ABSTRACT
Ontogenetic development involves the construction of increasingly complex levels of biological organization, including the brain and the cognitive and emotional processes it supports. As more complex structures are generated during development, different types of scientists use different methods and approaches appropriate for asking questions at that level of structure (genetic, cellular, multicellular) (see Johnson, 2011a). Thus, a complete account of developmental change specifically requires an interdisciplinary approach. Although these considerations suggest that the study of development requires collaboration and exchange of information between scientists with different methodological expertise, until the past two decades the study of behavioral development in humans was conducted largely independently of consideration of the brain or its underlying genetics. This relative neglect of biological factors in the study of behavioral development is somewhat surprising when one considers that the origins of developmental science can be traced to biologists such as Charles Darwin and Jean Piaget. Darwin (1965) was one of the first to take a scientific approach to human behavioral development and to speculate on relations between phylo-genetic and ontogenetic change. Piaget imported then current theories of embryological development, mainly due to the developmental biologist C. H. Waddington, to generate his accounts of human cognitive development (see Waddington, 1975). However, a curious aspect of Piaget’s biological approach to human cognitive development was his relative neglect of the importance of brain development, which Segalowitz (1994) attributed to a lack of information about brain development and function at the time Piaget developed his theories. In contrast to Piaget, some early developmental psychologists in the United States, such as Gesell (1929) and McGraw (1943), tried to integrate brain development with what was known of behavioral ontogeny. Although they focused on motor development, they also extended their conclusions to mental and social development. They described stages in the development of motor abilities from prone positions to walking and stair climbing, and McGraw proposed that the transition between these stages could be accounted for in terms of the maturation of the motor cortex and its inhibition of subcortical pathways, a notion that still provides a basis for some research today. Although both McGraw and Gesell developed sophisticated informal theories that attempted to apply nonlinear and dynamic approaches to development, their efforts to relate brain development to behavioral change remained largely speculative. In Europe, Konrad Lorenz and Niko Tinbergen, contemporaries of McGraw, Gesell, and Piaget, originated the field of ethology and were particularly concerned with causal factors in the development of the natural behavior of animals. Due to the more direct interventions possible with animals, they addressed issues about the relative contribution of “innate” as opposed to “experiential” contributions to behavior. The results of their experiments, in which early environmental conditions were manipulated, quickly led to the realization that the dissociation of behavior into innate and acquired components was inadequate to account for the complexities of behavioral development. However, the notion that some brain and cognitive systems are more impervious than others to experience during development remains important today. Furthermore, the notion that theories of behavioral development should take into account both the whole organism and the natural environment (social and physical) within which it develops has regained popularity (e.g., Gottlieb, 2007; Mareschal et al., 2007; Thelen & Smith, 1994).
