Introduction
Puberty
has been defined as
"the biological changes of adolescence" (Steinberg, 1996)
and "Biological developments [which] change boys and girls from
physical immaturity to biological maturity" (Cole & Cole,
1993).
What
changes occur during Puberty?
There are five main physical occurrences from puberty:
- Growth occurs
- Body composition
begins to change.
- The circulatory and respiratory systems begin to change
- The primary sex characteristics develop
- The secondary sex characteristics develop
There is a
great amount of variation in the rate of changes that may occur. Some
adolescents may experience these signs of maturity sooner or later than
others. It is important to remember that these changes happen at
different times for everyone. Being smaller or bigger than other
girls or boys is normal as each child experiences puberty at his/her own
time. The following are the average ages when puberty changes may occur:
Age
of puberty: Females |
Age
of puberty: Males |
8
to 13 years of age |
9.5
to 14 years of age |

Physical
Effects of Puberty
There are specific
stages of development that both boys and girls go through when developing
secondary sexual characteristics. The following is a brief overview
of the changes that occur in a girl:
- The start of puberty
is signalled by the development of breast buds - medically termed thelarche.
A
small mound is formed by the elevation of the breast and papilla
(nipple). The areola (the circle of different skin around the nipple)
also starts to increase in size
- Pubic hair
begins to grow - medically termed adrenarche. The initial growth
is soft
hair covering a small area around the genitals
There is a growth
spurt - with the feet, arms, legs, and hands sometimes growing
faster than the rest of the body. This may cause an adolescent girl
to experience a time of feeling clumsy
The
overall body shape begins to change as the hips get wider and the
waist relatively smaller. There may also be an increase in fat in the
buttocks, legs, and stomach
An
increase in oily
skin, sweating and acne may develop
The breasts
continue to enlarge. Eventually, the
nipples and the areolas will elevate again, forming another projection
on the breasts
Menstruation
begins, medically termed menarche. The girl is now a young woman
as she can become pregnant
Hair
growth continues to increase, not only the pubic area, but also under the arms and on the
legs. Most young woman start to shave the later areas
The breasts reach
their full adult
state, only the nipple remains erect
The following chart shows
the variations of physical changes at puberty, and the age range within
which that change typically occurs:
GIRLS |
BOYS |
Characteristics |
Age
of Occurrence |
Characteristics |
Age
of Occurrence |
Sudden rapid body growth in height and weight |
9˝ - 14˝ years |
Sudden rapid body growth in height and weight |
11 - 16 years |
Breasts
start budding (first visible sign of puberty) |
8 - 13
years |
Testes
and scrotal sac grow |
10 - 13
years |
Pubic
hair develops(shortly
after breast development) |
8˝ - 14
years
|
Pubic
hair develops |
10 - 15
years |
Menarche
occurs |
10 - 16˝ years |
Penis
growth |
11 - 14˝ |
Underarm
hair grows |
About
2 years after pubic hair |
Underarm
and facial hair |
About
2 years after pubic hair |
Oil/Sweat
glands develop |
Around
time of underarm hair |
Oil/Sweat
glands develop |
Around
time of underarm hair |
|
|
Voice
breaks (larynx grows) |
Around
the same time as penis growth |
Growth
Puberty
and the teenage years are also termed adolescence. During
this time, the teenager will see the greatest amount of growth in height
and weight. Adolescence is a time for growth spurts and puberty
changes. An adolescent may grow several inches in several months
followed by a period of very slow growth, then have another growth
spurt. Changes with puberty may occur gradually or several signs may
become visible at the same time. The growth spurt triggers the legs
to grow, followed by the body's trunk, and ending in the shoulders and
chest. Bones become harder and denser, while muscle and fat
contribute to an adolescent increase in weight.
The growth spurt usually occurs in
girls about two years before boys and in many countries the average height
of a 12-year old girl is similar or taller than the average 12-year old boy.
Physiological
Changes
During
puberty, the body undergoes considerable changes in its composition, and
in its circulatory and respiratory systems:
- Girls
develop breasts, acquire hips, and have a higher ratio of fat to
muscle. Females are healthier, live longer, and are able to tolerate
more long-term stress than males.
- Boys develop
wider shoulders, a more muscular neck, and lose fat during
adolescence. Males develop larger hearts and lungs, have higher blood
pressure, and lower resting heart rates than females. Overall,
males can exercise longer and with greater force than females.
The physical development of
girls during puberty is described in the Tanner model:

The following
diagram compiles several studies to show the average age at which American girls go through
the various stages of puberty:

