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Of this gradual spread of new types there should, at least in some cases, be some palæontological evidence.
It is likewise by no means easy to understand how species thus generated could stand solitary and isolated from kindred forms in the records of the earth. The pair of individuals which started a new persistent group, – its members all stamped with the same specific characters, while all around were in a state of flux and divergence, – differed from their immediate ancestors, as we have seen, only infinitesimally. They can have differed no more from many of their contemporaries, for all the lines of descent must ramify afresh in each generation, and so form a web rather than anything like a line. It is not very easy to understand how a pair here and there struck root and founded a species, while the thousands which jostled them round about failed to do so, for the others which survived longest must be supposed to have resembled them most nearly, and therefore to have participated in their advantages. At least, we should expect to find around them the débris of the multitude they vanquished in the struggle for existence.
We are told, moreover, that, with hardly an exception, the organic forms found in a fossil state must be supposed to be the last of their special line of development, which terminated in them; so that neither can they be claimed as the direct ancestors of any other forms, fossil or living, nor can any others which are actually known be claimed as their progenitors. The genealogies supplied for almost all known species, extinct or existing, are admittedly conjectural, and as in the most famous instance of all, namely the supposed common ancestor of simians and men, the links are persistently "missing." Thus M. de Quatrefages, speaking of the human pedigree as set forth by Professor Haeckel, writes thus:247
All species, existing or extinct, are said to have been preceded by ancestral forms which have disappeared without leaving the slightest vestige behind them. The amphioxus itself, which more than any other realizes the type of the group it represents, was preceded, according to Haeckel, by the provertebrate, which no man has ever seen, but of which, nevertheless, the Jena professor gives us a figure, and describes the anatomy.
Thus the number of forms postulated by the theory of genetic Evolution, must have been enormous beyond conception, in comparison with those belonging to the numerically insignificant groups which formed the mere extremities of branches on the genealogical tree.
This being premised, we must ask what Geology has to tell us on the subject, and it will be well to begin by briefly recalling the main features of the geological record.
The stratified rocks comprising the crust of the earth, in which fossil plants and animals are found embedded, have evidently been formed at successive periods, chiefly by the agency of water, each formation having begun as a sediment like the mud or ooze at the bottom of our oceans and seas. Geological investigation has proved that the chronological order of the strata thus deposited can be satisfactorily determined, and they are found to divide themselves, in respect of the organisms they contain, into three great series, lying above the Azoic (or lifeless) rocks, older than them all.
These series, beginning from the bottom, in which order we shall have to trace their history, are most conveniently named Primary, Secondary, and Tertiary, otherwise termed respectively, Palœozoic ("ancient life"), Mesozoic ("middle life"), and Kainozoic ("recent life"). Each of these again, contains various formations, or as we may call them volumes of its chronicle, each of which has its fixed place in order of sequence.
Thus, always proceeding from below upwards, in the Primary series, commencing with the Laurentian, we find successively the Huronian, Cambrian, Silurian, Devonian or Old Red Sandstone, Carboniferous, and Permian.
In the Secondary, the lowest formation is the Triassic or New Red Sandstone, followed by the Jurassic or Oolite, and the Cretaceous or Chalk.
Finally the Tertiary has three main divisions; the Eocene, or "dawn of the recent," Miocene, or "less recent," and Pliocene, or "more recent."
Above these comes the series now in progress, variously called, Quaternary, Post-Tertiary, and Pleistocene, or "most recent."
