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PubMed2004

Networking the seceder model: Group formation in social and economic systems.

The seceder model illustrates how the desire to be different from the average can lead to formation of groups in a population. We turn the original, agent based, seceder model into a model of network evolution. We find that the structural characteristics of our model closely match empirical social networks. Statistics for the dynamics of group formation are also given. Extensions of the model to networks of companies are also discussed.

Journal Article↗
PubMed2005

The leading eight: social norms that can maintain cooperation by indirect reciprocity.

The theory of indirect reciprocation explains the evolution of cooperation among unrelated individuals, engaging in one-shot interaction. Using reputation, a player acquires information on who are worth cooperating and who are not. In a previous paper, we formalized the reputation dynamics, a rule to assign a binary reputation (good or bad) to each player when his action, his current reputation, and the opponent's reputation are given. We then examined all the possible reputation dynamics, and found that there exist only eight reputation dynamics named "leading eight" that can maintain the ESS with a high level of cooperation, even if errors are included in executing intended cooperation and in reporting the observation to the public. In this paper, we study the nature of these successful social norms. First, we characterize the role of each pivot of the reputation dynamics common to all of the leading eight. We conclude that keys to the success in indirect reciprocity are to be nice (maintenance of cooperation among themselves), retaliatory (detection of defectors, punishment, and justification of punishment), apologetic, and forgiving. Second, we prove the two basic properties of the leading eight, which give a quantitative evaluation of the ESS condition and the level of cooperation maintained at the ESS.

Biological Evolution↗
PubMed1997

Information processing and symmetry-breaking in memory evolutive systems.

The aim of this paper is to evaluate the role of symmetry and symmetry-breaking processes on the complex information processing developed by hierarchical evolutionary natural systems, such as biological, neural, social or cultural systems. The study is conducted in the frame of the Memory Evolutive Systems, which give a mathematical model of these systems. The dynamics of a MES is modulated by the competition between a net of internal regulation centers which act apart-but encode overlapping strategies which have to be equilibrated. The main characteristics of these systems, at the root of their complexity and adaptability, is a symmetry-breaking in the passage from a higher (or macro) level to a lower (or micro) level: several disparate sub-systems with different comportments at the micro level can be undistinguishable at the higher macro level because of a similar macro behavior (Multiplicity Principle). It is responsible for the development of a dialectics between heterogeneous regulation centers, and for the emergence in time of more and more complex objects. An application to neural systems vindicates an emergentist dynamical reduction of mental states to physical states.

Animals↗
PubMed2001

Evolution of cooperation without reciprocity.

A long-standing problem in biological and social sciences is to understand the conditions required for the emergence and maintenance of cooperation in evolving populations. For many situations, kin selection is an adequate explanation, although kin-recognition may still be a problem. Explanations of cooperation between non-kin include continuing interactions that provide a shadow of the future (that is, the expectation of an ongoing relationship) that can sustain reciprocity, possibly supported by mechanisms to bias interactions such as embedding the agents in a two-dimensional space or other context-preserving networks. Another explanation, indirect reciprocity, applies when benevolence to one agent increases the chance of receiving help from others. Here we use computer simulations to show that cooperation can arise when agents donate to others who are sufficiently similar to themselves in some arbitrary characteristic. Such a characteristic, or 'tag', can be a marking, display, or other observable trait. Tag-based donation can lead to the emergence of cooperation among agents who have only rudimentary ability to detect environmental signals and, unlike models of direct or indirect reciprocity, no memory of past encounters is required.

Altruism↗
PubMed2006

Making sense of behavioral irregularities of great apes.

Psychopathology, mental illness, and psychiatric treatment are concepts relevant to modern medicine and medical psychology and replete with cumbersome intellectual and literary baggage. They bear the imprint of suppositions, world views, and general beliefs and values exemplified in the science, history, and general culture of Anglo European societies. The study in higher apes of phenomena addressed by such concepts raises conceptual dilemmas, usually termed speciesism and anthropomorphism, not unlike those encountered in comparative human studies of similar phenomena across cultures and historical periods, namely, ethnocentrism and anachronism. The authors' synthesis of literature and their analysis of the implications of higher ape psychopathology represent an epistemically compelling account that broadens the scope of the comparative study of behavioral irregularities, a topic that provides a different slant for examining challenging questions in evolutionary biology and primatology, such as cognition, self awareness, intentional behavior, culture and behavioral traditions, social intelligence, sickness and healing, and altruism. Theoretical and empirical study of this topic expands formulation and can help provide informative answers about human evolution as well as essential features of human psychiatric syndromes, with potential practical implications. The study of psychopathology of higher apes and other non human primates represents an appropriate focus for neuroscience and bio-behavioral sciences.

Animals↗
PubMed2005

Life history and social learning: megapode chicks fail to acquire feeding preferences from conspecifics.

