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PubMed2004

Social polyandry, parental investment, sexual selection, and evolution of reduced female gamete size.

Sexual selection in the form of sperm competition is a major explanation for small size of male gametes. Can sexual selection in polyandrous species with reversed sex roles also lead to reduced female gamete size? Comparative studies show that egg size in birds tends to decrease as a lineage evolves social polyandry. Here, a quantitative genetic model predicts that female scrambles over mates lead to evolution of reduced female gamete size. Increased female mating success drives the evolution of smaller eggs, which take less time to produce, until balanced by lowered offspring survival. Mean egg size is usually reduced and polyandry increased by increasing sex ratio (male bias) and maximum possible number of mates. Polyandry also increases with the asynchrony (variance) in female breeding start. Opportunity for sexual selection increases with the maximum number of mates but decreases with increasing sex ratio. It is well known that parental investment can affect sexual selection. The model suggests that the influence is mutual: owing to a coevolutionary feedback loop, sexual selection in females also shapes initial parental investment by reducing egg size. Feedback between sexual selection and parental investment may be common.

Animals↗
PubMed2006

Interspecific hybridization in ants: at the intersection of ecology, evolution, and behavior.

Ants are social and are haplodiploid. This combination may allow the evolution of a variety of unusual genetic pathways to achieve reproductive success. These include hybridizing across species, differential use of sperm to create a hybrid worker population, and reproductively isolated gene pools that depend on each other for their survival. Although there are demonstrable costs for colony development and reproduction, these phenomena may nevertheless be relatively common in nature. The specific ecological advantages that favor the evolution of these reproductive modes remain to be discovered.

Animals↗
PubMed2005

The descent of words: evolutionary thinking 1780-1880.

Histories of evolutionary thought are dominated by organic evolution. The colossus in our midst that is evolutionary biology casts its shadow over history, making it appear that what is so widespread and important today was always the primary subject of evolutionary speculation. Thus many histories assume that the core meaning of evolution is the change of organic life and that other forms of evolutionary thinking, such as linguistic, social or cultural evolution, are only analogies or offshoots of the main biological evolutionary trunk. Ironically this is an ahistorical understanding. Long before the work of Charles Darwin, scholars were independently developing evolutionary concepts such as descent with modification and divergence from a common stock in order to understand cultural change.

Biological Evolution↗
PubMed1998

Sociality and the rate of rDNA sequence evolution in wasps (Vespidae) and honeybees (Apis).

Sequence data of mitochondrial 16S ribosomal DNA (mt-rDNA) and nuclear 28S ribosomal DNA (nuc-rDNA) were compared in two honeybee species (Apis mellifera and Apis dorsata) and a selection of 22 wasp species (Vespidae) with different levels of sociality. The averge substitution rates in mt-rDNA and nuc-rDNA were almost-equal in solitary species. In species with larger nests, however, the difference between the nuclear and the mitochondrial substitution rate significantly increased. The average substitution ratio, psi (nucleotide substitutions in mt-rDNA/nucleotide substitutions in nuc-rDNA) was 1.48 +/- 0.12 (SE) among the solitary Eumeninae, 3.70 +/- 0.15 among five primitive social Stenogastrinae species, 3.24 +/- 0.20 among five Polistinae species, 5.76 +/- 0.33 among nine highly eusocial Vespinae, and 12.7 in the two Apis species. The high egg-laying rate and the effective population size skew between the sexes may contribute to the rise of the substitution ratio in the highly eusocial species. Drift and bottleneck effects in the mitochondrial DNA pool during speciation events as well as polyandry may further enhance this phenomenon.

Animals↗
PubMed2006

8. The development and evolution of division of labor and foraging specialization in a social insect (Apis mellifera L.).

