Imagine passing a concert hall and hearing the sound of a piano concerto. Is the sound coming from the piano, or from the pianist? I trust you will agree that this is not a sensible question. Both the pianist and the piano are essential to produce the sound, which is produced by the interaction between the two.
Neither is it sensible to ask whether nature (genetics) or nurture (environment) is responsible for this or that complex human characteristic, e.g. intelligence, ambition, personality etc. Such characteristics result from the interaction between genetics and environment.
It is true, of course, that certain physical characteristics, such as eye colour, depend almost entirely on genetic heritability, whereas others, e.g. a suntan, are caused almost entirely by the environment. Again, certain diseases, e.g. Duchenne Muscular Dystrophy, are caused by genetic defects and are inherited in a predictable manner.
But most of what we are as complex human beings, intellectually, emotionally and artistically etc, results from intimate interaction between our genes and our environment.
Whether we are determined by nature or nurture is a long-standing debate. At different times and in different places conventional wisdom adjudicated in favour of one or the other. Traditionally, biologists have tended to opt for nature and sociologists for nurture. Whenever one or other extreme held strong sway, much trouble and anguish resulted.
In the latter part of the 19th and the early decades of the 20th centuries eugenics was widely supported in scientific and intellectual circles in Europe and North America. This movement held that human nature is genetically determined, and proposed to improve the quality of human stock by selective breeding. Sterilisation of the mentally handicapped and of criminals became quite acceptable in certain places.
This idea was taken to a whole new plane in Nazi Germany. The collective ideal of race was elevated above the individual, and every effort was to be made to maintain and to improve the health of the race. This was to be done principally by genetic manipulation. People were classed as "superior" and "inferior" types. The former had to be fostered and protected from contamination by the latter type. This policy led to the Holocaust.
ON the other hand, the great communist experiment was based on the idea of the malleability of humanity under environmental influences. The collective idea of society (rather than race) was elevated above the individual, and intensive programmes of indoctrination and social surgery were implemented, sometimes involving massive cruelty.
The whole system eventually collapsed, but not before causing great misery and death. Although idealistically motivated, communist ideas in practice were unable to synchronise with some basic aspects of human nature.
The great excesses of communism never excited nearly the same interest in the West as did the Nazi atrocities. But it would have taken an entirely separate article to discuss why the opinion formers were so leaden-footed in this regard.
The communist belief in the plasticity of human nature under environmental influence spilled over into Soviet biological science. The Soviet geneticist Trofim D. Lysenko claimed to have proof of a huge degree of hitherto unexpected plasticity of plant behaviour in different environments.
He denied the chromosome theory of heredity and claimed that individual members of the same species do not compete with each other as most biologists believe, but rather co-operate.
This all harmonised nicely with communist ideology, and Lysenko became the leader of Soviet genetics. Geneticists who disagreed with him were silenced and for about 30 years Soviet genetics and biology went into a decline because Lysenko's ideas were wrong.
Over the course of the last century the pendulum swung back and forth from nature to nurture in the great debate. It is now swinging again towards nature in the face of relentless advances in molecular genetics.
We hear more and more speculation about imminent discoveries of a gene for complex characteristics such as homosexuality, depression, schizophrenia, criminality and so on. Not long ago such talk would be drowned in howls of opposition from supporters of nurture over nature, but such howls have become very soft of late.
Molecular genetics is a very powerful technique, and I don't wish to minimise its importance or its potential. Genetic engineering and allied techniques offer great prospects for curing disease, increasing agricultural production in a hungry world etc. But let us always remember that genes alone can do nothing.
They are dependent for their action on the rest of the cell in which they live. They receive instructions and vital information from the environment in addition to affecting the environment themselves. The living organism is the end product of this interaction and the future of biology should be the study of this interaction.
A fascinating demonstration that genes aren't everything is described by Ian Wilmut in the new book The Second Creation by Ian Wilmut, Keith Campbell and Colin Tudge (Headline, 2000). Four genetically identical sheep, named Cedric, Cyril, Cecil and Tuppence were produced at the Roslin Institute where Wilmut works.
One might expect the four would be pretty much identical in all respects. However, they are each readily identifiable on the basis of size and temperament. Since they are genetically identical the differences between them must be due to the manner in which their individual genetic makeups interacted with the environment.
William Reville is a senior lecturer in biochemistry and director of microscopy at UCC