Common Territories in Comparative and Developmental Psychology: Quest for Shared Means and Meaning in Behavioral Investigations

Comparative and developmental psychology have impacted one another for well over 100 years. Researchers have studied developmental processes of humans and nonhumans to formulate evolu-tionary theories and to determine the contributions of hereditary and experiential factors at ontoge-netic and phylogenetic levels. We discuss current directions in comparative and developmental re-search that attend to micro-developmental processes and ecological contexts as sources of variability in humans and nonhumans. This research has been a segue into studies of behavior that are integra-tive in scope, such the family of systems theories, which cross disciplinary boundaries. We present findings from our research on instrumental manual activity in human and nonhuman primates from a systems perspective, and argue that integrative systems approaches hold promise for understanding individuals and development of behavior across species. Historically, the fields of comparative and developmental psychology have been intertwined, using animal models as analogs in studying human developmen-tal processes, making cross-species comparisons at different points in the lifespan, and inquiring into the evolutionary history of humans and other species. Compara-tive psychology originated from Darwin’s theory of evolution, which yielded in