Hamilton goes empirical: estimation of inclusive fitness from life-history data.
(1/20)
Hamilton's theory of kin selection is one of the most important advances in evolutionary biology since Darwin. Central to the kin-selection theory is the concept of inclusive fitness. However, despite the importance of inclusive fitness in evolutionary theory, empirical estimation of inclusive fitness has remained an elusive task. Using the concept of individual fitness, I present a method for estimating inclusive fitness and its components for diploid organisms with age-structured life histories. The method presented here: (i) allows empirical estimation of inclusive fitness from life-history data; (ii) simultaneously considers all components of fitness, including timing and magnitude of reproduction; (iii) is consistent with Hamilton's definition of inclusive fitness; and (iv) adequately addresses shortcomings of existing methods of estimating inclusive fitness. I also demonstrate the application of this new method for testing Hamilton's rule. (+info)
Coronary heart disease, chronic inflammation, and pathogenic social hierarchy: a biological limit to possible reductions in morbidity and mortality.
(2/20)
We suggest that a particular form of social hierarchy, which we characterize as "pathogenic", can, from the earliest stages of life, exert a formal analog to evolutionary selection pressure, literally writing a permanent developmental image of itself upon immune function as chronic vascular inflammation and its consequences. The staged nature of resulting disease emerges "naturally" as a rough analog to punctuated equilibrium in evolutionary theory, although selection pressure is a passive filter rather than an active agent, like structured psychosocial stress. Exposure differs according to the social constructs of race, class, and ethnicity, accounting in large measure for observed population-level differences in rates of coronary heart disease across industrialized societies. American Apartheid, which enmeshes both majority and minority communities in a social construct of pathogenic hierarchy, appears to present a severe biological limit to continuing declines in coronary heart disease for powerful as well as subordinate subgroups: "Culture"--to use the words of the evolutionary anthropologist Robert Boyd--"is as much a part of human biology as the enamel on our teeth". (+info)
Sociality and the rate of molecular evolution.
(3/20)
The molecular clock does not tick at a uniform rate in all taxa but may be influenced by species characteristics. Eusocial species (those with reproductive division of labor) have been predicted to have faster rates of molecular evolution than their nonsocial relatives because of greatly reduced effective population size; if most individuals in a population are nonreproductive and only one or few queens produce all the offspring, then eusocial animals could have much lower effective population sizes than their solitary relatives, which should increase the rate of substitution of "nearly neutral" mutations. An earlier study reported faster rates in eusocial honeybees and vespid wasps but failed to correct for phylogenetic nonindependence or to distinguish between potential causes of rate variation. Because sociality has evolved independently in many different lineages, it is possible to conduct a more wide-ranging study to test the generality of the relationship. We have conducted a comparative analysis of 25 phylogenetically independent pairs of social lineages and their nonsocial relatives, including bees, wasps, ants, termites, shrimps, and mole rats, using a range of available DNA sequences (mitochondrial and nuclear DNA coding for proteins and RNAs, and nontranslated sequences). By including a wide range of social taxa, we were able to test whether there is a general influence of sociality on rates of molecular evolution and to test specific predictions of the hypothesis: (1) that social species have faster rates because they have reduced effective population sizes; (2) that mitochondrial genes would show a greater effect of sociality than nuclear genes; and (3) that rates of molecular evolution should be correlated with the degree of sociality. We find no consistent pattern in rates of molecular evolution between social and nonsocial lineages and no evidence that mitochondrial genes show faster rates in social taxa. However, we show that the most highly eusocial Hymenoptera do have faster rates than their nonsocial relatives. We also find that social parasites (that utilize the workers from related species to produce their own offspring) have faster rates than their social relatives, which is consistent with an effect of lower effective population size on rate of molecular evolution. Our results illustrate the importance of allowing for phylogenetic nonindependence when conducting investigations of determinants of variation in rate of molecular evolution. (+info)
Studying biobehavioral aspects of health disparities among older adult minorities.
(4/20)
Current projections suggest that by 2050, the total number of non-Hispanic Whites aged 65 and over will double, the number of Blacks aged 65 and over will more than triple, and the number of Hispanics will increase 11-fold. These significant increases in older minority adults in the United States are in direct contrast to the current limited knowledge about health behaviors like smoking, drinking, and drug use among older Americans. This represents a major area of opportunity for researchers to advance science on the long-term effects of substance abuse and HIV/AIDS. The provision of appropriate public health information for these populations depends, in part, on increased basic and social/behavioral research and particularly on integrative biobehavioral approaches in these understudied older groups. This article provides a brief overview of some of the challenges faced in studying older ethnic minority adults. These include issues such as recruitment, conceptualization, and methodology. Some potential areas for future research are offered. (+info)
Human dignity in the Nazi era: implications for contemporary bioethics.
