In rude and barbarous periods of English history choice animals were often imported, and laws were passed to prevent their exportation: the destruction of horses under a certain size was ordered, and this may be compared to the "roguing" of plants by nurserymen.

The principle of selection I find distinctly given in an ancient Chinese encyclopaedia.

Explicit rules are laid down by some of the Roman classical writers.

From passages in Genesis, it is clear that the colour of domestic animals was at that early period attended to.

Savages now sometimes cross their dogs with wild canine animals, to improve the breed, and they formerly did so, as is attested by passages in Pliny.