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 everyday life

The 1000-year-old novel The Tale of Genji, written by Murasaki Shikibu around 1002 CE, shows the operation of general principles of sociobiology. Isolated from western influences and cloaked in Japanese traditions, the common traits associated with reproductive processes are clearly evident. The novel depicts the differential investment of males and females in offspring, male competitive behaviors, and concerns for paternity, kin selection, reciprocal social exchange, species-typical emotional expression, female mate choice, positive assortative mating, and acknowledgment of hereditary transmission of physical and psychological traits. The nature of human behavior in Genji’s time seems little different than now and has all the attributes of species-specific and universal traits. Indeed, it can be argued that the fundamental characteristics of Homo sapiens have never changed, being influenced only in form by culture. The qualitative and quantitative evaluation of ancient texts is a strong methodology for understanding the invariant nature of human behavior.     

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.     

The sociobiology of sex: inclusive fitness consequences of inter-sexual interactions

The diversity of social interactions between sexual partners has long captivated biologists, and its evolution has been interpreted largely in terms of 'direct fitness' pay-offs to partners and their descendants. Inter-sexual interactions also have 'indirect effects' by affecting the fitness of relatives, with important consequences for inclusive fitness. However, inclusive fitness arguments have received limited consideration in this context, and definitions of 'direct' and 'indirect' fitness effects in this field are often inconsistent with those of inclusive fitness theory. Here, we use a sociobiology approach based on inclusive fitness theory to distinguish between direct and indirect fitness effects. We first consider direct effects: we review how competition leads to sexual conflict, and discuss the conditions under which repression of competition fosters sexual mutualism. We then clarify indirect effects, and show that greenbeard effects, kin recognition and population viscosity can all lead to episodes of indirect selection on sexual interactions creating potential for sexual altruism and spite. We argue that the integration of direct and indirect fitness effects within a sociobiology approach enables us to consider a more diverse spectrum of evolutionary outcomes of sexual interactions, and may help resolving current debates over sexual selection and sexual conflict.     

Cooperation: bridging ecology and sociobiology

Ecology is considered central to the evolution of cooperation, but there is little direct evidence for this. New support for the idea has come from a study which shifted the path of evolution from cooperation to cheating in flasks of bacteria, simply by altering their disturbance regime.     

Child sexual abuse sequelae and body-image surgery

Child sexual abuse is common and damages the body image. Child sexual abuse survivors may request body-image surgery. Seven patients are described in whom child sexual abuse sequelae complicated body-image surgery. Two patients viewed their surgeons as similar to sexual abusers. Yet two patients were clearly, and two possibly, helped by the surgery. Surgeons can detect and manage such patients by (1) having a child sexual abuse therapist on hand for consultation, (2) adding "abuse" to the medical history form, (3) recommending to known or suspected child sexual abuse patients preoperative therapy or a self-help book, (4) obtaining specific permission for any body contact, (5) stating belief in abuse, if revealed, (6) explaining the surgery in unusual detail, (7) recognizing the high-risk child sexual abuse groups, and, (8) declining to operate on the angry child sexual abuse patient.