orld in
the famous "Origin of Species."

Darwin was particularly impressed by the way mankind has dealt with the
various species of domesticated animals, and he was the first naturalist
to point out the correspondence between the breeder's method of
"artificial selection," and the world-wide process of natural selection.
As every one knows, the breeder of race horses finds that colts vary much
in their speed; discarding the slower animals, he uses only the swifter
for breeding purposes, and so he perfects one type of horse. With other
objects in view, the heavy draught horse, the spirited hackney, and the
agile polo pony have been severally bred by exactly the same method. Among
cattle many kinds occur, again the products of an artificial or human
selection; hornless breeds have been originated, as well as others with
wide-spreading or sharply curved horns; the Holstein has been bred for an
abundant supply of milk as an object, while Jerseys and Alderneys excel in
the rich quality of their milk. Various kinds of domesticated sheep and
rabbits and cats also owe their existence to the employment of the
selfsame method, unconsciously copied by man from nature; for men have
found variations arising naturally among their domesticated animals, and
they have simply substituted their practical purposes or their fancy for
nature's criterion of adaptive fitness, preserving those that they wish to
perfect and eliminating those unfitted to their requirements or ideas.

In the case of many of these and other examples, wild forms still occur
which seem to be like the ancestral stock from which the domesticated
forms have been produced. All the varied forms of dogs--from mastiff to
toy-terrier, and from greyhound to dachshund and bulldog--find their
prototypes in wild carnivora like the wolf and jackal. In Asia and
Malaysia the jungle fowl still lives, while its domesticated descendants
have altered under human direction to become the diverse strains of the
barnyard, and even the peculiar Japanese product with tail feathers
sometimes as long as twenty feet. That far-reaching changes can be brought
about in a relatively short time is proved by the history of the game
cock, which has nearly doubled in height since 1850, while at the same
time its slender legs, long spurs, and other qualities have been perfected
for the cruel sport for which it has been bred. Again, the wild rock
pigeon seems to be the ancestral form from which the fanta