Number Of Human Populations Research Articles

The Human Population: Accepting Species Limits

In “The Population Equation: Balancing What We Need with What We Have,” Dahl (2005) presented generally accepted thought and consensually validated data regarding the human population, even though he did not include an adequate scientific theory of absolute human population numbers. Dahl also appeared to confirm the wide agreement among scientists that it is difficult to make theoretical advances or conduct human population research because humankind is seen as essentially different from other species and the human world is viewed as being composed of many intricately connected things that interact in extremely complex ways. Therefore, the population dynamics of Homo sapiens are effectively relegated to the preternatural realm and are believed to include a number of factors that are so complicated and enormous as to be unsuitable for empirical research or else unknowable. A theory of human population numbers that could objectively explain the increase and decrease of the human population would be useful. Perhaps correlation data from Hopfenberg and Pimentel (2001) and the recent mathematical formulation of this biologic phenomenon by Hopfenberg (2003) provide a basis for an apparently unexpected theoretical perspective. According to the empirical research (Hopfenberg 2003), human population growth is a rapidly cycling positive feedback loop in which food availability drives population growth and this growth in human numbers gives rise to the mistaken impression that food production needs to be increased even more. The data of Hopfenberg (2003) and Hopfenberg and Pimentel (2001) indicate that the world’s human population—all segments of it—grows by approximately 2% per year, including more people with brown eyes and more with blue eyes; more tall people and more short people; and more people who grow up well fed and more who grow up hungry. We may or may not be reducing hunger by increasing food production; however, we are most certainly producing more and more hungry people. The evidence suggests that the remarkably successful efforts of humankind to increase food production to feed a growing population results in even greater increase in population numbers. Hopfenberg and Pimentel (2001) pointed out that the perceived need to increase food production to feed a growing population is a misperception, a denial of the physical reality of the space–time dimension. If people are starving at a given moment in time, increasing food production cannot help them. Are these starving people supposed to be waiting for sowing, growing, and reaping to be completed? Are they supposed to wait for surpluses to reach them? Without food they would die. In such circumstances, increasing food production for people who are starving is like tossing parachutes to people who have already fallen out of the airplane—the produced food arrives too late. However, this does not mean human starvation is inevitable. If this view of the human population is somehow correct, then human population dynamics are not biologically different in essence from the population dynamics of other species (Hopfenberg and Pimentel 2001). We do not find hoards of starving roaches, birds, squirrels, alligators, or chimpanzees in the absence of food as we do in many civilized human communities today, because these nonhuman species are not annually increasing their own production of food. Among tribal peoples in remote original habitats, we do not find people starving. Like nonhuman species, “primitive” human beings live within the carrying capacity of their environment. History is replete with examples of early humans and other ancestors not increasing their food production annually, but rather living successfully off the land for thousands of years as hunters and gatherers of food. Before the agricultural revolution and the production of more food than was needed for immediate survival, human numbers supposedly could not grow beyond their environment’s physical capacity to sustain them because human population growth or decline is primarily a function of food availability (Hopfenberg 2003; Hopfenberg and Pimentel 2001). Given its current scale and rate of growth, the human population worldwide has identifiable, potentially destructive ecological consequences. From this theoretical perspective, recent global human population growth can be understood as a primary causative factor of a range of phenomena including biodiversity loss and environmental degradation.

