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PubMedDate not supplied

The consumption bomb.

The explosion of the population bomb has long been predicted to cause massive famine in overpopulated countries. Rising consumption, even in a time of decreasing population growth rates, now threatens adverse global health effects more severe than localised famines. The world faces potential ecological entrapment. This has two dimensions: planetary eco-impoverisation and planetary eco-pathology. Eco-impoverisation, the depletion of natural capital, arises as the limit of the global human carrying capacity approaches. Eco-pathology, the disruption of ecological support systems, arises because of the way the biosphere has been modified by human activity and is caused particularly by unsustainable consumption for human purposes. Despite encroaching ecological entrapment, the dominant economic paradigm claims record levels of growth; a paradox that needs recognition. Reasons for denial of the gravity of ecological entrapment are discussed. Ways are suggested to defuse the consumption bomb and avert ecological entrapment.

Conservation of Natural Resources↗
PubMed2003

The evolutionary roots of our environmental problems: toward a Darwinian ecology.

It is widely acknowledged that we need to stabilize population growth and reduce our environmental impact; however, there is little consensus about how we might achieve these changes. Here I show how evolutionary analyses of human behavior provide important, though generally ignored, insights into our environmental problems. First, I review increasing evidence that Homo sapiens has a long history of causing ecological problems. This means that, contrary to popular belief, our species' capacity for ecological destruction is not simply due to "Western" culture. Second, I provide an overview of how evolutionary research can help to understand why humans are ecologically destructive, including the reasons why people often overpopulate, overconsume, exhaust common-pool resources, discount the future, and respond maladaptively to modern environmental hazards. Evolutionary approaches not only explain our darker sides, they also provide insights into why people cherish plants and animals and often support environmental and conservation efforts (e.g., Wilson's "biophilia hypothesis"). Third, I show how evolutionary analyses of human behavior offer practical implications for environmental policy, education, and activism. I suggest that education is necessary but insufficient because people also need incentives. Individual incentives are likely to be the most effective, but these include much more than narrow economic interests (e.g., they include one's reputation in society). Moralizing and other forms of social pressure used by environmentalists to bring about change appear to be effective, but this idea needs more research. Finally, I suggest that integrating evolutionary perspectives into the environmental sciences will help to break down the artificial barriers that continue to divide the biological and social sciences, which unfortunately obstruct our ability to understand ourselves and effectively address our environmental problems.

Animals↗
PubMed2003

An ethical assessment of anti-aging medicine.

This assessment presents and evaluates various ethical arguments for and against anti-aging medicine. After briefly defining human aging and how it could be viewed as a medical problem, the paper reviews scientific evidence that indicates that medical intervention could substantially change the rate of human aging in the foreseeable future. This evidence includes research in biochemistry, cell, and molecular biology (including research on mitochondrial DNA and oxidative stress as well as research on cellular and molecular replacement interventions), non-human animal studies, and human studies. The following six ethical arguments against anti-aging medicine are presented and evaluated: 1) inequity: the poor die young by the millions, while the rich refuse to age; 2) denying aging's immutability; 3) dominating nature, altering and commodifying ourselves; 4) overpopulation: carrying capacity concerns and the rights of future people to be born; 5) ennui: with no natural deadline, life itself outlives its value; 6) ageism: prejudice against the old and the young. The paper then evaluates four ethical arguments in favor of anti-aging medicine: 1) beneficence: duties to maintain health and prevent disease and death; 2) efficiency: slowing down aging would reduce the rates for all of the most common causes of death in developed societies; 3) limited autonomy: freedom to purchase anti-aging medicines that may or may not work, so long as they are not harmful; 4) improved quality of life: more active, healthier, and wiser (two propositions supporting this argument - that anti-aging medicine would allow for a longer, more active, healthier, and fuller life and that wisdom comes from experience, not senescence - are also presented and evaluated). The arguments in favor of anti-aging medicine are found to be more compelling than the arguments against it. The paper concludes with the recommendation that anti-aging medicine should be funded and regulated in ways that facilitate its potential both to reduce the incidence and prevalence of many diseases and to allow for longer, fuller, and more meaningful lives.

