PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Social Evolution”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed2006

Phenotypic plasticity, sexual selection and the evolution of colour patterns.

When a population comes to occupy a new environment, phenotypically plastic responses alter the distribution of phenotypes, and hence affect both the direction and the intensity of selection. Rates of evolution can be accelerated or retarded compared to what would happen in the absence of plasticity. Plastic responses in one trait result in novel selection pressures on other traits, and this can lead to evolution in completely different directions than predicted in the absence of plasticity. In this paper I use the concept of the adaptive surface in order to identify conditions under which the various different outcomes are expected. I then discuss differences between sexually and naturally selected traits. Sexually selected traits are often expected to be plastic in their expression, with individuals in high condition developing greater elaboration. As examples of sexually selected traits I review the evolution of colour patterns in birds with a view to assessing the magnitude of plastic responses in their development, and to ask how such responses may have influenced genetic evolution. The common colour pigments in birds are carotenoids and melanins. Both are used in social signaling, and consequently are expected to evolve to be phenotypically plastic indicators of an individual's quality. Perhaps partly because they are condition indicators, the quantity of carotenoids in the plumage can be strongly influenced by diet. Examples are described where alterations of carotenoids in the diet are thought to have altered the phenotype, driving genetic evolution in novel directions. Melanin patterns seem to be less affected by diet, but the intensity of melanization after moult is affected by social interactions during the moult and by raising birds in humid conditions. Hormonal manipulations can have dramatic effects on both the kinds of melanin produced (eumelanin or phaeomelanin) as well as the patterns they form. Differences between species in melanin patterns resemble differences produced by environmental manipulations, as well as those produced by simple modulations of parameters in computer simulations of pattern formation. While phenotypic plasticity is one way that genetic change in plumage patterns (and other traits) could be driven, there are others, including the appearance of major mutations and selection on standing variation whose distribution is not altered in the new environment. I consider some evidence for the different alternatives, and ask when they might lead to qualitatively different evolutionary outcomes.

Adaptation, Physiological↗
PubMed2005

Evolution of power law distributions in science and society.

Power law distributions have been observed in numerous physical and social systems; for example, the size distributions of particles, aerosols, corporations, and cities are often power laws. Each system is an ensemble of clusters, comprising units that combine with or dissociate from the cluster. Constructing models and investigating their properties are needed to understand how such clusters evolve. To describe the growth of clusters, we hypothesize that a distribution obeys a governing population dynamics equation based on a reversible association-dissociation process. The rate coefficients are considered to depend on the cluster size as power expressions, thus providing an explanation for the asymptotic evolution of power law distributions.

Adaptation, Physiological↗
PubMed1998

The concept of health and disease.

Examining the naturalist and normativist concepts of health and disease this article starts with analysing the view of C. Boorse. It rejects Boorse's account of health as species-typical functioning, giving a critique of his view based on evolutionary theory of contemporary biology. Then it gives a short overview of the normativist theories of health, which can be objectivist and subjectivist theories. Rejecting the objectivist theories as philosophically untenable, it turns to the subjectivist theories of Gert and Culver, and to the view of Nordenfelt. These theories give quite a good subjectivist account of health and disease, but they do not pay enough attention to the notion of the environment, without which it is impossible to define health and disease. Starting with their definitions but introducing the notion of "reasonable social norms", the article arrives at the following definition of health: The healthier a physical or mental characteristic, process, reaction is, the more it makes it possible for the individual to adapt to reasonable social norms without pain and suffering, and the longer, and happier a life it will be able to ensure him in that society.

Adaptation, Physiological↗
PubMed1988

The evolution of reciprocity in sizable groups.

Recently, several authors have investigated the evolution of reciprocal altruism using the repeated prisoner's dilemma game. These models suggest that natural selection is likely to favor behavioral strategies leading to reciprocal cooperation when pairs of individuals interact repeatedly in potentially cooperative situations. Using the repeated n-person prisoner's dilemma game, we consider whether reciprocal altruism is also likely to evolve when social interactions involve more individuals. We show that the conditions that allow the evolution of reciprocal cooperation become extremely restrictive as group size increases.

Altruism↗
PubMed2000

Vocal responsiveness in male wild chimpanzees: implications for the evolution of language.

