1. Biological Foundations in Adolescent Development
Physical and Hormonal Changes
Cultural & Psychological Responses to Puberty
Neural Changes

2. Physical changes Puberty – onset of sexual maturation
Three neuroendocrine changes:
Gonadal
Adrenal androgens
Growth

3. Gonadal and adrenal androgen axes

4. Gonadal (HPG) axis Gonadotropin releasing hormone
(LH, FSH are gonadotropins)
(testes or ovaries)
(sex hormones – testosterone & estradiol increase dramatically -- gonadarche)
(see next slide)

5. Sex Characteristics (examples)
Primary Sex Characteristics
Secondary Sex
Characteristics
Production of sperm (spermarche) or development of eggs
Development of sex organs
Pubic and axillary hair growth
Skin becomes rougher & oily
Voice deepens
Slight enlargement of breasts known as breast buds (also, in ¼ of boys)

6. Adrenal androgen (HPA) axis
(ACTH = adrenocorticotropic hormone)
(e.g., testosterone)
(leading to secondary changes)

7. Growth spurts and height changes
Notice the differential timing in when growth spurts begin
Notice when the difference in final height is achieved

8. Body composition changes
During puberty body fat increases more for girls than for boys
Notice prior to puberty boys and girls are very similar in muscle mass
Given that girls naturally develop a lower muscle-to-fat ratio than boys during puberty, why would any culture create physical ideals that demand thinness in females once they reach puberty? AND what are the health implications?

9. The Order of Pubertal Events (see Table 2.2)
GIRLS
BOYS
Growth of sexual and reproductive organs
Secretion of increased skin oil and sweat
Growth spurt
Downy pubic hair
Development of underarm hair
Appearance of breast buds
Menarche
Increased growth of penis
Secretion of increased skin oil and sweat
Growth of testes
Growth spurt
Deepening of the voice
Development of facial hair
Appearance of pubic hair

10. Pubertal Caveat
Virtually all the studies considered in the order of pubertal development have been conducted with White adolescents in the West
Variations may exist in other groups (see p. 45; e.g., Kikuyu culture in Kenya, Chinese girls, African-American girls and boys)

11. Earlier Puberty
Tanner Stage 2 (breast and pubic hair dev’t) by age 10 in the majority of girls (68% in Euro-American girls; 95% in African-American girls)
The downward trend in the age of menarche has occurred in every Western country for which records exist. Why?

12. Responses to Puberty Homework assignment Next section:
Cultural & Psychological responses to puberty

13. Cultural Responses to Puberty: Rituals in Traditional Cultures
79% of cultures had puberty rituals for girls
__________ (?) is the pubertal event that is most often marked by ritual
Cultural views are mixed as to the reaction to menstruation (see “Historical Focus” box in chapter)
68% of cultures had puberty rituals for boys (e.g., vision quest ) (“Roots” video)
Typically rituals require the young man to display courage, strength and endurance (often violent)
NOTE: Globalization has been credited with the decline in frequency of these rituals

14. Personal responses to puberty
Behavior and emotions
Problem behavior (e.g., aggression, conduct disorder symptoms, etc.) has been attributed to hormonal changes (but also to physical maturation and brain changes)
Testosterone (T) can lower boys’ frustration tolerance  readiness to engage in aggression
Rapid hormonal changes are associated with depression, but “hormonal storm” view is far too simplistic. In fact…
Hormonal levels account for only a tiny percentage of the variance in adolescents’ negative affect – social influences account for considerably more

15. Pubertal timing and adjustment
There is a lot of research (which is conflicting) on the effects of timing of physical development
Theoretically, being “off-time” creates more stress and vulnerability to adjustment problems

16. Maturation - Girls
According to Arnett, the effects of early maturation are especially negative for girls, who are at risk for a variety of problems:
Depressed mood, Negative body image, Eating disorders
Delinquency, Substance use, School problems, Conflicts with parents
Caveat: Early-maturing girls with no history of behavior problems experienced fewer problems than did girls with a history of behavior problems who matured on time
Late maturing girls have few of the problems that early-maturing girls have

17. Early Maturation - Boys
The effects of early maturation are more mixed for boys
Early maturing boys have:
More favorable body image
Higher popularity
Earlier involvement in substance use, delinquency, and sex

18. Late Maturation – Boys Late maturing boys show evidence of problems
Compared with boys who mature “on time” late maturing boys have higher rates of:
Alcohol use
Delinquency
Lower grades in school

19. Neural changes
New research in cognitive and affective neuroscience (Intro to “The Teenage Brain” PBS-DVD & Sci American podcast on the teen brain)
Brain actively reorganizes itself – cells and connections are pruned (for efficiency)
Prefrontal cortex (planning and decision making) undergoes a growth spurt in early A and continues to develop throughout A
Cortical-limbic pathways (thought-emotion connections) are slowly developing during adolescence (e.g., research on teens’ difficulty in reading emotions in people’s faces)
Implications?
Research example -- incarcerated adolescents displayed more impulsivity and poorer critical thinking than age-matched students (Chretien & Persinger, 2000).
Driving and multitasking
Much more research needed