This panel discussion will emphasize environmental-unit behavior-unit interactions. According to Peter Killeen, recent progress in evolutionary developmental biologyevo-devoprovides potentially useful templates for refining the definition of such units, and broadening possibilities of the modes in which they interact. Among these concepts are heterochrony, variation by changes in temporal sequence, such as neoteny; the role of modularity in evolution; how modifications of developmental processes lead to the production of novel features; the role of developmental plasticity in evolution; how ecology impacts development and evolutionary change; and the developmental basis of homoplasy and homology. As a familiar example, a homology in biology is any similarity between characters that is due their shared ancestry; in functional analysis, great efforts are taken to identify the variables of which behavior is a function. Is it useful to treat those that are under the control of the same reinforcer as homologs, and those that merely share a similar topography as analogs? Is the ability of the homeobox to activate correlated sets of genes enlightening for the analysis of establishing stimuli? Do the various forms of paedomorphisis and peramorphosisthe juvenilezation/senescization of morphologyhave analogs in behavior? Does the efficiency of evolution, crafting endless forms most beautiful from a meager number of genes, suggest mechanisms for the blossoming of creative behavior in Homo sapiens? The members of this panel discussion will address these evo-devo concepts. The audience will be encouraged to participate with behavioral analogs of the biological processes, and evaluate their potential utility.