Significant transformations have taken place in our understanding of evolution and development since the late nineteenth century, when the two seemed so closely related; at that time, the ideas of Charles Darwin, Ernst Haeckel, and other biologists played a prominent role in Freud’s creation of psychoanalysis. During the twentieth century, as biological research reached the molecular level, biological concepts of development and of evolution veered progressively further from each other and further away from psychoanalysis. Then most recently, in response to a flood of discoveries in the
last two decades, the long-separated fields of developmental and evolutionary biology have come ogether in the creation of a new field, informally referred to as “Evo–Devo.” In this paper, I trace these remarkable changes, and discuss how these recent advances have returned biological concepts to a closer alignment with psychoanalytic principles regarding the role of early experience in long-term developmental change and the importance of the role that early parent-infant interactions play in shaping our lives and those of our children. I have illustrated the changes in our thinking that have
taken place over the past half century by describing the different ways that I have thought about, puzzled over, and been enlightened by these changing concepts in the course of my psychobiological research on the roles of the mother-infant relationship in the development of a relatively simple model organism, the laboratory rat.