Seite - 45 - in The Origin of Species

SELECTION BY MAN 45 he does of the intermediate links in the long lines of descent, yet admit that many of our domestic races are descended from the same parents—may they not learn a lesson of cau- tion, when they deride the idea of species in a state of nature being lineal descendants of other species? PRINCIPLES OF SELECTION ANCIENTLY FOLLOWED, AND THEIR EFFECTS Let usnow briefly consider the steps bywhich domestic races have been produced, either from one or from several allied species. Some effect may be attributed to the direct and defi- nite 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. One of the most remarkable features in our domes- ticated 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 sud- denly, 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 sud- denly arisen in a seedling. 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. We cannot suppose that all the