An SIS model for cultural trait transmission with conformity bias

Epidemiological models have been applied to human health-related behaviors that are affected by social interaction. Typically these models have not considered conformity bias, that is the exaggerated propensity to adopt commonly observed behaviors or opinions, or content biases, where the content of the learned trait affects the probability of adoption. Here we consider an interaction of these two effects, presenting an SIS-type model for the spread and persistence of a behavior which is transmitted via social learning. Uptake is controlled by a nonlinear dependence on the proportion of individuals demonstrating the behavior in a population. Three equilibrium solutions are found, their linear stability analyzed and the results compared with a model for unbiased social learning. Our analysis focuses on the effects of the strength of conformity bias and the effects of content biases which alter a conformity threshold frequency of the behavior, above which there is an exaggerated propensity for adoption. The strength of the conformity bias is found to qualitatively alter the predictions regarding whether the trait becomes endemic within the population, and the proportion of individuals who display the trait when it is endemic. As the conformity strength increases, the number of feasible equilibrium solutions increases from two to three, leading to a situation where the stable equilibrium attained is dependent upon the initial state. Varying the conformity threshold frequency directionally alters the behavior invasion threshold. Finally we discuss the possible application of this model to binge drinking behavior

Leadership between decks: a synthesis and development of engagement and resistance theories of leadership based on evidence from practice in Royal Navy warships

Purpose To understand the role of interaction in the process of leadership. Interaction has been claimed to be a leadership competence in earlier research into leadership in the Royal Navy. The aim of this research is to define how interaction works within naval teams. Design/methodology/approach The research uses Grounded Theory. Following a series of leadership discussions in separate focus groups, discussion topics were coded and subjected to recursive qualitative analysis. The grounded approach is used to synthesise and develop existing leadership theory strands as well as to extend the trait-process approach to leadership. Findings The research discovers the key interaction behaviours of engagement, disengagement and levelling. Our findings support recent developments in follower-centric perceptions of leadership and in interaction specifically. We develop engagement theory by combining it with the less well researched area of leadership resistance. We then re-frame resistance as social levelling, a more comprehensive interaction mechanism. Research limitations/implications The research is highly contextual because of its qualitative approach. Some of the detailed reactions to leadership behaviours may not found in other naval or military teams and are unlikely to be generalizable to non-military environments. However, the mechanism described, that of engagement, disengagement and levelling is considered highly generalizable if not universal. Rather than develop new theory fragments in an already confusing research environment, we fuse engagement and resistance theory to extend trait-process theories of leadership. The result is a coherent and integrative model of leadership dynamics which frames leadership in the mundane interaction of leaders and followers. Practical implications Interaction as a competence is strongly supported as is the encouragement of cultures which promote interaction. Selection procedures for future leaders should include interaction skills. The use of subtle methods of resistance are highlighted. Such methods may indicate poor interaction long before more overt forms of resistance are apparent. Originality/value This research uniquely uses Grounded Theory to extend current theories (competence based leadership and trait-process theories of leadership), explaining the complexity of leadership-interaction. The research also synthesises and develops engagement and levelling (resistance to leadership) theories for the first time. As such the project suggests a full range model of follower response to leadership including subtle forms of resistance to power. The value of group-level analysis using focus groups is recommended, especially for other collective leader-follower approaches to leadership. The research is of interest to those studying leadership process theories, competencies, leader-follower traditions, engagement and power/resistance research

Do non-human primates synchronise their menstrual cycles? A test in mandrills

The concept of female cycle (or estrous) synchrony has enduring popular appeal. However, critical reviews of estrous synchrony studies in both humans and non-humans have found that synchrony has not been demonstrated convincingly, due to methodological artifacts and statistical problems. Studies of this phenomenon in animals living under naturalistic conditions are rare. We used long-term records of the timing of the female menstrual cycle in a semi-free-ranging population of mandrills, together with a randomisation procedure, to test hypotheses relating to cycle synchrony in a naturally reproducing primate species. We found evidence of significant synchrony of the peri-ovulatory period in only one of ten group-years – the year in which the largest number of cycles was recorded, both overall and per female. However, this result was no longer significant when we corrected for multiple tests of the same hypothesis. This suggests that mandrills in our study population do not synchronise their cycles, possibly because they usually conceive so quickly that they do not have the opportunity to synchronise. We also tested whether matrilineally-related females, which associate with one another more than other females, cycle significantly more closely together in time than unrelated females, finding that they did so in 2 of 10 group-years, but that they were significantly less likely to match their cycles in another group-year. Across 32 matriline-years, patterns of synchrony within individual matrilines (female lineages) fell outside the distribution based on chance in only one case. Thus we found little support for the pheromonal hypothesis for cycle synchrony, which predicts that females that associate with one another should be more likely to cycle together. Overall, our findings are in line with other studies that suggest that cycle synchrony does not occur in non-human primates

Modelling social learning in monkeys.

The application of modelling to social learning in monkey populations has been a neglected topic. Recently, however, a number of statistical, simulation and analytical approaches have been developed to help examine social learning processes, putative traditions, the use of social learning strategies and the diffusion dynamics of socially transmitted information. Here, I review some of the recent advances and show how they influence and combine with empirical studies of social learning

Interactions between cognition and culture

This chapter takes a broad and often comparative perspective to look at the interactions between cognition and culture. After a brief introduction of the methods used to study cultural evolution and gene-culture co-evolution (G-CC), there is a review of research on social transmission of information, including the conditions favouring the evolution of social learning, particular context or content-specifi c social learning biases, the infl uence of transmission mode on cultural evolution and the cognitive requirements for different social learning processes. The chapter then develops some of the key theories concerning the cognitive evolution of learning and intelligence inhominids, such as social, technical and cultural intelligence, the Baldwin effect, niche construction, the evolution of cooperative behaviour and cumulative cultural evolution. The chapter concludes in support of a multimodal niche-constructive framework to provide a full description of the interactions between cognition and culture

Gene-Culture Coevolution

Gene-culture coevolution theory explicitly accounts for the inheritance of genetic and cultural traits whose fitness and evolutionary trajectory are nonindependent. After describing how a gene-culture coevolutionary account is constructed, the framework is compared and contrasted against other evolutionary anthropology approaches to the study of human behavior. This is followed by highlighting a series of examples of gene-culture coevolution in human evolution, focusing largely on nutrition, disease, and the role of cumulative cultural evolution, which also shows how gene-culture coevolutionary mechanisms can affect both rates and evolutionary trajectories compared with a standard population genetic or cultural account. The approach is a powerful tool to understand both ancestral and contemporary human evolution

Modelling social learning in monkeys.

The application of modelling to social learning in monkey populations has been a neglected topic. Recently, however, a number of statistical, simulation and analytical approaches have been developed to help examine social learning processes, putative traditions, the use of social learning strategies and the diffusion dynamics of socially transmitted information. Here, I review some of the recent advances and show how they influence and combine with empirical studies of social learning