It seems advisable to begin our investigation with the vegetable kingdom, as its classification being comparatively simple, the essential points of its development are easily followed. We cannot do better than start with the summary of its main divisions furnished by Mr. Carruthers.248
The vegetable kingdom is divided into sections, according to the simplicity or complexity of structure. Associated with plants of simple structure we find, as a rule, more elementary organs of reproduction. Linnaeus made two great divisions, of flowering (Phanerogams) and flowerless plants (Cryptogams)… The higher group have flowers, with their stamens and pistils, which produce seeds, while the lower group are without flowers and bear spores, which are much simpler bodies than seeds. There are seven main groups of spore-bearers – the algæ or water-weeds; the fungi or mushroom family; the lichens, which cover old walls and rocks with patches of coloured vegetation; the mosses with their green leaves and urn-shaped fruit; the ferns with their large and usually much-divided leaves, on the back or edges of which the spores are borne; the horsetails, found in wet places, having jointed hollow stems and spores produced in little cones; and the club-mosses, upright or creeping leafy plants found on our mountains. These seven groups may be arranged in two divisions, according to the tissues of which they are formed. In the first four the whole plant is composed of cells, while in the last three a firm vascular skeleton is present. These characters are of great importance to the student of fossil plants… The flowering plants are more complex in their structure, and in their organs of reproduction. The lowest group of these plants is the Gymnosperms, or naked-seeded plants, like our yews and pines. The other flowering plants (Angiosperms) have their seeds in a closed fruit. These are divided into two sections from characters derived from the embryo plant in the seed, depending on whether this minute plant has one seed-leaf (cotyledon) or two, and so we have Monocotyledons and Dicotyledons. The higher group, or dicotyledons, have been arranged into three divisions, according to the complexity of the flower. In one large group (Apetalae) the pistil and stamens are not surrounded by petals, e.g. in the oak and the stinging nettle: superior to them are the plants (Monopetalae) in which the petals form a cup, as the blue-bell249 and the gentian, while the highest group (Polypetalae) have all the petals separate, as the buttercups and roses.250
It is most important to recollect that on evolutionary principles the first representatives of any such classes – and the same holds of animals as well – must have been generalized forms, representing the type in the rough, or, in Mr. Herbert Spencer's phrase, exhibiting by comparison with their successors indefinite incoherent homogeneity, as contrasted with definite coherent heterogeneity. They should bear the same sort of relation to the finished articles worked up by Evolution as did the first bone-shaker bicycle to our latest patterns, or the news-sheets of Cromwell's time to the Times or Graphic of to-day. On this, as we saw in the last chapter, Mr. Darwin strongly insists, confessing at the same time that the Geological record alone can establish such progress as a fact.
How these various classes of plants appear actually to have come upon the scene, Mr. Carruthers relates both in the paper from which we have just quoted, and at greater length in the address which he delivered as President of the Geologists' Association,251 to the following effect.
In the first place, he declares that although the geological record, at least as known to us, is very imperfect, and represents only an insignificant fragment of plant-history,
There is a large series of plant-remains completely and accurately known which supply a fair representation of the great events of plant-life that have taken place on the earth since Palæozoic times. And these are more than sufficient to establish or destroy this hypothesis [of genetic evolution] by their testimony.
There is – he goes on to say – indirect evidence of the existence of vegetable life, long before we find any actual remains. Such indirect evidence is afforded in the first place by the abundance during this period of animal life, needing plants for its sustenance, and secondly by the enormous quantity of carbon in the rocks, which must have been secreted from the atmosphere by vegetable tissues. There are also certain surface marks or impressions occasionally to be found, which are probably due to plants of a soft and perishable character like the cellular cryptogams, and which although extremely vague and undefined, at least do not contradict the evolutionist, who regards them as evidence that the Algæ were, as according to him they ought to have been, the primeval plants. Mr. Carruthers adds a caution however, which can find its application in other instances as well:
While making this admission in relation to the vegetation of these older rocks, I must protest against the practice of completing the record of life forms, by filling in particular groups without any authority except the writer's impression of an adopted hypothesis, and then basing arguments on these assumptions in support of the hypothesis which created them. So completely has phylogenetic [or racial] evolution become the creed of some leading naturalists that they unwittingly proceed in this manifestly unphilosophical method. But it is a first axiom, though one often forgotten, in this as in every scientific enquiry, that no step can be made in advance which is not based on fact.
