ABSTRACT
Early human development involves the emergence of motor and perceptual capacities that eventually become integrated. The conceptual distinction between growth and development is important because each plays distinctive and sometimes contrasting roles in the processes of neurobehavioral and psychobiological integration. Scientific opinion has changed dramatically in the last few decades regarding how the relationship between pre-and postnatal growth and development is understood in genetic, behavioral, and experiential terms. The doctrine that our body and brains are genetically preformed dominated embryological theory until the late 19th century, when experience was accorded a larger role. Well into the 20th century, physicians viewed infants as if they were governed solely by involuntary reflexes equivalent to persons with neural disorders, until the brain and cortex attained complete maturation. Only when it became evident that individual differences in brain, behavior, and cognition could not be explained by genetic factors alone did scientists acknowledge the experience-dependent nature of early development.
