The Evolution of Temporal Polyethism

Temporal polyethism is a method of division of labor exhibited by many eusocial insect colonies, where the type of task an individual attempts is correlated with its age. The evolutionary pressures that give rise to this widely-observed pattern are still not fully known. The long generation times of eusocial insects combined with the complications associated with performing artificial selection experiments on colonies of organisms makes this topic challenging to investigate using organic systems. In this paper, we use digital evolution to explore whether temporal polyethism may result from pressures to preserve colony members in the face of varying degrees of risk associated with different tasks. Specifically, we require a colony of digital organisms to repeatedly perform a set of tasks in order for the colony to replicate. We associate the different tasks with different lethality risks. Under these conditions, we observe that the digital organisms evolve to perform the less risky tasks earlier in their life and more risky tasks later in life, regardless of the order in which the tasks were performed by the ancestor organism at the start of the experiment. These results demonstrate that pressures resulting from the relative riskiness of various tasks and aging is sufficient to favor the evolution of temporal polyethism.