Australian brush-turkeys, Alectura lathami, are birds with an unusual life history: The young receive no parental care and first encounter conspecifics at an unpredictable age. Brush-turkey chicks that were 3-4 days old were presented with a robot model that appeared to feed from a distinctively colored dish. In control training trials, chicks saw a robot standing next to a different dish and scanning from side to side. Chicks expressed a strong tendency to feed from dishes of the type indicated by the pecking robot, but this effect proved ephemeral. Brush-turkeys hence appear to show no social learning under conditions that inculcate stable preferences in other galliforms such as chickens, suggesting that life history plays an important role in the evolution of learning.

Animals↗
PubMed1990

[Infanticide in primates and man and the problems of reconstructing the social behavior of the hominids].

The general analysis of infanticide distribution pattern in primate and human populations is given. The possibilities to use the sociobiological, ecological, psycho-analytical and structural-social approaches are considered to explain the infanticide functions in primates. The necessity of exact data concerning the sex, age and social position of both: killers and victims (victim's mothers either) is stressed, as well the estimation of social situation in the group in the period before the infanticide. The qualitative differences in infanticide mechanisms in lower monkeys, anthropoids and man is illustrated. It is proposed to differentiate the infanticide on the individual level and as a group social strategy. The probability of infanticide in hominid societies on the different stages of evolution is discussed.

Animals↗
PubMed1981

Control of complex conation and emotion in the neocortex by the limbic entorhinal, subicular, and cingulate cortices and the hypothalamus, mammillary body, and thalamus.

The neocortex appears to contain columnar neuron populations that function as unitary information structures. The interactions between these structures, and the sensorimotor relationships they process, are regulated by subcortical regions. The reticular formation, hypothalamus, thalamus and basal ganglia have been proposed as a hierarchical control system that regulates the processing carried out by hierarchies of the cortical information structures in basic behavioral states. The regulation is carried out by means of operations on conative information components that circulate through the subcortical-neocortical system. It is proposed that in complex behavioral states, composite modalities of conative information are formed. These are processed in a complex-state system that involves parts of the limbic lobe and related nuclei: the entorhinal cortex, subiculum, mammillary body, thalamus, and posterior and anterior cingulate cortices. This system can accommodate new modalities of conation, including those relating to social behavior. Genetic specification of engrams in the system provides for evolution of conative and emotional states, matching increases in sophistication of cognitive processing.

Animals↗
PubMed1995

[Mental disease between norm and history].

After a brief discussion of the concept of statistical, social and functional norm, the authors stress that the latter is related to the constant evolution and hence uncertain nature of scientific knowledge. With regard to mental disease it is underlined that, during the history of psychiatrics, social aspects have often been confused with functional ones, and uncommon statistical aspects have been interpreted as abnormal. Likewise, as it changes over time even the social norm has interfered with functional norms and consequently with the pathological process.

Humans↗
PubMed2006

Five rules for the evolution of cooperation.

Cooperation is needed for evolution to construct new levels of organization. Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation. Cooperation means that selfish replicators forgo some of their reproductive potential to help one another. But natural selection implies competition and therefore opposes cooperation unless a specific mechanism is at work. Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

Biological Evolution↗
PubMed2002

Volunteering as Red Queen mechanism for cooperation in public goods games.

The evolution of cooperation among nonrelated individuals is one of the fundamental problems in biology and social sciences. Reciprocal altruism fails to provide a solution if interactions are not repeated often enough or groups are too large. Punishment and reward can be very effective but require that defectors can be traced and identified. Here we present a simple but effective mechanism operating under full anonymity. Optional participation can foil exploiters and overcome the social dilemma. In voluntary public goods interactions, cooperators and defectors will coexist. We show that this result holds under very diverse assumptions on population structure and adaptation mechanisms, leading usually not to an equilibrium but to an unending cycle of adjustments (a Red Queen type of evolution). Thus, voluntary participation offers an escape hatch out of some social traps. Cooperation can subsist in sizable groups even if interactions are not repeated, defectors remain anonymous, players have no memory, and assortment is purely random.

Cooperative Behavior↗
PubMed2006

The evolutionary psychology of left and right: costs and benefits of lateralization.

Why do the left and right sides of the vertebrate brain play different functions? Having a lateralized brain, in which each hemisphere carries out different functions, is ubiquitous among vertebrates. The different specialization of the left and right side of the brain may increase brain efficiency--and some evidence for that is reported here. However, lateral biases due to brain lateralization (such as preferences in the use of a limb or, in animals with laterally placed eyes, of a visual hemifield) usually occur at the population level, with most individuals showing similar direction of bias. Individual brain efficiency does not require the alignment of lateralization in the population. Why then are not left--and right-type individuals equally common? Not only humans, but most vertebrates show a similar pattern. For instance, in the paper I report evidence that most toads, chickens, and fish react faster when a predator approaches from the left. I argue that invoking individual brain efficiency (lateralization may increase fitness), evolutionary chance or direct genetic mechanisms cannot explain this widespread pattern. Instead, using concepts from mathematical theory of games, I show that alignment of lateralization at the population level may arise as an "evolutionarily stable strategy" when individually asymmetrical organisms must coordinate their behavior with that of other asymmetrical organisms. Thus, the population structure of lateralization may result from genes specifying the direction of asymmetries which have been selected under "social" pressures.

