John Holland proposed an evolutionary model of adaptive agents called 'ECHO'. ECHO is a first step toward mathematical theory in the field of complex adaptive systems. The existing ECHO model has been used by
researchers in numerous disciplines, both to model and to explain complex system behaviors. This paper describes the effects of limited resources in a 3D simulation of an extended Holland ECHO model. The
simulation shows adaptive agents moving about the ECHO landscape and interacting with other agents in real-time. A genetic algorithm is used to breed the adaptive agents. The virtual environment contains limited
resources in the form of symbols. Agents develop elaborate relationships to utilize these resources through both competition and cooperation. By observing the emergence of complexity in real-time inside a virtual 3D world, researchers have a better tool by which to identify and explain complex adaptive system behavior. In addition to implementing Holland's basic ECHO model, several additions have been made including expanded resource metabolism and resource hierarchies. It is hoped that such new constructs will help to generate more realistic systems while maintaining a minimal set of underlying rules. This real-time 3D ECHO visualization allows an observer to quickly identify interesting and complex agent behaviors and resource interactions. Such a tool is a good first step in the young field of complex adaptive systems theory, a field involved in the identification, prediction, and control of emergent complex phenomena.