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Adolescence and Emerging Adulthood: A Cultural Approach Chapter 2 Biological Foundations Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey.

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Presentation on theme: "Adolescence and Emerging Adulthood: A Cultural Approach Chapter 2 Biological Foundations Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey."— Presentation transcript:

1 Adolescence and Emerging Adulthood: A Cultural Approach Chapter 2 Biological Foundations Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

2 Hormonal Changes Hormonal Changes Physical Changes Physical Changes Primary Sex Characteristics Primary Sex Characteristics Secondary Sex Characteristics Secondary Sex Characteristics Cultural, Social, Psychological Responses to Puberty Cultural, Social, Psychological Responses to Puberty Chapter Overview

3 Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. Puberty derived from the Latin word ‘pubescere’ which means to “grow hairy” derived from the Latin word ‘pubescere’ which means to “grow hairy” The body undergoes a biological revolution that dramatically changes the adolescent’s anatomy, physiology, and physical appearance The body undergoes a biological revolution that dramatically changes the adolescent’s anatomy, physiology, and physical appearance

4 The Endocrine System Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. Hormonal changes begin here Gradually increases production of gonadotropin-releasing hormone (GnRH) Recent evidence indicates that this occurs once a threshold level of body fat is reached Fat cells produce leptin that provides the signal to the hypothalamus

5 Pituitary Gland and Gonadotropins Increase in GnRH affects the pituitary gland Gonadotropins influence production of sex hormones Gonadotropins stimulate development of gametes Pituitary gland releases gonadotropins Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

6 Sex Hormones Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. Compare the differences in hormone production between boys and girls during puberty Testosterone Estradiol

7 Endocrine System Feedback Loop Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. Monitor levels of androgens and estrogens in the bloodstream Responds to the reduction in GnRH by reducing production of FSH, LH and ACTH Respond to lower levels of FSH and LH by reducing the amount of sex hormones produced “SET POINT” – when sex hormones reach an optimal level and the hypothalamus reduces GnRH to begin this process

8 Physical Growth during Puberty Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. Notice the differential timing in when growth spurts begin Notice when the difference in final height is achieved

9 Growth Spurts Not all parts of the body grow at the same pace Not all parts of the body grow at the same pace Asynchronicity in growth explains the “gangly look” in early adolescence Asynchronicity in growth explains the “gangly look” in early adolescence Extremities are the first to hit the growth spurt Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

10 Muscle Mass and Body Fat Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. Notice prior to puberty boys and girls are very similar in muscle mass During puberty body fat increases more for girls than for boys

11 Cultural Expectations In many cultures gender differences exist for physical activity In many cultures gender differences exist for physical activity Girls are sometimes discouraged from participating in sports (not confirming to “feminine” stereotypes) Girls are sometimes discouraged from participating in sports (not confirming to “feminine” stereotypes) Boys are more likely to exercise in adolescence Boys are more likely to exercise in adolescence This gender difference contributes to differences in athletic performance between adolescent boys and girls This gender difference contributes to differences in athletic performance between adolescent boys and girls Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

12 Is This True? Reaction time is slower in emerging adulthood. Is this true? Reaction time is actually faster in the early twenties than at any other time of life Is this true? Grip Strength in men peak in emerging adulthood Yes … and followed by a steady decline Cardiac output peaks at 18 years of age Is this true? Cardiac output, the quantity of blood flow from the heart, peaks at age 25

13 Physical Functioning in Emerging Adulthood Emerging adulthood is the period of the life span with the least susceptibility to physical illness Emerging adulthood is the period of the life span with the least susceptibility to physical illness … but that’s not the whole story … but that’s not the whole story Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

14 Physical Functioning in Emerging Adulthood Lifestyles of many emerging adults often include a variety of factors that undermine health such as Lifestyles of many emerging adults often include a variety of factors that undermine health such as Poor nutritionPoor nutrition Lack of sleepLack of sleep Stress of juggling school/work/multiple jobsStress of juggling school/work/multiple jobs Automobile accidents are the leading cause of death among emerging adults in the United States Automobile accidents are the leading cause of death among emerging adults in the United States Homicide is another common cause of death in the U.S. during emerging adulthood Homicide is another common cause of death in the U.S. during emerging adulthood Rates of contracting sexually transmitted diseases, including HIV are highest in the early twenties Rates of contracting sexually transmitted diseases, including HIV are highest in the early twenties Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