Several captive chimpanzees and bonobos have learned to use symbols and to comprehend syntax. Thus, compared with other nonhumans, these animals appear to have unusual cognitive powers that can be recruited for communicative behavior. This raises the possibility that wild chimpanzee vocal communication is more complex than heretofore demonstrated. To examine this possibility, I investigated whether wild chimpanzee vocal exchanges exhibit uniquely human conversational attributes. The results indicate that wild chimpanzees vocalize at low rates, tend not to respond to calls that they hear, and, when they do respond, tend to give calls that are similar to the ones they have heard. Thus, chimpanzee vocal interactions resemble those of other primate species, and show no special similarity to human conversations. The results support the view that we need to explore cognitive and social continuities and discontinuities with nonhuman primates to understand the origin and evolution of language, but also emphasize the need for fine-grained analyses of wild chimpanzee vocal interactions.

Animals↗
PubMed2001

Explaining social learning of food preferences without aversions: an evolutionary simulation model of Norway rats.

Norway rats (Rattus norvegicus) transmit preferences for novel foods socially by smelling each other's breath. However, rats fail to learn aversions, acquiring a preference even if the rat whose breath they smell has been poisoned. Rats can distinguish between sick and healthy conspecifics and social learning of both preferences and aversions is present in other species - hence it is unclear why rats cannot learn aversions socially. We constructed an evolutionary simulation in which a population of rats foraged from a central location, exploiting food sites that could contain edible or toxic foodstuffs. We examined the relationship between toxin lethality and selection for individual versus social learning and discrimination between sick and healthy conspecifics in order to allow learning of both preferences and aversions. At low lethality levels individual learning was selected for and at intermediate levels we found social learning of both preferences and aversions. Finally, given high lethality levels the simulated rats would employ social learning but failed to learn aversions, matching the behaviour of real rats. We argue that Norway rats do not learn aversions socially because their environment may contain only highly lethal toxins which make interaction with a sick conspecific an extremely rare event.

Animals↗
PubMed2001

[The population treated in the general psychiatric sector in 1993 and 1998. Clinical and demographic evolution].

BACKGROUND: The French information system in public psychiatry sectors does not collect morbidity data for the population being treated, estimated as more than a million persons in 1997. Consequently, two surveys were financed by the "Direction Générale de la Santé" and carried out in 1993 and 1998 in order to specify clinical, social and demographic characteristics of the patients. These surveys allowed a follow-up of evolutions according to the pathology and mode of treatment in a context where outpatient treatments are becoming increasingly frequent. METHODS: A census of the patients was made at a given moment, between one and fifteen days according to the mode of treatment. One sector out of two was surveyed, using a systematic selection process. The ICD-10 was used for diagnosis reference. The same methodology was applied in 1993 and 1998. Comparisons were made with the data supplied by the sectors annually and with the data concerning the general population in order to calculate rates per age groups. RESULTS: Between 1993 and 1998, the number of patients increased by +37% in outpatient care, and in part time care, and decreased by -12% in full time care. Rates for patients increased for all age groups in outpatient and part time care, more particularly for the 35 to 49 years old. Conversely, rates decreased in full time care, above all for patients over seventy. In each mode of treatment, the number of patients presenting mood disorders and neurotic disorders increased more than the average, and the proportion of patients with organic mental disorders and mental retardation decreased. Evolutions were different according to the mode of treatment schizophrenia, schizotypal and delusional disorders, and disorders of adult personality and behaviour. CONCLUSIONS: Recourse to outpatient care and part time care increased considerably over five years but evolutions were markedly different from one diagnosis to another. In full time care, the decrease more particularly concerned certain pathologies and age groups. Three phenomena, with possible interactions, could explain the evolutions observed: the population liable to have recourse to psychiatric care is increasing, health policies have changed and care supply has become diversified, and recourse to psychiatric care is now increasingly accepted.

Adult↗
PubMed2003

'Cooking as a biological trait'.

