Excerpts

CHAPTER 1 VARIATION UNDER DOMESTICATION IN WHICH I ARGUE THAT MAN'S PRODUCTIONS OF ANIMAL AND PLANT STOCKS ARE THE RESULT OF MANY GENERATIONS OF DOMESTIC BREEDING FROM ABORIGINAL ANCESTORS. TO ACHIEVE HIS ENDS OF DOMESTICATION, MAN HAS SEIZED ON THE SEEMINGLY LIMITLESS SPRING OF VARIATIONS FOUND IN ALMOST ALL ORGANISMS. When we compare the individuals of the same variety or sub variety of our older cultivated plants and animals, one of the first points which strikes us is, that they generally differ more from each other, than do the individuals of any one species or variety in a state of nature. Seedlings from the same fruit, and the young of the same litter, sometimes differ considerably from each other, though both the young and the parents, as Muller has remarked, have apparently been exposed to exactly the same conditions of life. This shows how unimportant the direct effects of the conditions of life are in comparison with the laws of reproduction, and of growth, and of inheritance; for had the action of the conditions been direct, if any of the young had varied, all would probably have varied in the same manner. How is it that all your adult pigs are black? The pigs eat the paint-root, which colours their bones pink, and which causes the hoofs of all but the black varieties to drop off. We select the black members of a litter for raising, as they alone have a good chance of living. From facts collected by Heusinger, it appears that white sheep and pigs are injured by certain plants, whilst dark-coloured individuals escape.... And we know certain traits are linked to others. Hairless dogs have imperfect teeth; pigeons with feathered feet have skin between their outer toes. This correlation of one trait's selection to another seemingly unrelated trait's appearance must mean that characteristics are inherited. So the variety in characteristics cannot be caused primarily by either environmental conditions or the relative use or disuse of parts. But how do the traits of parents carry on to their offspring? But when amongst individuals, apparently exposed to the same conditions, any very rare deviation, due to some extraordinary combination of circumstances, appears in the parent--say, once amongst several million individuals--and it reappears in the child, the mere doctrine of chances almost compels us to attribute its reappearance to inheritance.... INHERITABLE TRAITS AMONG DOMESTIC RACES You'll notice the size of the feet on this one, sir. She's the finest in this bunch, a strong animal. If strange and rare deviations of structure are truly inherited, less strange and commoner deviations may be freely admitted to be inheritable.... ...Perhaps the correct way of viewing the whole subject, would be, to look at the inheritance of every character whatever as the rule, and noninheritance as the anomaly. 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. If it could be shown that the grey-hound, 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. Believing that it is always best to study some special group, I have, after deliberation, taken up domestic pigeons.... The diversity of the breeds is something astonishing. Altogether at least a score of pigeons might be chosen, which if shown to an ornithologist, and he were told that they were wild birds, would certainly, I think, be ranked by him as well-defined species.... Great as the differences are between the breeds of pigeons, I am fully convinced that the common opinion of naturalists is correct, namely, that all have descended from the rock pigeon (Columba livia).... Let us now briefly consider the steps by which domestic races have been produced, either from one or from several allied species. 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.... SELECTION THROUGH BREEDING Just as 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 breeds were suddenly produced as perfect and as useful as we now see them; indeed, in several cases, we know that this has not been their history.... Breeders habitually speak of an animal's organisation as something quite plastic, which they can model almost as they please. I'm looking for a good healthy male to stud. Come look at this one. His father was my old stud, and his brother is now employed at that same work for me. By God. He'll raise lambs that'll keep us thick with customers, George. I'll take him. The key is man's power of accumulative selection: nature gives successive variations; man adds them up in certain directions useful to him.... 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 which are first given to him in some slight degree by nature. Eminent breeders try by methodical selection, with a distinct object in view, to make a new strain or subbreed, superior to anything existing in the country. You are raising some of the finest Border Leicesters around. But, for our purpose, a kind of Selection, which may be called Unconscious, and which results from every one trying to possess and breed from the best individual animals, is more important. UNCONSCIOUS SELECTION In the market for a dog, sir? I'll take that one, boy. Thus, a man who intends keeping pointers naturally tries to get as good dogs as he can, and afterwards breeds from his own best dogs, but he has no wish or expectation of permanently altering the breed. Nevertheless I cannot doubt that this process, continued during centuries, would improve and modify any breed. What a lovely dancer you are. Ahhh, one of the finest and sweetest pears in all of England. I've come from London to buy these for my restaurant. But the gardeners of the classical period, who cultivated the best pear they could procure, never thought what splendid fruit we should eat; though we owe our excellent fruit, in some small degree, to their having naturally chosen and preserved the best varieties they could anywhere find. One of the finest and sweetest pears in all of the Empire. I've come from Rome to buy these for my liege. Over all these causes of Change I am convinced that the accumulative action of Selection, whether applied methodically and more quickly, or unconsciously and more slowly, but more efficiently, is by far the predominant Power. Excerpted from Charles Darwin's on the Origin of Species: A Graphic Adaptation by Michael Keller All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.