The complexity and hierarchical structure of tasks in insect societies

To understand the functioning and organizational complexity of insect societies, a combination of different approaches is needed. One such approach, which we adopt in this study, is to consider tasks in insect societies not based upon their function, as is traditional, but upon their structure. Four types of task in insect societies have been proposed: individual, group, team and partitioned tasks. We examine the relationships among these four task types and consider ‘task complexity’ to mean the degree of cooperation and coordination required to complete a particular task successfully. In this respect, individual tasks are considered the simplest (low complexity), group tasks are more complex (medium), and team and partitioned tasks the most complex (high). We decompose tasks into their component subtasks to understand how the demands of a task influence how workers must work together to complete it successfully. We describe a simple method to measure the complexity of tasks using task deconstruction. Points are assigned to each subtask within the task and summed to give a total score. This measure, the task’s score, allows objective comparison of tasks (different tasks may be ranked in order of their complexity) within and between species, or even higher taxa, and we hope it will be of practical use to researchers. We propose that both team and partitioned tasks may contain individual, group, team and partitioned subtasks. We examine each of the possible task–subtask relationships and provide examples from known social insect behaviour.