an evolutionary perspective.     

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).     

How Many Times Has the Human Population Doubled? Comparisons with Cancer

Along with decreasing doubling times as a function of increasing rates of population growth over the past several thousand years, the human species has shown striking parallels with a malignant growth. Some cancers also display decreasing doubling times of cell proliferation during the most rapidly growing phase. At 6 billion, the number of doublings reached by the human population as of 1998 is 32.5, with the 33rd doubling (8.59 billion) expected early in the next century. In terms of total animal biomass, including that of domestic animals under human control, the 33rd doubling of human-related biomass has been passed. In terms of energy use, which is a more accurate, index of the global ecological impact of humans, the human species has passed its 36th doubling. These calculations are important because, in addition to the number of doublings, the human population is showing several important similarities with a malignant organismic tumor, which results in death of the host organism at between 37 and 40 doublings. At current growth rates, the number of individual humans will reach those levels within 200–400 years from the present, but the ecological impact will be felt much sooner since the number of doublings of energy consumed will pass 37 early in the next century. These observations support the hypothesis that the human species has become a malignant process on the planet that is likely to result in the equivalent, for humans, of ecosystem death, or at least in a radical transformation of the ecosystem, the early phases of which are being observed.     

Population and the energy problem

When energy is scarce or expensive, people can suffer material deprivation and economic hardship. When it is obtained in ways that fail to minimize environmental and political costs, these too can threaten human wellbeing in fundamental and pervasive ways. The energy problem today combines these syndromes: much of the world's population has too little energy to meet basic human needs; the monetary costs of energy are rising nearly everywhere; the environmental impacts of energy supply are growing and already dominant contributors to local, regional, and global environmental problems (including air pollution, water pollution, ocean pollution, and climate change); and the sociopolitical risks of energy supply (above all the danger of conflict over oil and the links between nuclear energy and nuclear weapons) are growing too. This predicament has many causes, but predominant among them are the nearly 20-fold increase in world energy use since 1850 and the cumulative depletion of the most convenient oil and gas deposits that this growth has entailed, resulting in increasing resort to costlier and/or environmentally more disruptive energy sources. The growth of world population in this period was responsible for 52% of the energy growth, while growth in per capita energy use was responsible for 48% (excluding causal connections between population and energy use per capita). In the United States in the same period, population growth accounted for 66% of the 36-fold increase in energy use. In the late 1980s, population growth was still accounting for a third of energy growth both in the United States and worldwide. Coping with global energy problems will require greatly increased investment in improving the efficiency of energy enduse and in reducing the environmental impacts of contemporary energy technologies, and it will require financing a transition over the next several decades to a set of more sustainable (but probably also more expensive) energy sources. The difficulty of implementing these measures will be greatest by far in the developing countries, not least because of their high rates of population growth and the attendant extra pressures on economic and managerial resources. If efficiency improvements permit delivering the high standard of living to which the world aspires based on a per capita rate of energy use as low as 3 kilowatts—about a quarter of the current U.S. figure—then a world population stabilized at 10 billion people would be using energy at a rate of 30 terawatts, and a population of 14 billion would imply 42 terawatts (compare 13.2 terawatts in 1990). Delivering even the lower figure at tolerable monetary and environmental costs will be difficult; each additional billion people added to the world population will compound these difficulties and increase energy's costs, making everyone poorer.Presented at the Symposium on Population and Scarcity: The Forgotten Dimensions.     

The Impact of the Use of Energy Sources on the Quality of Life of Poor Communities

Over the last few decades, the energy literature has been dominated by a theory of transition. The theory of transition is based on the notion that households gradually ascend an ‘energy ladder’, which begins with traditional biomass fuels (firewood and charcoal), moves through modern commercial fuels (kerosene and liquid petroleum gas (LPG)) and culminates with the advent of electricity. The ascent of the ‘energy body’, though not fully understood, is thought to be associated with rising income and increasing levels of urbanisation. Empirical evidence on energy and poverty issues has been to suggest that reality is rather more complex than the simple transitional theory would appear to suggest. To choose an appropriate set of indicators to measure the impact of electrification, this paper takes three basic different perspectives on human welfare, namely, basic needs, monetary, and non-monetary into consideration. According to the basic needs approach, welfare relates to people’s ability to satisfy their basic material needs. In the monetary approach it is a generally accepted view that the purchasing power of the household provides the best overall indicator of welfare. According to the non-monetary approach there has been a trend towards complementing economic measures of deprivation with non-monetary measures to obtain a multidimensional view of human well being, particularly by tracking health and education indicators. In the rest of the paper the two primary research projects conducted in two provinces in South Africa, namely KwaZulu-Natal and Limpopo, will be discussed. The one research project is still in process. However, the methodology will be discussed. In this project a comparison will be made of households’ experiences in villages with and without electricity to see if and to what extent electrification contributed to the welfare of the communities. In the second project households were interviewed about their experiences in the use of paraffin as source of energy.     

