Introduction: embodiment and epigenesis: a view of the issues.

Relational developmental systems' theories emphasize that any facet of individual structure or function is embodied with other features of the individual and with the characteristics of his or her proximal and distal ecology, including culture and history. Embodiment means that biological, psychological, and behavioral attributes of the person, in fusion with the contexts of human development, have a temporal parameter. Embodiment provides a basis for epigenetics across generations and for epigenetic (qualitative discontinuous) change across ontogeny. We describe how the chapters in this two-volume set present theory and research pertinent to the roles of evolutionary and ontogenetic processes in cognitive, emotional, and behavioral development across the life span. The scholarship presented in these volumes suggests that rigorous, relational developmental theory-predicated research about the plastic, mutually influential relations among individual and ecological processes will enable developmental science to better describe, explain, and optimize the fundamental relational process of human development.