2. The course of physical growth.
Theorists think that the slow course of physical growth
provides us with added time to learn the skills which are
required in a social live: Humans have not already depended on his
body to survive. We are social animal.
Physical growth are determined by environment. Physical
growth doesn´t happen independently of input from the
environment. Factors, like nutrition, cultural practices or
experience, affect to physical development.
3. The patterns of growth
There are two patterns of growth:
◦ Cephalocaudal: The develop happen in a head to toe direction.
For example, within the head, eyes and brain grow faster than
jaw.
◦ Proximodistal: The develop happen outwards from the centre
of the body. For example, baby will acquire control over the
muscles of the neck and trunk before it acquires control over
the fingers and the toes.
4. Body size
Changes in body size are the most obvious manifestation of physical growth.
5. In general, physical
developments in height and
weight tend to occur:
very rapidly in infancy
continue at a steady pace
throughout childhood
and then slow down
towards puberty
6. At puberty there is a marked
growth spurt, a very rapid
increase in size and weight.
This pubertal growth spurt
varies from person to person
in terms of its intensity, its
duration and its age of onset.
It tends to last around 4 ½
years.
7. In girls, it usually begins
around age 11 and boys
two years later.
Growth may still take
place after the completion
of the pubertal spurt
8. Hereditary factors play a strong role in physical growth
There is a large and stable correlation in identical twins (the
ones who come from the splitting of one fertilized egg)
Fraternal twins (fertilization of two different eggs) have smaller
correlations.
This suggest that genetic factors play an important role in
determining height
These patterns are observed for weight as well as for the timing of
growth spurts
9. Environmental factors in physical
growth: Nutrition
The human physical growth is, as we all know, controlled by our
genetic, but there is another aspects that can influence it, one
example is the nutrition, which means:
and
What do we eat How much do
we eat
10. The studies made during de WW2 showed that the wartime
conditions (few food) caused a decrease in the average height and
a reverse a trend towards increasing weight since the end of the
WW1.
11. Other problems caused by malnutrition are, for example:
The dietary restrictions had an effect in puberty like, for example,
the menarche is delayed by 3 years.
Cognitive development has also been affected:
1. Anemia – slowing of intellectual development
2. Intestinal worms – stole valuable nutrients for growth
13. The most important of this glands is the pituitary gland, located near
the base of the brain. The pituitary gland, triggers chemical
changes.
Via hormones which it secretes to the bloodstream, which act on
various tissues and indirectly by triggering other glands to release
different hormones.
14. The pituitary gland also controls the primary sexual characteristics
(growth involving the reproductive organs,) and the secondary
sexual characteristics ( visible changes which are associated with
sexual maturation) due to the segregation of big amounts of
testosterone in men and big amounts of estrogen's in women.
15. Sexual maturation
In the sexual maturation the most important changes are the
menarche and the spermarche.
Menarche: Is the first menstruation in females.
Spermarche: Is the first ejaculation in males.
After that, there is a period of sterility that can least about one
year in which menstruation and ejaculations occur but no eggs
or sperm are released (Tanner, 1990).
16. The pituitary gland releases hormonal signals that begin physical
transformation, because of different causes like genetic factors.
But they are not the only cause, for example:
In young women physical exercise can delay the onset of the
physical changes, associated with puberty (Brooks Gun, 1998).
Family conflict and the absence of fathers predicted an earlier onset
of menarche (Moffit, 1992).
An increased psychological distance between girls and their fathers
predicted an earlier menarche.
When fathers had good quality relationships with their daughters the
onset of pubertal maturation came later.
These studies highlight the importance of environmental factors in sexual
maturation.
17. Early maturation carries advantages for boys (Jones and
Bayley, 19500):
◦ Late-maturing boys are characterized as lower in physical
attractiveness, masculinity, and were rated as more childish.
◦ Early-maturing boys are characterized as independent , self-
confident, and as being better leaders and athletes, and they use
to have a much more positive body image, because with the
puberty they gain height and muscularity.
However, in girls early maturation has the contrary effects:
◦ Early-maturing girls are less popular, less self-confident, held fewer
leadership positions and tend to have a poorer self body image, in
part because in the pubertal maturation there is a gain of weight.
18. Behavioural problems have been associated with early
maturation.
Caspi and Moffit (1991) said that when stressful events such as
early maturation occur, girls may highlight dispositional
factors.
Brooks-Gunn and Warren (1995) believe that psychosocial
factors (parental warmth, parental approval, and the level of
family conflict) play an important role in how girls react to
early maturation.
There has been also found that early-maturing girls tend to
have smaller networks of friends and to associate with older
friends who often engage them in risky behaviours like
smoking, drinking or sexual intercourse.
Contextual and psychosocial factors play an important role in
behavior, but not all early-maturing girls will experience problems.
