[Darwin and the so-called social darwinism in nutrition].
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Biological Evolution↗
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[Place of the aged within the French population and their socioeconomic level. Foreseeable evolution].
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Aged↗
Evolution and depression: issues and implications.
Depression is well recognized to be rooted in the down-regulation of positive affect systems. This paper reviews some of the social and non-social theories that seek to explain the potential adaptive advantages of being able to tone down positive affect, and how dysfunctions in such affect control can occur in some contexts. Common to most evolutionary theories of depression is the view that loss of control over aversive events and/or major resources/rewards exert downward pressure on positive affect. Social theories, however, suggest that it is loss of control over the social environment that is particularly depressogenic. Two evolutionary theories (the attachment-loss, and the defeat-loss theories) are briefly reviewed and their interaction considered. It is suggested that phenotypes for toning down positive affect, in the face of loss of control, may become more severe in the context of socially hostile, unsupportive and/or excessively competitive environments. The paper briefly considers how human competencies for self-evaluation in relation to others, rumination, self-criticism, and modern social contexts can accentuate dysfunctional expressions of affect regulation.
Affect↗
Organization of work via a natural substance: regulation of nest construction in social wasps.
In social insects, colony-level complexity emerges from simple individual-level behaviors and interactions. In the evolution of insect societies, selection has acted to promote efficiency through division of labor. Nest construction of social wasps is an excellent model system to study division of labor and the performance of a decentralized behavioral regulation. After re-examination of Jeanne's (1996) demand-driven "non-taskmates feedback" hypothesis, an alternative mechanism is suggested whereby the regulation of behavior is based on a natural substance (water) which is itself also a building material. By experimenting with a simple model system, we show that the model's predictions agree with observational data and cover a wide range of evolutionary transitions. According to the internal and external parameters, the colony builds up storage of water that is used both as regulator and building material. Through individual interactions, pulp foragers and water foragers emerge from general laborers and their ratio becomes balanced. The emergent foragers ensure both the stabilization of the quantity of stored water and the steady construction of the nest according to the given conditions. Perturbations of the system alter colony-level dynamics in a similar way as was observed in nature: water and pulp addition increase pulp arrivals and building rate; removal of pulp foragers decreases pulp input and construction rate, but not the water influx; removal of water foragers causes overcompensation of water input after a delay. After comparing the predictions of the model to natural data, assumptions found in the literature on organization of work and regulation of behavior are re-examined. A new, more parsimonious model of organization of work is proposed that may cover wide variety of cases where hormones and learning cannot be accounted for the regulation of behavior.
Animals↗
Monogamy in mammals.
This review considers the behavioral, ecological, and reproductive characteristics of mammals exhibiting monogamy, i.e., mating exclusivity. From a discussion of the life histories of selected species of monogamous primates, carnivores, rodents and ungulates, several trends emerge. Two forms of monogamy occur, Type I, facultative, and Type II, obligate. The selective pressures leading to these two forms of monogamy may have been different. Facultative monogamy may result when a species exists at very low densities, with males and females being so spaced that only a single member of the opposite sex is available for mating. Obligate monogamy appears to occur when a solitary female cannot rear a litter without aid from conspecifics, but the carrying capacity of the habitat is insufficient to allow more than one female to breed simultaneously within the same home range. Within both types of monogamy, the following traits are typically seen: (1) adults show little sexual dimorphism either physically or behaviorally: (2) the adult male and female exhibit infrequent socio-sexual interactions except during the early stages of pair bond formation. Additional trends specific to mammals exhibiting obligate monogamy are: (1) the young exhibit delayed sexual maturation in the presence of the parents, and thus only the adult pair breeds; (2) the older juveniles aid in rearing young siblings; and (3) the adult male (father) aids in the rearing of young by any or all of the following: carrying, feeding, defending, and socializing offspring.
Animals↗
Subadult experience influences adult mate choice in an arthropod: exposed female wolf spiders prefer males of a familiar phenotype.
