scholarly journals Demographic Theory and Population Ethics – Relationships between Population Size and Population Growth

2021 ◽  
Author(s):  
Martin Kolk

Demographic theory aims at explaining how population systems regulate themselves given available resources. Population ethics is concerned with demography in the sense that the analytical objects of interest are births, deaths, and populations. However, demographic theory which explores theoretically when, how and why populations grow, based on empirically observed patterns, has up until now played a minor role in population ethics. Similarly, debates about population dynamics among demographers have seldom been concerned with ideas and concepts in population ethics. In this manuscript, I will give a brief outline of how population size, population growth, and welfare mutually affect each other. Theories on the endogeneity between population size, population growth, and welfare will be referred to as demographic theory. I will give a particular focus on how population growth responds with respect to welfare, as welfare, utility, well-being, and happiness are important concepts in population ethics. A key concept in demographic theory is population homeostasis (the dynamics of a system which maintains a population at a steady population size, or growth rate), in particular resource dependent homeostasis. I will also discuss demographic theory in relation to historical and future demographic change. This working paper was later published in Oxford Handbook of Population Ethics, and is available at https://osf.io/preprints/socarxiv/at5pj/

2021 ◽  
Author(s):  
Martin Kolk

Demographic theory is concerned with how population systems regulate themselves given available resources and external shocks to population size. This chapter provides an overview of demographic theory, focusing specifically on relationships between population size, population growth, and welfare. It then discusses four implications of demographic theory for population ethics. Speaking broadly, these four implications concern (1) the overreliance by some population ethicists on Malthusian assumptions about the average welfare of population declining with increasing population size, (2) the likelihood of certain hypothetical scenarios that feature in thought experiments used in population ethics, (3) the prioritization of extinction risks by population ethicists, and (4) the patterns of intergenerational and intertemporal inequality that population ethicists may anticipate over the long run. The chapter closes with a discussion of demographic theory in relation to historical and future demographic change.


2004 ◽  
Vol 4 (11/12) ◽  
pp. 2553-2560 ◽  
Author(s):  
M. Kulmala ◽  
L. Laakso ◽  
K. E. J. Lehtinen ◽  
I. Riipinen ◽  
M. Dal Maso ◽  
...  

Abstract. The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent – mainly condensational – growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm (diameter) in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhanced growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.


2010 ◽  
Vol 29 (1) ◽  
pp. 1-9
Author(s):  
Francois P. Retief ◽  
Louise C. Cilliers

Astrology is a pseudo-science based on the assumption that the well-being of humankind, and its health in particular, is influenced in a constant and predictable fashion by the stars and other stellar bodies. Its origins can probably be traced back to Mesopotamia of the 3rd millennium BC and was particularly popular in Graeco-Roman times and the Medieval Era. Astrology in Western countries has always differed from that in the Far East, and while it largely lost its popularity in the West after the Renaissance, it still remains of considerable significance in countries like China and Tibet. Astrology took on a prominent medical component in the Old Babylonian Era (1900-1600 BC) when diseases were first attributed to stellar bodies and associated gods. In the Neo-Babylonian Era (6th century BC) the zodiac came into being: an imaginary belt across the skies (approximately 16o wide) which included the pathways of the sun, moon and planets, as perceived from earth. The zodiac belt was divided into 12 equal parts (“houses” or signs), 6 above the horizon and 6 below. The signs became associated with specific months, illnesses and body parts – later with a number of other objects like planets, minerals (e.g. stones) and elements of haruspiction (soothsaying, mantic, gyromancy). In this way the stellar objects moving through a zodiac “house” became associated with a multitude of happenings on earth, including illness. The macrocosm of the universe became part of the human microcosm, and by studying the stars, planets, moon, etcetera the healer could learn about the incidence, cause, progress and treatment of disease. He could even predict the sex and physiognomy of unborn children. The art of astrology and calculations involved became very complex. The horoscope introduced by the 3rd century BC (probably with Greek input) produced a measure of standardisation: a person’s position within the zodiac would be determined by the date of birth, or date of onset of an illness or other important incident, on which information was needed. Egyptian astrological influence was limited but as from the 5th century BC onwards, Greek (including Hellenistic) input became prominent. In addition to significant contributions to astronomy, Ptolemy made a major contribution to astrology as “science” in his Tetrabiblos. Rational Greek medicine as represented by the Hippocratic Corpus did not include astrology, and although a number of physicians did make use of astrology, it almost certainly played a minor role in total health care. Astrology based on the Babylonian-Greek model also moved to the East, including India where it became integrated with standard medicine. China, in the Far East, developed a unique, extremely complex variety of astrology, which played a major role in daily life, including medicine. During Medieval times in the West, astrology prospered when the original Greek writings (complemented by Arabic and Hebrew contributions) were translated into Latin. In the field of medicine documents falsely attributed to Hippocrates and Galen came into circulation, boosting astrology; in the young universities of Europe it became taught as a science. It was, however, opposed by the theologians who recognised a mantic element of mysticism, and it lost further support when during the Renaissance, the spuriousness of the writings attributed to the medical icons, Hippocrates and Galen, became evident. Today Western standard medicine contains no astrology, but in countries like China and Tibet it remains intricately interwoven with health care. In common language we have a heritage of words with an astrological origin, like “lunatic” (a person who is mentally ill), “ill-starred”, “saturnine” (from Saturn, the malevolent plant) and “disaster” (from dis, bad, and astra, star).


