In this paper we will show how Qurashī patrilines and marriage records can be statistically analysed to generate an estimate of the tribe’s size at the time of Muḥammad. By extension this will also give us an estimate for the population size of Mecca. We will begin by using the marriage data preserved in a genealogical work to identify a cohort of adult Qurashī male contemporaries of Muḥammad. We will then divide this cohort into men who had (...) brothers versus those who did not. It will be shown that this ratio is exactly what we would expect if we were modelling a complete population and therefore it cannot be a sample. With this in place we can extrapolate the number of women and dependants that would have been linked to each man, giving us an estimate of the tribe’s size in the period. Supplementing this with selected historiographical data will give us the population size of Mecca. The resulting findings raise a series of questions concerning Qurashī origins that will then be addressed by applying a similar methodology to the eras before Muḥammad’s. This will illuminate the manner and timing of the emergence of the Quraysh as a distinct entity. (shrink)

We study the coupled dynamics of two populations of random replicators by means of statistical mechanics methods, and focus on the effects of relative population size, strategy correlations and heterogeneities in the respective cooperation pressures. To this end we generalise existing path-integral approaches to replicator systems with random asymmetric couplings. This technique allows one to formulate an effective dynamical theory, which is exact in the thermodynamic limit and which can be solved for persistent order parameters in a fixed-point (...) regime regardless of the symmetry of the interactions. The onset of instability can be determined self-consistently. We calculate quantities such as the diversity of the respective populations and their fitnesses in the stationary state, and compare results with data from a numerical integration of the replicator equations. -/- . (shrink)

Much human adaptation depends on the gradual accumulation of culturally transmitted knowledge and technology. Recent models of this process predict that large, well-connected populations will have more diverse and complex tool kits than small, isolated populations. While several examples of the loss of technology in small populations are consistent with this prediction, it found no support in two systematic quantitative tests. Both studies were based on data from continental populations in which contact rates were not available, and therefore these studies (...) do not provide a test of the models. Here, we show that in Oceania, around the time of early European contact, islands with small populations had less complicated marine foraging technology. This finding suggests that explanations of existing cultural variation based on optimality models alone are incomplete because demography plays an important role in generating cumulative cultural adaptation. It also indicates that hominin populations with similar cognitive abilities may leave very different archaeological records, a conclusion that has important implications for our understanding of the origin of anatomically modern humans and their evolved psychology. (shrink)

Just because an angel is better than a stone, it does not follow that two angels are better than one angel and one stone. So said Aquinas (Summa contra Gentiles III, 71), and the sentiment was echoed by Leibniz. In section 118 of the Theodicy he wrote: "No substance is either absolutely precious or absolutely contemptible in the sight of God. It is certain that God attaches more importance to a man than to a lion, but I do not know (...) that we can bc sure that he prefers one man to an entire species of lions." Even Kant was bitten by this bug. In one of his pre-Critical works he was moved to say, à propos of lice, that even though they “may in our eyes be as worthless as you like, nevertheless it is of more consequence to Nature to conserve this species as a whole than to conserve a small number of members of a superior species." In these passages Aquinas, Leibniz, and Kant gave expression to a distinctive and interesting view about the value of animal species and animal populations. At its simplest, this is the view that there is a special value in the existence of animal species or in the existence of a wide variety of different animal species. But the view also goes deeper than this. An animal species, after all, is nothing over and above the individual animals which make it up, and the value which it contributes to the world must therefore be some function of the values contributed by those individual animals. At the deepest level, what the view expressed by Aquinas, Leibniz, and Kant holds is that the value which an individual animal contributes to thc world is not constant but varies with the number.. (shrink)

While different worries about population size are present in public debates, political philosophers often take population size as given. This paper is an attempt to formulate a Rawlsian liberal egalitarian approach to population size: does it make sense to speak of ‘too few’ or ‘too many’ people from the point of view of justice? It argues that, drawing on key features of liberal egalitarian theory, several clear constraints on demographic developments – to the extent (...) that they are under our control – can be formulated. Based on these claims, we can clarify both the grounds and content of our obligations to future generations. (shrink)

