X. The Genealogy of Animals.
Life originated in the sea, and for an immense period of time after it commenced it was confined to the place of its origin. The civilisations of the earth were for many millions of years exclusively aquatic. It has, indeed, been estimated that the time required by the life process in getting out of the water—that is, that the time consumed in elaborating the first species of land animals—was much longer than the time which has elapsed since then. I presume that during a large part of this early period it would have seemed to one living at that time extremely doubtful whether there would ever be on the earth any other kinds of life than the aquatic. And if those who to-day weave the fashionable fabrics of human philosophy, and who know nothing about anything outside the thin edge of the present, had been back there, they would no doubt have declared confidently, as they looked upon the naked continents and the uninhabited air and the sea teeming with its peculiar faunas, that life upon solids or in gases, life anywhere, in fact, except in the sea, where it had always existed, and to which alone it was adapted, was absolutely, and would be forever, impossible; and that feathered fishes and fishes with the power to run and skip, and especially ‘sharks’ competent to walk on one end and jabber with the other, were unthinkable nonsense. Life originated in the sea for the same reason that the first of the series of so-called ‘civilisations’ which have appeared in human history sprang from the alluvium of the Euphrates and the Nile, because the conditions for bringing life into existence were here the most favourable. The atmosphere was incompetent to perform such a task as the inventing of protoplasm and there was no land above the oceans.
The first forms of life were one-celled—simple, jelly-like dots of almost homogeneous plasm—the protozoa. These primitive organisms were the common grandparents of all beings. From them evolved, through infinite travail and suffering, all of the orders, families, species, and varieties of animals that to-day live on the earth, and all those that have in the past lived and passed away. By the multiplication and specialisation of cells, and the formation of cell aggregates, the sponges, celenterates, and flat worms were developed from the protozoa.[1] The connecting links between the one-celled and the many-celled animals consist of a series of colonial forms of increasing size and complexity, some of which may be found in every roadside ditch and pool, while others are extinct. The development of these many-celled organisms (metazoa) from one-celled organisms was a perfectly natural process, a process which takes place in the initial evolutions of every embryo. There is no more mystery about it than there is about any other act of association. All association is simply a matter of ‘business.’ Many-celled organisms are colonies, or societies, of more or less closely co-operating one-celled organisms, and they have come into existence in obedience to the same laws of economy and advantage as have those more modern societies of metazoa known as nations, communities, and states, the organised bodies of men, ants, and millionaires.
The sponges are the lowest of the many-celled animals. They consist of irregular masses of loosely associated cells, hopelessly anchored to the sea-floor. They represent the social instinct in embryo. The cells are but slightly specialised, and each cell leads a more or less independent existence. The sponge stands at about that stage of social integration and intelligence represented by those stupendous porifera which cover continents and constitute the ‘social organisms’ of the civilised world. The nutritive system of sponges consists of countless pores opening from the surface into a common canal within, through which ever-waving cilia urge the alimental waters. In the celenterates the cells arrange themselves in the form of a cup with one large opening into and from the vase-like stomach. The unsegmented worms are flat and sac-like, with bilateral symmetry and the power to move about, but not tubular, as are the true worms. They are bloodless, like the celenterates and sponges.
From the flat worms developed the annelid worms, animals perforated by a food canal and possessing a body cavity filled with blood surrounding this canal. The body cavity is the space between the walls of the body and the alimentary canal, the cavity which in the higher animals contains the heart, liver, lungs, kidneys, etc. The worms and all animals above them have this cavity. The worms and all animals above them also have, as an inheritance from the flat worms, bodies with bilateral symmetry—that is, bodies with two halves similar. This peculiarity was probably acquired by the flat worms, and so fastened upon all subsequently evolved species, as a result of pure carelessness. It probably arose out of the habit of using continually, or over and over again, the same parts of the body as fore and aft. It has been facetiously said that if it had not been for this habit, so inadvertently acquired by these humble beings so long, long ago, we would not to-day be able to tell our right hand from our left. In the worm is found the beginning of that wonderful organ of co-ordination, the brain. The brain is a modification of the skin. It may weaken our regard for this imperial organ to know that it is, in its morphology, akin to nails and corns. But it will certainly add to our admiration for the infinite labours of evolution to remember that the magnificent thinking apparatus of modern philosophers was originally a small sensitive plate developed down in the sea a hundred million years ago on the dorsal wall of the mouths of primeval worms.
