| OCR Text |
Show 22 VARIATION [CHAP. I. when we find that there are hardly any domestic races, either amongst nimals or plants, which have not been • ranked by some con1petent judges as mere varieties, and by other competent judges as the descendants of aborigi- . nally distinct species. If any n1arked distinction existed between domestic races and specie~, this source of doubt could not so perpetually recur. It has often been stated that domestic races do not differ from each other in characters of generic value. I think it could be shown that this statement is hardly correct; but naturalists differ most widely in determining what characters are of generic value; all such valuations being at present empirical. Moreover, on the view of the origin of genera which I shall presently give, we have no right to expe((Jt often to meet with generic differences in our domesticated productions. When we attempt to estimate the amount of structural difference between the domestic races of the same species, we are soon involved in doubt, from not knowing whether they have descended from one or several parent-species. This point, if it could be cleared up, would be interesting; if, for instance,. it could be shown that the greyhound, bloodhound, terrier, spaniel, and bull-dog, which we all know propagate their kind so truly, were the offspring of any single species, then such facts would have great weight in making us doubt about the immutability of the many very closely allied and natural species-for instance, of the many foxes-inhabiting different quarters of the world. I do not believe, as we shall presently see, that all our dogs have descended from any one wild species ; but, in the case of some other domestic races, there is presumptive, or even strong, evidence in favour of this view. It has often been assumed that man has chosen for domestication animals and plants having an extraordinary inherent tendency to vary, and likewise to withstand diverse climates. I do not dispute that these capacities have added largely to the value of most of our domesticated productions; but how could a savage possibly know, when he first tamed an animal, whether it would vary in succeeding generations, and whether it would r CHAP. I. UNDER DOMESTICATION. 23 endure ot~er climates? Has the little variability of the ass or gumea-fowl, or the small power of endurance of warmth by th~ rein-dee~, or. of cold by the common camel, prevented thmr domestiCation? I cannot doubt that if o.ther animals a~d plants, equal in number to our domestiCated productions, and belonging to equally diverse classes and countries, were ,taken from a state of nature, and .could be n1ade to breed for an equal number of O'enerations under domestication, they would vary on5 an averag~ as largely a.s the parent species of our existing domesticated productions have varied. . In the case of most of our anciently domesticated anImals and plants, I do not think it is possible to cmne to any defip.ite conclusion2 whether they have descended from one or several ~peCI~s. The argument mainly relied on b~ those w~o bel:eve 1n the multiple origin of our domestiCated animals Is, that we find in the most ancient records,. mo:e ~specially on the monuments of Egypt, much diversity In the breeds; and that some of the breeds cl~se~y resemble2 pe:·haps are identical with, those still existing. Even if this latter fact were found more strictly and generally true than seems to me to be the case, what does It show, but that some of our breeds oriO'inated there four or five thousand years ago? But Mr.5 Horner's re: searches have rendered it in some degree probable that n1~n su~ciently civilized to have manufactured pottery existed 1n the valley of the Nile thirteen or fourteen thousand years ago; and ":ho will pretend to say how long before these anCient penods, savages like those of Tierra del Fuego or Australia, who possess 'a semi-domestic dog may not have existed in Egypt? ' . The whole subje?t must, I think, :emain vague; nevmtheless, I may, Without here entenng on any details, st~te t~at, ~rom geographical and other considerations, I think It highly probable that our domestic dogs have gescended from several wild .s~ecies. In regard to sheep and goats I can form no opinion. I should think fron1 fa~ts communic~ted. to me by Mr. Blyth, on the habits, vowe, and constitution, &c., of the. humped Indian cattle, that these had descended from a different aboriginal stock |
