The Evolution Hypothesis and Its Geological Record

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The Evolution Hypothesis and the Geological Record

Its ROBERT C. WEBU

[The fifth of a scries of articles written for the Era by the author, on allied subjects. Each article is complete in itself, but students should read the whole series. Editors.]

The arguments for organic evolution drawn from the succes sioii in time of the appearance of organic types, and from embryology, as setting forth, as is claimed, a "recapitulation" of the ancestral history of the individual, are, apparently, the best reasoned of the entire five heads of "evidence." The fact, so often indicated, that the geological record shows a certain succession in life-forms, from those comparatively "low" in the scale, to those "highest" and most elaborated, may be held to indicate that the "higher" forms appeared actually later in time than the "lower," although, whether by so many successive "special creations," as was argued by Agassiz and his "school," by a process of derivative descent, or in some other manner, is really as much of an open question now, as in the earliest days of geological science. This may seem like a foolish and indefensible statement, but when we consider the fact, already indicated, that the bulk of the so-called "evidences of variation" suggest rather real degradations of special organs, as in the cases of horses and whales, for example, the evolutionary significance of the apparent succession of life-forms, from "lower" to "higher," as argued from the rock records, is not so clear. In fact, a careful examination of the conditions involved quickly demonstrates the conclusion that the facts are incapable of supporting the Spencerian hypothesis of organic evolution, except in a very general sense, by inference, and by a certain not overwhelming percentage of the facts. In the first place, the geological record does not establish the conclusion that there was a gradual ascent from the simplest lifeforms to the more complex. Although the fossils found in the lowest and earliest formations indicate that the prevailing types in regions where sedimentary rocks were being deposited were, first mollusca, second low arthropods, third ganoid fishes, none of them distinctly in the very lowest ranges of organism, there is no direct conclusive evidence that the prevailing life-forms of still earlier periods represented still "lower" types, from which those in the Silurian rocks were, presumably, derived by natural descent. Consequently any conclusions in the premises, apart from obvious

128 IMPROVEMENT ERA deductions from established facts, are mere inferences and suppositions, and not even "circumstantial evidences." There is found, to be sure, in a serpentine marble of the Laurentian (Eozoic) formations of Canada, what several authorities have concluded to represent the remains of a species of rhizopod i I'rotozoon), and have called Eocoon ("dawn animal"), as indicating, perhaps, "the earliest known form of animal life." But whether or not Eocooii is really a fossil remnant, as some have strongly doubted, the presence of very extensive deposits of marble, graphite and iron ore in the same formations strongly suggest the contemporaneous existence of other, and, perhaps, more ad- — vanced forms of organism the marble and graphite indicating the existence of mollusca or coral-builders (Anthozoa) and vegeta- — tion, respectively the graphite (carbon) being in such quantities as to suggest a vegetation as plentiful and long continued as that of the Carboniferous Age while the iron ore, according to the ;

conclusions of many geologists and chemists indicates merely ancient "bog-iron" deposits, resulting from the deoxidizing action of vegetable organisms. In these cases, of course, subsequent metamorphosis of the rocks must have eliminated all traces of fos'sil remains. Consequently, we have no data on their character or relative position in the scale of life. In the second place, the geological record is necessarily and inevitably incomplete in life forms, a fact which has been sufficiently heralded by evolutionists, who argue that, were the record "complete," all "missing links," all "breaks in the chain" of life development, must infallibly have been recorded. The incompleteness of the record indicates, however, other, and perhaps as important considerations to the scientific investigator. Thus, the popular assumption that geology has demonstrated the earliest life-forms to have been marine, with the inference that land forms must have been derived from them by variation, is a clear presumption on the facts. Without referring to the immense improbability that a true water-dweller could ever have been modified into a true land-dweller, we must insist that the rock records tell us nothing whatever regarding the existence or non-existence of land forms contemporaneous with the earliest recognized marine deposits. And this must be held true for two very excellent reasons : first that sedimentary rocks, which are the only ones containing the fossil remains of organic forms, are deposited only on sea bottoms, lake bottoms, at the mouths of rivers, as bogs, or along ocean shores, where the breakers pound the primeval rocks into sand, which is later deposited in beds, eventually becoming rock second, that no remains of land animals can occur ;

as fossils in a rock deposit, unless representing individuals that have been drowned or devoured by water-dwelling carnivores, who have dropped the bones on the bottom. Consequently, there