An improved variant of the Jaya optimization algorithm, called Jaya2, is proposed to enhance the performance of the original Jaya sacrificing its algorithmic design. The proposed approach arranges the solutions in a ring topology to reduce the likelihood of premature convergence. In addition, the population size reduction is used to automatically adjust the population size during the optimization process. Moreover, the translation dependency problem of the original Jaya is discussed, and an alternative solution update operation is (...) proposed. To test Jaya2, we compare it with nine different optimization methods on the CEC 2020 benchmark functions and the CEC 2011 real-world optimization problems. The results show that Jaya2 is highly competitive on the tested problems where it generally outperforms most approaches. Having an easy-to-implement approach with little parameter tuning is highly desirable since researchers from different disciplines with basic programming skills can use it to solve their optimization problems. (shrink)

in Intergenerational Equity and Sustainability, edited by John Roemer and Kotaro Suzumura, (Palgrave Publishers Ltd., forthcoming 2007), ch.11.

Where there is a fixed population (i.e., who exists does not depend on what choice an agent makes), the deontic version of anonymous Paretian egalitarianism holds that an option is just if and only if (1) it is anonymously Pareto optimal (i.e., no feasible alternative has a permutation that is Pareto superior), and (2) it is no less equal than any other anonymously Pareto optimal option. We shall develop and discuss a version of this approach for the variable (...) class='Hi'>population case (i.e., where who exists does depend on what choice an agent makes). More specifically, we shall develop and discuss it in the context of a person-affecting framework—in which an option is just if and only if it wrongs no one according to certain plausible conditions on wronging. (shrink)

Strategies for combating climate change which advocate for human population limitation have recently been understandably criticised on the grounds that they embody a form of 'climate colonialism': a moral wrong that involves disproportionally shifting the burdens of climate change onto developing, historically exploited nations (which have low per capita emissions but high fertility rates) in order to offset burdens in affluent nations (which have high per capita emissions but low fertility rates). This article argues that once the relevance of (...) population growth to climate change has been correctly understood as working in tandem with consumption levels, this objection fails as a general criticism. Moreover, even if population could be ignored as a variable, the climate colonialism charge would re-emerge in a different form, since, at present population sizes, it would be environmentally catastrophic for developing nations to reach production ambitions which see their per capita emissions massively increase. Even if emission reductions in affluent nations are (rightly) prioritised, there are good reasons to prevent enormous growth of emissions in developing nations. Those environmental risks become much greater given those nations' projected population increases in the coming century. The article then explores how the necessary radical environmental policies pertaining to fertility rates might be enacted in non-coercive ways, reducing the sting of the ‘climate colonialism’ charge. The article ends by considering some reasons to be moderately sceptical about such policies. (shrink)

This chapter contains sections titled: The Malthusian Warning “Population Control” and its Critics “Leveling Off”: The Demographic Transition The Ethics of Population Programs Optimal Population Size: Fewer with More, or More with Less? A Thought‐Experiment About a Solution to the Population Problem References.

During the century before its final evacuation in 1930 the population of St Kilda declined from over 100 to 36. While undoubtedly emigration and natural disasters played a part in this depopulation, ongoing processes were also important. In particular, replacement levels were never sufficient to maintain a constant population size. In the early part of this period the main factor responsible was heavy neonatal mortality, almost all from tetanus (), but latterly the fertility of those who survived (...) was low, even though mortality rates had declined. In part at least, this decline in fertility could be ascribed to a lower frequency of marriage—a phenomenon seen elsewhere in the Outer Hebrides during the latter part of the 19th century. (shrink)

Population axiology concerns how to evaluate populations in terms of their moral goodness, that is, how to order populations by the relations “is better than” and “is as good as”. The task has been to find an adequate theory about the moral value of states of affairs where the number of people, the quality of their lives, and their identities may vary. So far, this field has largely ignored issues about uncertainty and the conditions that have been discussed mostly (...) pertain to the ranking of risk-free outcomes. Most public policy choices, however, are decisions under uncertainty, including policy choices that affect the size of a population. Here, we shall address the question of how to rank population prospects—that is, alternatives that contain uncertainty as to which population they will bring about—by the relations “is better than” and “is as good as”. We start by illustrating how well-known population axiologies can be extended to population prospect axiologies. And we show that new problems arise when extending population axiologies to prospects. In particular, traditional population axiologies lead to prospect-versions of the problems that they praised for avoiding in the risk-free settings. Finally, we identify an intuitive adequacy condition that, we contend, should be satisfied by any population prospect axiology, and show how given this condition, the impossibility theorems in population axiology can be extended to (non-trivial) impossibility theorems for population prospect axiology. (shrink)

