The sociobiology of biofilms

Biofilms are densely packed communities of microbial cells that grow on surfaces and surround themselves with secreted polymers. Many bacterial species form biofilms, and their study has revealed them to be complex and diverse. The structural and physiological complexity of biofilms has led to the idea that they are coordinated and cooperative groups, analogous to multicellular organisms. We evaluate this idea by addressing the findings of microbiologists from the perspective of sociobiology, including theories of collective behavior (self-organization) and social evolution. This yields two main conclusions. First, the appearance of organization in biofilms can emerge without active coordination. That is, biofilm properties such as phenotypic differentiation, species stratification and channel formation do not necessarily require that cells communicate with one another using specialized signaling molecules. Second, while local cooperation among bacteria may often occur, the evolution of cooperation among all cells is unlikely for most biofilms. Strong conflict can arise among multiple species and strains in a biofilm, and spontaneous mutation can generate conflict even within biofilms initiated by genetically identical cells. Biofilms will typically result from a balance between competition and cooperation, and we argue that understanding this balance is central to building a complete and predictive model of biofilm formation.     

The sociobiology of molecular systems

It is often assumed that molecular systems are designed to maximize the competitive ability of the organism that carries them. In reality, natural selection acts on both cooperative and competitive phenotypes, across multiple scales of biological organization. Here I ask how the potential for social effects in evolution has influenced molecular systems. I discuss a range of phenotypes, from the selfish genetic elements that disrupt genomes, through metabolism, multicellularity and cancer, to behaviour and the organization of animal societies. I argue that the balance between cooperative and competitive evolution has shaped both form and function at the molecular scale.     

Exemplars and the reproduction of everyday life: The Amherst affair

Frederick Errington is Aaaociate Professor of Anthropology, at Keene State College, New Hampshire. Deborah Gewertz is Professor of Anthropology, at Amherst College, Massachusetts.     

Fear and everyday life in rural Nepal

This paper analyses fear in a village in central Nepal during the ‘People’s War’. Spanning the years from 1999 to 2008, the paper illustrates how the different phases of the insurgency and individual circumstances resulted in people’s relationship with fear changing over time. By presenting a chronological analysis of fear, the authors draw attention to the interrelationship between fear, temporality and sociality and show that fear is always contextually situated, differently experienced through time and related to personal circumstances. Villagers had strongly developed coping strategies which they drew upon to support themselves and decrease their fear. Some people, however, suffered such a degree of structural violence that experiencing fear was seen as a privilege. Others denied their fear as part of their performance of manliness while others coped by ridiculing fear. Although a certain amount of suspicion and mistrust lingered, most people recovered from the impact of chronic fear. They fully returned to their field and forest work as well as their previous social activities following the peace agreement of 2006.     

Child abuse: The limits of sociobiology

A review of five population based studies indicates that rates of child abuse tend to be highest among young male children from poor families. Children from very large families, children from families with a history of marital disruption, and defective children are also at a high risk of abuse. Perpetrators are more apt to be fathers or stepparents than would be expected on the basis of their representation in families of abused children. Biological mothers are least apt to abuse their children.Although these data are consistent with an evolutionary model of child abuse, many of these findings are also consistent with alternative (especially economic) models for abuse. An attempt is made to develop testable predictions for child abuse that are consistent with evolutionary theory and inconsistent with more conventional models.     

Culture and sociobiology

Sociobiological concepts are easily misapplied to human behavior because the latter is culturally as well as biologically organized. Because biological and cultural evolution are two linked but conceptually distinct processes, sociobiology is more readily applied to the evolution of cultural capacity than to contemporary cultural behavior. The extent to which the latter is consistent with sociobiological expectation must be determined empirically, although there are theoretical grounds for predicting a limited degree of concordance . [sociobiology, culture, evolution, reductionism, biosocial anthropology]     

The sociobiology of ethnocentrism in an Indian City

In this article, I examine whether inter- and/or intraunit variation in ethnocentrism— a trait not automatically connected with mortality/natality rates—can be correlated with differential reproductive success. As a preliminary test of general theoretical models in the literature regarding the sociobiology of ethnocentrism, it was postulated that the more ethnocentric an ethnic unit is, the more important ethnocentrism is for the members of that unit. With the use of this postulate, hypotheses were generated and tested with empirical data obtained through field research among two ethnic units—Tamils and Gujaratis—in the city of Pune, India. It was concluded that: 1) if interunit aggression and kin selection were predominant characteristics of the early hominid environments of evolutionary adaptation, then from a sociobiological perspective, ethnocentrism can be explained as an evolved human trait, intimately linked to kin selection and interunit warfare; and, 2) under what I assumed to be novel environmental conditions ethnocentrism and reproductive success appear to be uncorrelated; and, 3) because the possibility exists that novel environmental contengencies were acting to level off reproductive variance upon which natural selection could have operated in my sample, only future research in a society similar in structure to those we tend to identify with early hominid environments of evolutionary adaptation will allow researchers to rule out the possibility that ethnocentrism is an evolved human “biocultural” trait.     

Functional explanations in sociobiology

Functional explanations in sociobiology