BIOLOGICAL FOUNDATIONS,
PUBERTY AND HEALTH
Evolution and Adolescent Development-we see
what has worked to allow us to survive in our current
behavior. If it is present today, it is because it
functioned adaptively.
Natural Selection-the natural process that favors
those members of a species that are best adapted to
survive and reproduce.
Evolutionary Psychology-emphasizes the
importance of adaptation, reproduction and ‘survival
of the fittest’ to explain behavior. It shapes our
relational behaviors, mating practices, etc.
Ingrained traits of aggression and risk-taking for
males or nurturance and sociability in females
developed over centuries because these behaviors
helped the species survive. Today they are not valued
in the same way and may actually produce stress in
today’s generations. Adolescents have some
evolutionary advantages to help them survivephysical advantages, also memory and shorter
experience of negative emotions. But the system is
not designed to allow A. maximum freedom to
experience their abilities. Social restrictions as well
as lack of responsibility, problems with sexuality and
lack of autonomy cause teens angst.
Social Cognitive View of Evolution-even though we
are subject to evolutionary influences, biology does
not dictate our development. Plasticity is a hallmark
of the human condition, so we can adapt to
environmental change as well as change our
environments. Each generation does…
Heredity and Environment
 Genotype-one’s genetic heritage, DNA code.
 Phenotype-how the genes are expressed in
observable characteristics. There is a range…
 Reaction range-the range of possible
phenotypes for each genotype- depending on the
richness of the environmental stimuli.
 Canalization-process by which characteristics
take a narrow path or course. Some inherent
processes protect us from environment extremes.
Behavior Genetics-study of the degree and nature of
behavior’s hereditary basis, using kinship studies.
 Twin studies-measuring the similarity on a trait
between identical (monozygotic) and fraternal
(dizygotic) twins.
 Adoption studies-comparing adoptive children
to parents and other siblings. In IQ studies,
educational levels attained by biological parents
were better predictors of adopted children’s IQ
than IQ of adopted parents. Genes greatly
influence IQ.
Temperament-one’s behavioral style and
characteristic way of responding. It is somewhat
noticeable soon after birth.
 Easy child- generally in a positive mood, regular
in routines, adapts easily to change. 40%
 Difficult child-reacts more negatively, fusses
more, irregular routines, slow to accept change.
10% Teens with this temperament often have
other behavior problems- depression, drug use,
lower family support.
 Slow-to-warm-up child-low activity level,
somewhat negative, low levels of adaptability,
low intensity of mood. 15%
 Goodness of fit model-adaptation is best when
there is congruence between A. temperament and
demands of social environment (expectations of
parents, school, peers)
Heredity-Environment Correlations-the concept
that one’s genes influence the types of environments
to which they are exposed.
 Passive genotype-environment correlationsbiological parents are genetically related to child,
also provide a rearing environment for the child.
It might be fairly well integrated with the child’s
needs, since s/he share genes with parents.
 Evocative genotype-environment correlationsadolescent’s genes elicit certain environments
due to his/her needs. Extroverted, happy children
get more positive attention and response than
introverted, moody children.
 Active (niche-picking) genotype-environment
correlations-when children actively seek
environments that fit them. Artistic kids seeking
the art teacher for special training outside school.
 Shared environmental influences-common
experiences adolescents share with siblingsparents’ personalities, SES, intellectual
influences.
 Nonshared environmental influences-the
unique experiences of each A.- different sports,
friends, treatment by siblings or parents.
Environment shapes genetic potential. They
each contribute to the outcome for the
individual. Early enriching experiences can
compensate for later trauma. Early setbacks do
not necessarily doom a person from then on.
The Nurture Assumption suggested that quality
of parenting doesn’t much matter in development.
Only genes and peers really influence
development. Many studies show that abuse by a
parent correlates with many long-term problems
for children- deficiencies in relationships, problems
with self-control, problems later parenting their
own children.
Puberty- period of rapid physical maturation
involving hormonal and bodily changes in early
adolescence.
 Menarche-point at which a girl experiences
first menstruation. The secular trend is the
tendency in developed countries for girls to
begin menstruation earlier as nutrition and
health improves in the society. This is also
genetically related (similar in timing to your
mothers’) but it also relates to weight and body
mass. Girls must get to 106+ 3# and fat must
make up 17% of body weight. This is why
severe weight loss can trigger amenorrhea.
Hormonal changes
 Hormones-powerful chemicals secreted by the
endocrine glands & carried in the bloodstream.