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isno inevitable necessity which would compel the presence of land remains in the rocks of any period, except under the general conditions specified. Now, regarding the conditions in which we should logically expect to find the remains of land animals plentiful in the rocks, we may say that they should be fulfilled when there exist highstanding land areas, filled with lofty mountains and elevated hills and plateaus, such as would form the abundant water-sheds of large and strong-flowing rivers. The rivers afford constant opportunity for carrying the bodies of land animals and plants, and depositing them at their mouths, or in the seas or lakes into which they empty, thus insuring some record in the forming rocks. But what does geology say of this? It certainly records that the earliest lands, those at least existing above sea level during the Paleozoic Time, were, on the whole, low-lying, with few lofty elevations, consequently few large and powerful streams to carry terrestrial remains, if any, and leave them in the sedimentary deposits. Indeed, so characteristic is such a land configuration of this ancient time that geologists have accepted as an established principle that the lower ranges of mountains are regularly the oldest in upheaval, while the loftier elevations are of comparatively recent occurrence. This fact alone should account for the absence of land forms in the Paleozoic rocks, before the Carboniferous Age, except for the few reported remains of scorpions, etc., in the upper Silurian. The remains of land snails, insects, centipedes, etc., occur often in the Carboniferous formations, when the deposits were formed largely from land plants growing in bogs — mostly cryptogams of the fern, and allied typss which were utterly different in character from the marine vegetable life of the lower deposits. The scattered and occasional remains of true land dinosaurs (reptiles) have been reported in the Permian rocks of the upper Carboniferous. Nor are there any suggestions of "in- termediate forms," either plant or animal, previous to this stage. The higher land animals appear, geologically, for the first time in the Triassic and Jurassic formations of the lower Mesozoic, when quite a different configuration of the dry land had already been established. With the close of the Paleozoic Time occurred an immense upheaval, in course of which the Appalachian range of eastern North America, as well as most of the Rocky Mountain system, on the west, came into existence. With the establishment of these vast water-sheds, remains of land animals become in- creasingly more common in the fossil-bearing rocks. The inevitable conclusion is, that, whether or not land life existed in the Paleozoic Time, it is perfectly evident that we have a good explanation for the fact that there are no traces of land forms in the lower measures, also for their presence in the later deposits. Even Professor Huxley strongly inclines to similar lines of expla-

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130 IMPROVEMENT ERA nation when he states deliberately (Paleontology and the Doctrine of Evolution) that all genera of life forms must be assumed to be ,

far older than would be supposed from the date of their first known appearance as fossils in the rocks. In another point, also, the "evidential value" of the rock records has been largely overestimated, and this lies in the fact that the earlier deposits were made, evidently, in comparatively shallow waters, leaving us no information as to the forms of life existing in greater depths of ocean, if there were such. The prevailing, or characteristic, life-forms of the shallower seas, therefore, furnish the principal records recognized as of this time. However, there must have been a steady and long-continued subsidence of the sea bottom in some areas, to compensate, perhaps, the rise of dry land in others, throughout the entire Paleozoic Time, as we may assume to explain the extreme thickness — depth of the deposits containing the remains of its life-forms. Indeed, if we assume that the same thickness of rock in any two geological "regions" indicates, even approximately, a corresponding rate of deposit, it may be said that, judging on this standard, the Paleozoic formations represent over two-thirds of all geologic time nor does this estimate make account of the vast deposits of :

metamorphic rock, which, by the theories of many geologists, represent still older sedimentary deposits, whose original character has been obliterated by the action of heat and other natural forces. But the characteristic marine life-forms of the Silurian, or lower Paleozoic, — fixed molluscs and arthropods, in the main, with fncoids and a few corals — certainly indicate that the portions of the sea inhabited by them were very shallow since in none of ;

these forms do we recognize deep-sea dwellers. Thus, with the slow, but steady subsidence of the sea bottom, as shown in known deposits, there were probably formed vaster depths in other, and perhaps unknown, areas of ocean, before the close of the Silurian formations. Whether the deposits formed in such regions are represented by some formations containing deep-sea life-forms, which have usually been supposed to be of later origin, because superposed on the former rocks, we cannot undertake to determine. The fact remains, however, that we have positively no assurance of more than the few beginnings of knowledge of the total conditions of early geologic life, or of the seas, islands or continents, in which it was manifested or of the forms in which ;

it must have appeared. It remains true, however, that such known forms as have persisted to the present time have come down practically unchanged; also that such extinct life-forms as trilobites. which, as frequently indicated, resemble embryonic stages of modern crustaceans, have never seemed to advance toward a "cosmic maturity" — they disappear suddenly at the close of the Paleozoic Time.