Aged↗
PubMedDate not supplied

Selective primary health care: strategies for control of disease in the developing world. XI. Dengue.

Since World War II, dengue viruses have progressively extended their geographic domain and have increased as causes of human morbidity and mortality. This complex of four flaviviruses is principally transmitted to humans by the bite of Aedes aegypti, the yellow fever vector. Factors that promote the indoor storage of water are congenial to the breeding of A. aegypti. These include the dislocations of wars, overpopulation , and urbanization. By the mid-20th century, A. aegypti eradication campaigns had nearly succeeded in much of the Western Hemisphere. Since then, there has been a steady degradation in ability to cope with this species despite the fact that a newly emerged, severe immunopathologic disorder, dengue hemorrhagic fever/dengue shock syndrome, endows dengue epidemics with grave consequences. Development of a vaccine against dengue is complicated by the need to develop four different live attenuated vaccines and by a justifiable caution imposed by dengue immunopathology. A wide range of proven methods have been and are available to reduce populations of A. aegypti. This paper argues that the eradication strategy adopted earlier in this century is still viable and cost effective. Critical to a successful control program is a prioritied approach, a thorough, disciplined planning effort, a commitment to assessment, adequate compensation of staff, and, above all, the will to succeed.

Aedes↗
PubMed1995

Designer contraceptive pills.

The present world population of 5.6 billion is projected to reach 9 billion by the year 2025. Overpopulation remains one of the overwhelming issues of the 21st century, but only limited effort and resources have been allocated to designing new contraceptives, as evidenced by the diminished interest of the pharmaceutical industry and funding agencies. Major advances have been made recently in our understanding of the genetic basis of an individual's risk to various reproductive cancers and sex steroid-related diseases. It has also become apparent that agonistic and antagonistic analogues of sex steroids with tissue-specific actions can be formulated. These new insights provide the opportunity to develop the next generation of 'designer' contraceptive pills with disease-prevention benefits.

Contraceptives, Oral, Hormonal↗
PubMed2003

How Helicobacter pylori urease may affect external pH and influence growth and motility in the mucus environment: evidence from in-vitro studies.

BACKGROUND: Survival of Helicobacter pylori is dependent upon urease in the cytoplasm and at the bacterial surface. We have sought to clarify how alkaline ammonium salts, released from urea by this enzyme, might alter mucus pH and so affect growth and motility of the bacterium in the gastric mucus environment. METHODS: Experiments were conducted in vitro to determine how the growth and motility of H. pylori are affected by changes in external pH, and how the bacterium, by hydrolysing urea, alters the pH of the bicarbonate buffer that occurs at the gastric mucosal surface. These data were fitted into experimental models that describe how pH varies within the mucus layer in the acid-secreting stomach. RESULTS: H. pylori was motile between pH 5 and 8, with optimal motility at pH 5. It grew between pH 6 and 8, with optimal growth at pH 6. The bacterium had urease activity between pH 2.7 and 7.4, as evidenced by pH rises in bicarbonate-buffered solutions of urea. Changes in buffer pH were dependent upon initial pH and urea concentration, with the greatest rate of pH change occurring at pH 3. Modelling experiments utilizing these data indicated that (1) in the absence of urease, H. pylori growth and motility in the mucus layer would be restricted severely by low mucus pH in the acid-secreting stomach, and (2) urease will sometimes inhibit H. pylori growth and motility in the mucus layer by elevating the pH of the mucus environment above pH 8. CONCLUSIONS: Urease is essential to the growth and motility of H. pylori in the mucus layer in the acid-secreting stomach, but, paradoxically, sometimes it might suppress colonization by raising the mucus pH above 8. This latter effect may protect the bacteria from the adverse consequences of overpopulation.

Bicarbonates↗
PubMed2006

Ovulation, pregnancy, placentation and husbandry in the African elephant (Loxodonta africana).

