Part 2
Assuming, then, that the earth was in a state of incandescence when it began to take a definite form, we shall at once see that the denser materials composing it would gravitate towards the centre, forming a semi-plastic mass surrounded by an envelope of gases and watery vapour. The gases would be quickly disposed of in various chemical combinations, and the watery vapour would be condensed and deposited in depressions on the surface of the central mass as soon as it had become cooled sufficiently. The outer crust of this central, semi-solid mass was soon converted, under the intense heat, into a hard, granite-like rock, which was continually subject to sudden upheavals, resulting partly from the violent escape of gases, and partly from water passing through fissures on the surface to the heated interior and giving rise to steam of great expansive power. In this manner great inequalities of the surface were, no doubt, produced, whose rugged edges, after the lapse of a vast period of time, were gradually softened down by the subsequent action upon them of air and water. This first rock formation is termed by geologists the Plutonic (from Pluto, monarch of hell), on account of its being the result of intense heat, and not, as is the case with all other rock formations, laid down in layers by water. Whether the Plutonic rock forms a solid centre to our earth is matter of uncertainty; but all are agreed that the internal heat of our planet, whether caused by the friction of the particles of a solid substance or by a molten fluid, is still, even in these later times, intense. In boring through the earth’s crust, the average increase in temperature for every fifty feet of descent, after the first hundred feet from the surface, is one degree Fahr., which would give us, at a depth of 125 miles, sufficient heat to melt most of the rocks. This intense internal heat has generated, in times long gone by, enormous forces, by which rocks of all ages have been raised and depressed, twisted and distorted, broken and forced out of position, and forcibly compressed, so as to eventually cause most important changes of surface level.
The next class of rock-formation is totally different from the Plutonic, or unstratified series, in that it is the result of the wear and tear of the surface when acted upon by air and water, and is laid down, in the first instance, by water, as sediment. Water, in the forms of seas, rivers, rain, and ice, has been the chief agent in the arrangement of all the stratified rocks, the determination of the earth’s contour, the direction of valleys, and, in fact, the regulation of the whole physical geography of the visible portion of the earth. With the help of this mighty agent, so soon as the earth had become sufficiently cool to permit condensation to take place in its vapoury envelope, the ceaseless wear and tear of the Plutonic—and, subsequently, of all other—rocks, which has accumulated so vast a mass of material, commenced. Large volumes of water were gradually deposited, without intermission, until permanent seas and rivers had become established, and the new process of stratification, which was henceforth destined to shape the crust of the earth and to provide the conditions of life, commenced to operate. This action is taking place daily in rivers and seas, as we may observe at any time. On the tops of mountains the same action is in operation, though under different conditions, snow and ice splitting fragments from the rocks to be borne away as grit into the valleys by impetuous torrents and deposited in other places. Within the Polar circles ice on a grander scale is levelling down the land; glaciers, covering thousands of square miles, are slowly sliding down the valleys, grinding their surfaces still deeper—forming sands, clays, and gravels, and forcing these down to the sea-shore; and icebergs, many miles in circumference, are carried by currents along coasts and against cliffs like huge ploughs, completely altering the face of the rocks beneath. This wear and tear results in the formation of immense quantities of detritus, which is deposited in layers at the bottom of seas and rivers, and consolidated by pressure, being frequently assisted by lime, iron, or silica as a cement. The coarser-textured rock has been laid down in rapidly-moving, shallow water; and the finer-textured in still, deep water. Thus, through many long ages—probably millions of years—the surface of the earth underwent continual change from the constant deposition of stratified rock, each layer of which completely buried beneath it the various life forms of the previous period, which circumstance enables us to ascribe to the various members of the animal and vegetable kingdoms particular geological periods; for fossilised remains of animals and vegetables have been unearthed in the different layers of the stratified rocks, conclusively proving their existence on the earth at those periods.
In the Plutonic or unstratified rock-formation period there was, of course, no life upon the earth, the conditions necessary for such development not being present; but in the very earliest of the stratified formations we find evidence of the dawn of marine life, both vegetable and animal. Geologists have divided the stratified rock into three chief divisions, the Palæozoic (ancient life), or Primary; the Mesozoic (middle life), or Secondary; and the Kainozoic (latest life), or Tertiary. Each of these, again, has been subdivided into smaller sections, according to the particular kind of deposit met with, the particular places where the best examples are to be found, or the particular life-forms existing. The Primary, the depth of which is unknown, is subdivided into seven periods—viz.:—
Laurentian, consisting of highly metamorphosed (that is, changed in appearance from the original stratified rock character, owing to its proximity to the molten Plutonic rock) limestone, containing fossil remains of the Foraminifera, some of the first living organisms.
