Describe The Process By Which Genes And Environment Operate Together To Influence Development.

Describe the process by which genes and environment operate together to influence development. Discuss the significance of these processes for our understanding of child development.

This essay will give a detailed account of the process by which genes and the environment operate together to influence development. Looking at Physical development and Language development and the perspectives of Natavism, Behaviourism. Constructivism and Social Constructivism it will explain the role of these perspectives in understanding child development. It is argued that the genetic blueprint can interact with the environment to encourage development. The process of genes and environment working together is often referred to as epigenetics and shows how environmental factors which can affect a parent can change the types of genes passed onto their children.

Looking at Physical Development it can be seen if the process of genes and environment operating together influence development. As the environment is constantly changing humankind needs to have changeable characteristics, some of which are physical, this is known as "Developmental Plasticity". Piaget studied water snails and found that shape of the snails shell varied depending on its habitat. Pond snails had longer shells than lake snails who had shorter shells to suit the water turbulence. Suggesting that cells have the properties to change and become "self-organising", cells can change the way they are developing in response to environmental stimuli. It is argued that genes can be switched "on" or "off" in response to this environmental stimuli and can alter the characteristics they produce.

"Piaget called this process "Epigenetic Development", Epigenetic information is constantly being acquired throughout development, giving the environment an active role in influencing development. The environment is shaping information in our genes and changing our physical development. Humankind standing on two legs and walking was a response to environmental changes. This has had a significant effect on our genetic makeup from the shape of our pelvis to the size of our skull.

Epigenetic systems can only change things during the period of maturation and once a characteristic is adapted it can not change back. Richardson, 1994, argues in relation to child development this would mean that once a child has learnt a particular behaviour this can not be changed or removed. Richardson argues because of our changing environment humankind need genetic characteristics which are changeable and can adapt through out a lifetime. We are constantly learning new things, and adapt our behaviour to what we have learnt.

Learning is one of the processes which require our behaviour patterns to adapt through our lifetime. Life long developmental plasticity is a form of epigenetic development more suitable to child development as aspects such as language, behaviour adapt to suit our environment. Other theories exist which explain the importance of genes and the environment in child development.

Belief that all human development can be explained by genetic make up is called genetic determination. This view sees behaviour as having end points and of humankind having little control over their development. The Genetic theories are rigid or Canalised systems.

Plotkin and Odling-Smee, 1979, argue genetic determination needs environment to remain constant for many years in order for advantages of adaptation and natural selection to emerge. This is unlikely to happen in our ever changing environment, humankind can change its own environment. This can be seen by the creation of nuclear weapons, and the cutting down of rainforests.

By studying twins and heritability it is possible to see to what extent genes influence our development. Heritability is what geneticists use to measure genetic differences, similarities are rated between 0 and 1. The higher the score the higher the heritability, indicating less genetic difference. Twins are usually reared in the same environment, monozygotic (identical) twins share the same genetic make up and dizygotic twins (non-identical) share only half of their genes. So if development is determined by an innate blueprint then monozygotic twins should have higher heritability characteristics. E.g. Temperament, intelligence etc. than dizygotic twins. Buss and Plomin, 1984, studied twins at 4 years of age and found identical twins were similar in emotionality, Activity and Sociability heritability. Non-identical twins showed no similarities. Buss and Plomin argues this was evidence of genetic influence on development. Berscheid and Walster, 1978, found problems with the relevance of twin studies it was suggested that because monozygotic twins looked alike they were more likely to be treated alike by parents and other members of the family. This could mean that their environmental influences were more similar than dizygotic twins.

To counteract this problem Buss and Loehlin, 1989, looked at twins who had been raised apart and found that monozygotic twins still had a high heritability for IQ. This suggests IQ could be genetic. Problems were also found with the relevance of this study it was suggested that it was difficult to find twins that had been reared apart. If the twins parted it was suggested by Komin, 1974, that most twins were then raised by different members of the same family in similar environments. Buss and Loehlin ignored the fact that the twins had shared the same womb environment before birth

Gesell a Natavist argues that development is the result of genetic influence. In "Gesell's principles of Development" he argued, the developmental process followed by children, in particular motor development sequence, is provided by an innate program found in the genes. Gesell called this maturation and argued that the genetic blueprint could not be altered and there was little point in encouraging a child to try to learn things before this innate program was ready to learn. This was known as the "Genetic Program" for development . With this view there would be little point in pre-school education as children would not benefit form it. They would not be able to learn skills quicker than their genetic programming allowed.

Chomosky, 1980, argues genetic programs are the only way to understand physical and cognitive development. Natavism argues humans are born with innate programming and with several motor reflexes such as the rooting reflex. They argue this is evidence of genetic programming in the womb since at birth they have not been subject to any external environmental influences. Critics of Natavism would argue that it's