The African elephant reproduces so efficiently in the wild that overpopulation is now a serious problem in some game parks in Zimbabwe, Botswana and South Africa. The female reaches puberty between 10 and 12 years of age in the wild and, when in captivity, shows oestrous cycles of 14-15 weeks duration. She readily conceives a singleton in the wild yet her uterus has the capacity for twins. She shows a gestation length of 22 months and, in the wild, shows a population density and feed dependent intercalving interval of 4-8 years. The trophoblast erodes the lumenal epithelium of the endometrium and stimulates upgrowths of blood vessel-containing stromal villi, which develop eventually into the broad, tightly folded lamellae of the zonary, endotheliochorial placenta. Significant quantities of leaked maternal erythrocytes and ferric iron are phagocytosed by specialized trophoblast cells in the haemophagous zones at the lateral edges of the placental band. Although the placenta itself is endocrinologically inert, the foetal gonads, which enlarge greatly during the second half of pregnancy can synthesize 5alpha-dihydryoprogesterone and other 5alpha pregnane derivatives from cholesterol and pregnenolone. These products may synergize with progestagens secreted by the 2-8 large corpora lutea which are always present in the maternal ovaries throughout gestation to maintain the pregnancy state.

Animal Husbandry↗
PubMed2002

Driven inelastic Maxwell models with high energy tails.

The solutions of the homogeneous nonlinear Boltzmann equation for inelastic Maxwell models, when driven by different types of thermostats, show, in general, overpopulated high energy tails of the form approximately exp(-ac), with power law tails and Gaussian tails as border line cases. The results are compared with those for inelastic hard spheres, and a comprehensive picture of the long time behavior in freely cooling and driven inelastic systems is presented.

Journal Article↗
PubMed2002

Driven low density granular mixtures.

We study the steady state properties of a two-dimensional granular mixture in the presence of energy driving by employing simple analytical estimates and direct simulation Monte Carlo. We adopt two different driving mechanisms, (a) a homogeneous heat bath with friction and (b) a vibrating boundary (thermal or harmonic) in the presence of gravity. The main findings are the appearance of two different granular temperatures, one for each species; the existence of overpopulated tails in the velocity distribution functions and of nontrivial spatial correlations indicating the spontaneous formation of cluster aggregates. In the case of a fluid subject to gravity and to a vibrating boundary, both densities and temperatures display nonuniform profiles along the direction normal to the wall, in particular, the temperature profiles are different for the two species while the temperature ratio is almost constant with the height. Finally, we obtained the velocity distributions at different heights and verified the non-Gaussianity of the resulting distributions.

Journal Article↗
PubMed2004

Gaussian kinetic model for granular gases.

A kinetic model for the Boltzmann equation is proposed and explored as a practical means to investigate the properties of a dilute granular gas. It is shown that all spatially homogeneous initial distributions approach a universal "homogeneous cooling solution" after a few collisions. The homogeneous cooling solution (HCS) is studied in some detail and the exact solution is compared with known results for the hard sphere Boltzmann equation. It is shown that all qualitative features of the HCS, including the nature of overpopulation at large velocities, are reproduced by the kinetic model. It is also shown that all the transport coefficients are in excellent agreement with those from the Boltzmann equation. Also, the model is specialized to one having a velocity independent collision frequency and the resulting HCS and transport coefficients are compared to known results for the Maxwell model. The potential of the model for the study of more complex spatially inhomogeneous states is discussed.

Journal Article↗
PubMed2004

Nucleation rate of critical droplets on an elastic string in a phi6 potential.

We obtain the nucleation rate of critical droplets for an elastic string moving in a phi(6) local potential and subject to noise and damping forces. The critical droplet is a bound soliton-antisoliton pair that carries a section of the string out of the metastable central minimum into one of the stable side minima. The frequencies of small oscillations about the critical droplet are obtained from a Heun equation. We solve the Fokker-Planck equation for the phase-space probability density by projecting it onto the eigenfunction basis obtained from the Heun equation. We employ Farkas' "flux-overpopulation" method to obtain boundary conditions for solving the Fokker-Planck equation; these restrict the validity of our solution to the moderate to heavy damping regime. We present results for the rate as a function of temperature, well depth, and damping.

Journal Article↗
PubMed1998

Is it good to make happy people?

