For example, a lot of changes in genes do not actually affect the composition of the protein for which that gene is a recipe.

ECONOMIST: Cancer genetics

This is either because they cause no change in the composition of the protein that the gene encodes (some apparently different genetic words actually have the same meaning to the protein-making apparatus), or because the change they make has no effect on the protein's function.

ECONOMIST: Genetics gets more complicated

This surprised Dr Rosenthal and Ms Garrett, who had expected that natural selection would have changed the DNA, and thus the composition of the resulting protein.

ECONOMIST: A hitherto-unknown way to evolve