How does complex social behavior evolve? What are the developmental building blocks of division of labor and specialization, the hallmarks of insect societies? Studies have revealed the developmental origins in the evolution of division of labor and specialization in foraging worker honeybees, the hallmarks of complex insect societies. Selective breeding for a single social trait, the amount of surplus pollen stored in the nest (pollen hoarding) revealed a phenotypic architecture of correlated traits at multiple levels of biological organization in facultatively sterile female worker honeybees. Verification of this phenotypic architecture in "wild-type" bees provided strong support for a "pollen foraging syndrome" that involves increased senso-motor responses, motor activity, associative learning, reproductive status, and rates of behavioral development, as well as foraging behavior. This set of traits guided further research into reproductive regulatory systems that were co-opted by natural selection during the evolution of social behavior. Division of labor, characterized by changes in the tasks performed by bees, as they age, is controlled by hormones linked to ovary development. Foraging specialization on nectar and pollen results also from different reproductive states of bees where nectar foragers engage in pre-reproductive behavior, foraging for nectar for self-maintenance, while pollen foragers perform foraging tasks associated with reproduction and maternal care, collecting protein.

Animals↗
PubMed1997

Major "anastrophes" in the origin and early evolution of biological energy conversion.

The metabolism of living organisms has long been usefully divided into anabolism and catabolism. Anabolism is constructive, being concerned with the assembly of complex molecules, whereas catabolism is destructive in the sense that it involves the degradation of molecules. In addition to the well-known word catastrophe for sudden, drastic destruction and its consequences, it has been found practical to introduce in the evolutionary context the word "anastrophe" (an old greek word for turning back, in the opposite direction-from anastrephein, where ana = back and strephein = to turn) to cover sudden, drastic constructive events and their consequences. Mutations in genes and genomes giving selective advantage to an organism are typical anastrophic events. A single site mutation in a gene coding for a protein may be good, neutral or bad, or anastrophic, neutral or catastrophic, respectively, for the organism. The consequence of an anastrophic mutation may be a decisive first step on the long way to a new species, whereas a catastrophic mutation may lead to major cell damage or death. This example of the use of the anastrophe concept in biological evolution leads to the question about its applicability to other parts and paths of the cosmic evolutionary process, such as physical, chemical, social and cultural evolution. Here it will be mainly considered in connection with the energy conversion aspects of the chemical evolution leading to the origin of life and of the subsequent early biological evolution. More specifically, it will be attempted to describe possible major anastrophes in energy conversion both before and after the first occurrence of life on earth.

Animals↗
PubMed1989

A social skills group for autistic children.

The evolution and preliminary evaluation of a social skills training group for 10 autistic children aged between 9 and 16 years was described. These children attended a special unit which aimed to integrate them into normal school provision. The paper consists of a description of the evolution of the group and the training methods employed and an evaluation of the effect of the group. This was accomplished by the use of a standard teacher's questionnaire. The results of the evaluation are described and the implications for further study of this means of helping autistic individuals discussed.

Adolescent↗
PubMed2006

The social brain hypothesis of schizophrenia.

The social brain hypothesis is a useful heuristic for understanding schizophrenia. It focuses attention on the core Bleulerian concept of autistic alienation and is consistent with well-replicated findings of social brain dysfunction in schizophrenia as well as contemporary theories of human cognitive and brain evolution. The contributions of Heidegger, Merleau-Ponty and Wittgenstein allow us to arrive at a new "philosophy of interpersonal relatedness", which better reflects the "embodied mind" and signifies the end of Cartesian dualistic thinking. In this paper I review the evolution, development and neurobiology of the social brain - the anatomical and functional substrate for adaptive social behaviour and cognition. Functional imaging identifies fronto-temporal and fronto-parietal cortical networks as comprising the social brain, while the discovery of "mirror neurons" provides an understanding of social cognition at a cellular level. Patients with schizophrenia display abnormalities in a wide range of social cognition tasks such as emotion recognition, theory of mind and affective responsiveness. Furthermore, recent research indicates that schizophrenia is a disorder of functional and structural connectivity of social brain networks. These findings lend support to the claim that schizophrenia represents a costly by-product of social brain evolution in Homo sapiens. Individuals with this disorder find themselves seriously disadvantaged in the social arena and vulnerable to the stresses of their complex social environments. This state of "disembodiment" and interpersonal alienation is the core phenomenon of schizophrenia and the root cause of intolerable suffering in the lives of those affected.

Journal Article↗
PubMed2006

The ties that bind: genetic relatedness predicts the fission and fusion of social groups in wild African elephants.