Would it be good, other things being equal, for additional people to exist whose lives would be worth living? I examine and reject several arguments for the answer that it would not be good; then I offer opposing arguments that I believe are more successful. Thus, I agree with utilitarians who say that it is better for there to be more happy people. Next I argue for the stronger claim that the happiness of potential people is as important as that of adults. Potential quality of life, then, matters in a host of bioethical issues: abortion, commercial surrogacy, the treatment of defective newborns, and so on. What is the practical upshot of all this? I reject the idea that we must do whatever is necessary to prolong life worth living. But I also reject the view that the side-effects of overpopulation always outweigh the value of realizing potential happiness. So I advocate a middle position, which I do not identify precisely. Even from this middle position, however, potential happiness is more important that is commonly assumed in bioethics.

Age Factors↗
PubMed1995

Reproductive technologies in developing countries.

Are there any ethical concerns about reproductive technologies that are specific or unique to developing countries? Three ethical concerns often mentioned specifically in regard to developing countries are (1), the "overpopulation argument"; (2) the limited resources argument; and (3) the ethical problem of poorly trained practitioners offering their services to unsuspecting and uninformed infertile individuals or couples. Each argument is explored in some detail, with the conclusion that ethical problems do, in fact, exist but are not unique to developing countries. Nevertheless, the difficulties relating to reproductive technologies are likely to be greater in developing countries than in developed ones because of limited resources and a larger number of poor people residing there.

Delivery of Health Care↗
PubMed1996

The argument from transfer.

Utilitarian arguments on bioethical issues regarding human reproduction typically start with the view that it is wrong, other things being equal, not to procreate when this would have resulted in an additional being with a life worth living. The paper takes this view for granted and examines the common utilitarian claim that overpopulation and destitution in the world mean that, in practice, this obligation to procreate, other things being equal, often turns into a (categorical) obligation not to procreate. A version of this argument is defended -- a version called the argument from transfer -- according to which, rather than having additional children and care for them in order to make them happy, many people in the West ought to abstain from procreation and take care of destitute children already existing. The reasoning leading up to this conclusion raises some philosophical questions, seldom discussed in connection with bioethics, which indicate that the argument from transfer, although supporting the claim above, cannot neutralise the obligation to create more happy people as easily as assumed by utilitarians. It is argued that the argument from transfer may place many people facing the choice of procreation in a peculiar moral dilemma.

Child↗
PubMed2006

Host physiological status determines phage-like particle distribution in the lysate.

Bacteriophage morphotype diversity and latent period duration upon induction were correlated with the host population growth. The prophages of the lysogenic Vibrio sp. (DSM14379) were induced with mitomycin C in a batch culture with different salinity, substrate concentration or composition, and at different temperatures. Under all experimental conditions, phages were induced and a population of different complete and incomplete phage-like particles was observed in the lysate. Under favorable growth conditions, the phage-like particle community in the lysate was overpopulated with phage tail-like rigid rods. The number of rods was reduced in samples with low organic carbon concentration, samples with 8% and 10% NaCl, and samples induced at 40 and 43 degrees C. Although all lysates contained all phage-like particle-size fractions, their relative abundances varied. Up to a fivefold difference in phage-like particle size was observed in lysates. Size distribution of phage-like particles changed along temperature, salinity and organic carbon gradients. Results also indicated that the latent period of the induced phage-like particle population converged to approximately 90 min above a growth rate of 1.0 h(-1). At lower host growth rates, the latent period generally increased. However, at 40 and 43 degrees C and at low peptone-yeast extract concentration in the growth medium, the latent period remained short. We propose that different host physiological conditions influence organic matter composition upon prophage induction and may thus affect virus-controlled flow of the energy and carbon in the ecosystem.

Bacteriophages↗
PubMed1997

Sperm antigens and their use in the development of an immunocontraceptive.

