Sophie's World

by Jostein Gaarder

‘All life and all reproduction is basically a matter of cell division. When a cell divides into two, two identical cells are produced with exactly the same hereditary factors. In cell division, then, we say a cell copies itself.’ ‘Yes?’ ‘But occasionally, infinitesimal errors occur in the process, so that the copied cell is not exactly the same as the mother cell. In modern biological terms, this is a mutation. Mutations are either totally irrelevant, or they can lead to marked changes in the behavior of the individual. They can be directly harmful, and such “mutants” will be continually discarded from the large broods. Many diseases are in fact due to mutations. But sometimes a mutation can give an individual just that extra positive characteristic needed to hold its own in the struggle for existence.’