Future population growth is uncertain and matters for climate policy: higher growth entails more emissions and means more people will be vulnerable to climate-related impacts. We show that how future population is valued importantly determines mitigation decisions. Using the Dynamic Integrated Climate-Economy model, we explore two approaches to valuing population: a discounted version of total utilitarianism (TU), which considers total wellbeing and is standard in social cost of carbon dioxide (SCC) models, and of average utilitarianism (AU), which (...) ignores population size and sums only each time period’s discounted average wellbeing. Under both approaches, as population increases the SCC increases, but optimal peak temperature decreases. The effect is larger under TU, because it responds to the fact that a larger population means climate change hurts more people: for example, in 2025, assuming the United Nations (UN)-high rather than UN-low population scenario entails an increase in the SCC of 85% under TU vs. 5% under AU. The difference in the SCC between the two population scenarios under TU is comparable to commonly debated decisions regarding time discounting. Additionally, we estimate the avoided mitigation costs implied by plausible reductions in population growth, finding that large near-term savings ($billions annually) occur under TU; savings under AU emerge in the more distant future. These savings are larger than spending shortfalls for human development policies that may lower fertility. Finally, we show that whether lowering population growth entails overall improvements in wellbeing—rather than merely cost savings—again depends on the ethical approach to valuing population. (shrink)

Population ethics contains several principles that avoid the repugnant conclusion. These rules rank all possible alternatives, leaving no room for moral ambiguity. Building on a suggestion of Parfit, this paper characterizes principles that provide incomplete but ethically attractive rankings of alternatives with different population sizes. All of them rank same-number alternatives with generalized utilitarianism.

The variance effective population size (NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eV}$$\end{document}) is frequently used to quantify the expected rate at which a population’s allele frequencies change over time. The purpose of this paper is to find expressions for the global NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eV}$$\end{document} of a spatially structured population that are of interest for conservation of species. Since NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} (...) \begin{document}$$N_{eV}$$\end{document} depends on allele frequency change, we start by dividing the cause of allele frequency change into genetic drift within subpopulations (I) and a second component mainly due to migration between subpopulations (II). We investigate in detail how these two components depend on the way in which subpopulations are weighted as well as their dependence on parameters of the model such a migration rates, and local effective and census sizes. It is shown that under certain conditions the impact of II is eliminated, and NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eV}$$\end{document} of the metapopulation is maximized, when subpopulations are weighted proportionally to their long term reproductive contributions. This maximal NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eV}$$\end{document} is the sought for global effective size, since it approximates the gene diversity effective size NeGD\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eGD}$$\end{document}, a quantifier of the rate of loss of genetic diversity that is relevant for conservation of species and populations. We also propose two novel versions of NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eV}$$\end{document}, one of which (the backward version of NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eV}$$\end{document}) is most stable, exists for most populations, and is closer to NeGD\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eGD}$$\end{document} than the classical notion of NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eV}$$\end{document}. Expressions for the optimal length of the time interval for measuring genetic change are developed, that make it possible to estimate any version of NeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{eV}$$\end{document} with maximal accuracy. (shrink)

Biologists studying short-lived organisms have become aware of the need to recognize an explicit temporal extend of a population over a considerable time. In this article we outline the concept and the realm of populations with explicit spatial and temporary boundaries. We call such populations “temporally bounded populations”. In the concept, time is of the same importance as space in terms of a dimension to which a population is restricted. Two parameters not available for populations that are only (...) spatially defined characterise temporally bounded populations: total population size, which is the total number of individuals present within the temporal borders, and total residence time, which is the sum of the residence times of all individuals. We briefly review methods to estimate these parameters. We illustrate the concept for the large blue butterfly (Maculinea nausithous) and outline insights into ecological and conservation-relevant processes that cannot be gained without the use of the concept. (shrink)

It is often claimed that reducing population size would be advantageous for climate change mitigation, on the grounds that lower population would naturally correspond to lower emissions. This apparently obvious claim is in fact seriously misleading. Reducing population size would indeed, other suitable things being equal, reduce the emissions rate. But it is well recognised that the primary determinant of the eventual amount of climate change is not the emissions rate, but rather cumulative emissions. It (...) is far less clear whether reducing population size would reduce cumulative emissions, or would in any other way prove an advantage for reasons related to climate change. This paper identifies and briefly discusses the issues relevant to assessing that less clear question. (shrink)