Many social animals live in stable groups. In contrast, African savannah elephants (Loxodonta africana) live in unusually fluid, fission-fusion societies. That is, 'core' social groups are composed of predictable sets of individuals; however, over the course of hours or days, these groups may temporarily divide and reunite, or they may fuse with other social groups to form much larger social units. Here, we test the hypothesis that genetic relatedness predicts patterns of group fission and fusion among wild, female African elephants. Our study of a single Kenyan population spans 236 individuals in 45 core social groups, genotyped at 11 microsatellite and one mitochondrial DNA (mtDNA) locus. We found that genetic relatedness predicted group fission; adult females remained with their first order maternal relatives when core groups fissioned temporarily. Relatedness also predicted temporary fusion between social groups; core groups were more likely to fuse with each other when the oldest females in each group were genetic relatives. Groups that shared mtDNA haplotypes were also significantly more likely to fuse than groups that did not share mtDNA. Our results suggest that associations between core social groups persist for decades after the original maternal kin have died. We discuss these results in the context of kin selection and its possible role in the evolution of elephant sociality.

Animals↗
PubMed2000

Female reproductive strategies as social organizers.

When male philopatry is linked to patriarchy, it is often assumed that female reproductive strategies are secondary to male reproductive strategies. By comparing the social structures of chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) with those of other non-human primates, I argue that female reproductive strategies can be viewed as primary principles of social organization, including the establishment of patriarchies through differential investment in offspring. Emphasis on the contributions of female reproductive strategies may lead to a different picture of the evolution of primate social organization.

Animals↗
PubMed2004

[Fight against smoking: information and misinformation].

For decades tobacco manufacturers have attempted to trivialise the health risks associated with tobacco, reinforce and enhance its social acceptability using powerful communication and reprehensible strategies. Prevention campaigns have contributed to raise public awareness on the health risks associated with smoking. They have also allowed for an evolution of the social representation of tobacco use. From 2001, to stop tobacco consumption taking off again, media campaigns have become more offensive both in content and form. Today the communication strategy places as priority objectives the reinforcement of the socially unacceptable character of tobacco use (denormalisation) via information on health risks and cessation support for smokers to quit. In 2002, a media campaign (TV, radio, press) denounced the toxicity of tobacco smoke provoking a true remobilisation of public opinion against tobacco.

Health Promotion↗
PubMed2003

[Social participation in health services: concepts of users and community leaders in two municipalities of Northeastern Brazil].

Social participation in management of the health care system at different levels of government is one of the key policies promoted by the Unified National Health System (SUS) in Brazil. As with any new policy, success hinges on several factors such as stakeholders' interests and opinions, which have not always been considered in the past. This paper analyzes the underlying concepts of two groups of stakeholders with respect to social participation in health and the potential influence of these concepts on the effectiveness of policy implementation. A case study of two municipalities in Northeast Brazil was conducted using a combination of qualitative and quantitative social science research methods. Health services users and community leaders were interviewed. Various concepts were found in which the participatory approach to health policies was only partially reflected. Likely influences on stakeholders' concepts of social participation in health are the evolution of the broader Brazilian social context and the traditional performance of health services. Particular attention should be paid to stakeholders' opinions and concepts if policy effectiveness is to be improved.

Adolescent↗
PubMed2002

Cleaner fish Labroides dimidiatus recognise familiar clients.

Individual recognition has been attributed a crucial role in the evolution of complex social systems such as helping behaviour and cooperation. A classical example for interspecific cooperation is the mutualism between the cleaner fish Labroides dimidiatus and its client reef fish species. For stable cooperation to evolve, it is generally assumed that partners interact repeatedly and remember each other's past behaviour. Repeated interactions may be achieved by site fidelity or individual recognition. However, as some cleaner fish have more than 2,300 interactions per day with various individuals per species and various species of clients, basic assumptions of cooperation theory might be violated in this mutualism. We tested the cleaner L. dimidiatus and its herbivorous client, the surgeon fish Ctenochaetus striatus, for their ability to distinguish between a familiar and an unfamiliar partner in a choice experiment. Under natural conditions, cleaners and clients have to build up their relationship, which is probably costly for both. We therefore predicted that both clients and cleaners should prefer the familiar partner in our choice experiment. We found that cleaners spent significantly more time near the familiar than the unfamiliar clients in the first 2 minutes of the experiment. This indicates the ability for individual recognition in cleaners. In contrast, the client C. striatus showed no significant preference. This could be due to a sampling artefact, possibly due to a lack of sufficient motivation. Alternatively, clients may not need to recognise their cleaners but instead remember the defined territories of L. dimidiatus to achieve repeated interactions with the same individual.

