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Janet Belsky’s Experiencing the Lifespan, 1e
Chapter 8:
Adolescence: Physical Development

Puberty is the set of hormonal and physical changes that make a human sexually mature.
Menarche: first menstruation
Spermarche: first ejaculation
Menarche is a more public event, so the age of menarche is typically used in research about age of puberty.

Puberty was, and in some cultures still is, celebrated by rites of passage or a “coming of age” ritual.
The declining age of puberty is directly related to the increase in teenage pregnancy.
Lack of “person-environment fit” related to age of becoming sexually active
The Secular Trend
Refers to the decline at which we achieve puberty in developing countries.
In 1830, the average age of menarche in Northern Europe was over 17.
Today, the age has fallen to under 13.
The Hormonal Programmers
Puberty is regulated by hormones from 2 sources:
Adrenal Gland
Adrenal androgens: hormones produced by the adrenal glands that regulate various aspects of puberty, such as growth of hair, skin changes, and sexual desire
This system begins at about age 6 to 8.
It plays a relatively minor role in sexual development.
HPG Axis: primary hormonal system regulating puberty
Hypothalamic hormone causes the pituitary to secrete its hormones, which in turn, trigger the gonads (ovaries and testes) to begin secreting their hormones.
The Hormonal Programmers
Primary hormones regulating puberty are from the gonads:
Testes produces testosterone, the hormone responsible for
maturation of the reproductive organs and other signs of puberty in boys
(with the adrenal androgens) sexual desire in both sexes
Boys have 8 times as much testosterone as girls.
Testes also produce small amounts of estrogen
Ovaries produce estrogen, the hormone responsible for
maturation of the reproductive organs and other signs of puberty in girls
Ovaries also produce small amounts of testosterone
What Starts Puberty?
Puberty can begin for many reasons:
Humans tend to reach puberty at the age their parents did.
Children with a high BMI (body mass index) tend to reach puberty at an earlier age.
High caloric diets showed a correlation to reaching puberty at an earlier age.

What Starts Puberty?
Warm temperatures speed up the start of puberty.
Bone density triggers the hypothalamus.
Poverty and difficult family situations can all factor in to early puberty.

Physical Changes
Primary Sexual Characteristics
Physical changes directly involved in reproduction
Menarche is the woman’s first period
Spermarche is the man’s first ejaculation
Secondary Sexual Characteristics
Physical changes not related to reproduction
Hair growth, voice changes, acne
Breasts take an average of 5 years to develop
Growth Spurt
Dramatic increase in weight and height
At puberty, the hands, feet, and legs grow first
Boys gain about 8 inches in height, vs. 4 inches for girls, & become much stronger than girls.
Puberty Timetables: Individual Differences
Race and ethnicity
African Americans tend to begin earlier than other groups.
This may be due to nutrition.
Asian Americans tend to lag slightly behind.
Single mother households
Studies found a correlation between early puberty and absent fathers.
Early stress
Absent fathers may be simply one type of early stress, which has been found to accelerate the onset of puberty.
Evolutionary psychology: frees the child from a bad nest
Puberty Timetables: Individual Differences
Socioeconomic status
Low SES in developing countries slows puberty.
Because it produces stunted growth
Low SES in developed countries speeds puberty.
More likely to have higher stress
More likely to have single mothers
More likely to be overweight
An Insider’s View of Puberty
Breast Development
Girls responding to the “social norm” look upon breast development favorably.
When bodies must be slender (ballerinas, gymnasts, etc.) it’s looked upon negatively.
Cultural reaction plays a role in the girl’s view.
Navajo see it as a spiritual growth
Mother’s have an important role in setting the attitude.
Can be misunderstood and scary.
Can be concealed; private and embarrassing.

