01 - Variations Under Domestication

01-09 - Principles of Selection anciently followed, and their Effects

Let us now briefly consider the steps by which domestic races have been produced, either from one or from several allied species.

Some effect may be attributed to the direct and definite action of the external conditions of life, and some to habit; but he would be a bold man who would account by such agencies for the differences between a dray- and race-horse, a greyhound and bloodhound, a carrier and tumbler pigeon.

Dray Horse

Race Horse

greyhound

bloodhound

Tumbler Pigeon

One of the most remarkable features in our domesticated races is that we see in them adaptation, not indeed to the animal's or plant's own good, but to man's use or fancy.

Some variations useful to him have probably arisen suddenly, or by one step; many botanists, for instance, believe that the fuller's teasel, with its hooks, which cannot be rivalled by any mechanical contrivance, is only a variety of the wild Dipsacus; and this amount of change may have suddenly arisen in a seedling.

Fuller's Teasel

So it has probably been with the turnspit dog; and this is known to have been the case with the ancon sheep.

But when we compare the dray-horse and race-horse, the dromedary and camel, the various breeds of sheep fitted either for cultivated land or mountain pasture, with the wool of one breed good for one purpose, and that of another breed for another purpose; when we compare the many breeds of dogs, each good for man in different ways; when we compare the game-cock, so pertinacious in battle, with other breeds so little quarrelsome, with "everlasting layers" which never desire to sit, and with the bantam so small and elegant; when we compare the host of agricultural, culinary, orchard, and flower-garden races of plants, most useful to man at different seasons and for different purposes, or so beautiful in his eyes, we must, I think, look further than to mere variability.

Ancon Sheep

Dray Horse

Race Horse

camel

sheep

We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them; indeed, in many cases, we know that this has not been their history. The key is man's power of accumulative selection: nature gives successive variations; man adds them up in certain directions useful to him. In this sense he may be said to have made for himself useful breeds.

01 - Variations Under Domestication

01-09 - Principles of Selection anciently followed, and their Effects

What English breeders have actually effected is proved by the enormous prices given for animals with a good pedigree; and these have been exported to almost every quarter of the world.

The improvement is by no generally due to crossing different breeds; all the best breeders are strongly opposed to this practice, except sometimes amongst closely allied sub-breeds.

And when a cross has been made, the closest selection is far more indispensable even than in ordinary cases.

If selection consisted merely in separating some very distinct variety, and breeding from it, the principle would be so obvious as hardly to be worth notice; but its importance consists in the great effect produced by the accumulation in one direction, during successive generations, of differences absolutely inappreciable by an uneducated eye- differences which I for one have vainly attempted to appreciate.

Not one man in a thousand has accuracy of eye and judgment sufficient to become an eminent breeder. If, gifted with these qualities, he studies his subject for years, and devotes his lifetime to it with indomitable perseverance, he will succeed, and may make great improvements; if he wants any of these qualities, he will assuredly fail.

Few would readily believe in the natural capacity and years of practice requisite to become even a skilful pigeon fancier.

pigeon

01 - Variations Under Domestication

01-09 - Principles of Selection anciently followed, and their Effects

In regard to plants, there is another means of observing the accumulated effects of selection- namely, by comparing the diversity of flowers in the different varieties of the same species in the flower-garden; the diversity of leaves, pods, or tubers, or whatever part is valued, in the kitchen garden, in comparison with the flowers of the same varieties; and the diversity of fruit of the same species in the orchard, in comparison with the leaves and flowers of the same set of varieties.

leaf

pod

tuber

orchard

See how different the leaves of the cabbage are, and how extremely alike the flowers; how unlike the flowers of the heartsease are, and how alike the leaves; how much the fruit of the different kinds of gooseberries differ in size, colour, shape, and hairiness, and yet the flowers present very slight differences.

cabbage

heartsease

gooseberry

It is not that the varieties which differ largely in some one point do not differ at all in other points; this is hardly ever,- I speak after careful observation, perhaps never, the case. The law of correlated variation, the importance of which should never be overlooked, will ensure some differences; but, as a general rule, it cannot be doubted that the continued selection of slight variations, either in the leaves, the flowers, or the fruit, will produce races differing from each other chiefly in these characters.