The social genome of friends and schoolmates in the National Longitudinal Study of Adolescent to Adult Health.

Humans tend to form social relationships with others who resemble them. Whether this sorting of like with like arises from historical patterns of migration, meso-level social structures in modern society, or individual-level selection of similar peers remains unsettled. Recent research has evaluated the possibility that unobserved genotypes may play an important role in the creation of homophilous relationships. We extend this work by using data from 5,500 adolescents from the National Longitudinal Study of Adolescent to Adult Health (Add Health) to examine genetic similarities among pairs of friends. Although there is some evidence that friends have correlated genotypes, both at the whole-genome level as well as at trait-associated loci (via polygenic scores), further analysis suggests that meso-level forces, such as school assignment, are a principal source of genetic similarity between friends. We also observe apparent social-genetic effects in which polygenic scores of an individual's friends and schoolmates predict the individual's own educational attainment. In contrast, an individual's height is unassociated with the height genetics of peers.

Modeling pluralism and self-regulation explains the emergence of cooperation in networked societies.

Understanding the dynamics of cooperative behavior of individuals in complex societies represents a fundamental research question which puzzles scientists working in heterogeneous fields. Many studies have been developed using the unitary agent assumption, which embeds the idea that when making decisions, individuals share the same socio-cultural parameters. In this paper, we propose the ECHO-EGN model, based on Evolutionary Game Theory, which relaxes this strong assumption by considering the heterogeneity of three fundamental socio-cultural aspects ruling the behavior of groups of people: the propensity to be more cooperative with members of the same group (Endogamic cooperation), the propensity to cooperate with the public domain (Civicness) and the propensity to prefer connections with members of the same group (Homophily). The ECHO-EGN model is shown to have high performance in describing real world behavior of interacting individuals living in complex environments. Extensive numerical experiments allowing the comparison of real data and model simulations confirmed that the introduction of the above mechanisms enhances the realism in the modelling of cooperation dynamics. Additionally, theoretical findings allow us to conclude that endogamic cooperation may limit significantly the emergence of cooperation.

Understanding others: Emotion recognition in humans and other animals.

Emotion recognition represents the ability to encode an ensemble of sensory stimuli providing information about the emotional state of another individual. This ability is not unique to humans. An increasing number of studies suggest that many aspects of higher order social functions, including emotion recognition, might be present in species ranging from primates to rodents, indicating a conserved role in social animals. The aim of this review is to examine and compare how emotions are communicated and perceived in humans and other animals, with the intent to highlight possible new behavioral approaches and research perspectives. We summarize the evidence from human emotion recognition, and latest advances in the development of nonhuman animal behavioral tests, using or implying the use of this cognitive function. The differential implication of sensory modalities used by animals to communicate and decipher emotional states is also discussed. The opportunity to measure emotion recognition abilities in rodents may allow us to better identify the neural mechanisms mediating this complex function, thus promoting the development of new intervention strategies for several neuropsychiatric disorders characterized by social cognitive dysfunctions.

The evolution of language families is shaped by the environment beyond neutral drift.

There are more than 7,000 languages spoken in the world today1. It has been argued that the natural and social environment of languages drives this diversity2-13. However, a fundamental question is how strong are environmental pressures, and does neutral drift suffice as a mechanism to explain diversification? We estimate the phylogenetic signals of geographic dimensions, distance to water, climate and population size on more than 6,000 phylogenetic trees of 46 language families. Phylogenetic signals of environmental factors are generally stronger than expected under the null hypothesis of no relationship with the shape of family trees. Importantly, they are also-in most cases-not compatible with neutral drift models of constant-rate change across the family tree branches. Our results suggest that language diversification is driven by further adaptive and non-adaptive pressures. Language diversity cannot be understood without modelling the pressures that physical, ecological and social factors exert on language users in different environments across the globe.

The Socioecology of Territory Size and a "Work-Around" Hypothesis for the Adoption of Farming.

This paper combines theory from ecology and anthropology to investigate variation in the territory sizes of subsistence oriented agricultural societies. The results indicate that population and the dependence of individuals within a society on "wild" foods partly determine the territory sizes of agricultural societies. In contrast, the productivity of an agroecosystem is not an important determinant of territory size. A comparison of the population-territory size scaling dynamics of agricultural societies and human foragers indicates that foragers and farmers face the same constraints on their ability to expand their territory and intensify their use of resources within a territory. However, the higher density of food in an agroecosystem allows farmers, on average, to live at much higher population densities than human foragers. These macroecological patterns are consistent with a "work-around hypothesis" for the adoption of farming. This hypothesis is that as residential groups of foragers increase in size, farming can sometimes better reduce the tension between an individual's autonomy over resources and the need for social groups to function to provide public goods like defense and information.

On the evolution of sport.

Sports have received little attention from evolutionary biologists. I argue that sport began as a way for men to develop the skills needed in primitive hunting and warfare, then developed to act primarily as a lek where athletes display and male spectators evaluate the qualities of potential allies and rivals. This hypothesis predicts that (1) the most popular modern male sports require the skills needed for success in male-male physical competition and primitive hunting and warfare; (2) champion male athletes obtain high status and thereby reproductive opportunities in ways that parallel those gained by successful primitive hunters and warriors; (3) men pay closer attention than do women to male sports so they can evaluate potential allies and rivals; and (4) male sports became culturally more important when opportunities to evaluate potential allies and rivals declined as both the survival importance of hunting and the proportion of men who experience combat decreased. The characteristics of primitive and modern sports are more consistent with these predictions than those generated by intersexual sexual selection theories of sport.

Rethinking the theoretical foundation of sociobiology.

Current sociobiology is in theoretical disarray, with a diversity of frameworks that are poorly related to each other Part of the problem is a reluctance to revisit the pivotal events that took place during the 1960s, including the rejection of group selection and the development of alternative theoretical frameworks to explain the evolution of cooperative and altruistic behaviors. In this article, we take a "back to basics" approach, explaining what group selection is, why its rejection was regarded as so important, and how it has been revived based on a more careful formulation and subsequent research. Multilevel selection theory (including group selection) provides an elegant theoretical foundation for sociobiology in the future, once its turbulent past is appropriately understood.

Exploring co-management theory: prospects for sociobiology and reciprocal altruism.

Co-management has gained prominence due to the sustained interest in participatory forms of natural resource management. While theoretical development posed an initial challenge, it has become an integral part of the co-management literature. This paper comprehensively explores co-management theory. It begins with an investigation of theory itself. The major elements of theory (concepts, variables and relational propositions) are described and a typology of theoretical statements (formats) is conceptualized. Co-management theory is subsequently charted according to the four schemes (modelling, propositional, analytical and meta-theoretical) which make up the typology. Given the maturing nature of the co-management literature and the absence of any meta-theoretical schemes, we examine the central and underlying assumption of co-operation through the science of sociobiology. Reciprocal altruism is pursued to explain why non-kin co-operate, and is adapted to elucidate the potentials and pitfalls of co-management. This meta-theory enriches understanding of co-management, provides guidance to the other theoretical schemes, and offers a foundational basis upon which construction of subtle predications is possible.

Are we born moral?

Reviews of: Hauser, Marc D. Moral minds: how nature designed our universal sense of right and wrong. (New York: Ecco, 2006); and Waal, F.B.M. de. Primates and philosophers: how morality evolved. (Princeton, N.J. : Princeton University Press, 2006).

The sociobiologic integrative model (SBIM): enhancing the integration of sociobehavioral, environmental, and biomolecular knowledge in urban health and disparities research.

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.