(5/20)
BACKGROUND: The justification for Nazi programs involving involuntary euthanasia, forced sterilisation, eugenics and human experimentation were strongly influenced by views about human dignity. The historical development of these views should be examined today because discussions of human worth and value are integral to medical ethics and bioethics. We should learn lessons from how human dignity came to be so distorted to avoid repetition of similar distortions. DISCUSSION: Social Darwinism was foremost amongst the philosophies impacting views of human dignity in the decades leading up to Nazi power in Germany. Charles Darwin's evolutionary theory was quickly applied to human beings and social structure. The term 'survival of the fittest' was coined and seen to be applicable to humans. Belief in the inherent dignity of all humans was rejected by social Darwinists. Influential authors of the day proclaimed that an individual's worth and value were to be determined functionally and materialistically. The popularity of such views ideologically prepared German doctors and nurses to accept Nazi social policies promoting survival of only the fittest humans.A historical survey reveals five general presuppositions that strongly impacted medical ethics in the Nazi era. These same five beliefs are being promoted in different ways in contemporary bioethical discourse. Ethical controversies surrounding human embryos revolve around determinations of their moral status. Economic pressures force individuals and societies to examine whether some people's lives are no longer worth living. Human dignity is again being seen as a relative trait found in certain humans, not something inherent. These views strongly impact what is taken to be acceptable within medical ethics. SUMMARY: Five beliefs central to social Darwinism will be examined in light of their influence on current discussions in medical ethics and bioethics. Acceptance of these during the Nazi era proved destructive to many humans. Their widespread acceptance today would similarly lead to much human death and suffering. A different ethic is needed which views human dignity as inherent to all human individuals. (+info)
What can microbial genetics teach sociobiology?
(6/20)
Progress in our understanding of sociobiology has occurred with little knowledge of the genetic mechanisms that underlie social traits. However, several recent studies have described microbial genes that affect social traits, thereby bringing genetics to sociobiology. A key finding is that simple genetic changes can have marked social consequences, and mutations that affect cheating and recognition behaviors have been discovered. The study of these mutants confirms a central theoretical prediction of social evolution: that genetic relatedness promotes cooperation. Microbial genetics also provides an important new perspective: that the genome-to-phenome mapping of social organisms might be organized to constrain the evolution of social cheaters. This constraint can occur both through pleiotropic genes that link cheating to a personal cost and through the existence of phoenix genes, which rescue cooperative systems from selfish and destructive strategies. These new insights show the power of studying microorganisms to improve our understanding of the evolution of cooperation. (+info)
A compensation election for binary social choice.
(7/20)
We report experimental results examining the properties of a bidding mechanism, the "Compensation Election," which is designed to implement a simple binary choice between two options. We may think of the group decision problem as a choice between a new rule and the status quo. The rule and the status quo are each common outcomes that apply across all individuals, but the value or cost that they induce on each individual differs according to each individual's circumstances: some gain, some lose, and others are unaffected by a change to the new from the old. Rather than casting votes, each subject submits a bid reflecting his willingness to pay to induce the group to select one option and the amount he wishes to be paid if the alternative option is selected. The Compensation Election chooses the option that receives the highest sum of bids. We find that, although the Compensation Election allows subjects to strategically bid above their value (or even for the option they do not prefer), such behavior is not the norm. We also find that subjects' bids more truthfully reveal their values when there are more bidders in the election. (+info)
The sociobiologic integrative model (SBIM): enhancing the integration of sociobehavioral, environmental, and biomolecular knowledge in urban health and disparities research.
(8/20)
Disentangling the myriad determinants of disease, within the context of urban health or health disparities, requires a transdisciplinary approach. Transdisciplinary approaches draw on concepts from multiple scientific disciplines to develop a novel, integrated perspective from which to conduct scientific investigation. Most historic and contemporary conceptual models of health were derived either from the sociobehavioral sciences or the biomolecular sciences. Those models deriving from the sociobehavioral sciences generally lack detail on involved biological mechanisms whereas those derived from the biomolecular sciences largely do not consider socioenvironmental determinants. As such, advances in transdisciplinary characterizations of health in complex systems like the urban environment or health disparities may be impeded. This paper suggests a sociobiologic organizing model that encourages a multilevel, integrative perspective in the study of urban health and health disparities. (+info)