Part 6

Three months before birth, the human babe is covered with a luxuriant growth of soft, brown hair, called the “lanugo,” precisely the same as the ape baby. And throughout life the body of every human being is covered with a rudimentary growth of hair. But this it not all. It is as suggestive as it is interesting that in man and in the anthropoid apes the hair on the upper arm and the hair on the lower arm always grows towards the elbow (Fig. 40)—a phenomenon which occurs nowhere else in the animal world except in a few American monkeys. In a primitive Australian race, the Ainos of Japan, and the pygmies of the Upper Nile, the extreme hairiness of the body is a notable characteristic. And the photograph of Julia Pastrana, a Siamese (Fig. 41), shows that this lady was not only bearded like a man, but that her entire body was plentifully clothed with hair. Some chimpanzees, on the other hand, are remarkably hairless. One variety is, in fact, almost entirely bald.

If any organ in the human body could distinguish man as a creature standing apart, and argue that he has not been evolved from ape-like ancestors, that organ should be the brain. But the brain yields surprising evidence of man’s kinship with these creatures. Fig. 42 is introduced to show the remarkable similarity in the brains of the anthropoid apes and men. The lower four are the brains of apes; the upper one to the right is the brain of a Bushman, and the one at the upper left is the brain of an European. Mark that while the brains of the apes differ from one another, there is also a striking difference between the brain of the savage and that of the civilized man. Observe, too, how wonderfully these ape brains resemble the human brains, not alone in general form, but also in the number and depth of their convolutions. In fact, the brains of man-like apes and men consist of the same parts—the cerebrum, the cerebellum, the corpus callosum, and the hippocampus minor—and in both anthropoid and man the cortex of the brain is folded in essentially the same convolutions.

If any thoughtful person is still unconvinced of man’s rise from ape-like ancestors, let him compare his mental image of some human beings he has seen with Fig. 43.

Consul II, a chimpanzee from Borneo, now in England, sits at the table, tucks his napkin under his chin, uses a knife and fork, drinks his tea from a cup, and has excellent table manners. After dinner, he sits back, lights his pipe, and enjoys a smoke. He washes himself with soap and water, dresses himself, shines shoes carefully, and, like a hotel waiter, expects a tip for his service. Another, and far more remarkable anthropoid, is Snooky, the educated chimpanzee who frequently appears in the “movies” in the Chester Comedies. Dressed like a man, this ape smokes a cigar, pretends to read a paper, poses as a chauffeur, rides a tricycle, takes care of children, performs capers with boys, and takes various parts with men and women. So intelligent and humorous is the acting of this chimpanzee, so clever and human-like are its numerous performances, that it is justly advertised as the “humanzee.”

(From a photograph by Hintze).]

In considering the relation between the anthropoid apes and men, we must not suppose that apes or ape-like creatures underwent a sudden transformation into human beings. The highest existing apes represent a development that preceded the appearance of man, some authorities think, by some two or three million years. The difference between these creatures and man is therefore the measure of life’s upward rise by slow steps during that inconceivable time.

Man is related to the apes not alone in the structure of his body and brain, but also in the blood stream that courses through his veins. This has been conclusively proved by the remarkable series of blood tests conducted by Professor G. H. F. Nuttall at Cambridge University. By these tests, it was shown that man and the chimpanzee are blood relations; that the gorilla is a more distant relative, and the orang a relative more distant still. Below the anthropoids, the blood relationship is represented with diminishing force in the baboons and monkeys. These blood tests confirm the conclusions of zoology and prove the truth of evolution.

Fig. 44 is a picture of Haeckel’s genealogical tree of humanity. It enables us to visualize in its main outline the history of the evolution of life. At the bottom of the tree are the monera and the amœbæ—tiny creatures consisting of a single cell. As growing life assumes diverse forms, the foremost creatures are represented by higher and higher positions on the trunk of the tree, or by diverging branches in the ascending order. Life is seen to progress from the simple to the complex, past the sponges, the molluscs and the fishes, through the amphibians, the reptiles, the marsupials, rising higher and higher in the scale of being, through lemurs, apes and anthropoids, until, at the topmost summit of the tree appears man.