After this initial stage, the story becomes much clearer, and at the same time less easy to reconcile with evolutionary requirements.
Instead of making their appearance singly and successively, and passing imperceptibly one into another, all three groups of Vascular Cryptogams, and the Gymnosperms into the bargain, come on the stage together, in the Devonian strata; and Monocotyledons in the lower Carboniferous immediately following. There is no trace whatever of the development of any of these forms from the earlier cellular cryptogams:
But [says Mr. Carruthers] the evolution of the Vascular Cryptogams, and the Phanerogams, from the green seaweeds, through the liverworts and mosses, if it took place, must have been carried on through a long succession of ages, and by an innumerable series of advancing steps; and yet we find not a single trace either of the early water forms or of the later and still more numerous dry-land forms. The conditions that permitted the preservation of the fucoids in the Llandovery rocks at Malvern, and of similar cellular organisms elsewhere, were, at least, fitted to preserve some record of the necessarily rich floras, if they existed, which through immense ages, led by minute steps to the Conifer [Gymnosperm] and Monocotyledon of these Palæozoic Rocks.
Further, these earliest plants are not generalized forms of the various tribes to which they belong, but they are as highly specialized as any subsequent representatives of the particular group to which they belong, and wherever they differ from later plants, it is in the possession of a more perfect organization.
From all which facts Mr. Carruthers thus argues:
The complete absence of intermediate forms, and the sudden and contemporaneous appearance of highly organized and widely separated groups, deprive the hypothesis of genetic evolution of any countenance from the plant-record of these ancient rocks. The whole evidence is against evolution, and there is none for it.252
Dicotyledons furnish evidence of especial value. On account of their higher organization, they are easily distinguished from both Monocotyledons and Gymnosperms; and they present features which clearly differentiate them amongst themselves. They did not make their entry till after a long interval – and their remains are therefore to be found in strata comparatively recent and better known to us than those of the older rocks. It is in the Chalk, the newest of the Secondary or Mesozoic formations, that they first exhibit themselves, and they do it in the same fashion as their predecessors.
When the Dicotyledons appear in the upper cretaceous beds, representatives of the three great groups [Apetalæ, Monopetalæ, Polypetalæ] appear together in the same deposit. Moreover, these divisions are represented, not by generalized types, but by differentiated forms, which, during the intervening epochs, have not developed even into higher generic groups.
And, here again, there is no vestige of intermediate species, linking dicotyledonous plants with other types.
No trace of a plant belonging to this great division has yet been detected in any earlier stratum [than the upper chalk]. There is no evidence whatever for Haeckel's statement that the Apetalæ probably existed in the Triassic and Jurassic periods… It cannot be doubted that the conditions favourable to the preservation of Monocotyledons and Equisetums would have secured the preservation of some of the Apetalæ, had they existed. This absence can be accounted for only on the supposition that they formed no part of the then existing vegetation. And in the deposits older than the Trias, or in any subsequent deposits, no intermediate form has been detected, – no Gymnosperm or Monocotyledon which exhibits in any point of its structure a modification towards the more highly organized Dicotyledon.
Nor, on the same authority, is this all.
It is equally important in its bearing on the hypothesis of genetic evolution that the generic groups above named have persisted from the first known appearance of Dicotyledons, throughout the whole of the intervening ages, and still hold their places unchanged among the existing forms of vegetation. The persistence of generic and specific types, and the certain knowledge we possess of the life of many existing species of Phanerogams and Cryptogams which have come down through the Glacial Epoch, have not been sufficiently considered in their bearing on the hypothesis.