Huronian, consisting of less highly metamorphosed sandstone, limestone, etc., and containing fossil remains of lowly-organised molluscs (soft-bodied organisms).
Cambrian, consisting of slates, sandstones, and conglomerates, and containing fossil remains of sponges, sea-weeds, star-fishes, sea-lilies, lowly shell-fish, marine worms, and the first land plants.
Silurian, consisting of slates, limestones, etc., and containing fossil remains of corals, chambered spiral shell-fish, crabs, sea-worms, and bony plates and scales of a low form of fish.
Devonian, consisting of old red sandstone, shales, and coralline limestone, and containing fossil land plants, fishes, belonging to shark, ray, and sturgeon families, and first fossil insect.
Carboniferous, consisting of mountain limestone, coal, sandstone, ironstone, clays, etc., and containing fossil scorpions, beetles, and amphibians.
Permian, consisting of new red sandstone, marls, magnesian limestones, etc., and containing fossils of true reptiles.
The Secondary division is subdivided into three periods, viz.:—
Triassic, consisting of sandstone, limestone, and clays, and containing fossils of gigantic reptiles and first mammals (small marsupials).
Jurassic, or Oölitic, consisting of limestones, coral rags, clays, and marls, and containing fossils of bird-reptiles and several species of marsupials.
Cretaceous, consisting of clays, sands, soft limestone, and lignites, and containing fossils of new bird-reptiles.
The Tertiary division is subdivided into four periods—viz.:—
Eocene (dawn of recent life), consisting of sandstone, limestone, sands, clays, marls, coral rags, and lignites, and containing fossil equine forms, birds, reptiles, bats, and marsupials.
Meiocene (less recent life), consisting of arctic coal, limestone, sands, clays, and lignites, and containing fossil apes and marsupials.
Pleiocene (more recent life), the white and red crags of Britain, containing fossil apes, bears, and hyenas.
Pleistocene (most recent life), consisting of glacial accumulations of all kinds of earths, and containing fossil remains of apes and men, and implements of stone, bone, and horn, and later still of remains of lake-dwellings, shell-mounds, etc.
These different layers of stratified rocks have not always kept their proper positions with regard to each other in the order they were originally laid down; but, owing to volcanic eruption, have frequently intruded upon each other, so that, at first sight, it would sometimes appear as though the regular order of deposition had not been adhered to; but that this is not so has been made apparent by careful investigation over large areas. The depth of the Secondary and Tertiary is from twenty to twenty-five miles. We see, therefore, that the first life-forms made their appearance as marine organisms in the Laurentian, or first stratified rock period; but whether the animal or the vegetable form first appeared, or whether both were developed from one primordial organism, it is impossible at present to say. In each successive layer of rock we meet with fossil remains of animal and vegetable life, which steadily develop into more highly organised forms, through the different periods, until, at last, they assume the exquisite phases we now behold around us. The vegetable kingdom was the first to exist upon the land, the first land-plant being found in the fossil state in the Cambrian layer, at the same time that marine animal life was assuming the forms of worms, shell-fish, and star-fishes. In the Silurian period the first vertebrate animals made their appearance in the form of lowly-organised fishes, from which, in the Carboniferous age, developed amphibious creatures, the first breathing animals, living both in and out of water, and the progenitors of the large kingdom of land animals, including man.
Now, if we take the pedigree of man, as arranged by Darwin and Haeckel, and compare it with this geological tree, we shall see how perfectly the sister sciences of Paleontology and Biology corroborate each other. The first form of life, says Haeckel, was the Moneron, a structureless albuminous atom of bioplasm, not even possessing the structure of a mere cell. We place this, which belongs to the primitive order Protozoa, in the Laurentian period, where we are told by geologists that fossil foraminifera have been found. This promordial organism gradually developed into single nucleated cells, called Amœbæ, and these again into masses of nucleated cells, called Synamœbæ. These simple and multiple cell organisms we place in the next period, Huronian, in the strata of which geologists tell us have been found fossil remains of lowly organised molluscs, or soft-bodied animals. Ciliata are the next forms of life, which consist of Synamœbæ, covered with vibratile cilia. These gradually developed a mouth, becoming Gastrœada, and afterwards Turbellaria, a low form of worm (Vermes), with a mouth and alimentary canal; and are placed in the Cambrian period, in which stratum have been found remains of this kind of life. The ascent continues through the transition stage of Scolecida to Himatega, or sack-worms, with their rudimentary spinal cords; from which gradually evolved Acrania, or the first vertebrate animals, without skulls, brains, central heart, jaws, or limbs; but with a true vertebral cord. This peculiar little animal was a lancet-shaped marine worm, akin to the lancelet or amphioxus of to-day. From these developed Monorrhini, or vertebrate hybrid worms and fishes, with skull, brain, and central heart, but no sympathetic system, jaws, or limbs, and with a single nasal cavity (lampreys). These three forms are placed in the Silurian period, in which stratum have been found fossilised bony plates and scales of fishes and Annelides, or sea-worms.