Adaptation, Physiological↗
PubMed2005

The evolutionary language game: an orthogonal approach.

Evolutionary game dynamics have been proposed as a mathematical framework for the cultural evolution of language and more specifically the evolution of vocabulary. This article discusses a model that is mutually exclusive in its underlying principals with some previously suggested models. The model describes how individuals in a population culturally acquire a vocabulary by actively participating in the acquisition process instead of passively observing and communicate through peer-to-peer interactions instead of vertical parent-offspring relations. Concretely, a notion of social/cultural learning called the naming game is first abstracted using learning theory. This abstraction defines the required cultural transmission mechanism for an evolutionary process. Second, the derived transmission system is expressed in terms of the well-known selection-mutation model defined in the context of evolutionary dynamics. In this way, the analogy between social learning and evolution at the level of meaning-word associations is made explicit. Although only horizontal and oblique transmission structures will be considered, extensions to vertical structures over different genetic generations can easily be incorporated. We provide a number of simplified experiments to clarify our reasoning.

Biological Evolution↗
PubMed2005

Current research in amphibians: studies integrating endocrinology, behavior, and neurobiology.

Amphibian behavioral endocrinology has focused on reproductive social behavior and communication in frogs and newts. Androgens and estrogens are critical for the expression of male and female behavior, respectively, and their effects are relatively clear. Corticosteroids have significant modulatory effects on the behavior of both sexes, as does the peptide neuromodulator arginine vasotocin in males, but their effects and interactions with gonadal steroids are often complex and difficult to understand. Recent work has shown that the gonadal hormones and social behavior are mutually reinforcing: engaging in social interactions increases hormone levels just as increasing hormone levels change behavior. The reciprocal interactions of hormones and behavior, as well as the complex interactions among gonadal steroids, adrenal steroids, and peptide hormones have implications for the maintenance and evolution of natural social behavior, and suggest that a deeper understanding of both endocrine mechanisms and social behavior would arise from field studies or other approaches that combine behavioral endocrinology with behavioral ecology.

Adrenal Cortex Hormones↗
PubMed1979

Suicide and attempted suicide in Greenland. A controlled study in Nuuk (Godthaab).

Suicidal behaviour in Eskimo populations has changed in pattern and quantity over the last decades. Rates have more than quadrupled and performers now are mainly young persons with obscure motivation. In a study from Greenland's major township all cases of attempted or completed suicide among Greenlanders are analysed for social, emotional, somatic, and environmental predisposing factors in comparison with a non-psychiatric, never-suicidal, matching group. Almost two per thousand of the adult population committed suicide yearly while attempts at suicide were five times as frequent. A quarrelsome, drinking, childhood home background was often found, at least as regards the attempters, who themselves frequently suffered from emotional conflicts with close contacts, alcohol affliction, criminality, and instability at work. Neither bereavement, cross-cultural exposure, broken homes, nor meteorological factors seemed to exert a significant influence. The results are discussed in relation to the social and cultural evolution of the Greenlandic society.

Adult↗
PubMed2003

Parents and children: ideas of heredity in the 19th century.

The concept of heredity played a powerful role in structuring 19th-century debates over sickness, morality, class, race, education, social change and evolution. But there was very little agreement as to which qualities were heritable and how new hereditary variants were acquired. In consequence, notions of heredity existed in a wide variety of forms, expressing anything from extreme determinism and a belief in the incorrigibility of individuals, social and racial groups, to unleavened optimism, and a faith in ultimate human perfectibility. This article explores these rich hereditarian discourses to convey an impression of a century that was at least as preoccupied with the concept of biological inheritance as we are today.

Adult↗