In certain circumstances the switched off version of a gene is useful. When it is useful because it causes a beneficial modification, it is spread in the population.
For example, the mutations that have changed a brown bear into a white polar bear in the Arctic could be described as advantageous mutations, but the actual basis to the change is loss of genes encoding the production of pigment in the fur.
Advantageous mutations and disadvantageous mutations are, in fact, exactly the same thing – they are both errors that cause dysfunction in the genome. But the effect on the physical body of the switching off of some genes is beneficial, and in these cases they are qualified as advantageous mutations.
The key to this new understanding of evolution is the definition of advantageous mutation.
Mutations are errors in the replication of DNA. Disadvantageous or deleterious mutation is very easy to understand – they cause genetic diseases. But what is advantageous mutation?
We know that when an advantageous mutation occurs, natural selection spreads the mutation throughout the population. This is the basis to Darwin’s theory of evolution.
Is advantageous mutation the opposite to disadvantageous mutation? If disadvantageous mutation is the incorporation of the wrong nucleotide base, is advantageous mutation a change to the right nucleotide base?
The answer to this is no.
Whereas a gene can be rendered dysfunctional by a single mutation, a new gene with new function would require hundreds of mutations to occur simultaneously and be fixed for the new gene to be a viable gene. The new gene would also have to be fixed in the population.
I realized that the term ‘advantageous’ is a qualification, not a thing. It is a way of describing what turned out, in hind sight, to be beneficial.