 Hypothalamus-appetite center in the brain, it
regulates eating, sexual behavior, cravings.
 Pituitary gland-controls growth and triggers
all other glands.
 Androgens-male sex hormones
 Estrogens-female hormones
 Testosterone-triggers male pubertal
development, development of testes, height
increase, voice changes T ^ 18 Xin M,2Xin F
Higher T levels are associated with greater
social confidence. T is triggered by aggression
 Estradiol-triggers female pubertal
development
Height and weight-growth spurt is 2 yrs. earlier for
girls than boys. (9 yrs,F; 11 yrs,M) Because boys
begin the spurt later in development, it allows them
to generally grow taller than girls overall. Weight
gains occur with onset of puberty, also. By age 14,
boys outweigh girls overall.
Sexual maturation-the most noticeable changes in
boys are penis and testes development & facial hair.
Most noticeable changes in girls are breast
development, body shaping, then menstruation.
African-Am. Girls enter puberty earlier in general
than white girls.
Early vs. late maturation-early maturing is more
positive for boys during puberty, late maturing is
more positive for girls. Later in life, late maturing
boys have a stronger sense of identity, farther ranging
than mere physical identity. Late maturing girls are
more likely to have a body that links to the American
ideal body, so they have a more positive body image.
Early maturing in girls is also linked to some
problems- smoking, drinking, depression, eating
disorders, older friends and earlier sexual
experiences. Unless development is severely offtime, it is not something to be concerned with. There
is some indication that girls in our culture are
entering puberty too early due to estrogens in our
foods and higher fat percentage in their bodies.
Body Image-is a big part of the psychological focus
of puberty. Girls are generally less satisfied with their
bodies and have more negative body images (all
during life). This negativity increases as body fat
develops. Boys’ become more satisfied as their
muscle mass increases. The American ideal body for
girls is unattainable for the most part, leading most
girls to feel inadequate.
Menarche in girls is mostly a positive thing for girls,
as they begin seeing themselves as more mature.
Only a minority express distress because of
menarche. If girls are prepared they don’t seem to
have a hard time adjusting.
Adolescent health
 Role of Adolescence in Positive Health
Behaviors-this period sets the stage for life as
far as health habits go. Many disease processes
occur gradually in response to specific
behaviors- sedentary life style, fatty foods, no
seat belts, unsafe sex, smoking, drug use, poor
sleep. Because they are so resilient and have a
sense of immortality, they often think their
behaviors at this point don’t matter. Exercise
alone can improve mental as well as physical
health.
 Leading causes of death in AdolescenceAccidents (50%), suicide(6-12% of deaths) and
homicide (especially among Af-Am males- they
are 3X more likely to be killed by guns than
natural causes). Many car accidents also include
substance use. Because teens have such poor
driving records, especially in the first year, some
states are changing the laws to prevent teens
driving other teens. The distractions cause as
much failure as drinking.
Influences on health behavior-teens are fairly
poorly informed about real health risks and their
vulnerability- especially to STDs, substance abuse.
Educators are still limited in how they can present
information about sexuality to teens. Poverty is
related for poor health in teens, due to poor food
available, lack of medical care, neglect by overstressed parents, self-perception of helplessness.
Families often don’t model proactive health habits.
Many poor youths connect with others who display
risk-taking behaviors, substance abuse, reckless
driving, violence. PE in the schools can make a
difference in helping kids to be more health
conscious. Females in general are more willing to
change unhealthy habits once educated.
BIOLOGICAL FOUNDATIONS,
PUBERTY AND HEALTH
Evolution and Adolescent Development
Natural Selection
Evolutionary Psychology
Social Cognitive View of Evolution
Heredity and Environment
 Genotype
 Phenotype
 Reaction range
 Canalization
Behavior Genetics
 Twin studies
 Adoption studies
Temperament
 Easy child
 Difficult child
 Slow-to-warm-up child
 Goodness of fit model
Heredity-Environment Correlations
 Passive genotype-environment
correlations
 Evocative genotype-environment
correlations
 Active (niche-picking) genotypeenvironment correlations
 Shared environmental influences
 Nonshared environmental influences
Puberty
 Menarche
Hormonal changes
 Hormones
 Hypothalamus
 Pituitary gland
 Androgens
 Estrogens
 Testosterone
 Estradiol
Height and weight
Sexual maturation
Early vs. late maturation
Body Image
Adolescent health
 Role of Adolescence in Positive Health
Behaviors
 Leading causes of death in Adolescence
Influences on health behavior