■ TAKE A MOMENT… Ask several parents of young children what they expect their sons and daughters to be like as teenagers. You will probably get answers like these: “Rebellious and irresponsible,” “Full of rages and tempers.” This widespread storm-and-stress view dates back to major early-twentieth-century theorists. The most influential, G. Stanley Hall, based his ideas on Darwin’s theory of evolution. Hall ( 1904 ) described adolescence as a period so turbulent that it resembled the era in which humans evolved from savages into civilized beings.

■ Similarly, in Freud’s psychosexual theory, sexual impulses reawaken in the genital stage, triggering psychological conflict and volatile behavior. As adolescents find intimate partners, inner forces gradually achieve a new, mature harmony, and the stage concludes with marriage, birth, and child rearing. In this way, young people fulfill their biological destiny: sexual reproduction and survival of the species.

The Social Perspective Contemporary research suggests that the storm-and-stress notion of

adolescence is exaggerated. Certain problems, such as eating disorders, depression, suicide, and lawbreaking, do occur more often than earlier (Farrington,  2009 ; Graber,  2004 ). But the overall rate of serious psychological disturbance rises only slightly from childhood to adolescence, reaching 15 to 20 percent (Merikangas et al.,  2010 ). Though much greater than the adulthood rate (about 6 percent), emotional turbulence is not a routine feature of the teenage years.

The first researcher to point out the wide variability in adolescent adjustment was anthropologist Margaret Mead ( 1928 ). She returned from the Pacific islands of Samoa with a startling conclusion: Because of the culture’s relaxed social relationships and openness toward sexuality, adolescence is perhaps the pleasantest time the Samoan girl (or boy) will ever know” ( p. 308 ). 

Mead offered an alternative view in which the social environment is entirely responsible for the range of teenage experiences, from erratic and agitated to calm and stress-free. Later researchers found that Samoan adolescence was not as untroubled as Mead had assumed (Freeman,  1983 ). Still, she showed that to understand

adolescent development, researchers must pay greater attention to social and cultural influences.

A Balanced Point of View

Today we know that biological, psychological, and social forces combine to influence adolescent development (Susman & Dorn,  2009 ). Biological changes are universal—found in all primates and all cultures. These internal stresses and the social expectations accompanying them—that the young person give up childish ways, develop new interpersonal relationships, and take on greater responsibility—are likely to prompt moments of uncertainty, self-doubt, and disappointment in all teenagers. Adolescents’ prior and current experiences affect their success in surmounting these challenges.

At the same time, the length of adolescence and its demands and pressures vary substantially among cultures. Most tribal and village societies have only a brief intervening phase between childhood and full assumption of adult roles (Weisfield,  1997 ). In industrialized nations, young people face prolonged dependence on parents and postponement of sexual gratification while they prepare for a productive work life. As a result, adolescence is greatly extended—so much so that researchers commonly divide it into three phases:

· 1. Early adolescence (11–12 to 14 years): This is a period of rapid pubertal change.

· 2. Middle adolescence (14 to 16 years): Pubertal changes are now nearly complete.

· 3. Late adolescence (16 to 18 years): The young person achieves full adult appearance and anticipates assumption of adult roles.

The more the social environment supports young people in achieving adult responsibilities, the better they adjust. For all the biological tensions and uncertainties about the future that teenagers feel, most negotiate this period successfully. With this in mind, let’s look closely at puberty, the dawning of adolescent development.

Puberty: The Physical Transition to Adulthood

The changes of puberty are dramatic: Within a few years, the body of the school-age child is transformed into that of a full-grown adult. Genetically influenced hormonal processes regulate pubertal growth. Girls, who have been advanced in physical maturity since the prenatal period, reach puberty, on average, two years earlier than boys.

 Hormonal Changes The complex hormonal changes that underlie puberty occur gradually and are under way by age 8 or 9. Secretions of growth hormone (GH) and thyroxine (see Chapter 7 ,  page 219 ) increase, leading to tremendous gains in body size and to attainment of skeletal maturity.Sexual maturation is controlled by the sex hormones.

 Although we think of estrogens as female hormones and androgens as male hormones, both types are present in each sex but in different amounts. The boy’s testes release large quantities of the androgen testosterone, which leads to muscle growth, body and facial hair, and other male sex characteristics. Androgens (especially testosterone for boys) exert a GH-enhancing effect, contributing greatly to gains in body size.

■ Because the testes secrete small amounts of estrogen as well, 50 percent of boys experience temporary breast enlargement. In both sexes, estrogens also increase GH secretion, adding to the growth spurt and, in combination with androgens, stimulating gains in bone density, which continue into early adulthood (Cooper, Sayer, & Dennison,  2006 ; Styne,  2003 ).

Estrogens released by girls’ ovaries cause the breasts, uterus, and vagina to mature, the body to take on feminine proportions, and fat to accumulate.

Estrogens also contribute to regulation of the menstrual cycle. Adrenal androgens, released from the adrenal glands on top of each kidney, influence girls’ height spurt and stimulate growth of underarm and pubic hair. They have little impact on boys, whose physical characteristics are influenced mainly by androgen and estrogen secretions from the testes.

As you can see, pubertal changes are of two broad types: (1) overall body growth and (2) maturation of sexual characteristics. We have seen that the hormones

responsible for sexual maturity also affect body growth, making puberty the time of greatest sexual differentiation since prenatal life.