The next forms of life to be developed, from the Monorrhini, were the Selachii (Amphirrhini), or true fishes, of the shark family, with two nasal cavities, swim-bladder, two pairs of fins, and jaws. From these evolved the Ganoidei, and thence all osseous fishes; and Dipnoi (mud fish), or hybrid fishes and amphibians, with both gills and lungs. These little animals live during winter in water, when they breathe air dissolved in water through their gills; and during the summer in mud, when they breathe with their lungs. Both these are placed in the Devonian period, in which have been found fossil sharks, etc. The next forms are Sozobranchii, or amphibians with persistent gills, from which evolved Urodela, or amphibians with transitory gills, but persistent tails, and legs; allied to the salamander. These are placed in the Carboniferous period, in which have been found fossilised amphibians. We next get Protamnia, or hybrid salamanders and lizards (frogs and toads), with no gills or tails, but possessing an amnion and cloaca. These represent the parent forms of the three great higher branches of vertebrates—Reptilia, Aves (which evolved from reptiles), and Mammalia, and are placed in the Permian period, in which have been found fossilised amphibians and true reptiles. Monotremata (Promammalia) are the next forms developed in our pedigree, the parent forms of the class Mammalia; with cloaca, amnion, and marsupial bones; which are placed in the Triassic period; and from which evolved Marsupialia, mammals with amnion and marsupial bones, but no cloaca; allied to the kangaroo and opossum of to-day. This species we place in the Jurassic and Cretaceous periods. From Marsupialia developed the large kingdom of Placentalia, which lose the marsupial bones and cloaca, and acquire a placenta, and which we divide into three main branches, according to the particular placental formation. The first division we call Villiplacentalia (tufty placenta), from which evolved Edentata (sloth, ant-eaters, and tertiary monsters), Cetacea (marine placental mammals, such as whale, dolphin, porpoise, and sea-cow), and Ungulata (horse, cow, pig, rhinoceros, and hippopotamus). The second division we term Zenoplacentalia (ring-like placenta), the earliest forms of which were Carnaria, or flesh-eaters, from which came Carnivora, or land beasts of prey (cats, dogs, bears, etc.), and Pinnipedia, or marine beasts of prey (seal and walrus). The third division we name Discoplacentalia (discoid placenta); and here we find, as the first development, the Prosimiæ, or tailed lemurs, quadrupeds with claws, and having the appearance of hybrid cats and monkeys. All these are placed in the Eocene period, in which stratum geologists have found fossilised placentals.
From the discoplacental-mammal Prosimiæ evolved the following species—viz., Prosimiæ of Madagascar (lemurs of to-day), with four feet and claws; Cheiroptera (bats); Rodentia (squirrels, mice, porcupines, hares); Insectivora (moles, shrew-mice, and hedgehogs); and Simiæ, or quadruped monkeys, with two feet, two hands, nails, and tails. We divide Simiæ into two classes, the Platyrrhini, or New World apes, with thirty-six teeth, tails, no cheek-pouches or callosities, and nasal cavities pointing outwards and divided by a thick septum (from which came the American howlers, weepers, capuchins, and squirrel-monkeys); and the Catarrhini (Menocerca), or Old World apes, with thirty-two teeth (like man), tails, cheek-pouches, callosities, and nasal cavities pointing downwards and divided by a thin septum (like man). These are placed in the Meiocene period, in which have been discovered the first fossil apes. From the Catarrhini developed the tailed baboons and macaques, with thirty-two teeth, cheek-pouches, and callosities; and the Anthropoidæ, with thirty-two teeth, but no tails, cheek-pouches, or callosities. These were evolved during the Pleiocene period. From the anthropoid (man-like) apes we get three distinct divisions—viz., the gibbon and orang families, with no tails or cheek-pouches, walking partly on hind legs, and wandering in companies in India; the chimpanzee and gorilla families of Africa, with no tails or cheek-pouches, no articulate speech, walking on hind legs only, living in companies in caves, and carrying their babes in their arms; and Alali, or ape-like men, commonly called the “missing links,” who were probably developed, during the Pleiocene period, in Lemuria, a submerged continent which formerly occupied the position of the Indian Ocean; or in the districts of the Nile and Ganges.
