Do behaviors become more or less variable over time? Since Thorndike’s pioneering research, investigations into behavioral variability have posed a challenging theoretical puzzle: Some indicate a winnowing of behavioral variants, whereas others suggest an ongoing waxing and waning of even dominant behavioral variants throughout rewarded training. Here, we found that pigeons progressively narrowed their behavioral repertoire while retaining some diversity throughout. This suggests an adaptive balance — what might be called "the edge of chaos" — in which reliable reward-securing responses are preserved alongside behavioral flexibility, allowing animals to adapt if contingencies shift or better options emerge. Wasserman, E. A., Orr, O. R. P., & Li, S. (in press). Variability, stability, and the Law of Effect. Journal of Experimental Psychology: Animal Learning and Cognition.