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Any further consideration of the geological record establishes the conclusion that the arguments in favor of Spencerian evolution are progressively weakened. In the first place, and nearly fatal to the theory it must seem, we find no evidences worth recording of series of small changes through immense periods: the newer forms of organism, as a rule nearly invariable, appear suddenly, and without preliminary warnings or preparations. In the second place, such upward-moving variations as have been supposedly established are of the most immaterial description, as is admitted by candid writers, Huxley among them, who may claim intimate acquaintance with the facts. Such conditions seem strange, if not positively destructive to the hypothesis that the geological record is really a record of progress from the relatively lower and simpler forms, to the highest and most complex. In his notable address before The Geological Society in 1871, Professor Huxley makes the following statements

"I stated (speaking on a previous occasion) that geographical provinces, or zones, may have been as distinctly marked in the Paleozoic Epoch as at present; and those seemingly sudden appearances of new genera and species, which we ascribe to new creations, may be simple results of migration. * * * "One of the latest pieces of foreign intelligence which has reached us is the information that the Austrian geologists have, at last, succumbed to the weighty evidence which M. Barrande has accumulated, and have admitted the doctrine of colonies. But the admission of the doctrine of colonies implies the further admission that even identity of organic remains is no proof of the synchronism of the deposits which contain them. * * * " * * * At the epoch of the Trias, therefore, the Marstfpialia must have already existed long enough to have become differentiated into carnivorous and herbivorous forms. But the Mnnotremata are lower forms than the Didclphia, which last are intercalary between the Ornithodelphia and the Monodclphia. To what point of the Paleozoic Epoch, then, must we, upon any rational estimate, relegate the origin of the Monotremata? "The investigation of the occurrence of the classes and of the orders of the Sauropsida in time points in exactly the same direction. If as there is good reason to believe. tr"e Birds existed in the Tnassic Epoch the ornithoscelidous forms by which Reptiles passed into Birds must have preceded them. Tn fact there is, even at present, considerable ground for suspecting the existence of Dmosauna in the Permian formations; but, in that case, lizards must be of still earlier date And if the very small differences which are observable between the CrocodiVa of the older Mesozoic formations and those of the present day furnish any sort of approximation toward an estimate of the average rate of change among the Sauropsida, it is almost appalling to reflect how far back in Paleozoic times we must go, be- hope arrive at that common stock from winch the fore we can to Ornithoscelida, and Pleswsauna, which had atCrocodilia, Lacertilia, Epoch, must have been tained so great a development in the Tnassic

^""The Amphibia and Pisces tell the same story. There is not a which, when animal, first appears, is it .ingle class nf vertebrated

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132 IMPROVEMENT ERA represented by analogues of the lowest known members of the same class. Therefore, if there is any truth in the doctrine of evolution, every class must be vastly older than the first record of its appearance upon the surface of the globe. But if considerations of this kind compel us to place the origin of vertebrated animals at a period sufficiently distant from the Upper Silurian, in which the first Elasmobranchs and Ganoids occur, to allow of the evolution of such li-lics as these from a Vertebrate as simple as the Amphioxus, I can only repeat that it is appalling to speculate upon the extent to which that origin must have preceded the epoch of the first recorded appearance of vertebrate life." Paleontology and the Doctrine of Evolution.

