DNA, or deoxyribonucleic acid, is the hereditary material in virtually all organisms. Therefore changes in DNA sequences, in other words, DNA mutations are critical in the recipe for evolution that generate variation and differences between individuals. Without mutation, everything would stay constant, generation after generation.
Virtually all cells in an individual’s body have the same DNA, which is mainly located in the cell nucleus.
The information in DNA is stored as a code made up of four chemical bases:
The order, or sequence, of these bases, determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
Mutations can happen as our DNA copies itself when our cells divide and our bodies develop. An A, for instance, can be replaced by a G or a C by a T. This can cause mutated body cells, which are killed off in a healthy individual.
When Mutations Make a Difference
When mutated body cells cannot be killed off by the body, and those mutated body cells reproduce uncontrollably in an individual, the individual gets cancer.
On the other hand, when mutations occur in the cells organisms pass down to their offspring, they can cause big changes, like turning a light-colored mouse dark.
Mutation seems to mean that something bad has happened. While it is true that most mutations are unfavorable for the offspring, there are also mutations that are neutral or even favorable.
If the mutation has a positive effect on the fitness of the offspring, it is called an adaptation. Thus, all mutations that affect the fitness of future generations are agents of evolution.
Source of Life
The first assumption of evolution by natural selection is that there is variation in the inheritable characteristics of individuals. Without such variation, nature would not have anything to select; under the same conditions, all individuals of a population would either thrive or die.
Mutations are essential to evolution; they are the raw material of genetic variation. Without mutation, evolution could not occur, and life as we know it could never emerge.