From the worms developed all of the highest four phyla of the animal kingdom—the echinoderms, the mollusks, the arthropods, and the chordate animals, the last of which were the progenitors of the illustrious vertebrates. The lowest of the mollusks are the snails, and from these humble tenants of our ponds and shores sprang the headless bivalves and the giant jawed cuttles. The mollusks were for a long time after their development the mailed monarchs of the sea, and shared with the worms the dominion of the primordial waters. But after the development of the more active arthropods, especially the crustaceans, the less agile worms and mollusks rapidly declined. Existing worms and mollusks are remnants of once powerful and populous races.
From the worms also developed the arthropods, the water-breathing crustaceans and the air-breathing spiders and insects. The crustaceans came early, away back in the gray of the Silurian period, just about the time North America was born. North America lay, a naked, V-shaped infant, in the regions of Labrador and Canada. The crustaceans rapidly superseded the mollusks as rulers of the sea, attaining, in extreme species, a length of four or five feet. The spiders and Insects came into existence toward the latter part of the Silurian period,[2] probably contemporaneous, or nearly so, with the appearance of land vegetation. The spiders and insects were the aborigines of the land and air. They are the only races of living beings, except the original inhabitants of the sea, who ever invaded and settled an unoccupied world. The earliest land fossils so far found are the fossils of scorpions. But the existence of a sting among the structural possessions of these animals indicates that there were already others who contended with them for supremacy in the new world. The first insects were the masticating insects, insects such as cockroaches, crickets, grasshoppers, dragon-flies, and beetles. They are found abundantly in the Devonian and Carboniferous rocks. The licking insects (bees) and the pricking insects (flies and bugs) appeared first in the Mesozoic Era, and the sipping insects (butterflies) in the Cenozoic. The flower-loving insects (the bees and butterflies) came into the world at the same time as did the flowers. The wings of insects may be modifications of the gills used by insect young in respiration during their aquatic existence. They are, hence, very different in origin from the wings of birds, which are the modified fore-legs of reptiles.
The most important class of animals arising out of the worms, on account of their distinguished offspring, were the hypothetical cord animals. The only existing species allied to these animals is the amphioxus, a strange, unpromising-looking creature, half worm and half fish, found in the beach sands of many seas. It has white blood and a tubular heart. It is without either head or limbs, and looks very much like a long semitransparent leaf, tapering at both ends. But it has two unmistakable prophecies of the vertebrate anatomy: a cartilaginous rod, pointed at both ends, extending along the back, and above this, and parallel to it, a cord of nerve matter. These are the same positions occupied by the spinal column and spinal cord in all true vertebrates. That the amphioxus is a genuine relative of the ancestor of the vertebrates is also shown by the fact that these simple forms of column and cord possessed by amphioxus are precisely the forms assumed by the spinal column and spinal cord in the embryos of all vertebrates, including man.
From these quasi-vertebrates developed the fishes—first (after the scaleless, limbless lampreys) the sharks with spiny scales and cartilaginous skeleton, and after these the lung fishes and the bony fishes, with flat, horny scales and skeletons of bone. From the beginning of the Devonian age, when fishes first came into prominence, till the rise of the great reptiles in the Triassic time, fishes were the dominant life of the sea. In the fishes first appeared jaws, a sympathetic nervous system, red blood, backbone, and the characteristic two pairs of limbs of vertebrates.