15 Sex Characteristics Primary Sex Characteristics Secondary Sex Characteristics Boys Production of sperm Production of sperm Development of sex organs Development of sex organs Hair growth in pubic areas, underneath arms, chests, face, shoulders and back Hair growth in pubic areas, underneath arms, chests, face, shoulders and back Skin becomes rougher Skin becomes rougher Sweat glands increase production Sweat glands increase production Girls Production of eggs Production of eggs Development of sex organs Development of sex organs Hair growth in public areas, underneath arms and a slight amount of facial hair Hair growth in public areas, underneath arms and a slight amount of facial hair Skin becomes rougher Skin becomes rougher Sweat glands increase production Sweat glands increase production Slight enlargement of breasts known as breast buds Slight enlargement of breasts known as breast buds Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

16 … the facts about females Women are born with about 400,000 immature eggs (follicles) in each ovary Women are born with about 400,000 immature eggs (follicles) in each ovary Once a girl reaches her first menstrual period (menarche) one follicle develops into a mature egg (ovum) about every 28 days Once a girl reaches her first menstrual period (menarche) one follicle develops into a mature egg (ovum) about every 28 days Females release about 400 eggs over the course of their reproductive lives Females release about 400 eggs over the course of their reproductive lives Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

17 … the truth about men Males have no sperm in their testes when they are born and do not produce any until they reach puberty Males have no sperm in their testes when they are born and do not produce any until they reach puberty The average age that sperm production begins (spermarche) is approximately 12 years old The average age that sperm production begins (spermarche) is approximately 12 years old Boys produce sperm in astonishing quantities – there are between 30 and 500 million sperm in the typical male ejaculation, which means they produce millions of sperm everyday Boys produce sperm in astonishing quantities – there are between 30 and 500 million sperm in the typical male ejaculation, which means they produce millions of sperm everyday Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

18 The Order of Pubertal Events GIRLS BOYS Downy pubic hair Appearance of breast buds Growth spurt Growth of sexual and reproductive organs Menarche Secretion of increased skin oil and sweat Development of underarm hair Appearance of pubic hair Deepening of the voice Development of facial hair Growth of testes Growth spurt Increased growth of penis Secretion of increased skin oil and sweat Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

19 Pubertal Caveat Virtually all the studies considered in the order of pubertal development have been conducted with White adolescents in the West Virtually all the studies considered in the order of pubertal development have been conducted with White adolescents in the West Three studies demonstrate the variations that may exist in other groups Three studies demonstrate the variations that may exist in other groups Worthman, 1987Worthman, 1987 Lee, Chang, and Chan, 1963Lee, Chang, and Chan, 1963 Herman-Giddens et al., 1997; 2001Herman-Giddens et al., 1997; 2001 Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

20 Kikuyu culture in Kenya (Worthman, 1987) Boys show the first physical changes of puberty before their female peer Boys show the first physical changes of puberty before their female peer a reversal of the Western pattern a reversal of the Western pattern African American Girls (Herman-Giddens et al., 1997; 2001) Many Black girls were found to begin developing breast buds and pubic hair considerably earlier than White girls Many Black girls were found to begin developing breast buds and pubic hair considerably earlier than White girls Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

21 Pubic hair began to develop in most girls about 2 years after the development of breast buds and only a few months before menarche Pubic hair began to develop in most girls about 2 years after the development of breast buds and only a few months before menarche In sharp contrast to the Western studies that found pubic hair and breast buds developed together about 2 years before menarche In sharp contrast to the Western studies that found pubic hair and breast buds developed together about 2 years before menarche Chinese Girls (Lee, Chang, and Chan, 1963) These three studies show the importance of investigating ethnic differences in the rates, timing, and order of pubertal events Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

22 Culture and Pubertal Timing Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. The secular trend downward in the age of menarche has occurred in every Western country for which records exist

23 Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. Discussion Stop Why is the secular trend for the age of menarche going down in Western countries? How do your answers compare to the following slide?