We have already seen something of an example which illustrates this point in a remarkable manner, – that of Salix polaris, the willow which has so obstinately preserved its specific identity amid great stress of circumstances. It belongs to a very variable genus – one in which if anywhere evidence of genetic development might be looked for. Yet it is found that since a period prior to the great Ice Age, or Glacial epoch, it has remained absolutely unchanged. At such a rate, we cannot but ask, how long would Evolution take to get back to the generalized type-form, or common ancestor, of the genus Salix, and then to that of the Order Salicineae, which includes poplars as well as willows. "The Ordinal form, if it ever existed, must necessarily be much older than the period of the upper Cretaceous rocks, that is than the period to which the earliest known Dicotyledons belong."
And it is obvious that when we had got back to the parental stock of the willow tribe, we should still, as evolutionists, be separated by a gulf still vastly greater from the common ancestor of all Dicotyledons, of oaks, apple-trees, primroses, and daisies no less than of willows and poplars.
The significance of all these various facts is thus summed up:
The whole evidence supplied by fossil plants is, then, opposed to the hypothesis of genetic evolution, and especially the sudden and simultaneous appearance of the most highly organized plants at particular stages in the past history of the globe, and the entire absence amongst fossil plants of any forms intermediate between existing classes or families. The facts of palæontological botany are opposed to Evolution, but they testify to Development, to progression from lower to higher types. The cellular Algæ preceded the Vascular Cryptogams and the Gymnosperms of the Newer Palæozoic rocks, and these were speedily followed by Monocotyledons, and, at a much later period, by Dicotyledons. But the earliest representatives of these various sections of the vegetable kingdom were not generalized forms, but as highly organized as recent forms, and in many cases more highly organized: and the divisions were as clearly bounded in their essential characters, and as decidedly separated from each other as they are at the present day.
So much for the vegetable world. As for the animal, although the number and complexity of its divisions makes it less easy to present so complete a sketch in these moderate limits, the features of its history are very similar. As Sir J. W. Dawson recounts it:253
In the Cambrian age, we obtain a vast and varied accession of living things, which appear at once, as if by a sudden and simultaneous production of many kinds of animals. Here we find evidence that the sea swarmed with creatures near akin to those which still inhabit it, and nearly as varied… Had we been able to drop our dredge into the Cambrian or Silurian ocean, we should have brought up representatives of all the leading types of invertebrate life that exist in the modern seas – different, it is true, in details of structure from those now existing, but constructed on the same principles, and filling the same places in nature.
In the latter half of the Palæozoic we find a number of higher forms breaking upon us with the same apparent suddenness as in the case of the early Cambrian animals. Fishes appear, and soon abound in a great variety of species, representing types of no mean rank, but, singularly enough, belonging in many cases to groups now very rare; while the commoner tribes of modern fish do not appear. On the land, Batrachian Reptiles now abound, some of them very high in the sub-class to which they belong. Scorpions, spiders, insects, and millipedes appear as well as land-snails: and this not in one locality only, but over the whole northern hemisphere… Nor do they show any signs of an unformed or imperfect state… The compound eyes and filmy wings of insects, the teeth, bones, and scales of batrachians and fishes; all are as perfectly finished, and many quite as complex and elegant, as the animals of the present day.
This wonderful Palæozoic age was, however, but a temporary state of the earth. It passed away, and was replaced by the Mesozoic, emphatically the age of Reptiles, when animals of that type attained to colossal magnitude, to variety of function and structure, to diversity of habitat in sea and on land, altogether unexampled in their degraded descendants of modern times… Strangely enough, with these reptilian lords appeared a few small and lowly mammals, forerunners of the coming age.254 Birds also made their appearance.
The Kainozoic, or Tertiary, is the age of Mammals and of Man. In it the great reptilian tyrants of the Mesozoic disappear, and are replaced on land and sea by mammals or beasts of the same orders with those now living, though differing as to genera and species. So greatly indeed did mammalian life abound in this period that in the middle part of the Tertiary most of the leading groups were represented by more numerous species than at present, while many types then existing
have now no representatives. At the close of this great and wonderful procession of living beings comes Man himself – the last and crowning triumph of creation the head, thus far, of life on the earth.
