Ruffin (2009) defines development as change or growth that occurs in a child during the life span from birth to adolescence. He elaborated that this change occurs in an orderly sequence, involving physical, cognitive, and emotional development. These three main areas of child development involve developmental changes which take place in a predictable pattern (age related), orderly, but with differences in the rate or timing of the changes from one person to another (Ruffin 2009). Maturation refers to those phases and products of growth which are wholly or chiefly due to innate and endogenous factors (Gesell 1928). The maturational theory is biologically based and assumes that children mature at rates according to their biological clock. Genetics promotes development in a specific sequence with minimal individual differences (Gesell 1928).
Developmental theory of Arnold Gesell can be used for examining development, particularly motor development. Gesell believes that biological maturation is the most important determinant of development; that is although past evolutionary developments and present are viewed to have some influence such as on the intensity or actual use of certain skills, development is thought to process through an orderly sequence that is primarily determined by heredity and may be altered only somewhat (Ruffin, 2009). Gesell admitted that environment might exert a more powerful influence during adolescence than during infancy.
Gesell came up with five basic principles of development that are largely influenced by Darwin's theory of evolution. These principles are thought to be characteristic of every child's growth pattern in motor, adaptive, language and personal-social behavior, but they were applied to motor of physical development (Wolraich 2003). These principles or characteristics describe typical development as a predictable and orderly process; that is, we can predict how most children will develop and that they will develop at the same rate and at about the same time as other children (Ruffin, 2009). These principles include: developmental direction, reciprocal interweaving, functional asymmetry, individual maturation and self regulatory fluctuation.
PRINCIPLE OF DEVELOPMENTAL DIRECTION
It states that development proceeds in a systematic direction as a programmed function of genetic mechanisms (Wolraich 2003). Development of the embryo and other aspects of physical and motor development follow two patterns; firstly, cephalocaudal, development proceeds from head to down example can be when arm buds appear before leg buds in the embryo, and also the infant shows voluntary motor control of the head and shoulders before control of the lower limps (Wolraich 2003). This is clear when we look at the growth in size of different body parts from birth to maturity: the head only doubles the size between birth and maturity, the lower parts of the body have to do more growing to reach adults size; torso triples the length, the arms and hands increase in length by about four times, and the legs and feet increase by about five times (Children Development, 2002).
The second pattern is proximodistal (near-far), development proceeds from the middle (near) of the organism to the periphery (far) examples are: in embryonic development, spinal cord develops before the arms buds; in the early development, the infant gains control over the entire arm before finer control of the individual finger (Wolraich 2003). This is supported by (Children Development, 2002). when observing an infant reaching for an object lying near her; at three months he/she uses the whole arm to reach the object, as he/she grows older he/she is able to reach for the object by using only the , elbow. Similarly, to pick up an object the child initially uses her whole hand. She can, pick it up using the fingers only at a later stage. Similarly, the child is able to control the movements of her legs before she can use the toes. These examples shows that at the first the child achieves the coordination of large muscles such as shoulders of the body since they are closer to the axis, before she can coordinate the small muscles (such as finger and toes) which are towards the periphery (Children Development, 2002).
PRINCIPLE OF RECIPROCAL INTERWEAVING
In this principle, inhibition, exhibition and excitation of different muscle operate in complementary fashion, resulting in different movement, this is illustrated in the development of walking and handedness; walking is viewed as a series of alterations between flexor (bending) and extensor (extending) movements of arms and legs in coordination (Wolraich 2003). Flexor and extensor movements oppose each other but they result in integration and progression to a mature movement (Wolraich 2003). This can be observed in Infants using two arms when reaching for small objects toward the end of their 1st year (Corbetta and Bojczyk 2002). This tendency is associated with the development of a new motor skill, specifically, the emergence of upright locomotion, sitting, crawling, or walking. In previous studies, the acquisition of new motor skills have been shown to dramatically reorganize infants' existing motor, perceptual, and cognitive abilities (Corbetta and Bojczyk 2002).
PRINCIPLE OF FUNCTIONAL ASYMMETRY
It describes a development as a process of sequential patterning; that is certain prerequisite physiological structures must be present for other development or learning to occur example, it is important for an infant to have certain degree or of trunk stability for walking to occur (Wolraich 2003). Providing practice in moving the legs in a stepping fashion will facilitate walking if the necessary physiologic development is absent. Gesell illustrates this complex principle with a basic response called the tone neck reflexes. This reflex is present when the child assumes the position like that of the fencer, with the head turned one side, one arm extended to that side and the leg one that side straight, and the other leg bent at the knee and the other arm folded across the chest. This asymmented behavior is a precursor to later development of systemically reaching, in which child's arm come together to grasp suspended object (Salkind 2004).
PRINCIPLE OF SELF REGULATORY FLUCTUATION
Similar to the principle of interweaving the principle of self regulatory fluctuation views development as alternating periods of stability and instability (Wolraich 2003). The fluctuation is not undesirable or irregular rather they are definite effort on the part of the organism's system to maintain its integrity while assuring that growth continues (Salkind 2004). There is a distant sequence of stages that occurs and allows the organism or function while accommodating growth (Wolraich 2003).
PRINCIPLE OF SELF INDIVIDUALIZING MATURATION
It describes development as a process of sequential patterning. That is, certain prerequisite physiological structures must be present for other development or learning to occur, example, it is important for an infant to have a certain degree of trunk stability for walking to occur (Wolraich 2003). Providing practice in moving the legs in a stepping fashion will not facilitate walking if the necessary development is absent. Changes in the brain and nervous system account largely for maturation. These changes in the brain and nervous system help children to improve in thinking (cognitive) and motor (physical) skills. Also, children must mature to a certain point before they can progress to new skills (Readiness). For example, a four-month-old cannot use language because the infant's brain has not matured enough to allow the child to talk. By two years old, the brain has developed further and with help from others, the child will have the capacity to say and understand words. Also, a child cannot write or draw until he has developed the motor control to hold a pencil or crayon (children development). Maturational patterns are innate, that is, genetically programmed. The child's environment and the learning that occurs as a result of the child's experiences largely determine whether the child will reach optimal development. A stimulating environment and varied experiences allow a child to develop to his or her potential (Ruffin 2009).
Ruffin (2009) acknowledges that each child is different and the rates at which individual children grow is different. Although the patterns and sequences for growth and development are usually the same for all children, the rates at which individual children reach developmental stages will be different. Understanding this fact of individual differences in rates of development should cause us to be careful about using and relying on age and stage characteristics to describe or label children (Ruffin 2009). Some children will walk at ten months while others walk a few months older at eighteen months of age. Some children are more active while others are more passive. This does not mean that the passive child will be less intelligent as an adult (Ruffin 2009). There is no validity to comparing one child's progress with or against another child. Rates of development also are not uniform within an individual child. For example, a child's intellectual development may progress faster than his emotional or social development (Ruffin 2009).
There are differences in the rate of development of boys and girls. In prenatal period the skeletal system of girls grows faster as compared to boys therefore, at birth girls are/ahead of boys in their skeletal development. The period of puberty is about two years earlier for girls than for boys (children development 2002).
In conclusion, the developmental change occurs due to maturation that is the physiological "ripening" of the system, which is determined by a fixed timetable. Development for all children follow a particular sequence, example, and the first learn to roll on their back, then sit, creep, walk, run and climb. However the ages at which these children acquire these abilities are different. Also physiological development follows certain direction; that is from up to bottom and from near to far.