A UK study suggests that British
girls are perhaps six months later, but conversely a South African study
suggests that girls in that country are up to a year earlier. The regional
differences mean very little given a consistent finding that locally boys lag
girls through puberty by one to two years.
Waist and Hips
One the most visually
obvious changes at puberty is the hormone induced differentiation of the previously similar
waist and hip shapes of boys and girls.
The Androgenic Body Form (genetically
XY and passed through a testosterone dominant puberty) typically has:- Increased subcutaneous fat deposition along the abdomen and
flanks
- Narrow pelvic brims (see
figure A below)
- Lower body fat than estrogenic forms
- A waist-to-hip ratio (WHR)
of 0.85 to 0.95 for men of normal weight
- The buttocks area has a ‘flatness’ or concavity (see
figure C below)

The Estrogenic Body Form (genetically
XX and passed through an estrogen dominant puberty)
has:- A greater proportion of fat deposited
on the buttocks and
hips
- Wider pelvic brims (see
figure B above)
- 10% more body fat compared to androgenic forms
- A waist-to-hip ratio (WHR)
of 0.65 to 0.80 for women of normal weight
- The buttocks have a ‘fuller’ round shape (See
figure D above)
Sexual
Development
The
sexual and other physical maturation that occurs during puberty results
from hormonal changes. As the adolescent nears puberty, a gland in the
brain called the pituitary gland increases the secretion of a hormone
called follicle-stimulating hormone (FSH). This hormone then causes
additional effects. In girls, FSH activates the ovaries to start
producing oestrogen.
In
boys, FSH causes sperm to develop.
Sexual
development involves
enlargement, maturity, and the reproduction of the primary sex organs.
The male testes produce sperm cells and the prostate gland produces semen. Males
are can ejaculate the semen, which contains the sperm. The
female ovaries release the mature ova into the fallopian tubes.
Menstruation occurs if conception does not.
As the primary sex
organs mature, the secondary sex characteristics distinguish
males from females.
Female
Sexual Development
Girls
experience puberty as a sequence of events, but their pubertal changes
usually begin before boys of the same age. Each girl is different
and may progress through these changes differently.

Figure 1: Changes during puberty, in girls. (A) shows a typical
girl before the onset of puberty; in (B) the breasts are beginning to
develop and there is the beginning of pubic hair. There is also increased
height and body fat. (C) shows a fully developed female figure at about
age 16 or 17.
In
girls, the first physical signs of sexual development are the budding of
breasts, usually between ages 8 and 13. Not uncommonly, one breast
may begin to develop before the other, or the breasts will be
asymmetrical. While this may seem a cause for concern, it usually is
not a sign of abnormality. Breasts are seldom exactly the same size, and
by adulthood they have usually evened out, so the differences are barely
noticeable. If the breasts remain markedly asymmetrical or, in rare
instances, one fails to develop, it can be a source of embarrassment and
sensitivity. A visit to a physician may assure a girl with
asymmetrical breasts that she does not have a disease, and that the
problem can be surgically corrected.
At
the same time as the breasts develop or shortly thereafter, pubic and
other body hair begins to grow. As puberty progresses, girls
experience an adolescent growth spurt and begin to accumulate body fat in
an adult female pattern: rounded hips and buttocks and a further filling
out of the breasts
- during puberty the typical girl will add about 35 pounds (15kg) of
"reproductive fat".
At the same time, vaginal discharge may increase, a sign of impending
menarche, or the onset of menstruation. By the time menstruation is
established, the growth spurt is largely completed, although some girls
add an inch or two in height after menstruation begins.
The average age of
menarche in the United States and other Western countries is now about
12.5 years, although menarche at any time between the ages of 8 and 16 is
considered normal. While the age of menarche has been declining by about 8
months per generation since the turn of the century, this decline appears
to have largely ceased.
The
reasons for the younger age of menarche are unclear, but improved
nutrition is believed to be a major factor. Studies have found that when a
girl of average height reaches about 105 pounds, menstruation shortly
follows. The
percentage of body fat is also believed to be a factor, presumably because
a certain amount of fatty tissue is needed for the hormonal changes
initiating menstruation. The
fact that ballet dancers, long-distance runners, and other girls with low
percentages of body fat generally experience menarche at a somewhat later
than average age supports this theory.
The onset of
menstruation does not necessarily coincide with the beginning of
ovulation. Many teenage girls experience irregular and/or very heavy
periods for the first year or two—possible signs of absent or irregular
ovulation. This is not abnormal but a sign that while enough female
sex hormones are being produced to cause a proliferation and shedding of
the uterine lining, not enough pituitary stimulating hormone (FSH and LH)
is being secreted to result in regular ripening and release of an egg from
one of the ovaries. Within 1 or 2 years of menarche, however, most girls
ovulate with some degree of regularity.
Male Sexual Development