What are the prospects for using population policy as tool to reduce carbon emissions? In this paper, we review evidence from population science, in order to inform debates in population ethics that, so far, have largely taken place within the academic philosophy literature. In particular, we ask whether fertility policy is likely to have a large effect on carbon emissions, and therefore on temperature change. Our answer is no. Prospects for a policy of fertility-reduction-as-climate-mitigation are limited by (...) population momentum, a demographic factor that limits possible variation in the size of the population, even if fertility rates change very quickly. In particular, a hypothetical policy that instantaneously changed fertility and mortality rates to replacement levels would nevertheless result in a population of over 9 billion people in 2060. We use a leading climate-economy model to project the consequence of such a hypothetical policy for climate change. As a standalone mitigation policy, such a hypothetical change in the size of the future population-much too large to be implementable by any foreseeable government programme-would reduce peak temperature change only to 6.4°C, relative to 7.1°C under the most likely population path. Therefore, fertility reduction is unlikely to be an adequate core approach to climate mitigation. (shrink)

Biological studies have demonstrated that it is possible to slow the ageing process and extend lifespan in a wide variety of organisms, perhaps including humans. Making use of the findings of these studies, this article examines two problems concerning the effect of life extension on population size and welfare. The first—the problem of overpopulation—is that as a result of life extension too many people will co-exist at the same time, resulting in decreases in average welfare. The second—the problem (...) of underpopulation—is that life extension will result in too few people existing across time, resulting in decreases in total welfare. I argue that overpopulation is highly unlikely to result from technologies that slow ageing. Moreover, I claim that the problem of underpopulation relies on claims about life extension that are false in the case of life extension by slowed ageing. The upshot of these arguments is that the population problems discussed provide scant reason to oppose life extension by slowed ageing. (shrink)

Conservation Biologists have found that demographic stochasticity causes the mean time to extinction to increase exponentially with population size. This has proved helpful in analyses determining extinction times and characterizing the pathway to extinction. The aim of this investigation is to explore the possible interactions between environmental/demographic noises and the scaling effect of the mean population size with its variance, which is expected to follow Taylor’s power law relationship. We showed that the combined effects of environmental/demographic (...) noises and the scaling of population size variability interact with the population dynamics and affect the mean time to extinction. (shrink)

Recently, in his Rolf Schock Prize Lecture, Derek Parfit has suggested a novel way of avoiding the Repugnant Conclusion by introducing what he calls “imprecision” in value comparisons. He suggests that in a range of important cases, populations of different sizes are only imprecisely comparable. Parfit suggests that this feature of value comparisons opens up a way of avoiding the Repugnant Conclusion without implying other counterintuitive conclusions, and thus solves one of the major challenges in ethics. In this article, I (...) try to clarify Parfit's proposal and evaluate whether it will help us with the paradoxes in population ethics. (shrink)

Whole genome sequencing and SNP genotyping arrays can paint strikingly different pictures of demographic history and natural selection. This is because genotyping arrays contain biased sets of pre‐ascertained SNPs. In this short review, we use comparisons between high‐coverage whole genome sequences of African hunter‐gatherers and data from genotyping arrays to highlight how SNP ascertainment bias distorts population genetic inferences. Sample sizes and the populations in which SNPs are discovered affect the characteristics of observed variants. We find that SNPs on (...) genotyping arrays tend to be older and present in multiple populations. In addition, genotyping arrays cause allele frequency distributions to be shifted towards intermediate frequency alleles, and estimates of linkage disequilibrium are modified. Since population genetic analyses depend on allele frequencies, it is imperative that researchers are aware of the effects of SNP ascertainment bias. With this in mind, we describe multiple ways to correct for SNP ascertainment bias. (shrink)

The aim of this work is twofold. First, we survey the techniques developed in Perthame and Zubelli (Inverse Probl 23(3):1037–1052, 2007 ), Doumic et al. (Inverse Probl 25, 2009 ) to reconstruct the division (birth) rate from the cell volume distribution data in certain structured population structured population models. Secondly, we implement such techniques on experimental cell volume distributions available in the literature so as to validate the theoretical and numerical results. As a proof of concept, we use (...) the experimental data experimental data reported in the classical work of Kubitschek (Biophys J 9(6):792–809, 1969 ) concerning Escherichia coli in vitro experiments measured by means of a Coulter transducer-multichannel analyzer system (Coulter Electronics, Inc., Hialeah, FL, USA). Despite the rather old measurement technology, the reconstructed division rates still display potentially useful biological features. (shrink)