It must be sufficient to quote one other remark:255
There is no direct evidence that in the course of geological time one species has been gradually or suddenly changed into another… On the other hand, we constantly find species replaced by others entirely new, and this without any transition. The two classes of facts are essentially different, though often confounded by evolutionists; and though it is possible to point out in the newer geological formations some genera and species allied to others which have preceded them, and to suppose that the later forms proceeded from the earlier, still, as the connecting links cannot be found, this is mere supposition, not scientific certainty. Further, it proceeds on the principle of arbitrary choice of certain forms out of many, without any evidence of genetic connexion.
Having given a tabular view of Geological periods and Life-epochs, similar to those presented above, our author remarks:256
If in the table above we were to represent diagrammatically the development of animals and plants, this would appear not as a smooth and continuous stream, but as a series of great waves, each rising abruptly, and then descending and flowing on at a lower level along with the remains of those preceding it.
And here may be noticed an observation made amongst others by the Comte de Saporta257 on the remarkable parallelism of Animal and Vegetable development. After a period in which these kingdoms were respectively represented by aquatic Algæ and Protozoa, land animals and land plants appear to have come in much at the same epoch; and afterwards dicotyledonous plants immediately preceded the advent of mammals.
Mr. Mivart is of like mind with the others we have heard. "The mass of palæontological evidence," he writes,258 "is indeed overwhelmingly against minute and gradual modification." He points out, with the North British Reviewer so frequently quoted, that had the later forms of life descended from the earlier, through such a series of imperceptible gradations as is imagined, the probability would be that no two fossil specimens would be exactly alike, whereas in fact numbers are found of certain particular patterns, and none whatever between them, fossil animals and plants falling naturally into species, genera, families, and other categories just like those of the present day.
It is this total absence of graduated series, linking different forms together, that is the great and fundamental difficulty in the way of genetic evolution. Yet this seems very seldom to be realized, and it seems constantly to be assumed that in order to establish the genetic continuity of two creatures no more is required than to discover another standing more or less between them. Thus in the most famous of all instances, how often do we hear of "the missing link" between man and ape, – as though should a generalized form be disclosed, which might be considered a common ancestor, the question of man's simian origin would be finally settled. In the same way, as we have seen, the existence of birds with reptilian features, is taken by some as conclusive proof that birds and reptiles have descended from one stock. But what is most imperatively wanted, is persistently wanting, – namely some evidence of a series in which one form passes to another, as in a dissolving view. And yet, genetic evolutionists must suppose such series to have been the universal rule throughout the whole course of life on earth.
Assuredly [writes M. de Quatrefages]259 is it not singularly unfortunate for the evolutionary theory that so many facts which tell against it should have been preserved in the scraps of Nature's great book which remain to us, and that invariably those which would have told in its favour were recorded in lost volumes and missing leaves?
In some particular instances the absence of any trace of intermediate forms is especially significant. The tribe of Bats, for instance, is a very singular one. The wings, in which form the fore-limbs are specialized, represent the same elements as our own hands; and other modifications of the same members have produced the paws of cats and dogs, the hoofs of horses and cattle, and the flippers of whales and porpoises, – to mention no others. What countless hosts of the Bat's ancestors must have lived and died while by accumulation of minute differences the primitive generalized limb whence all these diverse forms originated, was being turned into a wing capable of flight. Yet of all these no vestige is to be discovered. "Whenever the remains of bats have been found," says Mr. Mivart,260 "they have presented the exact type of existing forms." The same, he tells us, holds good of other flying creatures – birds and pterodactyles – (or flying lizards – now wholly extinct). No trace of any of these is forthcoming while their wings were in the making. "Yet had such a slow mode of origin as Darwinians [and genetic evolutionists generally] contend for, operated exclusively in all cases, it is absolutely incredible that bats, birds, and pterodactyles should have left the remains they have, and yet not a single relic be preserved in any one instance of any of these different forms of wing in their incipient and relatively imperfect functional condition!"