A gap exists in our current understanding of embodied intelligence (how we manipulate, modify, and exploit our environment) and social intelligence (how we interact with others). Our research aims at bridging the gap from body to mind to understanding other persons to yield what we call "interpersonal synergistic intelligence." Specifically, we address the issue of acquisition of early communication abilities in human and robot babies, including early language, by clarifying and modeling the emergence and development of cognition and behavior from bodily interactions. To achieve our objectives, we study sensorimotor learning in embodied systems, body schema and body image acquisition and their extensions (e.g. through tool usage), as well as imitation and other kinds of interactions with caretakers or parents. We employ robots and simulations thereof as a tool to synthetically model cognitive development.