Harvesting the biosphere: the human impact

The human species has evolved to dominate the biosphere: global anthropomass is now an order of magnitude greater than the mass of all wild terrestrial mammals. As a result, our dependence on harvesting the products of photosynthesis for food, animal feed, raw materials, and energy has grown to make substantial global impacts. During the past two millennia these harvests, and changes of land use due to deforestation and conversions of grasslands and wetlands, have reduced the stock of global terrestrial plant mass by as much as 45 percent, with the twentieth-century reduction amounting to more than 15 percent. Current annual harvests of phytomass have been a significant share of the global net primary productivity (NPP, the total amount of new plant tissues created by photosynthesis). Some studies put the human appropriation of NPP (the ratio of these two variables) as high as 40 percent but the measure itself is problematic. Future population growth and improved quality of life will result in additional claims on the biosphere, but options to accommodate these demands exist without severely compromising the irreplaceable biospheric services.     

Biodiversity and community structure of temperate butterfly species within a gradient of human disturbance: An analysis based on the concept of generalist vs. Specialist strategies

We monitored nine butterfly communities with varying degrees of human disturbance by conducting a census twice a month during 1980 by the line transect method in and around Tsukuba City, central Japan. We analyzed the biodiversity and community structures using the generalist/specialist concept. The site (community) order based on decreasing human disturbance was positively correlated with butterfly species diversity (H′), species richness (the total number of species), and the number of specialist species in a community, but not with the number of generalist species. The number of generalist species was rather constant, irrespective of the degree of human disturbance. Thus, both the butterfly species diversity and species richness were more dependent on the specialists than the generalists. Our analyses also showed that the generalist species were distributed widely over the communities, and they maintained high population densities, resulting in high rank status in abundance in a community, with more spatial variation in density per species. Specialist species showed the opposite trends. These results demonstrate that the generalist/specialist concept is a powerful tool applicable to analyse the biodiversity and structure of natural communities.     

The role of parasitoids in evolution of habitat and larval food plant preference by three Pieris butterflies

This article attempts to explain that parasitoids provide the evolutionary pressure responsible for relationships between habitat use and larval food plant use in herbivorous insects. Three species of butterflies of the genus Pieris, P. rapae, P. melete, and P. napi use different sets of cruciferous plants. They prefer different habitats composed of similar sets of cruciferous plants. In our study, P. rapae used temporary habitats with ephemeral plants, P. melete used permanent habitat with persistent plants, although they also used temporary habitats, and P. napi used only permanent habitat. The choice experiment in the field cages indicated that each of the three butterfly species avoided oviposition on plants usually unused in its own habitat, but accepted the unused plants which grew outside its own habitat. Their habitat use and plant use were not explained by intrinsic plant quality examined in terms of larval performance. Pieris larvae collected from persistent plants or more long lasting habitats were more heavily parasitized by two specialist parasitoids, the braconid wasp Cotesia glomerata and the tachinid fly Epicampocera succincta. The results suggest that Pieris habitat and larval food plant use patterns can be explained by two principles. The evolution of habitat preference may have been driven by various factors including escape from parasitism. Once habitat preference has evolved, selection favors the evolution of larval food plant preferences by discriminating against unsuitable plants, including those which are associated with high parasitism pressures. Received: December 3, 1998 / Accepted: January 20, 1999     

America's diversity and growth: signposts for the 21st century

This report provides a summary of the US demographic and population trends in the 21st century. It gives objective information on population growth, the determinants of population change, residential trends, racial and ethnic diversity, age profile, family life, households and families, measures of well-being, and future prospects. It is shown that US population is growing through relatively high fertility, migration and increasing life expectancy. Longer life expectancy has had a significant effect on American family life. Immigration fuels rapid population growth and social change creating increased ethnic diversity. Family life pattern also shifted, early marriage is replaced by cohabitation and divorce rates are increasing resulting in increased number of single-parent families. Many Americans have prospered well beyond their expectations; educational attainment vastly improved; more people moved out of poverty and more working women indicates a change in the workforce trends. Overall, it is noted that the US population will continue to grow. Prospect of such robust growth intensifies concerns about pollution and other environmental threats. At the same time, it seem that population growth is inextricably linked to the nations's prosperity.     