Figure 2:
Changes during puberty, in boys. (A) shows a boy at about age 9
before the onset of puberty. In (B) secondary sex characteristics are
beginning to develop; e.g., the beginning of pubic hair and enlargement of
the penis and testes. There is also increased height and muscle
development. (C) shows a fully developed male at about age 18.
Boys generally
enter puberty about a year later than girls, i.e. between the
ages of 10 and 14. The first physical signs are growth of the testes
and penis, accompanied or shortly followed by the appearance of pubic and other body
hair. About two years after puberty begins there is significant
growth spurt - many 12-13 year-old girls are similar in size and weight
to boys of the same age, but are then rapidly overtaken. During
the growth spurt, breast tissue may develop in up to two-thirds of
adolescent boys, but this usually disappears in about 6 months (although
in some it may persist for a year or longer).
The torrent of 'male'
testosterone hormones on the pubertal boy trigger significant changes to
their larynx, causing a deepening of the voice and the growth of an "Adam's
apple". There is stimulation of facial hair
that begins with a moustache
and within a few years extends over most of the lower face. The rising testosterone
levels also causes an increase in muscle mass - in particular the
biceps, shoulder and thigh muscles all grow larger and stronger than in girls.
Ejaculations
generally begin sometime between the ages of 11 and 15, although anytime
between the ages of 8 and 21 is considered normal. Ejaculation may
occur during sleep or in response to masturbation or a sexual fantasy.
Although the major
events of adolescence in boys are usually completed by the age of 17 or
18, growth may continue (albeit at a slower rate) until the age of 20 or
21.
Hormones and Adolescents
What are
Hormones?
Hormones are a specific organic product of living cells that,
transported by body fluids, produces a specific effect on the activity of
cells remote from its point of origin.
The human endocrine
system consists of glands (adrenal, thyroid, pituitary, pancreas, ovaries,
testes) that manufacture & release hormones into the
bloodstream. Hormones are vital chemical messengers that instruct
target organs to perform or cease to perform actions that are vital to
life, e.g., normal growth, proper metabolism, spermatogenesis (in men),
periodic ovum release (in women). The endocrine system produces,
moves, and adjusts levels of hormones in the body. Hormones are very
specific substances secreted by one or more endocrine glands.
Because receptors in our cells respond to some hormones and not to others,
the action of each hormone is unique. Hormones influence organs
throughout the body, and regulate growth and many other aspects of normal
body function.

Maddie Whitley started taking
oestrogen hormones when age 14 and was soon "wearing
a really big sweatshirt all the time to hide my new boobs".
Pictured age
17 after transition.
|
Androgens are a
class of hormone, found mainly in males although also in females, of which
testosterone is the most important. Manufactured in the testes of
men (and in the adrenal cortex & ovaries of women), testosterone is
responsible for the differentiation of male & female primary sex
characteristics at about the 7th week of foetal life.
Oestrogens are
thought of as female hormones and androgens are thought of as male
hormones, both types are present in each sex, but in different
amounts. Hormonal activation may influence excitability, arousal, or
emotionality. These in turn may influence how individuals behave.
The hypothalamus
responds to the levels of sex hormones within an adolescent's body.
When the endocrine system levels of oestrogen and androgen fall, the
hypothalamus stimulates the pituitary gland to release sex hormones
through the gonads. The gonads are the ovaries in females and testes
in males. The sex hormones stimulate the females' ovaries to produce
oestrogen and progesterone. This stimulation triggers the release of
mature ova from the ovaries to allow for future reproduction. These
hormones also stimulate the testes and adrenal glands among males.
This stimulation produces the hormone testosterone for producing
sperm. Puberty begins when the hypothalamus is signalled, and the
pituitary gland is activated.