Contrary to political and philosophical consensus, we argue that the threats posed by climate change justify population engineering, the intentional manipulation of the size and structure of human populations. Specifically, we defend three types of policies aimed at reducing fertility rates: choice enhancement, preference adjustment, and incentivization. While few object to the first type of policy, the latter two are generally rejected because of their potential for coercion or morally objectionable manipulation. We argue that forms of each policy (...) type are pragmatically and morally justified tools for preventing the harms of global climate change. (shrink)

Scientists use models to understand the natural world, and it is important not to conflate model and nature. As an illustration, we distinguish three different kinds of populations in studies of ecology and evolution: theoretical, laboratory, and natural populations, exemplified by the work of R.A. Fisher, Thomas Park, and David Lack, respectively. Biologists are rightly concerned with all three types of populations. We examine the interplay between these different kinds of populations, and their pertinent models, in three examples: the notion (...) of “effective” population size, the work of Thomas Park on /Tribolium/ populations, and model-based clustering algorithms such as /Structure/. Finally, we discuss ways to move safely between three distinct population types while avoiding confusing models and reality. (shrink)

Population ethics is the subfield of philosophy that focuses on the moral aspects of how actions affect who exists in a particular population and what quality of life they have. The choices regarding what policies are adopted in response to climate change will affect the identities of those who exist in the future, the size of future populations, and the quality of life that future people will have. This chapter examines the nonidentity problem, various theoretical outlooks on (...) population ethics, some recent policy proposals aimed at reducing fertility, and the relationship between population reduction and the impacts of climate change. After summarizing the relevant issues, the relevance of the discourse to climate policy is highlighted, and points of consensus and dissensus are noted. Disagreement on some of the key theoretical questions in population ethics is significant and poses a challenge for deriving meaningful conclusions about climate policy. Fortunately, emerging points of consensus on other aspects of climate policy and its relationship to population provide reasons to think moral decision-making about these matters is far from hopeless. (shrink)

When applied to a family of sets, the term differentiation designates a measure of the totality of those members which appear in only one of the sets. This basic set theoretic concept involves the formation of intersections, unions, and complements of sets. However, populations as special kinds of sets may share types, but they do not share the carriers of these types; intersections of different populations are thus always empty. The resulting conceptual dilemma is resolved by considering the joint representation (...) of members of different populations that have the same type; populations then intersect with respect to joint representation of types. Two forms of representation reflect relative and absolute characteristics of differentiation by accounting for the distributions of types as relative frequencies within populations (as is commonly done) and as absolute frequencies (including effects of population sizes on differentiation), respectively. Corresponding classes of differentiation measures are developed, and existing measures are discussed in relation to these classes. In particular, the affinity of the measurement of distances between populations and the special case of differentiation of two-population families is examined in order to distinguish between the notions of distance and differentiation. (shrink)

Studies on the development of cell populations are often based on results of the theory of stochastic birth- and death-processes (continuous or discrete (seee.g. references inVogel, Niewisch &Matioli (1969), in some cases, death may be interpreted not as actual death of the cell bute.g. as a recruitment of the cell considered into another cell compartment, etc.). It is usually assumed that the conditions for the development are homogeneous,i.e. that the probabilities of births and deaths are independent on the time. However, (...) in most situations, this assumption is not fulfilled (owing to the maturation and differentiation of cells, changes of the microenvironment, inducing factors, etc.). Then it is necessary to study the development of cell populations under non-homogeneous conditions. In this paper, some properties of appropriate birth- and death-processes under nonhomogeneous conditions are studied; formulae given in section 4 permit calculation of some characteristics describing the cell population size distribution at individual discrete epochs (at individual generations) during the development of the cell population considered. (shrink)

Although there is empirical evidence of neural filling-in, this does not necessarily entail “isomorphic” theory. Most cortical neurons do not respond to a uniform surface and are instead sensitive to surface size and quality. I propose that a population of such neurons encodes the presence of a surface. This scheme is different from either the “cognitive” or “isomorphic” theories.

