Part 1 (2/2)
2. Every kind of animal and plant transmits a general likeness, with individual differences, to its offspring.
3. Past time has been practically infinite.
4. Every individual has to endure a very severe struggle for existence, owing to the tendency to geometrical increase of all kinds of animals and plants, while the total animal and vegetable population (man and his agency excepted) remains almost stationary.
5. Thus, every variation of a kind tending to save the life of the individual possessing it, or to enable it more surely to propagate its kind, will in the long run be preserved and will transmit its favorable peculiarity to some of its offspring, which peculiarity will thus become intensified till it reaches the maximum degree of utility. On the other hand, individuals presenting unfavorable peculiarities will be ruthlessly destroyed (_Survival of the Fittest_), [tr. note: sic punctuation]
The basis of the theory then is that animals and plants multiply very rapidly and, second, that the offspring always vary slightly from the parents, though generally very closely resembling them. Mr. Alfred Russel Wallace says: ”From the first fact or law there follows, necessarily, a constant struggle for existence; because while the offspring always exceeds the parents in number, generally to an enormous extent, yet the total number of living organisms in the world docs not, and can not, increase year by year. Consequently every year, on the average, as many die as are born, plants as well as animals; and the majority die premature deaths. They kill each other in a thousand different ways; they starve each other by some consuming the food that others want; they are destroyed largely by the powers of Nature--by cold and heat, by rain and storm, by flood and fire. There is thus a perpetual struggle among them which shall live and which shall die; and this struggle is tremendously severe, because so few can possibly remain alive--one in five, one in ten, often only one in a hundred or even in a thousand.
”Then comes the question, Why do some live rather than others? If all the individuals of each species were exactly alike in every respect, we could only say it is a matter of chance. But they are not alike. We find that they vary in many different ways. Some are stronger, some swifter, some hardier in const.i.tution, some more cunning. An obscure color may render concealment more easy for some, keener sight may enable others to discover prey or escape from an enemy better than their fellows. Among plants the smallest differences may be useful or the reverse. The earliest and strongest shoots may escape the slug; their greater vigor may enable them to flower and seed earlier in a wet autumn; plants best armed with spines or hairs may escape being devoured; those whose flowers are most conspicuous may be soonest fertilized by insects. We can not doubt that, on the whole, any beneficial variations will give the possessors of it a greater probability of living through the tremendous ordeal they have to undergo. There may be something left to chance, but on the whole _the fittest will survive.” (_”Darwinism”_ p. 7)_.
The same writer gives a probable instance of the working of _Natural Selection_ in the origin of certain aquatic birds called dippers. He says: ”An excellent example of how a limited group of species has been able to maintain itself by adaptation to one of these 'vacant places' in Nature, is afforded by the curious little birds called dippers or water-ouzels, forming the genus _Cinclus_ and the family _Cindidae_ of naturalists. These birds are something like small thrushes, with very short wings and tail, and very dense plumage. They frequent, exclusively, mountain torrents in the northern hemisphere, and obtain their food entirely in the water, consisting, as it does, of water-beetles, caddis-worms, and other insect-larvae, as well as numerous small fresh-water sh.e.l.ls. These birds, although not far removed in structure from thrushes and wrens, have the extraordinary power of flying under water; for such, according to the best observers, is their process of diving in search of their prey; their dense and somewhat fibrous plumage retaining so much air that the water is prevented from touching their bodies or even from wetting their feathers to any great extent.
Their powerful feet and long curved claws enable them to hold on to stones at the bottom, and thus to retain their position while picking up insects, sh.e.l.ls, etc. As they frequent chiefly the most rapid and boisterous torrents, among rocks, waterfalls, and huge boulders, the water is never frozen over, and they are thus able to live during the severest winters. Only a very few species of dipper are known, all those of the old world being so closely allied to our British bird that some ornithologists consider them to be merely local races of one species; while in North America and the northern Andes there are two other species.
”Here, then, we have a bird, which, in its whole structure, shows a close affinity to the smaller typical perching birds, but which has departed from all its allies in its habits and mode of life, and has secured for itself a place in Nature where it has few compet.i.tors and few enemies. We may well suppose,* [[*Note characteristic phrase ”We may suppose that,--.” G.]] that, at some remote period, a bird which was perhaps the common and more generalized ancestor of our thrushes, warblers, wrens, etc., had spread widely over the great northern continent, and had given rise to numerous varieties adapted to special conditions of life. Among these some took to feeding on the borders of clear streams, picking out such larvae and mollusks as they could reach in shallow water. When food becomes scarce they would attempt to pick them out of deeper and deeper water, and while doing this in cold weather many would become frozen and starved. But any which possessed denser and more hairy plumage than usual, which was able to keep out the water, would survive; and thus a race would be formed which would depend more and more on this kind of food. Then, following up the frozen streams into the mountains, they would be able to live there during the winter; and as such places afforded them much protection from enemies and ample shelter for their nests and young, further adaptations would occur, till the wonderful power of diving and flying under water was acquired by a true land-bird.” (_”Darwinism,”_ p. 81-82.)
