ABSTRACT
Anatomical, physiological, and psychological growth are all dramatic in infancy, but because of its infinite complexities and astonishing ability to regulate and integrate information, the development of the nervous system is especially noteworthy. The adult human brain contains approximately 100 billion neurons. Because relatively few new neurons are generated after birth, an average of 250,000 new cells must be generated every minute prenatally. In the space of approximately 9 months, a single fertilized egg evolves into a complex, self-regulating, differentiated nervous system, and in an additional 9 to 12 months after birth develops into a conscious child capable of intelligent feelings, thoughts, and actions. In this chapter, we consider several aspects of physical development including development of the autonomic and central nervous systems and motor development. In addition, we consider the roles of biology and experience in shaping infant growth.
