Presentation Information
[C15-05]The evolution of teachers in population dynamics
*Hirotaka Goto1, Joshua B. Plotkin2 (1. Meiji University (Japan), 2. University of Pennsylvania (United States of America))
Keywords:
division of labor,population dynamics,social behavior
Human societies often have a set of individuals that do not directly benefit but nonetheless contribute to the population by increasing the productivity of others or elevating their expertise. The evolution of a "teacher" class within a population also appears to have occurred in many biological systems from the molecular to the organismal level. For example, chaperone proteins are those that assist others to fold properly but do not provide specific folding information, nor do they become part of their final structures. Soldier ants—whose bodies are distinctively larger and stronger than worker ants—protect their colony by fighting off predators but do not engage in foraging or nest building. To understand the fundamental mechanism underlying the evolution of a teacher class within a population, we develop a simple, tractable mathematical model of a hunting population where some of the members are only dedicated to enhancing the hunting productivity of others. We then explore how the population size of a community determines the optimal proportion of teachers. We find that a population must first reach a critical size to justify allocating anyone at all to a teacher role—a result that is robust across various extensions of the model. We also find that a teacher class comprising more than 50% of the population is never optimal under any circumstances, regardless of parameter values. Finally, we extend this baseline model to a more nuanced scenario where there are three distinct levels of expertise, the highest two of which are achievable through "education" as well as self-learning. We provide mathematical insights into not only what proportion of the population should teach but also which level they should teach.