Current sexual selection theory proposes several potential mechanisms driving the evolution of female mating preferences, few of which involve social interactions. Although vertebrate examples of socially influenced mating preferences do exist, the invertebrate examples are virtually nonexistent. Here I demonstrate that the mating preferences of female wolf spiders can be acquired through exposure as subadults to unrelated, sexually active adult males. I first conducted exposure trials during which subadult females of the wolf spider Schizocosa uetzi were allowed to interact with mature males of an experimentally manipulated phenotype (either black or brown forelegs). After maturation, these previously exposed females were paired with a male of either a familiar or unfamiliar manipulated phenotype for mate-choice trials. Subadult females that were exposed to directed courtship by mature males of a particular morphological phenotype were subsequently more likely to mate with a male of a familiar phenotype as adults. Furthermore, females that were exposed as subadults were more likely, as adults, to cannibalize a courting male with an unfamiliar phenotype. Unexposed females did not distinguish between phenotypes in either mate choice or cannibalism frequency. These results suggest a previously uncharacterized mechanism influencing the origin of female mating preferences and ultimately the evolution of male traits: subadult experience. This study also stresses the potential importance of learning and memory on adult mate choice in an arthropod.
Animals↗
Life history and the competitive environment: trajectories of growth, maturation, and reproductive output among chacma baboons.
The social environment is a key feature influencing primate life histories. Chacma baboons (Papio hamadryas ursinus) are a female-bonded species with a strict linear dominance hierarchy. In this species, the allocation of energy to competing demands of growth and reproduction is hypothesized to vary as a function of competitive ability, which in turn increases with social rank. Since growth rate is a major component of life history models, measures of age-specific growth were used to analyze variation in life history traits across social ranks. Weights of 42 immature baboons were obtained without sedation or baiting from a troop of well-habituated chacma baboons in the Okavango Delta, Botswana. Using demographic and weight data from this wild population, five main findings emerged: 1) Weight for age and growth rate of infant and juvenile females are positively associated with maternal rank. 2) Male growth is not influenced by maternal rank. 3) Female growth shows smaller variation across feeding conditions than male growth. 4) Low-ranking adult females continue investment in offspring through prolonged lactation until they reach a weight comparable to that of high-ranking infants. 5) The benefit of rank to reproductive success shown in this study is 0.83 additional offspring. Reproductive span determined predominantly by age at maturation contributes 27-38% to the difference in expected number of offspring by rank, vs. 62-73% due to reproductive rate. These findings have major implications for understanding the role of social environment in phenotypic plasticity of life history traits, and in the evolution of primate life histories.
Animals↗
The genetic consequences of primate social organization: a review of macaques, baboons and vervet monkeys.
Primates, as long-lived, iteroparous, socially complex mammals, offer the opportunity to assess the effects of behavior and demography on genetic structure. Because it is difficult to obtain tissue samples from wild primate populations, research in this area has largely been confined to terrestrial and semi-terrestrial old world monkeys (e.g., rhesus and Japanese macaques, vervets and several subspecies of baboons). However, these species display a multi-male, multi-female social structure commonly found in many other primate and non-primate mammals. Electrophoretic analyses of blood proteins from individually recognized and/or marked wild Himalayan rhesus monkeys, themselves the subject of long-term behavioral and demographic research, have begun to reveal the genetic consequences of such phenomena as social group fission, male-limited dispersion, non-consanguineous mating patterns, and agonistically defined male dominance. Specifically, rhesus social groups, consisting primarily of clusters of maternal relatives, appear to be non-random samples of a population's genotypes and genes. The genetic effects of social group fission are highly dependent on each group's size, demographic structure, and average degree of relatedness. In all cases fission contributes to the degree of intergroup genetic differentiation. Male-limited dispersion appears both to retard genetic differentiation between social groups and to lead to mating patterns that result in an avoidance of consanguinity. Groups, therefore, appear to be genetically outbred. Comparing these results with studies of other free-ranging or wild cercopithecines allows several generalizations: (a) genetic variation seems to be evenly distributed throughout each local population of multi-male social groups; (b) social groups, however, because they contain clusters of relatives, are distinctive in their specific frequencies of genes; (c) the degree of genetic differentiation between a population's social groups, because of the effects of social group fission and non-deterministic forms of male dispersal, is somewhat greater than expected on the basis of migration rates alone; and (d) the asymmetrical pattern of dispersion with respect to sex effectively precludes inbreeding in any one social group or the population as a whole. These observations have important implications for understanding the unusually rapid rates of evolution among the primates.
Animals↗
Evolution of indirect reciprocity.
