When is bigger better? The effects of group size on the evolution of helping behaviours.

Understanding the evolution of sociality in humans and other species requires understanding how selection on social behaviour varies with group size. However, the effects of group size are frequently obscured in the theoretical literature, which often makes assumptions that are at odds with empirical findings. In particular, mechanisms are suggested as supporting large-scale cooperation when they would in fact rapidly become ineffective with increasing group size. Here we review the literature on the evolution of helping behaviours (cooperation and altruism), and frame it using a simple synthetic model that allows us to delineate how the three main components of the selection pressure on helping must vary with increasing group size. The first component is the marginal benefit of helping to group members, which determines both direct fitness benefits to the actor and indirect fitness benefits to recipients. While this is often assumed to be independent of group size, marginal benefits are in practice likely to be maximal at intermediate group sizes for many types of collective action problems, and will eventually become very small in large groups due to the law of decreasing returns. The second component is the response of social partners on the past play of an actor, which underlies conditional behaviour under repeated social interactions. We argue that under realistic conditions on the transmission of information in a population, this response on past play decreases rapidly with increasing group size so that reciprocity alone (whether direct, indirect, or generalised) cannot sustain cooperation in very large groups. The final component is the relatedness between actor and recipient, which, according to the rules of inheritance, again decreases rapidly with increasing group size. These results explain why helping behaviours in very large social groups are limited to cases where the number of reproducing individuals is small, as in social insects, or where there are social institutions that can promote (possibly through sanctioning) large-scale cooperation, as in human societies. Finally, we discuss how individually devised institutions can foster the transition from small-scale to large-scale cooperative groups in human evolution.

Securing Disunion: young people’s nationalism, identities and (in)securities in the campaign for an independent Scotland.

This paper explores ethnic and religious minority youth perspectives of security and nationalism in Scotland during the independence campaign in 2014.  We discuss how young people co-construct narratives of Scottish nationalism alongside minority ethnic and faith identities in order to feel secure. By critically combining literatures from feminist geopolitics, international relations (IR) and children’s emotional geographies, we employ the concept of ‘ontological security’. The paper departs from state-centric approaches to security to explore the relational entanglements between geopolitical discourses and the ontological security of young people living through a moment of political change. We examine how everyday encounters with difference can reflect broader geopolitical narratives of security and insecurity, which subsequently trouble notions of ‘multicultural nationalism’ in Scotland and demonstrate ways that youth ‘securitize the self’ (Kinnvall, 2004). The paper responds to calls for empirical analyses of youth perspectives on nationalism and security (Benwell, 2016) and on the nexus between security and emotional subjectivity in critical geopolitics (Pain, 2009; Shaw et al., 2014). Funded by the Arts and Humanities Research Council (AHRC), this paper draws on focus group and interview data from 382 ethnic and religious minority young people in Scotland collected over the 12-month period of the campaign. Keywords: nationalism, young people, race and ethnicity, ontological security, everyday geopolitics