development and growth: early childhood The transformation that occurs in the first five years of life is extraordinary. William Blake speaks of the baby at the time of birth:My mother groan'd: My father wept
Into the dangerous world I leapt:
Helpless, naked, piping loud:
Like a fiend hid in a cloud.
Struggling in my father's hands:
Striving against my swaddling bands,
Bound and weary I thought best
To sulk upon my mother's breast.
Arnold Gessell who worked in the Yale Clinic of Child Development described the 5-year-old as a ‘self-assuming conforming citizen of his small world’. During these five years, the child builds up a store of knowledge about the environment, masters motor skills, and learns to look after itself. Language with which to communicate and think, and socially acceptable patterns of behaviour, are built on the confidence gathered within a secure relationship with parents or other carers. Thus they learn how to relate to and behave appropriately with others. This mental growth or development is dependent on maturation of the nervous system and on experience. Piaget, a psychologist working in Geneva in the first half of the twentieth century, stated that ‘maturation of the central nervous system only opens up the possibility for new responses and functional development but does not result in actualization of any given response unless the appropriate environmental circumstances are available.’

Learning and development

During the first year the brain of the infant increases in weight by about 750 g to reach 1100 g. Much of this increase is membrane phospholipid — cell membrane material — which forms the many new dendritic processes, developing multiple links among the nerve cells which were themselves already established during fetal life. As many as 10 000 or more ‘boutons’ or dendritic connections may form on each neuron. At the same time there is an increase in the brain cells — the glial cells — which are not neurons, but which support the functioning of the neurons by providing nutrients and regulating the chemical environment. Neuroglial cells cover with a myelin sheath the long processes (axons) of the neurons which transmit messages over long distances (e.g. head to toe). The process of myelination of the axons speeds the rate at which messages are transmitted.

There is evidence that the chemical composition of brain phospholipids can be affected by the type of dietary fats fed to the infant in the first year of life and it is thought that these differences in chemical composition might affect learning processes and longer-term functioning of the brain cell membranes. It is the phospholipid membrane and different neurotransmitter receptors installed in the membrane which subserve the processes of learning and memory. These developing interconnections between cells result in patterns of behaviour which determine the general similarities and basic trends of child development. However, the acquisition of knowledge and the refinement of skills depend on the child's opportunity to observe, copy, and experiment. Children actively construct their understanding of the world by interactions with it, thus developing schemes and strategies that can be applied to a wide variety of situations. Intelligence reflects the child's capacity to initiate and assimilate new experiences and to profit by past experience.

Language and communication

There are no innate ideas or memories in the brain of a newborn infant. They must all be acquired. Many of the normal infant cyclical activities, such as breathing, feeding, sleeping are controlled at lower brainstem level. Interactive imitative behaviours between mother and infant, e.g. smiling at 6 weeks, are processed at higher cerebral cortical levels and are learned behaviours. These interactions promote the development of pathways of communication between the retina of the eye of the infant, the occipital region of the brain and the motor cortex which controls the facial muscles to produce a smile, and also begin to build a memory bank which gives the associated ‘pleasant’ feeling which goes with smiling and happiness. Similar patterns of behaviour are mediated and built up for aural signals. Mothers quickly learn to distinguish a cry of hunger from one of discomfort or frustration and respond appropriately.

Babies are born with a preference for looking at the human face and responding to the human voice. Within a few days they are able to distinguish their mother's face, voice, and smell. When babies are awake in their parents' arms, they will spend a lot of time staring at their faces. Trevarthen from the Department of Psychology in Edinburgh University has videotaped such interactions and has shown that babies only a few weeks old will copy a parent's facial expressions. However, the baby is not for long a passive recipient and by 3 months is shaping the interaction by smiling, scowling, turning away, vocalizing, and so forth. This intricate human dialogue (reciprocity), which gives enormous pleasure and delight, is immensely important for the child in learning about social interaction and in forming a trusting bond with one or more adults. This secure bond allows children to broaden their horizons and explore the world with confidence. Failure to develop appropriate learned patterns in early life can cause permanent disruption to the child's later emotional responses.

Re-learning or restructuring of these learned processes is possible but difficult to achieve in later life. The establishment of the interneural connections associated with this learning requires the provision of an adequate supply of nutrients for brain growth as well as the environmental stimuli from the parents. Evolutionary processes in the mammal over the last 100 million years and in modern man over the last 0.5 million have resulted in the development of a milk specifically adapted to the needs of the human infant and its complex brain. Maternal–infant interactions during breast feeding are important determinants of early acquisition of language and behaviour in later childhood.