The House Sparrow (Passer domesticus), formerly a common bird species, has shown a rapid decline in Western Europe over recent decades. In The Netherlands, its decline is apparent from 1990 onwards. Many causes for this decline have been suggested that all decrease the vital rates, i.e. survival and reproduction, but their actual impact remains unknown. Although the House Sparrow has been dominant in The Netherlands, data on life history characteristics for this bird species are scarce: data on reproduction are non-existent, (...) and here we first present survival estimates based on live encounters and dead recoveries of marked individuals over the period 1976–2003, 14 years before and 14 years during the decline, reported to the Dutch Ringing Centre. We show that there is an indication that both juvenile and adult survival are lower during the period of decline. Secondly, to be able to analyse the relative impact of changes in the vital rates, we formulated a general matrix model based on a range of survival values between zero and one with a step size of 0.01 (both juvenile and adult yearly survival) and a range of realistic reproduction values (one, three or five fledglings per pair per year). With the matrix model, we calculated the finite rate of population change (λ) and applied elasticity analysis. To diagnose the cause of the decline in the Dutch House Sparrow, we parameterised the model with estimates of survival values before and during the decline and present the resulting λ. With the survival estimates from the declining period, λ < 1 only if reproduction is relatively low. We discuss this result within the light of available literature data on survival in the House Sparrow. Finally, we evaluate which of the suggested causes of population decline should be reversed to mitigate the decline and how this can be achieved. (shrink)

James V. Neel, one of the leading human geneticists of the 21st Century, has long been concerned about the consequences of human overpopulation and the accompanying destruction of the earth's ecosystem. His point of view, summarized in this paper, is contrasted with some recent optimistic projections presented by demographers and population biologists who believe the population bomb has been defused by evidence of a decrease in worldwide fertility along with a significant increase in food production. The authors of (...) this paper are not so optimistic and see a continuing need for concern rather than complacency based on ever increasing human wants and aspirations together with the minimal results of recent environmental summits. The case of HIV/aids is used to illustrate the evolutionary implications of the interaction between population dynamics and genetic change based on the concepts of population bottlenecks, genetic drift and founder effects. What becomes evident from this illustration is that epidemics by viral and other pathogens in the 21st Century can affect the size of human populations and thereby the course of the species' evolutionary makeup. The potential of evolutionary medicine and in particular molecular biology to improve our prediction capabilities and modulate some of the possible consequences is discussed. (shrink)

The exogenous cycles and population dynamics of the community at Penrith, Cumbria, England, have been studied (1557-1812) using aggregative analysis, family reconstitution and time series analysis. This community was living under marginal conditions for the first 200 years and the evidence presented is of a homeostatic regime where famine, malnutrition and epidemic disease acted to regulate the balance between resources and population size. This provides an ideal historic population for an investigation of the direct and indirect (...) effects of malnutrition. Throughout the period studied, a short wavelength oscillation in grain prices was apparently the major external factor that drove exogenous cycles in mortality, birth rate, and migration. In particular, the different responses of children to variations in food supply are emphasised; fluctuations in poor nutrition correlated significantly with the variations in mortality rates for infants (probably indirectly during pregnancy and directly during the first year of life) and for young children (via susceptibility to lethal infectious diseases). Migratory movements contributed to the maintenance of homeostasis in the population dynamics. A medium wavelength cycle in low winter temperatures was associated with a rise in adult mortality which, in turn, promoted an influx of migrants into this saturated habitat. A model incorporating these interacting associations between vital events and exogenous cycles is presented: grain prices were an important density-dependent factor and constituted the major component of the negative feedback of this population and drove the exogenous, short wavelength mortality cycles. Cycles of births and immigration provide a positive feedback for the build-up of susceptibles and the initiation of smallpox epidemics and increased population size. (shrink)

Some philosophers argue that we should limit procreation – for instance, to one child per person or one child per couple – in order to reduce our aggregate carbon footprint. I provide additional support to the claim that population size is a matter of justice, by explaining that we have a duty of justice towards the current generation of children to pass on to them a sustainable population. But instead of, or, more likely, alongside with, having fewer (...) children in in each family, we could also create families with more than two parents. I explore this possibility by pointing out the ways in which multi-parenting can advance children’s interests: in higher levels of well-being, in non-monopolistic child-rearing, and in a future opportunity to become themselves parents. (shrink)

