Aspects of child development

Child development is not a matter of a single topic, but progresses somewhat differently for different aspects of the individual. Here are descriptions of the development of a number of physical and mental characteristics.  

Physical growth

 What develops?

Physical growth in stature and weight occurs over the 15–20 years following birth, as the individual changes from the average weight of 3.5 kg and length of 50 cm at full-term birth to full adult size. As stature and weight increase, the individual's proportions also change, from the relatively large head and small torso and limbs of the neonate, to the adult's relatively small head and long torso and limbs.

Speed and pattern of development

The speed of physical growth is rapid in the months after birth, then slows, so birth weight is doubled in the first four months, tripled by age 12 months, but not quadrupled until 24 months.Growth then proceeds at a slow rate until shortly before puberty (between about 9 and 15 years of age), when a period of rapid growth occurs. Growth is not uniform in rate and timing across all body parts. At birth, head size is already relatively near to that of an adult, but the lower parts of the body are much smaller than adult size. In the course of development, then, the head grows relatively little, and torso and limbs undergo a great deal of growth.

 Mechanisms of developmental change

Genetic factors play a major role in determining the growth rate, and particularly the changes in proportion characteristic of early human development. However, genetic factors can produce the maximum growth only if environmental conditions are adequate. Poor nutrition and frequent injury and disease can reduce the individual's adult stature, but the best environment cannot cause growth to a greater stature than is determined by heredity.

 Population differences

Population differences in growth are largely related to adult stature. Ethnic groups that are quite tall in adulthood are also longer at birth and throughout childhood, as compared to groups that have short adult stature. Males are also somewhat taller, although this is more apparent in ethnic groups with strong sexual dimorphism in adulthood. Populations that are characteristically malnourished are also shorter throughout life. However, there are few population differences in growth rates or patterns, except that poor environmental conditions may delay puberty and the associated growth spurt. The markedly different age at puberty of boys and girls means that boys and girls of age 11 or 12 are at very different points in maturation and may reverse the usual sex difference in physical size.Individual differences

Individual differences in height and weight during childhood are considerable. Some of these differences are due to family genetic factors, others to environmental factors, but at some points in development they may be strongly influenced by individual differences in reproductive maturation.

Individual differences

Individual differences in height and weight during childhood are considerable. Some of these differences are due to family genetic factors, others to environmental factors, but at some points in development they may be strongly influenced by individual differences in reproductive maturation.