Oestrogen levsl
in
Women |

Testosterone levels
in
Men |
The
changes in hormone levels at puberty are dramatically different
between boys
and girls, unsurprisingly this results in dramatically different
physical changes.
|
Males
and Hormones
At puberty a boy's testes start releasing large quantities of the
androgen testosterone, which leads to muscle growth, body and facial hair,
and other male sex characteristics. Testosterone also contributes to
gains in body size. The production of hormones is associated with
emotionality, specifically aggressive behaviour in boys. These
effects may be greatest when the endocrine system is being turned on.
Testosterone
is responsible for the differentiation of the central nervous system
(mainly the hypothalamus) into male and female types with regard to the
different reproductive cycles and functions. Males also receive
major surges of testosterone at puberty so that the task of sex
differentiation can be completed - oestrogen surges occur at that time in
females.
Testosterone
is responsible for the development of secondary sex characteristics in
males such as pubic & facial hair, deepening of the voice, &
ability to ejaculate sperm-laden semen.
Androgens
are also responsible for baldness.
Females and
Hormones
Oestrogen is responsible for menarche & breast development.
Oestrogen released by a girl's ovaries cause the breasts, uterus, and
vagina to mature and the body to take feminine proportions. In
addition, oestrogens contribute to regulation of the menstrual
cycle. Girls also are affected by androgens secreted by the kidneys
for their growth spurt, underarm and pubic hair. The production of
hormones is associated with emotionality, both depressive and aggressive
affects in girls. These effects may be greatest when the endocrine
system is being turned on.
How
do Hormones
affect adolescents and his/her transition into adulthood?
Despite the advance of feminisism and sexual equality, there is still
(correctly or incorrectly) often perceived to be a great difference
between the role of boys and girls, in the so called "Western
Societies" For boys, puberty is believed to expand role
possibilities into the realm of work and achievement. Girl's roles
are believed to be confined, even on the eve of the 21st century a writer
suggested: "Boys are classified as Doing and girls are classified as
Being". Girls may be more vulnerable to problems with autonomy,
a sense of oneself as a separate self-governing individual, than boys
may. Girls have been characterized to be more emotionally focused
and less individualized the identity status of self-chosen values and
goals, from their mothers than boys do. Girls are more
interpersonal, intimate, and relationally focused. Girls tend to be
more intimate while boys may develop intimacy problems or become more
salient at Puberty. Emotional health, depression, conduct disorders,
and eating disorders are all linked to gender.
A common belief is
that pubertal change has something to do with adolescent moodiness and the
desire for greater physical and emotional separation from parents.
Indeed, higher hormone levels are suspected to be related to greater
moodiness, in the form of anger and irritability for males and anger and
depression for females, between nine and fourteen years of age.
Studies indicate that low points of mood swings are associated with time
spent with friends and in self chosen leisure and hobby activities while
high points tended to occur in adult structured settings- class, job,
school halls, school libraries, and church. These finding suggest
that situational factors may act in concert with hormonal influences to
affect teenagers' moodiness.
Biological
as well as social plays an important role. Early maturation in
boys appears at more of an advantage in many aspects of emotional
and social functioning. Adolescent boys are viewed as relaxed,
independent, self-confident, and physically attractive. Late
maturing boys are viewed as anxious, overly talkative, attention
seeking in behaviour. Among girls the impact of early versus
late maturation is just the opposite. Early maturers are below
average in popularity, appeared withdrawn and lacking in
self-confidence, and held fewer positions of leadership roles. Late
maturers are regarded as physically attractive, lively, sociable and
leaders in school.
In conclusion, it
is safe to say that hormones and their effects on adolescents vary with
age and gender. Not
every transition into adulthood will be easy, but to enhance and help
adolescents cope with all the chemical changes taking place, one needs to
be supportive, understanding, and patient to all trial and errors.

Jamie (left, shown age 23) and Chloe O'Herlihy
(age 20, formerly Daniel). Jamie became unsure about her
gender age 14 her and when she finally transitioned and began
hormones age 22, her younger brother did the same. |
Brothers to Sisters
"Brothers who became sisters" was a hot topic in
the Psychology press during the 1980s.
There is at least one recorded instance of three brothers becoming
sisters.
While transsexual sisters are very rare, they
are also far less rare than might be expected if we accepted (for
example) that 1 in 2000 male babies suffer from gender dysphoria on a
random basis. Other biological and sociological factors seem to come
in to play, and this remains a source of medical interest.

16 year old Kim Petras,
formerly Tim. Pictured just after her SRS, following four
years of hormone treatment. |
Effects of Hormone Treatment on the Transsexual Male-to-Female
Boy/Girl
Ideally, in order to maximise the physical benefits, low level
oestrogen treatment of the young transsexual boy-to-girl should begin at
age 8-9 years. Before the onset of male puberty (at about age 11,
but can vary by 2 years) a bilateral orchiectomy (castration) should be
performed to remove both testes and hormonal treatment then increased to
induce a female type puberty age 10-11. The results are usually
extremely successful, with many clearly female
aspects (e.g. limited muscle growth and flattering fat deposits) resulting
as the child moves to adulthood, whilst avoiding clearly male aspects (e.g.
broken voice and facial hair). However, even in this best possible
case, it's impossible to totally overcome the combination of XY chromosomes
and a hormonal legacy dating back to the womb, with typical results still
being above average shoe size and below average bra size for a woman.
For much more information about the female hormone treatment of the
young transsexual see this article.
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