From 5–6 months, the infant starts to look at objects in the wider environment. Parents follow the infant's gaze, will bring or take them to the object, name it, and let them handle it. This coincides with the time that the child is able to produce an increasing variety of sounds and thus will slowly start to approximate the sounds made to the words heard — allowing the realization that objects have names. Children will often use one word for a wide range of similar objects, only slowly refining its use (e.g. ‘dog’ for all animals). Parents' responses of delight, and their willingness to interpret and elaborate the child's first speech sounds, enhance not only language development but also communication and social skills such as taking turns.

Children clearly do not learn their early language just by copying. The sentences they use in the third year of life are telegraphic; they select the important words and make an attempt at correct grammatical order; they eliminate small words and sometimes word endings; they can create combinations they have never heard, e.g. ‘light bye bye’ (when a candle is blown out). Children can create sentences to convey their experience from whatever vocabulary they have.

Motor development

Children's motor development depends not only on improved control of body and limbs resulting from maturation of the brain but also on the child building up a mental scheme of the environment and of their own body; they learn where their arms and legs are from vision, from touch, and from proprioception, sensing stretch and position in muscles and joints. The child has to learn through experience to judge the depth of a step, the speed and trajectory of a ball, and the weight of an object, and that muscle tone and body posture can be automatically adjusted to perform the task. If we pick up what we think is a full teapot but it is empty, we use too much muscle effort and it will shoot up into the air — but the brain also learns to make very rapid adjustments on the basis of sensory feedback.

Hand function matures from crude swiping movements, through whole-hand palmar grasp, to the accurately controlled reach and pincer grasp of a one-year-old child. This allows the child to use tools such as a spoon or a pencil. During the fourth year the child learns to cut with scissors and to thread beads, develops a mature pencil grasp, and learns to draw. By 3 years the child is capable of drawing circles, lines, and crosses and uses these to draw the sun, and people with increasing numbers of body parts. The ability to draw a square for a car is acquired at age 4–5 years.

Social development

When children learn to crawl and walk, they are physically able to move away from their parents but initially they will be continuously checking and will get very anxious if their parent disappears. A child who is securely emotionally attached to parents will become increasingly confident in exploring and being separated. In this way they develop a sense of self which can lead to stubborn negative behaviour — the ‘terrible twos’ or toddler omnipotence. At this age, children become much more aware of other children and will watch them intently, but will play in parallel, talking to themselves and not expecting an answer. By 3 years the child will begin to play with others and get involved with complex social interchange and is ready for nursery experience. Gessell described the 3-year-old as ready to come out of the home but almost completely ignorant of the wide world.

During the nursery years motor and self help skills improve so that with some prompting children are able to look after themselves in school. Language becomes increasingly complex so that by 5 years they are able to converse with adults and other children with only minor errors of grammar and pronunciation. They move away from being able to think not only of the here and now but also about things which have been or might be. This is associated with a love of imaginative stories, but there may be confusion over what is real and what is not; this can lead to fears and fantasies. Children of this age constantly ask questions and clearly are beginning to consider and solve problems. They require time and patience from adults who are able to put themselves in the child's shoes and explain and explore the world with them. There is a fundamental urge to make sense of the world and young children will behave in ways which produce results with no rewards except success. The child needs to be encouraged to see the options, to solve incongruities, and to risk errors rather than avoiding them. What children work out for themselves will be far more meaningful than anything they are told.

Growth

Meanwhile during all these developments, the body has been steadily growing and its proportions changing (see figures). Growth decelerates in the early years — it is never again as rapid as in the first year of life — but between 3 and 5 it is still as fast as it will be again later in the pre-pubertal ‘growth spurt’. Given good health and an adequate diet, final stature will be genetically determined, but undernutrition or severe illness can slow down growth towards that potential at any stage. On recovery there is an acceleration until the child has caught up with the predicted growth curve, although severe malnutrition or disease can cause permanent growth restriction. Increasing height implies lengthening of the leg bones. This growth occurs at the epiphyses, where the main shaft of a bone joins the parts which are shaped to fit a joint at each end. Solid fusion does not occur here until growth is completed. All the bones of the skeleton, including the spine, are also continually enlarged and remodelled. Many hormones are involved and necessary for normal growth throughout the body, notably growth hormone from the pituitary.

What progress has been made in the first five years?At first, the infant
Mewling and puking in the nurse's arms
And then the whining schoolboy, with his satchel
And shining morning face, creeping like snail
Unwillingly to school.
Shakespeare . As you like it

Ruth Day, and Forrester Cockburn

Bibliography

Donaldson, M. (1978). Children's minds. Fontana, London.
Gessell, A. (1950). The first five years of life. Methuen, London.
Sylvia, K. and and Lunt, I. (1983). Child development — a first course. Blackwell, Oxford.