And what has been the secret, the driving force back of this process of evolution? To understand the causes of evolution, it is necessary to understand the four fundamental laws of life. First, that while creatures resemble their parents through heredity, they nevertheless differ more or less from their parents—this is the law of variation. Secondly, that more creatures are born than can survive—this is the law of surplus population. Thirdly, that among living creatures, and owing largely to over-population, there is continually going on a struggle for existence—this is the law of struggle. And fourthly, that out of this struggle there results the survival of the fittest. Variation, surplus population, struggle, spell the survival of the fittest. In the struggle for existence, those creatures possessing the best bodies and the keenest minds, those that could best protect themselves from their enemies and obtain their food—in a word, those that were best adapted to their environment—survived, while the others perished. Those whose variations were unfavorable, the weak, the inferior, died. But those whose variations were an advantage, the strong, the superior, survived. In consequence of the survival of the fittest, Nature, throughout the unfolding ages, kept breeding from the best. And this practice could have but one result—the gradual improvement of every race of creatures.

It will be well to elucidate somewhat the principles thus summarily stated. First, then, as to variation. The offspring is never exactly like its parents, and no two creatures are ever quite alike. The stems, the leaves, the blossoms of the plants of any species, the size and contour of their fruits, vary greatly. No two blades of grass, or ears of corn, or grains of wheat are alike. Every tree has an individuality of form. The young of dogs, cattle, horses, sheep, of fowls and birds, invariably differ from their parents in size and form, in coloring and character.

G-Gibbon. H-Chimpanzee. I-Orang. K-Gorilla. L-Bushman. M-Teuton. From Haeckel’s “Evolution of Man.”]

So, too, in a large assemblage of people, you will see noses and ears of numerous shapes and sizes, eyes displaying a variety of coloration and expressiveness; you will observe that some foreheads are low and others high, some heads flat and others pointed, some round and others square; some men have long arms and legs, some the reverse; some have long bodies and short limbs, some the opposite; some have one ear, or shoulder, or hip, higher than the other, or are otherwise disproportioned. Moreover, great differences may be observed in the features of almost any family. The black haired mother has red haired daughters; the father’s features are bequeathed to his sons except, perhaps, for the eyes of one or the nose of another. Variation is a basic law of life.

Secondly, as to the multiplication of creatures beyond the power of Nature to sustain them. Darwin, in the “Origin of Species” says: “There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five years, and at this rate, in less than a thousand years, there would literally not be standing-room for his progeny.”

On the fertility of the elephant, Darwin remarks: “The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase; it will be safest to assume that it begins breeding when thirty years old, and goes on breeding till ninety years old, bringing forth six young in the interval, and surviving till one hundred years old; if this be true, after a period of from 740 to 750 years there would be nearly nineteen million elephants alive descended from the first pair.”

An illustration from the opposite extreme of the animal world will show that the breeding propensities of the largest existing animal are rivalled by those of the smallest. “The aphis or plant louse,” says Dr. D. Kerfoot Shute in “A First Book in Organic Evolution,” “is so very prolific that it has been estimated that the tenth brood of one female alone would contain more ponderable matter than all the population of China,—estimating this population at five hundred millions.”

The rabbits introduced into Australia, where they found conditions ideally favorable to their increase, have multiplied so exceedingly that they have become a veritable pest. In a brief period, the progeny of a few rabbits has multiplied into millions, and these creatures have become so destructive of agriculture that rabbit-killing parties are organized from time to time and tens of thousands of the animals are killed with sticks and stones, in open places, the object being to exterminate as many rabbits as possible in the interest of the farmers’ crops.

In 1850, some enterprising citizens of Brooklyn imported a hundred English sparrows and gave them to the free city air. A little later, New York City imported two hundred and twenty of the noisy birds and liberated them in the parks of the metropolis. Rochester imported one hundred of the birds, and Philadelphia, with generous public spirit, opened the bosom of brotherly love to one thousand of the little strangers whose perpetual chatter formed a striking contrast to the worshipful quiet dear to the heart of the Quaker City. In the parks, among the trees, and in the streets of these cities, the sparrows—at home everywhere—twittered and quarreled in their friendly way, and multiplied. In twenty-five years the children of these birds had spread over five hundred square miles. Ten years later they had flung their domain over fifteen thousand square miles, and men were beginning to doubt the wisdom of those who had invited them to our shores. Since then the ubiquitous sparrow has about completed the conquest of the continent. Darting like an arrow amongst horses’ feet, or dodging hurrying automobiles, his legions are familiar sights among the traffic of busy streets. He builds his rude nest under the eaves of houses, and in the architectural pockets around the roofs of public buildings, and thrives and multiplies through his wary association with man. The phenomenal increase in the number of sparrows in North America during a period of seventy years has been due to the gregarious habit of these birds and to the favorable character of the environment.