Invoking the Precautionary Principle

The article on the precautionary principle, risk perception, and assessment by Wiedemann and Schutz (2005) deserves praise and careful consideration because of the growing awareness that certain human activities could potentially seriously harm human and environmental health. The precautionary principle (United Nations Conference on Environment and Development 1992) holds forth that a point can presumably be reached when human well-being and environmental health are put at risk by a large-scale human activity or man-made system over which humans have control. At such a point the problem could be identified, a course charted, and precautionary actions taken to ameliorate or prevent a potential threat to human and environmental health on behalf of current and future generations. Despite the incontrovertible element of uncertainty and other limitations of scientific methods, it is implicitly assumed that science plays the vital role of providing humanity with the best knowledge of how the world works and of the placement of humankind in the natural order of living things. To the extent scientific methods are incorporated and used to inform both the proclamation of a problem and the implementation of its remedy, the precautionary principle affords humanity a mechanism to focus attention and to examine data on potential impacts of human activities and systems upon the natural world. With such attentiveness and knowledge, humans become able to make choices and to engage in the regulation of behaviors that are advantageous rather than detrimental to human and environmental health. As a mechanism of science, the precautionary principle becomes a useful tool in raising awareness and determining aspects of human culture that are and are not sustainable. Absolute global human population numbers (Hopfenberg 2003; Hopfenberg and Pimentel 2001), increasing human consumption worldwide (Imhoff et al. 2004), and the seemingly limitless expansion of the world’s predominant human economy (Czech and Daly 2004; Meritt 2001) point to the existence of a rapidly spreading culture that could be characterized by its proclivity for unlimited growth—growth that increasingly outruns humanity’s capabilities to anticipate and address the potential for devastating consequences of growth. Given the current scale and rate of this growth relative to the small, finite, noticeably fragile planet we inhabit, it could be that this cultural predisposition for increasing growth is patently unsustainable and, moreover, could give rise to the potential for recognizable, worst-case scenarios. Global warming; diminishing nonrenewable energy resources; destruction of the ozone layer; biodiversity loss; acid rain; deforestation; solid waste disposal; pollution of the air, water, and land; and desertification are regularly referenced in this context. Not unexpectedly, the evolution of science gives rise to new approaches for examining large-scale human activities such as human propagation and human consumption and man-made constructions such as the prevailing economic system. Although relatively new, “top-down” research focuses on data acquisition and analysis regarding certain human behaviors and global human systems. This development complements the “bottom-up” research with which scientists are so familiar (Cairns 2003). As the adage goes, scientists have had difficulty “seeing the forest for the trees” because traditional scientific methods focus primarily on parts of a large system, not on the large system itself. Another dimension of this change in focus is the development of “joining edge” research, in which leading ideas and best practices from multiple disciplines are brought together in a collaborative effort to examine large, complex systems. This approach complements the more familiar pursuit of progressively narrowing “cutting-edge” research of components of a whole system (Cairns 2003; Kriebel et al. 2001). Perhaps, scientific data to advance human understanding about why global-scale human activities and systems are sustainable or unsustainable could be vital to protecting humanity from endangerment, biodiversity from extinction, and Earth from irreversible degradation, even in these early years of the 21st century.

The Next Pandemic?

SCI ENTI ST S HAVE long forecast the appearance of an influenza virus capable of infecting 40 percent of the world's human population and killing unimaginable numbers. Recently, a new strain, HSN1 avian influenza, has shown all the earmarks of becoming that disease. Until now, it has largely been confined to certain bird species, but that may be changing. The havoc such a disease could wreak is commonly compared to the devastation of the 1918-19 Spanish flu, which killed 50 million people in 18 months. But avian flu is far more dangerous. It kills loo percent of the domesticated chickens it infects, and among humans the disease is also lethal: as of May 1, about log people were known to have contracted it, and it killed 54 percent (although this statistic does not include any milder cases that may have gone unreported). Since it first appeared in southern China in 1997, the virus has mutated, becoming heartier and deadlier and killing a wider range of species. According to the March 2005 National Academy of Science's Institute of Medicine flu report, the current ongoing epidemic of H5N1 avian influenza in Asia is unprecedented in its scale, in its spread, and in the economic losses it has caused. In short, doom may loom. But note the may. If the relentlessly evolving virus becomes capable of human-to-human transmission, develops a power of contagion typical of human influenzas, and main tains its extraordinary virulence, humanity could well face a pandemic

