The first replicators on Earth evolved abilities beyond those possible to RNA molecules replicating in test tubes. By the time they reached the bacterial stage, they had developed the “modern” system of using DNA, RNA, and ribosomes to construct protein. Mutations then changed not only the replicating DNA itself, but protein machines and the living structures they build and shape. Teams of genes shaped ever more elaborate cells, then guided the cellular cooperation that formed complex organisms. Variation and selection favored teams of genes that shaped beasts with protective skins and hungry mouths, animated by nerve and muscle, guided by eye and brain.
As Richard Dawkins puts it,*(42) genes built ever more elaborate survival machines to aid their own replication. When dog genes replicate, they often shuffle with those of other dogs that have been selected by people, who then select which puppies to keep and breed. Over the millennia, people have molded wolf-like beasts into greyhounds, toy poodles, dachshunds, and Saint Bernards. By selecting which genes survive, people have reshaped dogs in both body and temperament. Human desires have defined success for dog genes; other pressures have defined success for wolf genes.
Mutation and selection of genes has, through long ages, filled the world with grass and trees, with insects, fish, and people. More recently, other things have appeared and multiplied- tools, houses, aircraft, and computers. And like the lifeless RNA molecules, this hardware has evolved.
Page 25 , Engines of Creation – K.Eric Drexler