Optimality and Evolutionary Stability in Social Decision-Making

Animals need to make important decisions under uncertainty throughout their lives relating to their survival, such as finding resources, avoiding predators or finding safe resting places. Access to social information provides supplementary information to individuals with incomplete personal information and under some conditions can ameliorate their decision-making.

Traditionally, social behaviour is modelled as an observed trait. Here, I assume that social behaviour, i.e. having access to, and utilising social information is an adapted trait: those who are able to make good use of the available information and as a result make more successful decisions, are preferred by evolutionary selection. This piece of work contributes new insight into social behaviour and provides a more neutral context for understanding the occurrence of some commonly observed behaviours.

In chapters 5 and 7 the evolutionary stability of well-mixed groups is explored. I find that sociality evolves in relation to environmental uncertainty and heuristic decision-making rules, while I also establish a necessary constraint on this process. Chapter 6 explores the long-term behaviour of groups employing different decision-making rules, using Markov chains. In chapter 8 I explore the evolution of sociality in relation to the position of an agent in the sequence for unmixed groups, and explore the dynamics between groups with homogeneous behaviour and a single agent with a behaviour different to the collective one. Finally, chapter 9 summarises this work and proposes some directions for future research.