CHAPTER 1: INTRODUCTION INTRODUCTION What makes adolescents tick? The answer to that question has changed considerably since the fourth century B.C.E., when early Greek philosophers Plato and Aristotle identified two qualities that distinguish adolescents from children—reasoning ability and self-determination. During the eighteenth century, Rousseau believed infants, children, adolescents, and young adults demonstrated unique behavior during distinct developmental phases. G. Stanley Hall began the process of scientifically studying adolescence in the 1800s. Guided by Darwinian thought, he investigated the influence of biological and environmental factors, identifying genetics as a dominant force. Unlike Darwin and Hall, Margaret Mead concluded that sociocultural influences affect the adolescent experience to a greater extent than genetics. Historical events of the early twentieth century subsequently influenced remarkable maturational, intellectual, and psychosocial changes characteristic of adolescents. Sociohistorical circumstances may be considered the most influential aspect of change for adolescents. The Inventionist view posits that adolescence resulted from: • declines in adolescent apprenticeships; • increases in skill and educational requirements; • urbanization and separation of work and home life; • creation of age-segregated systems for education and socialization; and • restrictions on drinking, voting, and working due to age—all mechanisms of childhood. By 1950, the developmental period of adolescence had not only physical and social identities, but a legal identity as well. The voices of adolescents were heard loud and clear during the political protests in the 1960s and 1970s. The women’s movement of the 1970s changed how research on adolescents was conducted; research now included female as well as male adolescents. Today in the United States, a more diverse population results in adolescents who are more open-minded and tolerant than past generations. Adolescents in the twenty-first century are growing up immersed in technology. The technological revolution is having both positive and negative effects on today’s adolescents. Groups tend to gather stereotypical d