No human foragers have been recorded as living without cooking, and people who choose a 'raw-foodist' life-style experience low energy and impaired reproductive function. This suggests that cooking may be obligatory for humans. The possibility that cooking is obligatory is supported by calculations suggesting that a diet of raw food could not supply sufficient calories for a normal hunter-gatherer lifestyle. In particular, many plant foods are too fiber-rich when raw, while most raw meat appears too tough to allow easy chewing. If cooking is indeed obligatory for humans but not for other apes, this means that human biology must have adapted to the ingestion of cooked food (i.e. food that is tender and low in fiber) in ways that no longer allow efficient processing of raw foods. Cooking has been practiced for ample time to allow the evolution of such adaptations. Digestive adaptations have not been investigated in detail but may include small teeth, small hind-guts, large small intestines, a fast gut passage rate, and possibly reduced ability to detoxify. The adoption of cooking can also be expected to have had far-reaching effects on such aspects of human biology as life-history, social behavior, and evolutionary psychology. Since dietary adaptations are central to understanding species evolution, cooking appears to have been a key feature of the environment of human evolutionary adaptedness. Further investigation is therefore needed of the ways in which human digestive physiology is constrained by the need for food of relatively high caloric density compared to other great apes.

Animals↗
PubMed1999

The importance of ethology in understanding the behaviour of the horse.

Domestication has provided the horse with food, shelter, veterinary care and protection, allowing individuals an increased chance of survival. However, the restriction of movement, limited breeding opportunities and a requirement to expend energy, for the benefit of another species, conflict with the evolutionary processes which shaped the behaviour of its predecessors. The behaviour of the horse is defined by its niche as a social prey species but many of the traits which ensured the survival of its ancestors are difficult to accommodate in the domestic environment. There has been a long association between horses and man and many features of equine behaviour suggest a predisposition to interspecific cooperation. However, the importance of dominance in human understanding of social systems has tended to overemphasize its importance in the human-horse relationship. The evolving horse-human relationship from predation to companionship, has resulted in serial conflicts of interest for equine and human participants. Only by understanding the nature and origin of these conflicts can ethologists encourage equine management practices which minimise deleterious effects on the behaviour of the horse.

Animal Husbandry↗
PubMedDate not supplied

[The role of nursing in the current health and social health system: nursing management in Italy].

The objects can substantially synthesizes: 1. To reflect on the evolution of the organizational configuration of the nursing function based on the various theoretical contributions; 2. To make a picture of the organizational configurations of nursing function that more frequently appear in the immense and heterogeneous health system; 3. To formulate future hypotheses that concur on nursing autonomy in the comparisons with new and old professions and to strengthen out direct responsibility.

Delivery of Health Care↗
PubMed2003

Fitness effects of group merging in a social insect.

Animal social groups often consist of non-relatives, a condition that arises in many cases because of group merging. Although indirect fitness contributions are reduced in such groups compared with those in groups composed of close kin, the genetic-heterogeneity hypothesis suggests that these groups may benefit from increased intracolony genetic variation, which may boost group performance through increased task efficiency or parasite resistance. We confirm one prediction of the task-efficiency explanation by demonstrating a genetic basis for task thresholds of socially important behaviours in eastern tent caterpillars. However, we found no evidence that the expanded range of task thresholds in mixed colonies translates into improved individual or colony performance in the field. By contrast, increased group size, a less commonly considered correlate of group mixing, was found to enhance individual fitness through its effects on larval growth. We conclude that fitness benefits offsetting the dilution of relatedness in heterogeneous social groups may often stem from augmented group size rather than increased genotypic diversity.

Animals↗
PubMed2001

Toward an understanding of violence: neurobehavioral aspects of unwarranted physical aggression: Aspen Neurobehavioral Conference consensus statement.