These primitive ape-like men were the connecting links between men and the apes, and are divided into two main branches—viz., woolly-haired Alali, who migrated from Lemuria, west and south; and straight-haired Alali, who migrated from Lemuria, north, east, and south. Both these branches had skulls of the same character as those of the chimpanzee and gorilla—that is, they were dolichocephalic (long-headed) prognathous (prominent jaws), and also, like their ape brethren, were troglodytes, or cave-dwellers. From the woolly-haired Alali evolved the Papuans of New Guinea and Tasmania, and the Hottentots of Africa, whose descendants of to-day are but little removed in brain development from the higher apes. They are dolichocephalic prognathous savages, with black, hairy skins, long arms, and short, thin legs, with ill-developed calves; are semi-erect, walk on hind legs, and have no true articulate speech. A higher development of the woolly-haired Alali is the Negro, and higher still the Caffre, both of whom are dolichocephalic prognathous savages, with black, semi-hairy skins, and imperfect articulation. From the straight-haired Alali are derived the Australian natives and the large family of Malays or Polynesians. The Australians migrated south, and were dolichocephalic prognathous savages, with smooth, dirty brown skins, and straight black hair. The lowest tribes of the present day have no true articulate speech. The Polynesians migrated north and east, and were dolichocephalic prognathous troglodytes (as the gorilla and chimpanzee), with clear, smooth brown skins, and true articulate speech. This branch split up into two large families, the Mongolian or Turanian, and the Caucasian or Iranian. The former covered Northern and Eastern Asia, Polynesia, and America, and were originally brachycephalic (broad-headed) prognathous men. They subdivided into two distinct species, the Mongols of China, Japan, Lapland, Finland, and Hungary, who are brachycephalic, but not prognathous, with smooth, brownish yellow skin, and straight black hair; and the Mongols of America, who are mesocephalic (round-headed), but not prognathous, with smooth red skins and straight black hair. The Caucasian family covered Western Asia and most of Europe, being mesocephalic prognathous troglodytes (afterwards agriculturalists) with smooth dark skins and long straight hair; and subdivided into two branches, the Semitic, of Arabia and Syria, and the Aryan or Indo-European; both of whom are mesocephalic, but not prognathous.
It is true that, so far, no fossil remains of Alali have been found, with the exception of the Neanderthal skull; but it is equally true that they may soon be discovered. It is only comparatively recently that the other species have been found fossilised; and it must be recollected that only a very small portion of the earth’s crust has yet been explored, and that not the most likely for finding. No attempts have been yet made to unearth the life-remains in the neighbourhood of the Indian Ocean, where it is believed man first evolved from his ape-like ancestors. It does not, however, seem to me to be essentially necessary that the “missing link” be found in order to substantiate the Evolution theory. There is so little difference between the higher anthropoid apes and man, compared with the enormous differences observed between the earlier forms of life and the ape species, that the sequence and continuity appear now conclusively settled to any reasonable observer. Comparative anatomists and embryologists both declare in favour of the theory of development of Darwin and Haeckel. It is a fact beyond dispute that every human being commences his individual existence as a tiny piece of structureless bioplasm, from which condition he passes through the Amœba stage to the Synamœba, and thence in regular order through each successive stage of development marked in the genealogy given above, becoming worm, fish, and mammal in turn, and finally being born into the world as a member of the human family. Each of these lower forms also passes through all the species preceding it in precisely the same manner. This is one of the strongest arguments in favour of Evolution. It is said that the power of speech possessed by man opposes a strong barrier to the theory; but it has been shown clearly that other animals besides man can use articulate sounds, which convey meanings to each other. Monkeys certainly understand each other’s chattering, and it is highly probable that birds also understand each other’s cries. It is true that the sounds made by animals are chiefly monosyllabic; but philologists now tell us that the languages spoken by primitive races of men are compounded of quite simple elements, perfectly within the grasp of an ape’s voice. Travellers, whose veracity and ability cannot be impugned, have described long conferences held by monkeys, where one individual addressed the assembly at great length, fixing the attention of all upon himself, and quelling every disturbance by a loud and harsh cry, which was at once recognised and obeyed by the multitude. Is it credible that this should be purposeless? Is it not actually the exercise of speech?
Is it not possible—nay, even extremely probable—that, under the irresistible pressure of civilised man, his immediate precursor may have become extinct? All the human races that now tend to bridge the interval between the highest man and the highest ape are fast becoming extinct under this very pressure. The gulf widens, and will widen. The Caribs and Tasmanians have passed away, while the Australians, New Zealanders, aboriginal Americans, Eskimo, and others, are fast following in their wake, and this all in a comparatively short space of time. There is undoubtedly now a far greater physical and mental interval between the Hottentot woman and such men as Gladstone and Darwin than between the Hottentot and an ape. It is a fact beyond dispute that man was not in such a high state of development ages gone by as at present. The earliest traces of man exhibit him to us in the Palæolithic, or old stone, age, as wild and living in caves, using only the rudest stone implements with which to battle with the ferocious monsters around him. His jaw was then prognathous, like the ape, and his body large and powerful.