Many heuristic optimization approaches have been developed to combat the ever-increasing complexity of engineering problems. In general, these approaches can be classified based on the diversity of the search strategies used, the amount of change to those search strategies during the optimization process, and the level of cooperation between the strategies. A review of the literature indicates that approaches which are simultaneously very diverse, highly dynamic, and cooperative are rare but have immense potential for finding high quality final solutions. In this work, a taxonomy of heuristic optimization approaches is introduced and used to motivate a new approach, entitled Protocol-based Multi-Agent Systems. This approach is found to produce final solutions of much higher quality when its implementation includes the use of multiple search protocols, the adaptation of those protocols during the optimization, and the cooperation between the protocols than when these characteristics are absent.