Natural selection is conventionally assumed to favour the strong and selfish who maximize their own resources at the expense of others. But many biological systems, and especially human societies, are organized around altruistic, cooperative interactions. How can natural selection promote unselfish behaviour? Various mechanisms have been proposed, and a rich analysis of indirect reciprocity has recently emerged: I help you and somebody else helps me. The evolution of cooperation by indirect reciprocity leads to reputation building, morality judgement and complex social interactions with ever-increasing cognitive demands.
Altruism↗
The competitive advantage of sanctioning institutions.
Understanding the fundamental patterns and determinants of human cooperation and the maintenance of social order in human societies is a challenge across disciplines. The existing empirical evidence for the higher levels of cooperation when altruistic punishment is present versus when it is absent systematically ignores the institutional competition inherent in human societies. Whether punishment would be deliberately adopted and would similarly enhance cooperation when directly competing with nonpunishment institutions is highly controversial in light of recent findings on the detrimental effects of punishment. We show experimentally that a sanctioning institution is the undisputed winner in a competition with a sanction-free institution. Despite initial aversion, the entire population migrates successively to the sanctioning institution and strongly cooperates, whereas the sanction-free society becomes fully depopulated. The findings demonstrate the competitive advantage of sanctioning institutions and exemplify the emergence and manifestation of social order driven by institutional selection.
Cooperative Behavior↗
[The demented patient: his family, social and therapeutic environment].
The patient's environment determines to a large extent the evolution of his illness. His family, which is almost always thrown into a state of confusion by the patient's illness, has the crucial role of providing support and protection even if they are overwhelmed by his needs. The support of the community is indispensable in order to assure the continuity of the parental role; therefore the need to create specialized services such as geriatric hospitals, hospices, special residences, out-patient therapeutic units, and social and medical services for care at home. The Geneva geriatric and gerontological experience is presented to better illustrate these needs.
Aged↗
The selfish karyotype. An analysis of the biological basis of morals.
An analysis is made of the kin-selection/group-selection debate on the issue of the biological basis of morals. The kin-selection view sees altruism, and morals in the case of humans, as resting solely on genetic factors; in fact, on this view, evolution itself is to take place only through genetic change -- a position which cannot be reconciled with our knowledge that species evolution involves karyotypic change. Morality is thought to stem from a particular gene which at one time was completely absent from the human population but which later entered and spread through it. On the generally accepted conception of kin selection, this 'altruistic' gene is to be responsible not only for apparently altruistic behaviour towards near relatives, but also for parental care. Thus this view, among other things, has the absurd consequence that there was a period directly after humans first came into existence during which we did not care for our young. In contrast, the group-selection view, as developed here, sees morality as stemming from the species' karyotype, and to be passed on karyotypically from species to species through evolution. As suggested by Darwin, morality is thus derived from our social instincts, and is fundamentally directed to members of one's tribe or community, not to members of one's family. In keeping with this perspective, it is suggested here that the biological basis of morals does not concern the continuation of each individual's gene line, but the continuing existence of the individual's community, and thus, indirectly, the survival of the human species, through supporting the continuing instantiation of its karyotype.
Altruism↗
Mating systems, sperm competition, and the evolution of sexual dimorphism in birds.
Comparative analyses suggest that a variety of factors influence the evolution of sexual dimorphism in birds. We analyzed the relative importance of social mating system and sperm competition to sexual differences in plumage and body size (mass and tail and wing length) of more than 1,000 species of birds from throughout the world. In these analyses we controlled for phylogeny and a variety of ecological and life-history variables. We used testis size (corrected for total body mass) as an index of sperm competition in each species, because testis size is correlated with levels of extrapair paternity and is available for a large number of species. In contrast to recent studies, we found strong and consistent effects of social mating system on most forms of dimorphism. Social mating system strongly influenced dimorphism in plumage, body mass, and wing length and had some effect on dimorphism in tail length. Sexual dimorphism was relatively greater in species with polygynous or lekking than monogamous mating systems. This was true when we used both species and phylogenetically independent contrasts for analysis. Relative testis size was also related positively to dimorphism in tail and wing length, but in most analyses it was a poorer predictor of plumage dimorphism than social mating system. There was no association between relative testis size and mass dimorphism. Geographic region and life history were also associated with the four types of dimorphism, although their influence varied between the different types of dimorphism. Although there is much interest in the effects of sperm competition on sexual dimorphism, we suggest that traditional explanations based on social mating systems are better predictors of dimorphism in birds.
Animals↗
Cognitive strategies and the representation of social relations by monkeys.