The lung fishes (Dipneusta), a small order of strange salamander-like creatures which live ingeniously on the borderland between the liquid and the land, may be looked upon as physiological, if not morphological, links between the fishes and the frogs. They combine the characters of both fishes and frogs, and zoologists have been tempted to make a separate class of them, and place them between the two classes to which they are related. They are like fishes in having scales, fins, permanent gills, and a fish-like shape and skeleton. They resemble frogs in having lungs, nostrils, an incipiently three-chambered heart, a pulmonary circulation, and frog-like skin glands. There are three genera with several species. One genus (Neoceratodus) is found in two or three small rivers of Queensland, Australia; another (Protopterus) lives in the Gambia and other rivers of Africa; and the third (Lepidosiren) inhabits the swamps of the Amazon region. They all breathe ordinarily by means of gills, like true fishes, but have the habit of coming frequently to the surface and inhaling air. The air-bladder acts as an incipient lung in supplementing respiration by gills. They all live in regions where a dry season regularly converts the watercourses into beds of sand and mud. During the season of drought these strange animals build for themselves a cocoon or nest of mud and leaves. This cocoon is lined with mucus, and provided with a lid through which air is admitted. Here they lie in this capsule throughout the hot southern summer, from August to December, breathing air by means of their lungs and living upon the stored-up fat of their tails, until the return of the wet season, when they again live in the rivers and breathe water in true piscatorial fashion. These capsules have often been carried to Europe, and opened 3,000 miles from their place of construction without harming the life within.
Here, in these eccentric denizens of the southern world, we find the beginnings of a grand transformation—a transformation in both structure and function, a transformation made necessary by the transition from life in the water to life in the air, a transformation which reaches its maturity in the higher air-breathing vertebrates, where the simple air-sac of the fish becomes a pair of lobed and elaborately sacculated lungs, performing almost exclusively the function of respiration, and the gills change into parts of the ears and lower jaw.
The air-bladder of ordinary fishes, which is used chiefly as a hydrostatic organ to enable the fish to rise and fall in the water, is probably the degenerated lung of the lung fishes.
From the lung fishes or allied forms developed the amphibians, the well-known fish quadrupeds of our bogs and brooks. The amphibians are genuine connectives—living links between the life of the sea and the life of the land. In early life they are fishes, with gills and two-chambered hearts. In later life they are air-breathing quadrupeds, with legs and lungs and three-chambered hearts. Here is evolution, plenty of it, and of the most tangible character. And it takes place right before the eyes. The transformation from the fish to the frog is, however, no more wonderful than the embryonic transformations of other vertebrates. It is simply more apparent, because it can be seen. The lungs of amphibians and the lower reptiles are simple sacks opening by a very short passage into the mouth. Some amphibians, as the axolotl of Mexican lakes, ordinarily retain their gills through life, but may be induced to develop lungs and adapt themselves to terrestrial life by being kept out of the water. Others, as the newts, which ordinarily develop lungs, may be compelled to retain their gills through life by being forced to remain uninterruptedly in the water. The black salamander, inhabiting droughty regions of the Alps, brings forth its young bearing lungs, and only a pair at a time. But if the young are prematurely removed from the body of the mother and placed in the water, they develop gills in the ordinary way. These are remarkable instances of elasticity in the presence of a varying environment.
In the amphibians the characteristic five-toed or five-fingered foot, which normally forms the extremities of the limbs of all vertebrates except fishes, is first met with. It was this pentadactyl peculiarity of the frog, inherited by men and women through the reptiles and mammals, that gave rise to the decimal system of numbers and other unhandy facts in human life. The decimal system arose out of the practice of early men performing their calculations on their fingers. This method of calculating is still used by primitive peoples all over the world. The sum of the digits of the two hands came, in the course of arithmetical evolution, to be used as a unit, and from this simple beginning grew up the complicated system of tens found among civilised peoples. It has all come about as a result of amphibian initiative. Our very arithmetics have been predetermined by the anatomical peculiarities of the frog’s foot. If these unthinking foreordainers of human affairs had had four or six toes on each foot instead of five, man would no doubt have inherited them just as cheerfully as the number he did inherit, and the civilised world would in this case be to-day using in all of its mathematical activities a system of eights or twelves instead of a system of tens. A system of eights or twelves would be much superior in flexibility to the existing system; for eight is a cube, and its half and double are squares; and twelve can be divided by two, three, four, and six, while ten is divisible by two and five only.
