It is instructive to look at the various kinds of cabbages, such as
cauliflower and Brussels sprouts, kale and curly greens, and remember
that they are all scions of the not very promising wild cabbage found on
our shores. And are not all the aristocrat apple-trees of our orchards
descended from the plebeian crab-apple of the roadside? We know far too
little about the precise origin of our cultivated plants, but there is
no doubt that after man got a hold of them he took advantage of their
variability to establish race after race, say, of rose and
chrysanthemum, of potato and cereal. The evolution of cultivated plants
is continuing before our eyes, and the creations of Mr. Luther Burbank,
such as the stoneless plum and the primus berry, the spineless cactus
and the Shasta daisy, are merely striking instances of what is always
going on.
There is reason to believe that the domestic dog has risen three times,
from three distinct ancestors--a wolf, a jackal, and a coyote. So a
multiple pedigree must be allowed for in the case of the dog, and the
same is true in regard to some other domesticated animals. But the big
fact is the great variety of breeds that man has been able to fix, after
he once got started with a domesticated type. There are over 200
well-marked breeds of domestic pigeons, and there is very strong
evidence that all are descended from the wild rock-dove, just as the
numerous kinds of poultry are descended from the jungle-fowl of some
parts of India and the Malay Islands. Even more familiar is the way in
which man has, so to speak, unpacked the complex fur of the wild rabbit,
and established all the numerous colour-varieties which we see among
domestic rabbits. And apart from colour-varieties there are long-haired
Angoras and quaint lop-eared forms, and many more besides. All this
points to evolution going on.