One of the biggest mistakes made by evolution denialists is to claim that all mutations are deleterious, and as a consequence evolution could never occur. This betrays a deep ignorance of current research into evolutionary biology, which shows that mutations don't cause the disasters special creationists think they do. In Arrival of the Fittest: Solving Evolution's Greatest Puzzle, respected evolutionary biologist Andreas Wagner points out that as a consequence of the fact that genotypes form a huge interconnected network, they are actually quite robust. As evolutionary biologist Mark Pagel notes in his review of Wagner's book, these mutated networks are very much able to function:
...and it is this insensitivity to random change that makes biology robust to mutations and mishaps, and evolvable. Even better, Wagner finds that he does not have to travel very far along these mutational pathways before he encounters new neighbourhoods, where the networks produce different products. For instance, a network that can consume glucose might lie near one that can consume other fuels, such as acetate. Wagner thinks that these features of gene networks are repeated in proteins, metabolisms and the basic chemistry of cells. In vivo studies back him up.
This offers an answer to one of the most fundamental questions of evolution: how has natural selection had time to search the almost limitless library of life? The answer, posits Wagner, is that it does not usually have to search very far: squid and albatrosses are closer neighbours than we might have expected. Arrival of the Fittest will give you a new appreciation of the sheer improbability, but also the plausibility, of the diversity of life.
Full review is here.