How helpless human beings are—in fact, how helpless all beings are! How hopelessly dependent we are upon the past, and how impossible it is to be really original! What the future will be depends upon what the present is, for the future will grow out of, and inherit, the present. What the present is depends upon what the past was, for the present has grown out of, and inherited, the past. And what the past was depends upon a remoter past from which it evolved, and so on. There is no end anywhere of dependence, either forward or backward. Every fact, from an idea to a sun, is a contingent link in an eternal chain.
From the amphibians (probably from extinct forms, not from living) there arose the highest three classes of vertebrates—the true reptiles, the birds, and the mammals—all of whom have lungs and breathe air from the beginning to the end of their days. Gills, as organs of breathing, disappear forever, being changed, as has been said, into parts of the organs of mastication and hearing. In the reptiles first appear those organs which in the highest races overflow on occasions of tenderness and grief, the tear glands. These organs are, however, in our cold-blooded antecedents, organs of ocular lubrication rather than of weeping. There are but four small orders of existing reptiles—snakes, turtles, lizards, and crocodilians. These are the pygmean descendants of a mighty line, the last of a dynasty which during the greater part of the Mesozoic ages was represented by the most immense and powerful monsters that have ever lived upon the earth. Mesozoic civilisation was pre-eminently saurian. Reptiles were supreme everywhere—on sea and land and in the air. Their rulership of the world was not so bloody and masterful as man’s, but quite as remorseless. Imagine an aristocracy made up of pterosaurs (flying reptiles), with teeth, and measuring 20 feet between wing-tips; great plesiosaurs (serpent reptiles) and ichthyosaurs (fish reptiles), enormous bandits of the seas; and dinosaurs and atlantosaurs, giant land lizards, 30 feet high and from 50 to 100 feet in length. A government of demagogs is bad enough, as king-ridden mankind well know, but dragons would be worse, if possible. The atlantosaurs were the largest animals that have ever walked upon the earth. They were huge plant-eaters inhabiting North America. It has been surmised that one of these behemoths ‘may have consumed a whole tree for breakfast.’ It was the mighty saurians of the Mesozoic time who brought into everlasting subordination the piscatorial civilisation of the Devonian and carboniferous ages.
Toward the latter part of the Reptilian Age, and somewhere along about the time of the appearance of hard-wood forests, came the birds, those beautiful and emotional beings who, in spite of human destructiveness, continue to fill our groves and gardens with the miracles of beauty and song. The bird is a ‘glorified reptile.’ How the ‘slow, cold-blooded, scaly saurian ever became transformed into the quick, hot-blooded, feathered bird, the joy of creation,’ is a considerable mystery, yet we know no reason for believing that the transformation did not take place. Although in their external appearance and mode of life birds and reptiles differ so widely from each other, yet, in their internal structure and embryology, they are so much alike that one of the brightest anatomists that has ever lived (Huxley) united them both into a single class under the name Sauropsida. It might naturally be supposed that the birds are descendants of the flying reptiles, the pterosaurs. But this may not be true. The pterosaurs were structurally much further removed from the birds than were certain extinct terrestrial reptiles. The fact that birds and pterosaurs both had wings has really nothing to do with the case. For the wings of reptiles, we almost know, were not homologous with the wings of birds. The bird’s wing is a feathered fore-leg; the wing of the reptile was an expanded skin stretching from the much-elongated last finger backwards to the hind-leg and tail. Wings, it may be remarked in passing, have had at least four different and distinct beginnings in the animal kingdom, represented by the bats, the birds, the reptiles, and the insects. This does not include the parachutes of the so-called flying squirrels, lemurs, lizards, phalangers, and fishes.
