Broadly stated, physical development refers to the elements and processes involved in the expression of the biological potential of humans at multiple levels of organization: microbiological, cellular, anatomical, behavioral, and functional. And, inasmuch as humans are material, physical development is at the core of human conative (directed thought and behavior), affective (emotion), and cognitive (mental processing) functioning and development. For these reasons, appreciation and study of physical development is necessary for the advancement of any discipline [Page 793]concerned with human behavior, such as educational psychology.

Identifying work from a variety of disciplines—anatomy, physiology, evolutionary biology, physics, genetics, chemistry, the cognitive sciences—what follows in the next sections are a brief history of physical development as an element in the study of human development and a review of ...