The Evolving and Complementary Impacts of Transportation Infrastructures on Population and Employment Change in the United States, 1970–2010

Transportation infrastructures play an essential role in influencing population and employment change. While railroads, highways, and airports were constructed in different time periods, now they complement each other in terms of providing accessibility. This study uses county-level data to examine the impacts of the three forms of transportation infrastructure on population and employment change in the continental United States from 1970 to 2010. The findings suggest that transportation infrastructures play evolving but complementary roles in affecting population and employment change during the study period: railroads act as a distributive factor, highways take a facilitator role, and airports behave like growth poles. Diversification of the roles indicates that transportation infrastructures have evolved from a pure growth factor to an essential multifaceted development element of human society.     

人口转变的储蓄效应和增长效应--论中国增长可持续性的人口因素

人口转变是挑战中国经济持续增长的一个重要因素.在这个过程中,个人的生命周期和代际更替之间的相互叠加,通过劳动供给、储蓄和科技进步等渠道对长期经济增长施加影响.本文分析表明,人口转变使得中国从20世纪60年代中期开始享受人口红利,并一直持续到2015年前后.为了迎接人口老龄化冲击,中国需要通过扩大就业、加快人力资本积累和建立适合于中国国情的可持续的养老保障模式三条途径来充分挖掘未来潜在的人口红利,推动中国经济持续增长.     

Seasonal host alternation by the andromeda lace bug,Stephanitis takeyai (Heteroptera: Tingidae) between its two main host-plant species

I studied the seasonal occurrence of the andromeda lace bug,Stephanitis takeyai, on its two main host-plant species. In a secondary forest in Kyoto, this bug altered its hosts seasonally, i.e., from an evergreen shrub,Pieris japonica, in winter to a deciduous shrub,Lyonia elliptica, in summer. In contrast, in Nara park where fewL. elliptica were available, the bug exploited onlyP. japonica. Thus, seasonal host alternation by this bug is not obligate. A comparison of adult longevity and fecundity on the two host-plant species demonstrated the higher quality ofL. elliptica as a food resource. Corresponding to this difference in host quality, there was a dramatic difference in the seasonal population growth in the two study sites. In Nara, the population size at the beginning of the 2nd generation was almost the same as in the overwintered generation, whereas in Kyoto the population size in the 2nd generation was approximately one hundred times as large as in the overwintered generation. Thus seasonal host alternation is adaptive for the bug. In a previous study, I reported that overwintering as eggs in living leaves of their hosts is likely to be common among all the related species of this bug. Thus, this trait can be considered to be a phylogenetic constraint to the group. I speculate that host alternation by this bug has been derived because it is more adaptive from autoecy on an evergreen plant, similar to the pattern currently found in Nara, and that this bug can not only exploit deciduous host due to a phylogenetic constraint.     

J. R. Hicks on the Economics of Population

Sir John Hicks (1904–89), professor of political economy at Oxford University from 1952 to 1965, was one of the foremost economists of his time, making notable contributions to the theory of wages, general equilibrium theory, and welfare economics. He received (jointly with Kenneth Arrow) the 1972 Nobel prize in economics. Value and Capital (1939), his best-known book, is held as a classic; his 1937 exegesis of Keynes's General Theory has long been a staple of undergraduate economics. Population does not figure appreciably in his writings, although an almost offhand footnote attached to the concluding paragraph of Value and Capital suggests that it could have: “[0]ne cannot repress the thought that perhaps the whole Industrial Revolution of the last two hundred years has been nothing else but a vast secular boom, largely induced by the unparalleled rise in population.” (He added: “If this is so, it would help to explain why, as the wisest hold, it has been such a disappointing episode in human history.”) In his late work, A Theory of Economic History (1969), however, the principal driving force in economic development is depicted as the expansion of markets. A sustained discussion of the topic of population by Hicks is contained in one of his earlier books. The Social Framework: An Introduction to Economics (Oxford University Press, 1942). Chapters 4 and 5 of this book treat “Population and Its History” and “The Economics of Population”; one of the appendixes is “On the Idea of an Optimum Population.” Chapter 5 and this appendix are reprinted below. The Social Framework was written as an introductory text, although its lucid style characterized all of Hicks's work. It covered both theory and applications with particular attention to the then novel subject of national accounting. Hicks described the book as “economic anatomy” in contrast to the “economic physiology” of how the economy works. Chapter 5 gives equal attention to under- and overpopulation, both seen as posing dangers. The Preface to the 1971 (fourth) edition of The Social Framework notes that the population and labor force chapters “have been rather substantially altered—to take account of the curious things that have happened in these fields (which one might have expected to be slow moving).” In 1971 he is more cautious than in 1942 about suggesting that slowing population growth might have been a factor in the 1930s depression, and readier to admit of countries where “a continuing rise in population, even while there is some continuing agricultural improvement, is likely to lead in the end to unemployment and destitution.” The appendix on optimum population was retained through all editions.     