The first birds had teeth and vertebrated tails. The archeopteryx, which is the earliest toothed bird whose remains have yet been found, was about the size of a crow. It had thirty-two teeth and twenty caudal vertebrae. Two specimens of it have been found in the Jurassic slates of Bavaria. One of these fossils is in the British Museum, and the other in the Museum of Berlin. Other toothed birds have been found fossil by Dr. Mudge in the cretaceous chalk of North America. These last had short, fan tails like existing birds.
From the toothed birds developed the beaked birds—the keel-breasted birds (the group to which most existing birds belong) and the birds with unkeeled breasts, i.e., the ostrich-like birds. The ostrich-like birds are runners. They have rudimentary wings, and the keel of the breast-bone, which in the keel-breasted birds acts as a stay for the attachment of the wing muscles, is lacking. The ostrich-like birds are probably degenerate flyers, the flying apparatus having become obsolete through disuse. The feathers of birds are generally supposed to be the modified scales of reptiles.
The most brilliant offspring of the reptiles were the mammals, animals capable of a wider distribution over the face of the earth than the cold-blooded reptiles, on account of their hair and their warm blood. Cold-blooded animals of great size are able to inhabit but a small zone of the existing earth’s surface—the torrid belt. They cannot house themselves during the seasons of cold, as men can; nor escape to the tropics on the wings of the wind, as do the birds; nor bury themselves in subaqueous mud, as do the frogs, snakes, and crustaceans. During the Mesozoic period, when cold-blooded reptiles of gigantic size flourished over a wide area of the earth’s surface, the planet was far warmer than now. Animals, therefore, like the mammals (or birds), capable of maintaining a fixed temperature regardless of the thermal fluctuations of the surrounding media, are the only animals of large size and power capable of uninterrupted existence over the greater part of the surface of the existing earth. The pre-eminent life of the Cenozoic time was mammalian. But the decline and fall of the saurian power was not wholly due to the rise of the more dynamic mammals. It was in part due, no doubt, to adverse conditions of climate, and also to the fact that mammals and birds guard their eggs, and saurians do not.
The lowest of the mammals are the monotremes, animals which blend in a marvellous manner the characteristics of birds, reptiles, and mammals. Only two families of these old-fashioned creatures are left, the echidna and the duck-bill (ornithorhynchus), both of them found on or near that museum of biological antiquities, Australia. They are covered with hair and suckle their young like other mammals, but they have only the rudiments of milk glands, and they lay eggs with large yolks from a cloaca, like the reptiles and birds. The duck-bill hides its eggs in the ground, but the echidna hatches its eggs in a small external brooding pouch, periodically developed for this purpose. The young of the monotremes feed on the oily perspiration which exudes from the body of the mother. The monotremes first appear in the fossiliferous rocks of the Triassic Age.
From the monotreme-like mammals developed the marsupial mammals, animals possessing a purse-like pouch on the after part of the abdomen, in which they carry their young. The young of marsupials are born in an extremely immature state, and are carried in this pouch in order to complete their development. The young of the kangaroo, an animal as large as a man, are only about an inch in length when they are born. They are carried for nine months after their birth in the marsupium of the mother, firmly attached to the maternal nipple. The marsupials came into existence during the Jurassic Age, and during the next age, the Cretaceous, they arose to considerable power. During this latter age they were found on every continent. But they have been almost exterminated by their more powerful descendants.
From the marsupials developed the placental mammals, animals so called because their young are developed within the parental body in association with a peculiar nourishing organ called the placenta. From the herbivorous marsupials developed the almost toothless edentates, the rodents, or gnawing animals, the sirenians, the cetaceans, and the hoofed animals, or ungulates. The sirenians are fish-like animals with two flippers, and are often called sea-cows. They resemble whales in many respects, and are sometimes classed with them. They are plant-eaters exclusively, and are found grazing along the bottoms of tropical estuaries and rivers. They have tiny eyes, teeth fitted for grinding (not spike-like as in the whales), and a strong affection for their young, the mother, when pursued, often carrying her little one under her flippers. An immense sirenian, known as Steller’s manatee, was discovered on the Behring Islands, along the Kamschatka coast, in 1741. Twenty-seven years afterwards not one of them was left, all having been murdered by the Russian sailors. The sirenians are probably degenerate forms of land quadrupeds, having lost their hind-limbs and developed the fish-like shape in adapting themselves to aquatic conditions. They appear first in the Eocene Age.