Lines of Evidence.
The evolutionary hypothesis (both in its atheistic and theistic or ”Christian” form) is understood to rest on the following lines of proof:
i. _Primary:_ The evidence of palaeontology (the study of fossil remains in the rocks). The surface of the earth underneath the top soil consists of layers of rock. Some of them are made up of lime deposits, others of the sh.e.l.ls of sh.e.l.l-fish, others of sand-stone, others of dead trees of the forest (coal), all of them turned hard by the pressure of the weight lying on top of them. Besides these sedimentary rock there are formations like granite, showing the influence of heat. Digging among the sedimentary rock (limestone, sand-stone, princ.i.p.ally) we come across preserved remains of all sorts of animals; some just like those which live to-day, some similar but somewhat different, others quite dissimilar from living animals of our day. These are the fossils. Now, evolutionists a.s.sert that the oldest and simplest animal and plant remains are found in the oldest layers of rock. This is said to prove that in the history of plants and animals on earth, the simplest forms are the oldest and that later the more complex forms were developed from these. LeConte states the matter thus: ”The farther back in time we go, the simpler the forms of animal and plant life become, and these forms occur in the order of their origination, just as if they were developed one from another.”
2. _Corroborative:_ a) The Argument from Morphology (Structure). The resemblance of the structure of various animal types is a.s.serted to imply a community of descent. ”Large groups of species, whose habits are widely different, present certain fundamental likenesses of structure.
The arms of men and apes, the fore-legs of quadrupeds, the paddles of whales, the wings of birds, the breast-fins of fishes, are constructed on the same pattern, but altered to suit their several functions. Nearly all mammals, from the long-necked giraffe to the short-necked elephant, have seven neck-bones; the eyes of the lamprey are moved by six muscles which correspond exactly to the six which work the human eye; all insects and Crustacea--moth and lobster, bettle [tr. note: sic] and cray-fish---are alike composed of twenty segments; the sepals, petals, stamens, and pistils of a flower are all modified leaves arranged in a spire.” (Clodd, _”The Story of Creation,”_ p. 102.) These _resemblances_ are looked upon as evidence of a common origin.
b) The Argument from Embryology. The individual animal in embryonic development pa.s.ses through temporary stages which are similar to permanent conditions in some of the lower forms in the same group.
Evolutionists believe that these forms were actually possessed by the ancestors of these animals in the course of their evolution. They hold that the changes which take place in the embryos epitomize the series of changes through which the ancestral forms pa.s.sed. Because the embryos of some four-footed animals have gill-slits, this is pointed out as evidence that land animals are evolved from fishes.
c) Geographical Distribution. In geological time, natural barriers have sprung up which separated the species which have since developed. In this way the existence of marsupials (pouched animals--kangaroo, oppossum) [tr. note: sic] on certain limited areas, the limitation of certain plants to certain islands, etc., are explained.
d) Cla.s.sification. The so-called Tree of Life. All living forms can be arranged in a diagram called the Tree of Life. The Tree has a short trunk, indicating common origin of the living from the non-living, and is divided into two large trunks representing plants and animals respectively. ”From each of these start large branches representing cla.s.ses, the larger branches giving off smaller branches representing families, and so on with smaller and smaller branches representing orders and genera, until we come to leaves as representing species, the height of the branch from which they are hanging indicating their place in the growth of the great life-tree.” (Clodd, _”Story of Creation,”_ p. 103.) There is an exact gradation from the lowest life forms to the highest. First such simple forms as the sponges and corals, then, through the worms, crabs, oysters, and snail to the fish, and thence through amphibia, reptiles, beasts of prey, ungulates (hoofed animals) and apes to man. Evolutionists say that in this gradation of life we see ill.u.s.trated the evolution of complex from simple forms.
The Descent of Man.
According to the evolutionary hypothesis man is related to the animal kingdom by descent from a brute ancestor, who, apelike in appearance, is the common ancestor of ape and man. The evidence of such derivation is believed to be:
i. Rudiments of structure which were useful in some brute ancestor.
There remain in man a few elementary muscles for twitching the skin, as in the forehead; and it is pointed out that many animals have such muscles at the present time, and it is argued that the ability of some men to move the whole scalp points to the existence of muscles with such function in our brute ancestors. The vermiform appendix in man is termed rudimentary, being but a remnant of the much longer and more complex appendix of the same nature in living animals today.
2. Embryonic Development. Because the young of all animals resemble one another while in the embryo stage, and since such resemblances are found in man, it is concluded that the evolution of man from some related animal form must be accepted as the most reasonable explanation.
3. Some diseases are common to animals and man (tuberculosis, cholera, hydrophobia, etc.).
4. The similarity in structure of man and the apes.
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