PROBLEM: Overpopulation is a global problem of significant magnitude, with grave implications for the future. World population is predicted to reach 10 billion people by the year 2050, an increase of more than 75% over the current population. Development of new contraceptives is necessary, since current forms of birth control are unavailable to many individuals due to sociological, financial, or educational limitations. METHODS: In an effort to identify new contraceptive alternatives, sperm-specific antigens are under the investigation as the basis for immunological regulation of fertility through contraceptive immunization. Anti-sperm antibodies (ASA) inhibit sperm function in vitro, induce infertility in experimental models, and have been implicated in some cases of clinical infertility. Furthermore, the development of ASA in vasectomized men does not lead to physiological complications despite the persistence of these antibodies for years; thus, ASA induced by immunization of men and women may be similarly harmless. Immunization has several conceptual advantages as a method of fertility regulation. Employment of non-pharmacologically active agents, convenience of administration, low cost, and the potential for relatively long-lasting yet reversible effects. RESULTS: Various approaches have been taken to identify candidate sperm antigens for immunocontraceptive development. Studies that utilized monoclonal antibodies and polyclonal antisera generated against sperm preparations have identified such promising candidates as PH-20, fertilin, SP-17, and SP-10. In animal model, 100% contraceptive effects were induced following PH-20 immunization and the effects were reversible. More recently, ASA from the sera of infertile patients were employed to identify several candidates as expressed by testis cDNA libraries. Perhaps the most extensively characterized and effective immunogen candidate identified thus far is lactate dehydrogenase-C4 (LDH-C4). Active immunization with LDH-C4 suppressed fertility in a variety of mammalian species, including primates, and the reversibility of these effects was demonstrated. CONCLUSION: The successful results obtained thus far support the feasibility of an effective immunocontraceptive and indicate the importance for continued investigation of additional sperm antigens as contraceptive immunogen candidates.

Contraception, Immunologic↗
PubMed1967

Changing man.

The human condition is changing both culturally and biologically. Although the cultural evolution overshadows the biological, the two are connected by feedback relationships; culture has a biological foundation. Natural selection continues to operate in modern mankind, but its action ought to be supplemented by artificial selection. The problems of the management of human evolution are, however, as much sociological as they are biological. The success of any eugenical program depends on the creation of favorable conditions for human development and self-actualization. In particular, the urgency of the problem of uncontrolled overpopulation exceeds at present that of genetic improvement. Contrary to the alarmist views of some biologists, the evolutionary perspectives for the human species may be regarded as favorable, although, of course, subject to improvement. Man should be the maker of his history, including his evolutionary history. The trend toward increasing social mobility and equality of opportunity may have desirable genetic effects because of the positive assortative mating which it encourages. It makes possible the realization of many hitherto concealed genetically conditioned talents and aptitudes. Rapid progress of both molecular and organismic, Cartesian and Darwinian, biology gives hope of development of new and powerful methods of genetic engineering, control of gene action, betterment of the environment, and improved understanding of the evolutionary processes in the living world, including man.

Biological Evolution↗
PubMed1981

Promotion of the translocation of enteric bacteria from the gastrointestinal tracts of mice by oral treatment with penicillin, clindamycin, or metronidazole.

Specific pathogen-free mice were treated orally with antibiotics to determine whether the resulting disruption of the normal flora ecology would allow certain gram-negative enteric bacteria to overpopulate the ceca, thereby promoting the translocation of these bacteria from the gastrointestinal tract. The mice were treated orally with penicillin, clindamycin, or metronidazole for 4 days, and then the antibiotic was discontinued. The mice were tested at various intervals for viable enteric bacilli translocating from the gastrointestinal tract to the mesenteric lymph nodes. Penicillin treatment decreased the total anaerobe population levels in the ceca an average of 1,000-fold, whereas clindamycin treatment decreased these anaerobe levels only 10-fold, and metronidazole treatment slightly increased the anaerobe levels. Penicillin or metronidazole treatment slightly increased the anaerobe levels. Penicillin or metronidazole treatment increased the enteric bacilli populations in the ceca an average of 1,000-fold, whereas clindamycin treatment increased the enteric bacilli populations 100,000-fold. The peak incidence of translocation of the enteric bacilli to the mesenteric lymph nodes averaged 100% after penicillin treatment, 97% after clindamycin treatment, and 62% after metronidazole treatment. Thus, oral treatment of mice with penicillin, clindamycin, or metronidazole for only 4 days disrupts the normal flora ecology, allowing an overgrowth in the ceca of the gram-negative enteric bacilli and promoting their translocation to the mesenteric lymph nodes.

Administration, Oral↗