Among the most interesting derivatives of the herbivorous marsupials, because the most aberrant, are the whales. They are true mammals—have warm blood, breathe the air with lungs, and suckle their young like other mammals. But, like the sirenians, they live in the surface of the waters, and have flippers and a fish-like tail and form. They differ from the sirenians, however, in being carnivorous, in having inguinal instead of pectoral milk glands, and in being structurally less like quadrupeds. They probably degenerated from land quadrupeds during the Jurassic period, and, owing to their longer residence in the waters, have become further removed from the quadrupedal type than the sirenians. Whales have two limbs, the hind-limbs having disappeared as a result of the pre-eminent development of the tail. The tails of whales and sirenians are flattened horizontally, not vertically, as in fishes.
Out of generalised forms of hoofed animals now extinct developed the odd-toed and even-toed races of existing ungulates. The original ungulates had five hoofs on each foot, and were highly generalised in their structure. From these original five-toed forms have arisen the variously hoofed and variously structured tribes of existing ungulates: the five-toed elephant, the four-toed tapir and hippopotamus, the three-toed rhinoceros, the two-toed camel, sheep, swine, deer, antelope, giraffe, and ox, and the one-toed horse and zebra.
The carnivorous branch of the placental animals came from the carnivorous branch of the marsupials. From early forms of carnivorous placentals developed the ape-like lemurs and those generalised forms of rapacious animals from which arose the insect-eaters, the bats, and the true carnivora. The seals represent a by-development from the main line of the carnivora, a third defection, and a comparatively recent one, from land faunas. Seals live at the meeting of the land and the waters rather than in or on the waters, as do the cetaceans and sirenians. They have retained their fur and their four limbs, but have almost lost their power of land locomotion by the conversion of their feet into flippers. The two front-limbs of seals are the only ones used as ordinary limbs are used. The hind-limbs in most seals stretch permanently out behind, the webbed digits spreading out fan-shaped on either side of the stumpy tail, and constituting a rowing apparatus functionally homologous with the tail of fishes and whales. According to Jordan, the fur seals and the hair seals are descended from different families of land carnivora, the former probably from the bears, and the latter from the cats.
The lemurs are of especial interest to human beings, because in them are found the first startling approximation in looks and structure to the ‘human form divine.’ The lemurs are monkey-like creatures living in trees, but differ enough from true monkeys to be often placed in an order by themselves. Their milk glands are abdominal instead of pectoral, as in the monkeys, and the second digit of each hand and foot ends in a claw. The most of them live in Madagascar. They are generally nocturnal in their habits, although some species are diurnal. They appear first in the Eocene rocks, and Haeckel thinks they may have developed from opossum-like marsupials in the late Cretaceous or early Eocene Age.
From lemurs or from some other similar sort of semi-apes developed the true apes—the flat-nosed (platyrhine) apes of the New World and the narrow-nosed (catarhine) apes of the Old World. There is considerable difference between the New World apes and those of the Old World. The differences between the two classes is, in fact, so striking that they are thought by some to have developed independently of each other from distinct species of semi-apes. The apes of the New World have flat noses, and the nostrils are far apart and open in front of the nose, never below. The Old World apes have narrow noses, the nostrils being close together and opening downwards as in man. The tail of (nearly) all New World apes is prehensile, being used regularly as a fifth limb, while among Old World apes the tail is never so used. The Old World apes all have the same number and kinds of teeth as man has, while the New World apes (excepting the Brazilian marmosets) have an additional premolar in each half-jaw, making thirty-six in all. The catarhine apes are, therefore, structurally much nearer to man than their platyrhine cousins. All tailed apes probably sprang originally from a single stirp of semi-apes, and spread over the earth at a time when the eastern and western land masses of the southern hemisphere were connected with each other. The earliest remains of apes appear in the Miocene Age.
