It's easy to think that the traits we love in our pets -- floppy ears on dogs, silky fur on cats, or the varied colors of parakeets -- occur naturally, but the real story is a bit different. These traits resulted from selective breeding, or encouraging certain traits to emerge and become the norm over many generations.
Thousands of years ago, when man initially domesticated the wolf (the first dogs to be selectively bred), the occasional genetic mutation occurred, lending the wolf a different shape to the ear or color to the fur. Another wolf might have a decidedly different disposition or variation in size. In the wild, these wolves might not have survived to pass their genes on, but because man cared for these creatures and kept them alive, the traits recurred as new generations were born.
It wasn't long before man learned to deliberately encourage these traits in dogs, cats, ferrets, rabbits, guinea pigs, and even goldfish. The rounded face of a pug, the size of a ferret, the shape of a rabbit's ears, the lack of hair on certain guinea pigs, and the roundness of goldfish -- these all came about through long periods of domestication and selective breeding. Selective breeding has also changed the fundamental relationship between animals and humans. Over time and out of practicality we have bred pets that adapted well to domestication -- ones that are easy to handle and enjoy being part of our everyday lives.