Animals↗
PubMed1984

The compleat otolaryngologist: Burton Alexander Randall.

The practicing otolaryngologist and resident is the beneficiary of a highly organized educational system which has evolved over the past 100 years. A number of social, scientific and technical advances were involved in the evolution of these training programs; however, one of the most important developments was the emergence of the Clinician Educator Concept. Burton Alexander Randall was prominent in the profession in the late nineteenth century and early twentieth century and is an example of the clinician-teacher who participated in the development of otorhinolaryngologic instruction. His unpublished memoirs, recently made available, illustrate the difficulties in obtaining appropriate training, organizing clinical services, and establishing professional relationships. These interesting documents provide insight into the present and illustrate that although there have been great technical advances, some problems in interpersonal relationships remain the same.

Education, Medical↗
PubMed2001

Genetic susceptibility for breast cancer--risk assessment and counseling.

The incorporation of genetic information into clinical oncology practice is a process in evolution, necessitating consideration of cancer risk assessment, ethical and social implications of testing and efficacy of treatment, and prevention interventions. Although most cancers do have a hereditary component, recognizing individuals who are at unusually high risk is important for planning their surveillance practices and considering options for risk management over a lifetime, and because of implications for their family members. Genetic information has enormous potential to inform and transform cancer risk identification, risk reduction, and treatment practices. In this review, we summarize basic information about breast cancer genetics, examine accumulating data about the prevalence and penetrance of deleterious mutations and management options for BRCA1 and BRCA2 mutation carriers, and discuss some of the counseling issues that may occur as physicians and patients explore this exploding area of oncology. The rapid incorporation of careful genetic testing into oncology practice is an important step toward more precise risk management. Currently, the time necessary for careful discussion of the complex issues raised by genetic testing for inherited breast/ovarian cancer susceptibility may necessitate referral to geneticists or genetic counselors for truly informed consent to be obtained. However, identification of women for whom testing is appropriate and management of cancer risk with women after testing, are critical new functions for oncologists. They are only the beginning of exciting new opportunities in cancer risk and prevention.

BRCA2 Protein↗
PubMed2001

Long-term follow-up study of West syndrome associated with tuberous sclerosis.

AIM: To analyze the evolution of seizures, electroencephalographic (EEG) features, seizure outcomes, and social outcomes, in order to formulate a basis for the long-term prognosis of West syndrome (WS) associated with tuberous sclerosis (TS). METHOD: The clinical profiles of 50 patients with TS, who presented with WS in infancy and had been monitored for more than 10 years after the initial examination, were analyzed. RESULTS: In 86% of the patients the seizure type did not change throughout the course of this study. However, 14% of patients had developed other types of seizures by the end of the follow-up period. The seizure outcome was unfavorable for patients with generalized seizures. Partial seizures were controlled in nine (64%) of the 14 patients, and normal or slightly subnormal intelligence accounted for seven of the 14 patients. CONCLUSIONS: Therefore, in patients with WS associated with TS, the seizure outcome and social activity depended on the type of seizure that developed during the course of this disorder. The outcome of patients with WS associated with TS seems to be better than that of WS in general.

Electroencephalography↗
PubMed1996

Machiavellianism: a synthesis of the evolutionary and psychological literatures.

Manipulative strategies of social conduct (Machiavellianism) have been studied by both psychologists and evolutionary biologists. The authors use the psychological literature as a database to test evolutionary hypotheses about the adaptive advantages of manipulative social behavior. Machiavellianism does not correlate with general intelligence and does not consistently lead to real-world success. It is best regarded as 1 of several social strategies, broadly similar to the "defect" strategy of evolutionary game theory, which is successful in some situations but not others. In general, human evolutionary psychology and evolutionary game theory provide useful frameworks for thinking about behavioral strategies, such as Machiavellianism, and identify a large number of specific hypotheses that have not yet been tested by personality and social psychologists.

Animals↗
PubMed2005

Evaluating the effectiveness of community-based dementia care networks: the Dementia Care Networks' Study.

PURPOSE: The Dementia Care Networks' Study examined the effectiveness of four community-based, not-for-profit dementia networks. The study involved assessing the relationship between the types of administrative and service-delivery exchanges that occurred among the networked agencies and the network members' perception of the effectiveness of these exchanges. DESIGN AND METHODS: With the use of a case-study method, the evolution, structure, and processes of each network were documented. Social network analysis using a standardized questionnaire completed by member agencies identified patterns of administrative and clinical exchanges among networked agencies. RESULTS: Differences were found between the four networks in terms of their perceptions of service-delivery effectiveness; perceptions of administrative effectiveness did not factor significantly. Exchanges between groups of agencies (cliques) within each of the four networks were found to be more critical than those between individual agencies within each network. IMPLICATIONS: Integration-measured by the types of exchanges within as opposed to across networks-differentiated the four networks studied. This research contributes to our understanding of the use of multiple measures to evaluate the inner workings of service delivery and their impact on elder health and elder health care.

Aged↗