From the Old World tailed apes were developed the tailless, man-like, or anthropoid apes—the gorillas and chimpanzees of Africa, and the orangs and gibbons of Asia and the East Indies. The anthropoids arose from the tailed apes by the loss of the tail, the thinning of the hairy covering, the enlargement of the fore-brain, and by structural adaptations to a more nearly vertical position. No remains of anthropoids are found earlier than the Pliocene Age.
The man-like apes are the nearest living relatives of the human races. It is not probable that man has been derived directly from any of the existing races of man-like apes. For no one of them in all particulars of its structure stands closer to him than the rest. The orang approaches closest to man in the formation of the brain, the chimpanzee in the shape of the spine and in certain characteristics of the skull, the gorilla in the development of the feet and in size, and the gibbon in the formation of the throat and teeth. The earliest human races probably sprang from man-like races of apes now extinct, who lived in southern Asia or in Africa during the Pliocene Age (possibly as early as the Miocene), and who combined in their structures the various man-like characters possessed by existing anthropoids.
The earliest races of men were speechless—the ape-like ‘Alali’—beings, living wholly upon the ground and walking upon their hind-limbs, but without more than the mere rudiments of language. The vertical position led to a much greater development of the posterior parts, especially of the muscles of the back and the calves of the leg. The great toe, which in the ape is opposable, lost its opposability, or all except traces of it, after the abandonment of arboreal life. It must have been a sight fit to stir the soul of the most leathern, these children of the night, with low brows, stooping gait, and ape-like faces, armed with rude clubs, clothed in natural hair, and wandering about in droves without law, fire, or understanding, hiding in thickets and in the holes of the earth, feeding on roots and fruits, and contending doubtfully with the species around them for food and existence.
From the ‘Alali’—the speechless ape-men—we may imagine the true men to have evolved—talking men, men with erect posture and mature brain and larynx, the woolly-haired ulotrichi and the straight-haired lissotrichi. There are four existing species of woolly-haired men: the Papuans of New Guinea and Melanesia, and the Hottentots, Caffres, and Negroes of southern, equatorial, and north central Africa respectively. They all have long heads, slanting teeth, very dark skin, and black, bushy hair, each individual hair in cross-section being flat or oval in shape. In the straight-haired races the skin is much fairer than in the woolly-haired races, being seldom darker than brown, and each individual hair in cross-section is round like the cross-section of a cylinder. The principal species of straight-haired men are the sea-roving Malays of the East Indies and the Pacific, the round-faced Mongols of eastern and northern Asia, the aboriginal Americans of the western hemisphere, and the incomparable Aryans, including the ancient Greeks and Romans and the modern peoples of India, Persia, and Europe.
Man is to-day the pre-eminent animal of the planet. The successive ascendancies of the Worm, the Mollusk, the Crustacean, the Fish, the Reptile, and the Mammal, are followed triumphantly by the ascendancy of the Children of the Ape.
A large part of the life of the earth has remained steadfastly where it was cradled, beneath the waves. But more restless portions have left the sea and crept forth upon the land, or swarmed into the air. One migration, the most numerous, is represented by the insects. Another, the most enterprising, was the amphibian. After ages of evolution the amphibian branch divided. One branch acquired wings and sailed off into the air. The other divided and subdivided. One of these subdivisions entered the forests, climbed and clambered among the trees, acquired perpendicularity and hands, descended and walked upon the soil, invented agriculture, built cities and states, and imagined itself immortal. Human society is but the van—the hither terminus—of an evolutional process which had its beginning away back in the protoplasm of primeval waters. There is not a form that creeps beneath the sea but can claim kinship with the eagle. The philosopher is the remote posterity of the meek and lowly amoeba.
[1.] See ‘Genealogy of Animals,’ at the end of the chapter.
[2.] See table of geological ages, at the end of the previous chapter.
