Mutations

Olivia Judson, an evolutionary biologist and author of Dr. Tatiana’s Sex Advice to All Creation, writes The Wild Side science blog at the NY Times. Her most recent post is the first in a series on genetic mutations. She admits to being obsessed by mutations:

It’s wondrous to think that mutations, accumulated over billions of years through the action of natural selection and the other forces of evolution, have produced such diverse life forms as vampire squid, coconut palms, death cap mushrooms, giant Gippsland earthworms, Etruscan pygmy shrews, E. coli — and us.

So what exactly are these mutations?

They are accidental changes to an organism’s DNA; they typically happen when the cellular machinery makes a mistake as it copies DNA from one cell to the next.
...
The canonical mutation — the one everyone learns about in biology class — alters the part of a gene that contains the instruction to make a protein.

But, only about 2% of the genetic material contains instructions to make proteins. So what happens to mutations in the remaining 98%? On possibility is that this 98% is involved

... in regulating where and when the genes they are made from will get switched on. ... So mutations to the switches can alter how the protein is deployed.

Much research still needs to be on these "switches". The article gives lots of examples of the effects of different types of mutations and makes fascinating reading.