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Show 38 SELECTION BY MAN. CHAP. I. or modify most of our plants up to their present standard of usefulness to man, we can understand how it is that neither Australia, the Cape of Good Hope, nor any other region inhabited by quite uncivilised man, has afforded us a single plant worth culture. It is not that these countries, so rich in species, do not by a strange chance possess the aboriginal stocks of any useful plants, but that the native plants have not been improved by continued se· lection up to a standard pf perfection comparable with that given to the plants in countries anciently civilised. In regard to the domestic animals kept by uncivilised man, it should not be overlooked that they almost always have to struggle for their own food, at least during certain seasons. And in two countries very differently circumstanced, individuals of the same species, having slightly different constitutions or structure, would often succeed better in the one country than in the other, and thus by a process of " natural selection," as will hereafter be more fully explained, two sub-breeds might be formed. This, perhaps, partly explains what has been remarked by some authors, namely, that the varieties kept by savages have more of the character of species than the varieties kept in civilised countries. On the view here given of the all-important part which selection by man has played, it becomes at once obvious, how it is that our domestic races show adaptation in their structure or in their habits to man's wants or fancies. We can, I think, further understand the frequently abnormal character of our domestic races, and likewise their differences being so great in external characters and relatively so slight in internal parts or organs. Man can hardly select, or only with much difficulty, any deviation of structure excepting such as is externally visible; and indeed he rarely cares for what is internal. He can never act by selection, excepting on variations CHAP. I. SELECTION BY MAN. 39 which are first given to him in some slight degree y nature. No man would ever try to make a fan t il till he saw a pigeon with a tail developed in som ligh egree in an unusual manner, or a pouter till he w a pigeon with a crop of somewhat unusual ize ; and the more abnormal or unusual any character was wh nit fi t appeared, the more likely it would be to catch his att ntion. But to use such an expres ion as trying to mak a fantail, is, I have no doubt, in most case , utterly incorrect. The man who first selected a pigeon ith a slightly larger tail, never dreamed what the de cendants of that pigeon would become through long-continued, partly unconscious and partly methodical selection. P rhaps the parent bird of all fantails had only fourteen tailfeathers somewhat expanded, like the present Java£ ntrul, or like individuals of other and distinct breed , in which as many as seventeen tail-feathers have be n count d. Perhaps the first pouter-pigeon did not inflate it crop ~uch more than the turbit now does the upper part of Its ~sopha~us;'-a habit which is disregard d by all fanciers, as It IS not one of the points of the bre d. Nor let it be thought that some great de vi tio f · structure. would be necessary to catch the fanci r eye : he perceives extremely small difference , and it is in hu~an nature to value any novelty, however light, in one s own possession. Nor must the value which woull formerly be set on any slight differenc sin th individ u I of the same species, be judged of by the valu whi h would ~ow be set on them, after several bre d have o~ce fauly .been established. ~Iany slight d:iffi r nee might~ and Indeed do now, arise amongst pigeon' hi h are reJ~cted as faults or deviations from the st ndard of p~rfect~on of each breed. The common goo e ba not gi~nhrise to any marked varieties; hence the Thoulou e an t e common breed, which differ only in colour, th t |