CHAPTER X THE ASCENT OF MAN A fire mist and a planet, A crystal and a cell, A jellyfish and a saurian, And caves where cavemen dwell- And some call it God. -W. H. GARRUTH THE INFINITE VARIETY OF LIVING THINGS The untrained eye, easily misled by superficial resemblances, fails to note the trifling differences which distinguish one form of life from another. Everyday experience proves the truth of this statement. John Doe claims that he has been bitten by the house fly. The student asserts that the culprit was a stable fly which John Doe confuses with the former. The average reader will be astonished at the results if he will but check himself as to his knowledge of details of life about him. This difficulty is increased by the necessity of describing new forms in old terms. The Roman soldier who described the elephants of Hannibal as "enormous oxen with tails at both ends" stands side by side with the Indians who thought that the boats of the Europeans must have been hollowed from the trunks of enormous trees. So too the Europeans coming to America fastened old names on local animals. The animals we call rabbits are, in reality, hares. It took man long centuries to get away from careless descriptions to accurate names of fixed value and even to-day com mon names the world over are confused and confusing. Even the binomial classification of Linnæus did not wholly meet the problem when man became able to distinguish varieties as well as species. That the shepherd knew his sheep and could call them by name was known of old. Man has always developed the keenest vision in dealing with things of everyday importance to himself. Yet how many of us can tell toadstools from mushrooms? Outside of a narrow field man's information has always been shaky and often incorrect. Only by a very slow process of accumulation has he achieved wide knowledge of things on earth-and many gaps still exist. Man Asks Why? As if the difficulty of listing the various forms of organic life were not great enough in itself man creates another. He is like the small child with its eternal "Why?" That is, man wants explanation of what he sees, and begins the development of speculation and theory. Both are excellent and unavoidable but they bring a new danger. Man now sees things in the light of a theory and tends, unconsciously, to make his facts conform. This is peculiarly true when the theories have become fixed beliefs, traced to some authority which is not open to question. Theology versus Science It so happens that most of the development of natural science has taken place in countries whose inhabitants have long held a belief that the early chapters of the Bible gave an accurate account of the origin of living beings and their relations to one another. Hence it has happened that any evidence from the book written in the rocks or in the habits of animals, a record written by God if ever one was, has been opposed as antagonistic to religion if it could not be made to agree with the Biblical account. Neither church nor state has been logical or consistent in the upholding of this position but they have stressed it often enough to make it a real factor in our development. The merits of the question do not now concern us but a couple of illustrations may be given. For long ages the earth was held to be the center of the universe. When Galileo among others began to make the sun the center, the authorities of the Roman Church were disturbed and thus expressed their disapproval: The proposition that the sun is the center of the world and immovable from its place is absurd, philosophically false, and formally heretical, because it is expressly contrary to the Holy Scripture. The proposition that the earth is not the center of the world, nor immovable, but that it moves, and also with a diurnal motion, is also absurd, philosophically false, and, theoretically considered, at least erroneous in faith.1 The story of Noah's ark caused no difficulty until the Europeans began to travel about the earth and to find many species of animals both new and strange. How would so many have found refuge in one boat? As a solution to this problem Origen suggested that the cubit was six times longer than had been supposed while Bede claimed that Noah had spent one hundred years in its construction and that the animals on board had been miraculously fed. Even the Encyclopædia Brittanica in the first edition (1771) asserted: The number of species of animals will be found less than is generally imagined, not amounting to a hundred species of quadrupeds, nor to two hundreds of birds: out of which in this case are excepted such animals as can live in the water. Zoologists usually reckon but one hundred and seventy species in all: and Bishop Williams shows that only seventy-two of the quadruped kind needed a place in the ark. . . . It is agreed that the lower story was for beasts, the middle for food, and the upper for the birds with Noah and his family, each story being subdivided into different apartments, stalls.2 Marco Polo claimed to have seen the ark resting on Mount 'Ararat on one of his voyages but he appears to have failed to measure it. To-day we know that there are thousands of species. Species What, then, is a species? To the men of the Middle Ages this was a simple question. The Lord at the time of creation had made at least two (more according to some authorities) of each sort of animal and that these had reproduced throughout the ages and that new forms had not reappeared. This idea was held in early life even by such men as Linnæus, Lamarck and Darwin. The answer to-day is far less simple. Through the window I see a bunch of little bantams frisking about a bevy of sedate White Rocks. If the naturalist found these two forms in a new country he would unhesitatingly label them as two species. It happens that we know that they and all the other races of chickens are to be traced back to the jungle fowl of India. Shall we call these various races of chickens "species" or "varieties"? Much more is involved than a mere choice of terms. Hybrids According to the older belief, species could not cross and produce fertile offspring. In some cases this seems to be true as in the cross of the horse and the ass or of the two camels. Even here we do not know that fertile offspring never result nor do we know why the half-breeds are not fertile. The crosses of the European cattle and the American bison are fertile. Fertile crosses of ducks and geese are known. Crossbred plants are very numerous. To-day we do not know where the limits are which nature may have established. We have to speak of varieties as well as species. Varieties In reality species often shade into each other by almost imperceptible degrees. When I was a boy all the bird lists gave two species of American hawks as distinct species, the common red-tailed hawk and the rare Harlan's hawk. When the collection of skins at the National Museum became large enough it was seen that one shaded into the other and Harlan's hawk was relegated to the position of a color variety of the common form. The heath hen of Nantucket was long identified with the prairie chicken of the West. The goldenwinged woodpecker of the East and the red-shafted flicker of the West are distinct enough but the intermediate forms are endless. As knowledge has increased the number of varieties has grown. Whereas the older students based their classifications largely on external characters, now every detail of anatomy is compared and many shifts even from one genius to another have been necessary. The results are often surprising. The whale is nearer to the pig than any fish. The eel is a fish and not a water snake. The meaning of all this is that the extent of the relationship between various forms of life is greater than was once thought. Stated in another way, the known facts no longer fit the old theory and some new interpretations must be sought. Again we see that nature cares nothing for the hard and fast lines of distinction which man has sought to establish. Fossils Even in primitive times man must have found fossil remains. When he began to notice them and seek for an explanation we shall never know. In Europe during the Middle Ages fossils were known and variously interpreted. Sometimes large fossils were exhibited in churches as proof of the Biblical statement that "there were giants in those days." |