24 Downward Secular Trend of Menarche Puberty begins earlier in cultures where good nutrition and medical care are widely available Puberty begins earlier in cultures where good nutrition and medical care are widely available Illness and thinness tend to inhibit the development of body fat resulting in delayed puberty Illness and thinness tend to inhibit the development of body fat resulting in delayed puberty Advances in food production have enhanced nutrition and therefore puberty has come sooner Advances in food production have enhanced nutrition and therefore puberty has come sooner Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

25 Cultural Responses to Puberty: Rituals Traditional Cultures 68% of cultures had puberty rituals for boys 68% of cultures had puberty rituals for boys Typically rituals require the young man to display courage, strength and endurance Typically rituals require the young man to display courage, strength and endurance The rituals are often violent, requiring boys to submit to and sometimes engage in bloodletting of various kinds The rituals are often violent, requiring boys to submit to and sometimes engage in bloodletting of various kinds 79% of cultures had puberty rituals for girls79% of cultures had puberty rituals for girls Menarche is the pubertal event that is most often marked by ritualMenarche is the pubertal event that is most often marked by ritual Cultural views are mixed as to whether menstrual blood is an omen or a positive sign of fertilityCultural views are mixed as to whether menstrual blood is an omen or a positive sign of fertility Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. NOTE: Globalization has been credited with the decline in frequency of these rituals

26 How do parent-adolescent relations change at puberty? Conflict increases Conflict increases Closeness decreases Closeness decreases Parents and adolescents seem less comfortable in each other’s presence Parents and adolescents seem less comfortable in each other’s presence Distancing hypothesis: it may be adaptive for young people to move away from closeness to their parents once they reach sexual maturity so that they mate and reproduce with persons outside the family, thus avoiding the genetic problems that often result from incest Distancing hypothesis: it may be adaptive for young people to move away from closeness to their parents once they reach sexual maturity so that they mate and reproduce with persons outside the family, thus avoiding the genetic problems that often result from incest Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

27 Frequency of Adolescent-Mother Touching and Talking Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved. Research based on 122 pairs of mother and children aged 6 to 16 Mothers and early adolescents talked more than mothers and younger children, suggesting that parent- child communication styles shift toward talking and away from touching when puberty is reached

28 Early Maturation - Girls The effects of early maturation are especially negative for girlsThe effects of early maturation are especially negative for girls Early maturing girls are at risk for a variety of problems:Early maturing girls are at risk for a variety of problems: Depressed mood Depressed mood Negative body image Negative body image Eating disorders Eating disorders Substance use Substance use Delinquency Delinquency School problems School problems Conflicts with parents Conflicts with parents Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

29 Late Maturation - Girls Late maturing girls have few of the problems that early-maturing girls haveLate maturing girls have few of the problems that early-maturing girls have Although they can suffer from:Although they can suffer from: Teasing Teasing Negative body image (during the years when other girls have begun to develop) Negative body image (during the years when other girls have begun to develop) However, by their late teens they tend to have a more favourable body image than other girlsHowever, by their late teens they tend to have a more favourable body image than other girls They are more likely to end up with the lean body build that tends to be regarded as attractive in Western majority cultures.They are more likely to end up with the lean body build that tends to be regarded as attractive in Western majority cultures. Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

30 Early Maturation - Boys The effects of early maturation tend to be positive for boysThe effects of early maturation tend to be positive for boys Early maturing boys have:Early maturing boys have: More favorable body image More favorable body image Higher popularity Higher popularity Although not everything is favorable. They tend to be involved in:Although not everything is favorable. They tend to be involved in: Substance use Substance use Delinquency Delinquency Sex Sex Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

31 Late Maturation - Boys Late maturing boys show evidence of problemsLate maturing boys show evidence of problems Compared with boys who mature “on time” late maturing boys have higher rates of:Compared with boys who mature “on time” late maturing boys have higher rates of: Alcohol use Alcohol use Delinquency Delinquency Lower grades in school Lower grades in school Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

32 Genotype Genotype A person’s inherited genesA person’s inherited genes According to the theory According to the theory Both genotype and environment make essential contributions to human developmentBoth genotype and environment make essential contributions to human development Genotype-environment interactions take three forms: Genotype-environment interactions take three forms: PassivePassive EvocativeEvocative ActiveActive Genotype-Environment Interactions Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.

33 DescriptionInteraction Active Occur when people seek out environments that correspond to their genotypic characteristics Evocative Occur when a person’s inherited characteristics evoke responses from others in their environment Passive Occur in biological families when parents provide both genes and environment Genotype-Environment Interactions

34 Unravelling genotype-environment interactions Adoption studies Adoption studies These studies avoid the problem of passive genotype-environment effects because one set of parents provided the adolescent’s genes but a different set of parent provided the environmentThese studies avoid the problem of passive genotype-environment effects because one set of parents provided the adolescent’s genes but a different set of parent provided the environment Adolescence and Emerging Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright © 2004 by Pearson Education. All rights reserved.


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