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PART ONE

The Beginning

The science of human development has many beginnings. Chapter 1 introduces the science, explaining some theories, strategies, and methods used to understand how people grow and change. Chapter 2 traces early development, from the genetic interactions that produce all inherited characteristics to the newborn’s first movements, sounds, and reactions.

Throughout these chapters, the interplay of nature (heredity) and nurture (the environment) is illustrated. For instance, whether or not a person will develop type 2 diabetes at age 60 depends on both nature (genetic vulnerability) and nurture (the mother’s diet during pregnancy and the adult’s exercise and eating habits). Understanding the interplay of biology and culture is the foundation that allows us to reach the goal of our study: a happy and meaningful life for all 7 billion people on Earth, of all ages, cultures, and aspirations.