The Human Population: Accepting Earth’s Limitations

I thank Fowler and Hobbs for their letter (2004) and their research (2003). The view that a complexity of factors impacts human population growth certainly makes sense, and they have correctly pointed out that scientifically organized efforts to deal with human problems must take account of manifold interconnected events. Although it is necessary to recognize and acknowledge the complexities inherent in cultural life and the natural world, it is equally important that a dizzying array of variables not blind us to certain scientific facts of biophysical reality. Humankind is bound by such predominant facts because the workings of the world exist independently of human wishes and beliefs. With this in mind, I thank Hopfenberg for his article (2003) in which he provided an elegant model that accounts for the salient factors governing the dynamics of global human population numbers. According to his findings, the size of the human population is determined primarily by food availability. The realization that these two points of view differ—that there is complexity and simplicity in the world we inhabit—does not necessarily mean that one is correct and the other incorrect. To the contrary, it could be that each point of view is valid based on the scope of observation. It may be somehow not quite right to agree with the entire idea of Hobbs and Fowler (2004) that “human population size is beyond human capacity to list, comprehend, and synthesize” without noticing that the same can be said regarding any observable phenomenon. Reality is likely just as complex as Hobbs and Fowler described; but it is also clear from the research of Hopfenberg (2003) and Hopfenberg and Pimentel (2001) that the dynamics of human population growth is no longer preternatural but knowable, and that the population dynamics of Homo sapiens is not essentially different from the population dynamics of other species in both the complexity and the simplicity of the governing elements. A comprehensive and objective approach to human problems and human potentiality must acknowledge that humankind is a part of the biophysical world, not apart from it. Although Hobbs and Fowler (2004) are correct to note the control human culture exercises in “value systems, economics, politics and religion” in taking account of what is real, human and environmental health could be increasingly at risk because humanity denies scientific facts over which living beings may not have control. In light of the different sets of data presented by Fowler and Hobbs (2003) and by Hopfenberg (2003), perhaps it is a misnomer for Hobbs and Fowler (2004) to uniformly describe the many, complicated ways humanity is changing the natural world as an “unprecedented success.” Are particulate and solid-waste pollution or the conversion of biomass into human mass with resulting bio-diversity loss examples of success? Perhaps the economic success of the prevailing culture is not sustainable and cannot be maintained much longer. Unbridled economic globalization, unrestricted increases in human consumption of resources, and growing absolute human population numbers are negatively affecting Earth by degrading its fitness as a habitat for humans and other species. A point in human history may have been reached when the scale and rate of growth of economic expansion, the consumption of natural resources, and the increasing human population can be seen as patently unsustainable. Understanding the causes of and limits to humanity’s impact in the world is a necessary step toward changing human production, consumption, and population trends. Regardless of how long a culture prizes growth and chooses to leave it unchecked, surely it is not too late to accept limits to growth of the human economy, human consumption, and human numbers worldwide by altering human behavior accordingly.

The Hyperexponential Growth of the Human Population on a Macrohistorical Scale

A qualitative comparison of human population dynamics with some other biological populations growth in free regime is given in this paper along with a quantitative description of human population growth in the last 2000 years. It is shown that human population growth law is very different from the growth laws of other populations: all biological populations grow according to exponential law, whereas the human population grows according to hyperexponential law which essentially moves ahead of the exponential one. It is found that unlike cell populations, the differential equation of rate of human population growth is of second order. This phenomenon can be described due to accelerating function which grows simultaneously with human population number. An analytical hyperexponential equation, which allows to describe dynamics of human population, was obtained.

Human Population Numbers as a Function of Food Supply

Human population growth has typically been seen as the primary causative factor of other ecologi- cally destructive phenomena. Current human disease epidemics are explored as a function of population size. That human population growth is itself a phenomenon with clearly identifiable ecological/biological causes has been overlooked. Here, human population growth is discussed as being subject to the same dynamic processes as the population growth of other species. Contrary to the widely held belief that food production must be increased to feed the growing population, experimental and correlational data indicate that human population growth varies as a function of food availability. By increasing food production for humans, at the expense of other species, the biologically determined effect has been, and continues to be, an increase in the human population. Understanding the relationship between food increases and population increases is proposed as a necessary first step in addressing this global problem. Resistance to this perspective is briefly discussed in terms of cultural bias in science.

The Power of Association Studies to Detect the Contribution of Candidate Genetic Loci to Variation in Complex Traits

The statistical power of five association study test statistics (two haplotype-based tests, two marker-based tests, and the Transmission Disequilibrium Test-Q5) to detect single nucleotide polymorphism (SNP)/phenotype associations in a linkage-disequilibrium-based candidate gene scan employing a number of SNPs is examined. Power is estimated as a function of realistic parameters expected to affect the likelihood of detecting a significant association: the number of SNPs examined, the scaled recombination size of the region examined, the proportion of variance in the trait attributable to a hidden causative polymorphism within the region, and the number of individuals or families examined. For the different combinations of parameter values, power is estimated from a large number of realizations of a simulated coalescent describing a single random mating population with mutation, random genetic drift, and recombination. This explicit population genetics model results in a distribution of DNA marker heterozygosities and linkage disequilibria that are likely to resemble those expected in actual population samples. The study concludes that (1) marker-based permutation tests are more powerful than simple haplotype-based tests, (2) there is sufficient power to detect the presence of causative polymorphisms of small effect if on the order of 500 individuals are sampled, (3) greater power is achieved by increasing the sample size than by increasing the number of polymorphisms, (4) association studies are generally more powerful than transmission disequilibrium-based tests, and (5) for the range of parameters considered association studies have a low repeatability unless sample sizes are on the order of 500 individuals. Estimates of 4Nc for a number of gene regions and human populations will be of use in determining the density of SNPs that are likely to be required for successful association studies.

