Cognition and Social Life
Does an individual need a larger or more complex brain to deal with the dynamic social environment of living in a group? In primates at least, brain volume tends to be correlated with social group size. Primates live in hierarchical societies, where each individual has their own personality and is recognised by other members of the social group. This is necessary to direct appropriate behaviour towards others, depending on the individual’s position in the ‘pecking order’, and to determine how to navigate that established order to maximise individual fitness. Unlike some more derived social insect colonies of ants, bees, and termites Polistes dominula also display individual recognition and strict dominance hierarchies, and behave in specific ways to their superiors/inferiors, and all this in a brain of around 1 cubic millimetre in volume. We are investigating whether this ‘social brain hypothesis’ applies in insect social systems. As well as investigating a correlative relationship between brain size/complexity and social life, we are manipulating the social order in this system by removing dominant individuals and therefore promoting subordinates in the hierarchy. This allows us to investigate whether there is any plasticity in the brains of individuals to adapt to the demands of their new positions, or whether individuals with specific neural architecture have an anatomical advantage from the outset.