Balancing the Costs and Benefits of Learning Ability

We study the costs and benefits of plasticity by evolving agents in environments with different rates of environmen-tal change. Evolution allows both hard-coded strategies and learned strategies, with learning rates varying throughout life. We observe a range of change rates where the balance of costs and benefits are just right for evolving learning. Inside this range, we see two separate strategies evolve: lifelong plas-ticity and sensitive periods of plasticity. Sensitive periods of plasticity are found to reduce the learning cost while re-taining the benefits of learning. This affects the evolutionary process, by limiting genetic assimilation of learned character-istics, making agents able to remain adaptive after relatively long periods of environmental stability