1970 ◽  
Vol 17 ◽  
pp. 145-146
Author(s):  
U. Horstman ◽  
A. Colina ◽  
W. Schramm

Eucheuma striatum and Eucheuma spinosum, are red algae of commercial value because of their carrageenin content, to an increasing extent are cultivated in the Philippines. The influence of environmental factors on growth rate and photosynthesis of these seaweeds were studied through observations in their natural biotope in seaweed farms, from in-situ experiments, and photosynthesis experiments in an incubator. While difference in light intensity and temperature play only a minor role, the algae were found out to be sensitive to low salinity and to the amount of dissolved gases and nutrients in the surrounding seawater. The algae can only be cultured in areas where there is sufficient current but to a cer-tain extent lack of current can be compensated by exposing the plants to wave action. This leads to certain conclusions regarding the most suitable method of commercial Eucheuma culture. Eucheuma can be successfully cultured in small rafts or in floating baskets in areas where there is insufficient current for the use of fixed nets or strings. There is evidence that-the CO2 -02 metabolism in the surrounding water plays an important role in Eucheuma growth. Eucheuma harvest can be further increased by introducing more nutrients. Fertilizing with phosphate caused a bigger increase in growth rate than with nitrogen. The method of spraying plants after temporarily removing them from the water, found to be more effective than fertilizing solutions by the use of clay pots. The presence of a bacterial disease, locally referred to as "ice-ice", was recognized as a clear indication that certain environment conditions were unfavourable for Eucheuma culture. Low salinity, in the first place, but also lack of current favors the attack of "ice-ice". Finally, it was found that Eucheuma adapts itself to its culture site in such a way that after maintaining seedlings in an area for a sufficient length of time, the cultured plants showed better growth rates and were resistent to unfavorable conditions than plants recently transferred to the area.


2021 ◽  
Author(s):  
Anna Fijarczyk ◽  
Mathieu Hénault ◽  
Souhir Marsit ◽  
Guillaume Charron ◽  
Christian R Landry

Mutation rates and spectra vary between species and among populations. Hybridization can contribute to this variation but its role remains poorly understood. Estimating mutation rates requires controlled conditions where the effect of natural selection can be minimized. One way to achieve this is through mutation accumulation experiments coupled with genome sequencing. Here we investigate 400 mutation accumulation lines initiated from 11 genotypes spanning intra-lineage, inter-lineage and interspecific crosses of the yeasts Saccharomyces paradoxus and S. cerevisiae, and propagated for 770 generations. We find significant differences in mutation rates and spectra among crosses, which are not related to the level of divergence of parental strains, but are genotype specific. We find that departures from neutrality, differences in growth rate, ploidy and loss of heterozygosity only play a minor role as a source of variation and conclude that unique combinations of parental genotypes drive distinct rates and spectra in some crosses.


2009 ◽  
Vol 6 (41) ◽  
pp. 1121-1134 ◽  
Author(s):  
Joel C. Miller

Networks of person-to-person contacts form the substrate along which infectious diseases spread. Most network-based studies of this spread focus on the impact of variations in degree (the number of contacts an individual has). However, other effects such as clustering, variations in infectiousness or susceptibility, or variations in closeness of contacts may play a significant role. We develop analytic techniques to predict how these effects alter the growth rate, probability and size of epidemics, and validate the predictions with a realistic social network. We find that (for a given degree distribution and average transmissibility) clustering is the dominant factor controlling the growth rate, heterogeneity in infectiousness is the dominant factor controlling the probability of an epidemic and heterogeneity in susceptibility is the dominant factor controlling the size of an epidemic. Edge weights (measuring closeness or duration of contacts) have impact only if correlations exist between different edges. Combined, these effects can play a minor role in reinforcing one another, with the impact of clustering the largest when the population is maximally heterogeneous or if the closer contacts are also strongly clustered. Our most significant contribution is a systematic way to address clustering in infectious disease models, and our results have a number of implications for the design of interventions.


Author(s):  
C. Y. Cyrus Chu

The Malthusian theory hypothesizes that the natural environment imposes various capacity constraints on human population growth and that population size has been and will be checked by these constraints. In such a classical theory, which was presumably motivated by observations of the ancient world, population might be the most important dynamic variable, although its role is rather passive: population is a variable that would be affected by, but would not affect, the environment. Boserup (1981), however, sees the role of population in the development of human economy as more consequential. She gave many persuasive examples that showed that, at least for the period up to the mid-twentieth century, population size might be a variable which actively spurred technological progress. This is also the viewpoint held by Lee (1986) and Pryor and Maurer (1982). After the Industrial Revolution, the role of population in economic dynamics, along with the reduction of mortality fluctuations and the increasing control of female fertility, evidently became secondary. The key variable that dominates the analysis of economic dynamics in the neoclassical growth theory along the lines of Solow (1956) is capital (or per capita capital). In Solow’s growth model, the role of population is minimal in the steady state: neither the level nor the growth rate of the steady-state per capita consumption has anything to do with the size of a population; only the steady-state per capita income level will be affected by the population growth rate. The growth pattern in the latter half of the twentieth century is markedly different. A key feature of our recent growth experience is the rapid innovation of new technologies. Modern growth theory has embraced the concept of increasing returns to explain such a unique growth pattern. However, various versions of the theory of increasing returns turn out to be necessarily linked to population. The hypothesis of learning by doing implies that growth in productivity is an increasing function of aggregate production, which is itself positively related to the size of population.


2004 ◽  
Vol 4 (5) ◽  
pp. 5433-5454 ◽  
Author(s):  
O. Kulmala ◽  
L. Laakso ◽  
K. E. J. Lehtinen ◽  
I. Riipinen ◽  
M. Dal Maso ◽  
...  

Abstract. The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent – mainly condensational – growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhance growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.


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