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Adaptation, Biological↗
Unhealthy European health policy.
The European Union claims that the defense of its welfare state is one of today's most important challenges. This article analyzes whether the European governments and the European Union really pursue a policy that strengthens their health and social security systems, or one that is in itself a threat to health and social security. After a summary of the origin and evolution of the European health systems, the authors pinpoint underlying reasons for reform and demonstrate how, since the 1990s, the European Union has built a strict financial and political straitjacket, forcing these systems to carry out privatization and cutbacks. Reform measures can be divided into three interdependent categories: (1) the increasing influence of governments on health care organization, to enable restructuring; (2) measures aimed at reducing public expenses, including higher financial contributions by patients and restrictions on the range of services provided; and (3) measures that establish competition and hidden or open privatization of services and insurance systems. Through these mechanisms public expenses are reduced while private health care expenses (and private profits) rise freely. Ongoing European health care reforms thus struggle with the contradictions between responding to growing collective needs and securing or increasing private profits.
Delivery of Health Care↗
Sociobiology for social scientists: a critical introduction to E.O. Wilson's evolutionary paradigm.
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Altruism↗
Depression and social change. From transcultural psychiatry to a constructivist model.
Based on the findings of previous studies carried out by our group, which will be briefly summarised, the present paper puts forward several hypotheses to account for the evolution of depressive symptoms and the possible increase observed in risk of depression subsequent to social changes. The particular mood disorders presented by Senegalese emigrants and several protective factors which appear to determine a low risk in these populations, such as a strong social support, will be examined. Based on a previous investigation carried out by our group, which seems to indicate the presence of depressive pictures among poorly westernised populations such as the Peul nomads or Dogon farmers from the Sub-Saharian regions, the hypothesis that "westernalisation" (considered as the loss at an individual level of traditional ways of life, working habits, cultural patterns and languages in favour of different attitudes influenced by western culture) may represent a risk factor for depressive illness, in its clinical expressions commonly observed in western contexts, has been considered. In these populations, with the exception of educated individuals, the albeit rare depressive symptoms appear to be secondary to serious somatic disorders. Research performed identified two well-defined means of clinical expression, which has been termed, respectively, "western style" or "guilty" and "traditional" or "dislocation from the group". Further studies carried out in rapidly changing areas seem to indicate how environmental factors are able to influence the evolution of depressive symptoms from the first form to the latter and to modify the threshold of onset of emotive, behavioural and depressive patterns. It has been hypothesised that rapid changes in the social organisation tend to exacerbate attitudes of "compulsive hyper-responsibilisation", a cognitive set of basic assumptions which may be considered at the same time both as a product of "westernalization" at an individual level and a risk factor for depression. Individuals who possess these basic characteristics, subsequent to the opportunities afforded by the social changes, tend to develop new complex systems of interpreting reality, causality, controlling of events and ways of expressing emotions. Accordingly, we herewith propose a reviewal of the entire threshold concept and provide a means of interpreting the transformation in depressive phenomena in view of the fact that, although the new levels of knowledge and learning better equip subjects to face the new situations, they also render them more vulnerable to depression.
Adult↗
The aging brain: the cognitive reserve hypothesis and hominid evolution.
Compared to other primates, humans live a long time and have large brains. Recent theories of the evolution of human life history stages (grandmother hypothesis, intergenerational transfer of information) lend credence to the notion that selection for increased life span and menopause has occurred in hominid evolution, despite the reduction in the force of natural selection operating on older, especially post-reproductive, individuals. Theories that posit the importance (in an inclusive fitness sense) of the survival of older individuals require them to maintain a reasonably high level of cognitive function (e.g., memory, communication). Patterns of brain aging and factors associated with healthy brain aging should be relevant to this issue. Recent neuroimaging research suggests that, in healthy aging, human brain volume (gray and white matter) is well-maintained until at least 60 years of age; cognitive function also shows only nonsignificant declines at this age. The maintenance of brain volume and cognitive performance is consistent with the idea of a significant post- or late-reproductive life history stage. A clinical model, "the cognitive reserve hypothesis," proposes that both increased brain volume and enhanced cognitive ability may contribute to healthy brain aging, reducing the likelihood of developing dementia. Selection for increased brain size and increased cognitive ability in hominid evolution may therefore have been important in selection for increased lifespan in the context of intergenerational social support networks.
Aging↗