A Chimpanzee couple of Edward’s Zoological Exhibition. From Dr. Paul Carus’s “The Rise of Man.” Courtesy of The Open Court Publishing Co.]

Some animals tend to multiply ten fold in a generation; some would multiply to a hundred fold, and others to ten thousand fold. Not only could the progeny of any land animal, if given the right of way, soon crowd the earth, but the fishes, under favorable conditions, would, in a short time, literally fill the sea. A million eggs are spawned by the cod-fish in order that two cod-fish may reach maturity. The eel also spawns millions of ova that a few eels may reach the spawning age. It is clear, therefore, that if all these eggs produced fishes, and if these reached maturity and in their turn multiplied with such lavish prodigality, a few generations would suffice to transform the ocean into a solid mass.

The same phenomenon obtains in the plant world. Every plant gives its seeds to the soil as Autumn’s spendthrift hand gives its withered leaves to the wind, but of the millions of seeds thus scattered, comparatively few take root and mature and reproduce their kind.

Notwithstanding Nature’s tremendous efforts to overwhelm the earth with the creatures of every species, the checks upon over-population are so numerous and so effective that, speaking generally, the number of animals and plants in any given area where the conditions are unchanging remains fairly constant. This relatively rigid limitation of the number of creatures that shall survive in any environment is due to the operation of Nature’s efficient machinery whose grim function is the destruction of life.

Millions of creatures live only by devouring other creatures. The carnivorous animals eat the flesh and drink the blood of the herbivorous. The larger carnivores feed upon the smaller. That the badger may make a meal, a whole nest of bees must be destroyed. The ant-eater swallows a tongue load of ants at a single gulp. The eagle and the hawk dine on doves and other birds. To the appetite of smaller birds are sacrificed worms, insects and larvae. Big fishes eat the little ones; bigger fishes eat the eaters and in turn are eaten. On land, in the air, and in the sea the incalculable sacrifice of life proceeds without cessation. Pursuit and flight, capture and death—a tragedy on which the curtain never falls!

This is the struggle for existence. In this struggle which, in a sense, is a constant test of skill, the most highly qualified creatures are the ones best adapted to catch their prey or to escape their enemies. Differing from their parents and from one another in numerous variations, some animals excel others in important respects—in having stronger legs with which to run, better eyes with which to see, a keener sense of smell, hearing more acute, and teeth and claws better fitted to hold and rend their prey. To the animal that would obtain food or avoid being eaten, some or all of these characters are prime essentials. In the struggle for existence the animals possessing these attributes in superior form will survive while those in which they are less developed must perish.

Harmless creatures, no less than harmful, survive through favorable characters—some by the wit with which they elude the pursuer, some by flight, some by protective coloration; like the hare whose summer coat resembles the ground and whose winter garment rivals the whiteness of the snow, and the gorgeous butterfly, whose folded wings are a perfect simulation of the form and color of a dead leaf.

Where the herbivorous food was insufficient for the mouths that would feed upon it, and where animals devoured one another, it was inevitable that the weak, the stupid, the ill-favored, the incompetent, should fail in the struggle for existence, and that the strong, the cunning, the efficient should survive and hand their superior qualities to their offspring. And this survival of the fittest by right of might that has been the supreme law of the animal world since life appeared upon this globe, was bound to result in the accumulation of favorable variations, in the consequent production of an ever increasing wealth of species, and in the development of ever higher forms of life.

The fitness of the present forms has been moulded by the death dealing teeth of the past.

Though not by this means alone. Another potent factor that has wrought tremendously for evolution has been the changing environment. We may briefly consider the character of its work. For millions of years before the close of the Carboniferous period, some ten million years ago, the whole earth enjoyed a perpetual summer. During the last million years or more of that vast era, while the dense Carboniferous forests, overwhelmed again and again by the growing soil, were forming the coal deposits of the earth, many kinds of amphibians and low reptiles wandered over the marshes and among the trees.

Then in the succeeding period—the Permian—the climate began to be colder. For a hundred thousand years or thereby the cold increased. At last the summit of an ice age was reached, and some four million square miles of the earth’s surface lay beneath a thick mantle of ice and snow. That ice sheet covered a continent that then extended from India to Australia, on the one hand, and to Africa on the other. The ice age, which was due, probably, to the gradual elevation of the land, wrought fearful havoc among the land animals, and with a ruthless hand pushed evolution forward. It compelled animals—and plants also—to change or die.