The House Sparrow (Passer domesticus), formerly a common bird species, has shown a rapid decline in Western Europe over recent decades. In The Netherlands, its decline is apparent from 1990 onwards. Many causes for this decline have been suggested that all decrease the vital rates, i.e. survival and reproduction, but their actual impact remains unknown. Although the House Sparrow has been dominant in The Netherlands, data on life history characteristics for this bird species are scarce: data on reproduction are non-existent, (...) and here we first present survival estimates based on live encounters and dead recoveries of marked individuals over the period 1976–2003, 14 years before and 14 years during the decline, reported to the Dutch Ringing Centre. We show that there is an indication that both juvenile and adult survival are lower during the period of decline. -/- Secondly, to be able to analyse the relative impact of changes in the vital rates, we formulated a general matrix model based on a range of survival values between zero and one with a step size of 0.01 (both juvenile and adult yearly survival) and a range of realistic reproduction values (one, three or five fledglings per pair per year). With the matrix model, we calculated the finite rate of population change (λ) and applied elasticity analysis. To diagnose the cause of the decline in the Dutch House Sparrow, we parameterised the model with estimates of survival values before and during the decline and present the resulting λ. With the survival estimates from the declining period, λ < 1 only if reproduction is relatively low. We discuss this result within the light of available literature data on survival in the House Sparrow. Finally, we evaluate which of the suggested causes of population decline should be reversed to mitigate the decline and how this can be achieved. (shrink)

This handbook presents up-to-date theoretical analyses of problems associated with the moral standing of future people in current decision-making. Future people pose an especially hard problem for our current decision-making, since their number and their identities are not fixed but depend on the choices the present generation makes. Do we make the world better by creating more people with good lives? What do we owe future generations in terms of justice? Such questions are not only philosophically difficult and important, but (...) also directly relevant to many practical decisions and policy issues, including on climate, health, population control and taxation. If we are to adequately assess such issues, we must be able to determine the value of differently sized populations. The aim of this handbook is to shed light on the value of population change and the nature of our obligations to future generations, and to offer practical guidance to policy-makers as to how our duties to future generations should be discharged. It contains an extensive and accessible introduction for those unfamiliar with the topic of population ethics as well as original work from key figures in academic debates on population ethics covering three main themes: ways out of the paradoxes of population ethics, questioning some philosophical and methodological assumptions underlying these paradoxes, and several applications of population ethics to real world issues. (shrink)

Why do societies collapse? We use an individual-based evolutionary model to show that, in environmental conditions dominated by low-frequency variation (“red noise”), extirpation may be an outcome of the evolution of cultural capacity. Previous analytical models predicted an equilibrium between individual learners and social learners, or a contingent strategy in which individuals learn socially or individually depending on the circumstances. However, in red noise environments, whose main signature is that variation is concentrated in relatively large, relatively rare excursions, individual learning (...) may be selected from the population. If the social learning system comes to lack sufficient individual learning or cognitively costly adaptive biases, behavior ceases tracking environmental variation. Then, when the environment does change, fitness declines and the population may collapse or even be extirpated. The modeled scenario broadly fits some human population collapses and might also explain nonhuman extirpations. Varying model parameters showed that the fixation of social learning is less likely when individual learning is less costly, when the environment is less red or more variable, with larger population sizes, and when learning is not conformist or is from parents rather than from the general population. Once social learning is fixed, extirpation is likely except when social learning is biased towards successful models. Thus, the risk of population collapse may be reduced by promoting individual learning and innovation over cultural conformity, or by preferential selection of relatively fit individuals as models for social learning. © 2009 Elsevier Inc. All rights reserved. (shrink)

This book presents Bertram Murray's philosophy of science, unpublished papers, and rebuttals to critics of these papers. Subjects include clutch size, population dynamics, life history tables, and mating systems.

New advances in genomics changed the research landscape significantly in the last few years. The power and significance of already existing tissue collections is enhanced by their growing size, and all over the world national projects aim to connect with each other at the international level, calling for integrated and common regulations in the transnational research field. The post genomics era faces problems that are partially different from those within the classical bioethical framework. The challenge is to find new (...) ways to deal with regulations in order to facilitate research without frustrating personal rights. Informed Consent has been the center of this wide debate. We propose a model for rethinking consent in an open-time/open-goal framework suitable to genomics research. Consensus becomes more than a single legal step and goes more in the direction of a participated governance mechanism, a circular open process of communication which the IC sheet signature is just one instance of. This approach provides a governance framework based on different levels of consensus and participation that already contains mechanisms to resolve conflicts between different instances and to protect both the interest of research and the rights of participants. (shrink)