Introduction

From the moment of birth until old age, a person keeps changing in ways that go far beyond the physical. Growing children learn to communicate, walk, count, read and write; they learn to tell right from wrong, make friends, go through puberty, and later marry, raise children of their own, and grow old. Even though every individual's path looks different in its details, there are broad patterns almost everyone shares — for instance, most infants learn to walk within the first year of life and to talk within the second. This chapter traces the changes people go through across the major periods of the life-span — before birth, infancy, childhood, adolescence, adulthood, and old age — looking at physical, mental (cognitive) and social-emotional change together, since in real life these never happen in separate, disconnected tracks. Studying human development this way is meant to be as much a journey of understanding yourself as it is of understanding the people around you.