What is the relationship between behavior and the processes which shape evolution? Why has behavior, whether it amounts to no more than a flower's reaction to light or encompasses the complexities of human thought, been so neglected by traditional evolutionary theory? Beginning with these questions, Jean Piaget offers a dazzling, at time demanding, inquiry into the state of our understanding of evolution. This is a task that takes Piaget from an investigation of the early giants Darwin and Lamarck, to the contributions of Weiss and Baldwin, to the role of cybernetics. Along the way he outlines the relation between instinct and evolution, habits and acquired characteristics. He criticizes those who reduce the question to a genetic determinism. And he challenges those who see no qualitative difference between the evolution of anatomical structures and the evolution of behavioral structures. What Piaget develops in this concise and remarkable work is a subtle, sophisticated theory of behavior in both the plant and the animal worlds. Drawing on his life's work, he argues that all organisms are active and creative, and that the forms of organization they create in their environment go to the heart of the meaning of behavior and the processes of evolution. A prolific writer on philosophy and biology, as well as the father of the development psychology he calls genetic epistemology, Jean Piaget has had as his main area of concern the genesis of abstract concepts (classes, relations, numbers) and physical concepts (space, speed, chance, time) in the developing child. His theories have been widely applied to education.