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. Slide 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 Slide 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 adolescents anatomy, physiology, and physical appearance The
body undergoes a biological revolution that dramatically changes
the adolescents anatomy, physiology, and physical appearance Slide
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 Slide 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. Slide 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 Slide 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 Slide 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
Slide 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. Slide 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
Slide 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. Slide 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 Slide 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 thats not the
whole story but thats not the whole story Adolescence and Emerging
Adulthood: A Cultural Approach by Jeffrey Jensen Arnett. Copyright
2004 by Pearson Education. All rights reserved. Slide 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. Slide 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. Slide 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. Slide 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. Slide 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. Slide 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. Slide 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. Slide 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. Slide 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 Slide
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? 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. Slide 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 Slide 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
others presence Parents and adolescents seem less comfortable in
each others 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. Slide 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 Slide 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. Slide 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. Slide 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. Slide 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. Slide 32 Genotype Genotype A persons inherited
genesA persons 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. Slide 33 DescriptionInteraction Active Occur when people
seek out environments that correspond to their genotypic
characteristics Evocative Occur when a persons inherited
characteristics evoke responses from others in their environment
Passive Occur in biological families when parents provide both
genes and environment Genotype-Environment Interactions Slide 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 adolescents 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 adolescents 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.