OBJECTIVE: Violence is a global problem that poses a major challenge to individuals and society. This document is a consensus statement on neurobehavioral aspects of violence as one approach to its understanding and control. BACKGROUND: This consensus group was convened under the auspices of the Aspen Neurobehavioral Conference, an annual consensus conference devoted to the understanding of issues related to mind and brain. The conference is supported by the Brain Injury Association and by individual philanthropic contributions. Participants were selected by conference organizers to represent leading opinion in neurology, neuropsychology, psychiatry, trauma surgery, nursing, evolutionary psychology, medical ethics, and law. METHODS: A literature review of the role of the brain in violent behavior was conducted and combined with expert opinion from the group. The major goal was to survey this field so as to identify major areas of interest that could be targeted for further research. Additional review was secured from the other attendees at the Aspen Neurobehavioral Conference. RESULTS: The group met in the spring of 1998 and 1999 for two 5-day sessions, between which individual assignments were carried out. The consensus statement was prepared after the second meeting, and agreement on the statement was reached by participants after final review of the document. CONCLUSIONS: Violence can result from brain dysfunction, although social and evolutionary factors also contribute. Study of the neurobehavioral aspects of violence, particularly frontal lobe dysfunction, altered serotonin metabolism, and the influence of heredity, promises to lead to a deeper understanding of the causes and solution of this urgent problem.

Adult↗
PubMedDate not supplied

[Evolutionary concepts of affective disorders].

Mood may be considered the module of the human mind, which has evolved to tune the activity ofthe organism to the specific environmental conditions in a better way. In some cases depression may be adaptive, for example in aborting the activity associated with too many obstacles. At the same time hypomania may be related to the capability of mobilising the organism to gain many resources in a short period of time. Severe mood disorders may be related to the genetic variants, eg. of the serotonin transporter or brain-derived neurotrophic factor, which in several situations may give some evolutionary advantage. Affective temperaments, observed in the relatives of patients with affective disorders may be associated with some benefits in the social life. The relationship between early adversities and adult depression may be related to the phenomenon of the stress axis programming, which has deep evolutionary roots. Some infectious factors may cause behaviours similar to the affective symptoms, which may increase their reproductive success. The evolutionary perspective, which is complementary to the current etiopathogenic theories may help in understanding, why genes and traits which

Affective Symptoms↗
PubMed2005

Emergence of cooperation: state of the art.

This review presents a review of prevalent results within research pertaining to emergent cooperation in biologically inspired artificial social systems. Results reviewed maintain particular reference to biologically inspired design principles, given that current mathematical and empirical tools have provided only a partial insight into elucidating mechanisms responsible for emergent cooperation, and then only in systems of an abstract nature. This review aims to provide an overview of important and disparate research contributions that investigate utilization of biologically inspired concepts such as emergence, evolution, and self-organization as a means of attaining cooperation in artificial social systems. An introduction and overview of emergent cooperation in artificial life is presented, followed by a survey of emergent cooperation in swarm-based systems, the pursuit-evasion domain, and RoboCup soccer. The final section draws conclusions regarding future directions of emergent cooperation as a problem-solving methodology that is potentially applicable in a wide range of problem domains. Within each of these sections and their respective themes of research, the mechanisms deemed to be responsible for emergent cooperation are elucidated and their key limitations highlighted. The review concludes that current studies in emergent cooperative behavior are limited by a lack of situated and embodied approaches, and by the research infancy of current biologically inspired design approaches. Despite these limiting factors, emergent cooperation maintains considerable future potential in a wide variety of application domains where systems composed of many interacting components must cooperatively perform unanticipated global tasks.

Animals↗
PubMed2002

Active formation of mixed-species grouse leks: a role for predation in lek evolution?

Behavioural ecologists have interpreted avian leks as products of sexual selection, in which males display socially to increase their opportunities to mate. However, without invoking reproductive queuing or kin selection, this paradigm does not necessarily explain why many males that fail to mate participate in leks. An alternative solution, that males also aggregate to reduce predation, has previously lacked compelling support. We show that mixed-species leks, comprising two congeneric grouse, form when single males or small groups of one species, the greater prairie chicken Tympanuchus cupido, join leks of another, the sharp-tailed grouse T. phasianellus. We documented the process by observing lek dynamics and comparing group sizes between mixed- and single-species leks. Joining implies that prairie chickens benefit from displaying with sharp-tailed grouse. The numbers of females of each species attending a lek increased with the number of conspecific, but not heterospecific, males. This suggests that the joining of heterospecifics is unlikely to increase mating opportunities, and leaves lowered predation risk as the most likely benefit of associating with heterospecifics. Active formation of mixed-species leks therefore suggests that predation may be sufficient to drive lek formation. The benefits of participation in mixed leks may be asymmetrical because prairie chickens display more and are less vigilant than sharp-tailed grouse.

Animals↗