Metropolitan Influence and Land Use Competition in Potential Biomass Crop Production: A Spatial Demographic Analysis

Biomass is one alternative energy source that is currently being investigated to combat the growing U.S. dependence on foreign oil. In this study, we explore where traditional farming practices and metropolitan influence will compete for land use against farmland located in optimal biomass crop production zones. To date, no consideration of the impact of urbanization and human development has been taken into account. Here we make a take a seminal approach to examining this relationship given previous analyses. We use overlapping LISA statistics to identify significant clusters of counties facing competition for land use. To measure competition for land use in counties located within biomass zones circa 2000, we use population growth and housing data from Census Bureau estimates, farmland data from the Census of Agriculture, and remotely sensed land use/cover data from the United States Geological Survey. The implications of these factors and how they will potentially affect biomass crop production are discussed.     

More people - more energy: it seems obvious enough,but Carter plan ignores population

In President Carter's National Energy Plan, there are variable factors, including the coal production rate, standards for home insulation and auto mileage, various taxes, but not the population growth rate. The latter factor is considered to be beyond the influence of public policy; it is a constant. This seems irrational to zero population growth proponents, for there are alternatives to continued U.S. population growth, and these alternatives are more readily attainable than some of the elements in Carter's plan. With some national initiatives in population planning, energy use would be considerably less. Thus, the question remains - Why would Carter not deal with the population factor? 1 reason for this is the fact that population planning is a long-term approach; the results are indirect and not reflected immediately in energy comsumption. Yet, a start must be made in the short-term if there are ever to be long-term benefits. Russell Peterson has suggested that Carter could be ignoring the population factor because of "political sensitivity." Carter's people have ignored the population issue, and press coverage following Carter's energy pronouncements has excluded the population factor. In a situation such as this there seems little hope for increased public awareness of the population factor in energy or other public concerns.     

Prey capture tactics of spiders: An analysis based on a simulation model for spider's growth

Summary The prey capture tactics of spiders was analyzed, considering the energy gained by the capture of prey and that required for it. For the purpose of it, a growth model of spiders was constructed, expressing the flow rate of prey biomass to the spider's body by differential equations. Solving these equations under the differing values of three parameters, growth curves of spiders was obtained. These three parameters are the amount of prey biomass supplied daily to spiders,x ₀, the rate of prey capture of spiders, α, and a coefficient of the respiration rate required for the capture of prey,k. When the value ofk increased, spiders could grow only at high value ofx ₀. These results suggest that habitats with small prey biomass are preferred by spiders adopting a sit-and-wait tactics for prey capture, which requires small values ofk. Wolf spiders are one of these spiders showing that tactics. On the other hand, web-builders which require large amount of energy for spinning webs (namely, take large value ofk), are able to grow only in the habitats with large prey biomass. Each species of spiders are considered to locate in a certain point between both extremes of these tactics for the capture of prey.     

Population,resources, environment: an uncertain future

This issue analyzes the economic and environmental consequences of rapid population growth in developing countries (LDC), the population decline in developed countries, the limits that life on a finite planet impose on economic and demographic expansion and progress, and the proper governmental response to promote the welfare of its current and future citizens. The links between population growth, resource use, and environmental quality are too complex to permit straightforward generalizations about direct causal relationships. However, rapid population growth has increased the number of poor people in LDC, thus contributing to 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 consumption of the nonrenewable resources of fossil fuels, metals, and nonmetallic 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 accelerating technological change make future interrelationships of population, resources, and the environment uncertain as well as complex. 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 LDC below the additional 5 billion indicated in current UN medium projections. This coupled with proven management programs in both LDC and developed countries could brake and reverse the depletion and degradation of natural resources.     