Will Limits of the Earth's Resources Control Human Numbers?

The current world population is 6 billion people. Even if we adopted a worldwide policy resulting in only 2.1 children born per couple, more than 60 years would pass before the world population stabilized at approximately 12 billion. The reason stabilization would take more than 60 years is the population momentum – the young age distribution – of the world population. Natural resources are already severely limited, and there is emerging evidence that natural forces already starting to control human population numbers through malnutrition and other severe diseases. At present, more than 3 billion people worldwide are malnourished; grain production per capita has been declining since 1983; irrigation per capita has declined 12% during the past decade; cropland per capita has declined 20% during the past decade; fish production per capita has declined 7% during the past decade; per capita fertilizer supplies essential for food production have declined 23% during the past decade; loss of food to pests has not decreased below 50% since 1990; and pollution of water, air, and land has increased, resulting in a rapid increase in the number of humans suffering from serious, pollution-related diseases. Clearly, human numbers cannot continue to increase.

Parent and offspring strategies in the transition at adolescence.

Adolescence signifies a transition from the use of prereproductive to reproductive strategies in the life history of Homo sapiens. Insofar as human generations overlap, events at adolescence, surrounding the onset of puberty, offer a unique glimpse into human adaptation from the point of view of the changing strategies of both parents and offspring. The timing of puberty is an important life history trait that varies between species, but also between and within the sexes in human beings. The onset of puberty marks the beginning of the reproductive life, is affected by previous experience, and serves as a trigger for behavioral change. Surbey (1988, 1990) reported relationships between father absence, heightened levels of childhood stress, and early menarche and considered them within the context of human evolutionary history. Subsequently, similar findings have been reported in a number of human populations and have been interpreted from several evolutionary perspectives. This article discusses the extent to which these and related findings regarding alterations in the timing of human puberty reflect evolved parental or offspring strategies. It entails a consideration of the applicability of the concepts of phenotypic plasticity, nonadaptive genetic variation, and conditional and alternative reproductive strategies in describing the interwoven nature of strategies employed by parent and child in the transition at adolescence.

Relative mutation rates at di-, tri-, and tetranucleotide microsatellite loci.

Using the generalized stepwise mutation model, we propose a method of estimating the relative mutation rates of microsatellite loci, grouped by the repeat motif. Applying ANOVA to the distributions of the allele sizes at microsatellite loci from a set of populations, grouped by repeat motif types, we estimated the effect of population size differences and mutation rate differences among loci. This provides an estimate of motif-type-specific mutation rates up to a multiplicative constant. Applications to four different sets of di-, tri-, and tetranucleotide loci from a number of human populations reveal that, on average, the non-disease-causing microsatellite loci have mutation rates inversely related to their motif sizes. The dinucleotides appear to have mutation rates 1.5-2 times higher than the tetranucleotides, and the non-disease-causing trinucleotides have mutation rates intermediate between the di- and tetranucleotides. In contrast, the disease-causing trinucleotides have mutation rates 3.9-6.9 times larger than the tetranucleotides. Comparison of these estimates with the direct observations of mutation rates at microsatellites indicates that the earlier suggestion of higher mutation rates of tetranucleotides in comparison with the dinucleotides may stem from a nonrandom sampling of tetranucleotide loci in direct mutation assays.

Impacts of growth in resource use and human population on the Nechako River: A major tributary of the Fraser River, British Columbia, Canada