Being Early
Early development in boys tends to be ambiguous.
Since the penis, testicles, and pubic hair are the first to develop in boys, others tend to not notice.
But will also be taller & stronger, advantage for sports
Can be a social advantage, although may get in trouble with older friends
Early blooming for girls can be a negative experience.
Noticed more often, especially by older boys
More likely to get involved in risky activities
More likely to have unprotected intercourse
More likely to become depressed
More likely to not fit into society’s “slim model” look
Wrapping Up Puberty
Children’s reactions to puberty depend on the views of the specific environment in which they physically mature.
With early maturing girls, it is important to arrange the right environment– i.e., stay in the same school.
Communication about puberty can be vastly improved, especially for boys.
Parents (especially fathers) should sensitively discuss what is happening with the same sex child.
Not easy to do in a one-parent household.
Society should consider the benefits of K-8 schools and better, earlier sex education.

Body Image Issues
Susan Hartman’s Five Dimensions: related to teenager’s overall self-esteem
Scholastic Abilities
Athletic Skills
Peer Likeability
Far outweighs any of the above
One out of two teenage girls are trying to lose weight

Body Image Issues
Body Image Issues
Pressures that make us self-conscious about our weight:
Being teased by family and friends
Media: where both genders are vulnerable
Introducing Fiji to Western media, girls began having the same concerns about food and weight as did girls in Western nations.
But African-American girls do not have these same ideas about being thin.
Eating Disorders
Eating disorders are a pathological obsession with getting and staying thin.
They appear in every SES level.
There is a hereditary component, which may combine with certain environmental factors.
They can be related to a general tendency to be anxious and depressed.
At the core of eating disorders is low self-efficacy (a sense of being helpless and out of control of one’s life).

Eating Disorders
Anorexia Nervosa
Refusing to eat and having a distorted body image
Found in about 1 in 1000 teenagers
Must be at or below 85% body weight to be classified as having anorexia
Severe starvation can destroy vital organs.
Eating Disorders
Binging (eating to excess) and purging (removing the food before there is significant caloric intake)
Stomach acid can produce major problems
Mouth sores, loss of tooth enamel, ulcers, esophageal cancer
The prevalence of bulimia is increasing, suggesting a greater environmental cause.
Eating Disorders
Improving Self-Image
Self-esteem improves physical appeal.
Your personality can strongly influence others’ concepts of your physical appearance.
Accepting objective images makes one vulnerable.
Those who feel that their mirror image determines who they are as a person, are more likely to be unhappy.
If you believe it is your feelings about yourself that shape how you look, than you are more likely to be happy.
“I am in control of my own beauty.”

A person’s sexuality (within limits) is more acceptable today. However, it is still more acceptable to wait until marriage.
When does sexual desire begin?
As adrenal androgen production is rising, but before testosterone production commences; attraction to others can occur as early as 10 years old.
A threshold of androgen is required to prime initial feelings of sexual desire.
Environmental feedback helps trigger our feelings.
Our own changing bodies make us think and consider sex.
How others react towards us triggers thoughts of sex.

Who IS having intercourse?
Average age at first encounter is late teens, but 1 in 4 teens began having sex at age 15.
What can be used to predict sexual activity?
SES & ethnic differences
TV-watching behavior
Age of puberty
Other sexual activities lead to intercourse
Oral sex is more common among higher SES levels.
Gender Differences
The sexual double standard: boys can have sex, girls are supposed to remain virgins.
More African-American and Hispanic males are sexually active than females.
The opposite is true for white students.
A majority of boys under 17 are still virgins.
Boys do put a higher priority on having sex than girls do, but both boys and girls put their highest priority on intimacy.
Wrapping Up Sexuality
ABC’s of Sex Education
If not, Be Monogamous
Use a Condom
U.S. policy is to “Just Say No”
21 states required by law to stress abstinence, which doesn’t always achieve desired results
teenage pregnancy
1 out of 4 teenage “virgins” have had oral sex
Teens need education about preventing pregnancy and STDs.
Teens also need education about relationships.
Wrapping Up Sexuality