An Optimum Population for North and Latin America

The population of North America, which now stands at nearly 300 million people, is projected to double in about 60 years, while the population of nearly 500 million people in South America is projected to double in less than 40 years. Both of these populations obtain more than 99% of their food from the land, and this percentage will increase as these populations grow. Maintaining fertile and ample land is critical if these large populations are to be fed. Soil degradation by soil erosion is a serious problem on both continents. In addition, agricultural land is being lost to urbanization and highways because of rapid population growth. Nearly a half hectare of land is needed for urbanization for each person added to the North American population; this is already causing serious problems with agriculture in some states in the United States. The land resources that are critical for food production will be especially so if the populations of both continents double to nearly 2 billion. Land resources will also be critical when both continents deplete their fossil fuels in less than 100 years and have to turn to renewable energy sources. With about 2 billion people, there will be serious shortages of food, water, and energy resources and the standard of living will significantly decline. Our assessment suggests that for a relatively high standard of living in North and South America each continent should have no more than about 200 million people, or a total of 400 million.     

A sound population program

A sound population program must respond to real human needs, must be rooted in values, must generate results, must be administered in an integrated manner, must be based on the ethic and goal of self reliance and on the belief that it must operate and grow on its own steam, and must release human resources for productive economic endeavors. To make any sense at all, population must be linked to the gut level needs of the individual. People should not be viewed as demographic statistics, and the word human should be used in the basic sense of hunger and poverty. If the goal is to bring about lasting change in the way that Filipinos manage their lives and their living, it is necessary to probe their values. If social change is the goal, tradition must be challenged. In the area of family planning, persons who can communicate the fact that the program seeks to enrich life more than prevent birth must be chosen. There has been some criticism that the population/family planning program is "too contraceptive oriented" and too mechanistic in the approach to population. Contraception is behavior, a good measure of acceptance and an effective measure of commitment. The delivery of welfare must be horizontally integrated. Thus it is necessary to learn to work in teams, teams of development workers. The value of self determination and the conscious practice of planning and shaping one's life is the very logic of family planning. The program needs to implant the values of family planning firmly in the community, or, more accurately, in the small face to face primary groups where social norms are set and where change must take place if it is to last. The answer to how to achieve a sound population program lies less in what is done than how it is done.     

Population Scenarios Based on Probabilistic Projections: An Application for the Millennium Ecosystem Assessment

Probabilistic population forecasts offer a number of advantages to users. However, in some cases population is one component of a larger analysis that may take a different approach to uncertainty. For example, integrated assessments of environmental issues such as climate change or ecosystem degradation have typically used a small number of alternative scenarios to explore uncertainty in future environmental outcomes. In such cases, population projections that are provided only as probability distributions are difficult to use. I present a method of employing probabilistic population projections to derive individual, deterministic projections that can be used within scenarios for integrated assessments. The principal advantages of this approach are that (1) it provides a less ad hoc way of defining deterministic projections intended to be consistent with more comprehensive scenarios that describe, among other things, future socio-economic developments; (2) it provides more flexibility in specifying input assumptions for deterministic projections as compared to choosing off-the-shelf projections, allowing population assumptions to be tailored to the scenario; and (3) it provides a quantitative assessment of the uncertainty associated with any given deterministic projection. I describe the application of the method to the development of population projections used in integrated scenarios for the Millennium Ecosystem Assessment, an international scientific effort to assess the current conditions of and future outlook for global ecosystem goods and services. Results show that the MA scenarios are each consistent with a relatively wide range of demographic outcomes. For some scenarios, ranges of plausible outcomes in some regions overlap substantially, indicating that particular population projections could be consistent with more than one scenario. In other cases, uncertainty ranges for different scenarios are distinct, indicating that a projection consistent with one scenario is unlikely to be also consistent with another. Comparing variances of the conditional projections also provides insight into how much different storylines constrain future demographic developments. The development of the MA projections points to important areas of future research on correlations among demographic rates and on uncertainty across scales. It also serves as an illustration of how probabilistic and alternative scenario-based approaches to uncertainty can be combined within a single integrated analysis.This revised version was published online in April 2005 with corrections to figures 1-3.