Hydroelectric development, forest exploitation, agricultural land use and related human population numbers have increased rapidly during the last 40 years, in the basin of the Nechako River, a major tributary system of the Fraser River. The Kemano project of the Aluminum Company of Canada Ltd. begun in 1950, was the largest industrial scheme in the area. A key feature of the first stage of it was a dam which diverted about 40% of flow of the south branch of the Nechako River, through a tunnel in the mountains, to the Pacific Ocean. In 1987 an agreement for the Kemano Completion Project (KCP), which would have diverted 87% of the flow, was signed. This final phase of the project would have put important fisheries resources of the upper Fraser River at high risk. Mitigation for fisheries protection were inadequate or untested in the system at the time. Potential cumulative impacts of water abstraction, elevated pollution levels, increased water temperature and natural sediment were not addressed. In January 1995 KCP was cancelled but there remain at present no adequate measures to protect the fish and the river ecosystem. These measures are to be negotiated in the future. Future management of the whole Kemano development must provide biologically realistic flow and temperature regimes in the Nechako River, and must deal with cumulative impacts of population and industrial growth. To achieve ‘sustainability’ of fisheries in the Nechako River and upper Fraser watershed the present approach to the Kemano development must be changed fundamentally. The future of the Kemano development must be set in the context of the whole future of the upper Fraser system. Continued growth and development, as has occurred in the upper Fraser and total basin, can not go on without inimical changes to ecosystem conditions and loss of fisheries resources.

Changes in diurnal patterns related to changes in ozone levels.

Ozone is an ubiquitous air pollutant that affects both human health and vegetation. There is concern about the number of hours human populations in nonattainment areas in the United States are exposed to levels of O3 at which effects have been observed. As improvement in air quality is achieved, it is possible that O3 control strategies may produce distributions of 1-h O3 concentrations that result in different diurnal profiles that produce greater potential exposures to O3 at known effects levels for multiple hours of the day. These concerns have prompted new analysis of aerometric data. In this analysis, the change in the seasonally averaged diurnal pattern was investigated as changes in O3 levels occurred. For the data used in this analysis, 25 of the 36 sites that changed compliance status across years showed no statistically significant change in the shape of the average diurnal profile (averaged by O3 season). For 71 percent (10 out of 14) of the sites in southern California and Dallas-Fort Worth, Texas, that showed improvement in O3 levels (i.e., reductions in the number of exceedances over the years), but still remained in nonattainment, a statistically significant change in the shape of the seasonally averaged diurnal profile occurred. Based on the results obtained in this study, the evaluation of diurnal patterns may be useful for identifying the influence of changes in emission levels versus meteorological variation on attainment status. Using data from the southern California and Dallas-Fort Worth sites, which showed improvements in O3 levels, changes were observed in the seasonally averaged diurnal profiles.(ABSTRACT TRUNCATED AT 250 WORDS)

Scaphocephaly in a Prehistoric Skeleton from Harappa, Pakistan

Irregularities of cranial suture closure resulting in scaphocephaly are documented for a number of prehistoric and historic human populations of the eastern and western hemispheres, but what may be the first recorded case from southern Asia appeared during the 1987 archaeological field season at the Indus Valley Civilization site of Harappa, Pakistan. The female specimen with this condition also exhibits indicators of developmental abnormalities in the postcranial skeleton. These features are discussed in the context of assessing anatomical and ontogenetical relationships of craniostenostic eccentricities with abnormalities of facial, dental and postcranial regions of the skeletons of scaphocephalic individuals.

Gene frequencies of Gc and PGM subtypes

Allele frequencies are presented for subtypes of phosphoglucomutase locus 1 and the group-specific component (Gc) in samples from a number of human populations. Compared with each other and with published data, continental samples are very similar in gene frequency to their reported distributions in the literature, but the small island populations are much more variable.

The distribution of esterase D variants in different ethnic groups.

Blood samples collected from a number of human populations belonging to various ethnic groups were screened on cellogel for red-cell esterase D (ESD) variants. These data gathered during the present study together with those that have already appeared in the literature indicate that the common variant allele ESD2 occurs most frequently in the Mongoloid populations, least frequently in the Negroid, and with intermediate frequencies in the Caucasoids. An east to west cline was noticed in the northern populations of the Indian subcontinent; ESD2 gene frequencies in these populations were found to range between those among the Mongoloids and the Caucasoids.

Present Educational Needs in Fishery Biology

Abstract Trends in human population numbers, aggregations, and life styles, with their associated environmental impacts and resource allocation problems, pose important new problems for fishery biologists. Colleges and universities that train students for dealing with such problems must now produce more different kinds of fishery biologists, including many with both skills and inclinations for working closely with people of other disciplines on integrated management plans for sizeable ecological units. Accordingly, colleges should offer more diverse course and program options, and encourage students to narrow down as slowly and symmetrically as possible during their undergraduate years. The undergraduate program should include core courses in the biology and the population ecology of fishes, and a fishery management course that includes coverage of the economic, legal, political, and policy aspects. Probably few students have time to specialize in a particular area of fishery biology before graduate school.