There was evidently an element of "firm faith" in the constitution of Professor Huxlev. which enabled him to believe in his pet hypothesis, precisely after the manner of a religious fanatic, even after he has catalogued enough difficulties in its way to convince any logical mind that his conclusions are far from obvious. Thus, the migrations which, as he formerly held "may" have taken place, he supposes at this writing to have been established by "the weighty evidence which M. Barrande has accumulated" to argue to "the doctrine of colonies." But, as must be evident, any such doctrine merely seeks to evade the fact that there is no evidence of preparatory variations before the sudden appearance of a new type, by the unmitigated assumption that such must have taken place elsewhere, and that in the case of every known record, evidently. We may fully admit the truth of the colonies doctrine in any number of cases — since M. Barrande has accumulated so — much "weighty evidence" but when it is invoked, repeatedly and constantly to explain the presence of life-forms, assumed to — have been evolutionally developed elsewhere, and the scenes of this supposed variation process never seem to be fully identified it is certainly sadlv overworked and all for the mere purpose of :

avoiding the suoposed alternative of immediate "special creation," which is so often ridiculed by "scientists." When invoked, as above, to "explain" the absence of "intermediate forms" in the case of land animals, we cannot contradict it. of course, but, when — used to exnlain the same fact in r°gard to fishes, etc., the evolution nf Elasmobranchs and Ganoids "from a vertebrate as simple as the Amphioxus," for example — the absurdity of the process of reasoning need not be pointed out, when we consider the conditions under which organic remains are preserved in sedimentary rocks as previously explained. Proceeding, however, to discuss the statements made in a former address, Huxley states that "If we confine ourselves to positively ascertained facts, the total amount of change in the forms of animal and vegetable life, since the existence of such' forms is recorded, is small When compared with the lapse of time since the first appearance of these forms, the amount of change is wonderfully small. Moreover, in each great group of

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the animal and vegetable kingdoms, there arc certain forms which i termed persistent types, which have remained, with but very little apparent change, from their first appearance to the present time. In answer to the question, 'What, then, does an impartial survey of the positively ascertained truths of paleontology testify in relation to the common doctrines of progressive modification, which suppose that modification to have taken place by a necessary progress from more to less embryonic forms, from more to less generalized types, within the limits of the period represented by the fossiliferous rocks?' I reply, 'It negatives these doctrines; for it cither shows us no evidence of such modifications, or demonstrates such modification as has occurred to have been very slight; and as to the nature of that modification, it yields no evidence whatsoever that the earlier members, of any long-continued group were more generalized in structure than the later ones.'" He then proceeds to qualify his former statements on these points by a line of arguments, whose sufficiency may be judged by any candid reader, as follows "So far, indeed, as the Invcrtebrata and the lower Vertebrate are concerned, the facts and the conclusions which are to be drawn from them appear to me to remain what they were. For anything that, as yet. appears to the contrary, the earliest known Marsupials may have been as highly organized as their living congeners; the Permian lizards show no signs of inferiority to those of the present day; the Labyrinthodonts cannot be placed below the living Salamander and Triton; the Devonian Ganoids are closely related to Polyptcrus and Lcpidosircn. "But when we turn to the higher Vertebrata, the results of recent investigations, however we may sift and criticize them, seem to me to leave a clear balance in favor of the doctrine of the evolution of living forms one from another. Nevertheless, in discussing this question, it is very necessary to discriminate carefully between the different kinds of evidence from fossil remains which are brought forward in favor of evolution. "Every fossil which takes an intermediate place between forms of life already known, may be said, so far as it is intermediate, to be evidence in favor of evolution, inasmuch as it shows a possible road by which evolution may have taken place. But the mere discovery of such a form does not, in itself, prove that evolution took place bv and through it, nor does it constitute more than presumptive evidence in favor of evolution in general. Suppose A, B, C, to be three forms, while B is intermediate in structure between A and C. Then the doctrine of evolution offers four possible alternatives. A may have become C by way of B; or C may have become A by way of B; or A and C may be independent modifications of B; or A. B, and C may be independent modifications of some unknown D. Take the case of Pigs, the Anohlotheridae and the Ruminants. The Anoplotheridae are intermediate between the first and last; but this does not tell us whether the Ruminants have come from the Pigs, or the Pigs from Ruminants, or both from Anoplotheridae, or whether Pigs, Ruminants, and Anoplotheridae alike may not have diverged, from some common stock. "But if it can be shown that A, B, and C exhibit successive stages in the deerree of modification, or specialization of the same type; and if. further, it can be proved that thev occur in successively newer deposits. A being in the oldest and C in the newest, then the intermediate character of B has quite another importance, and T should accept it. without hesitation, as a link in the genealogy of C.

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134 IMPROVEMENT ERA I should consider the burden of proof to be thrown upon any one who denied C to have been derived from A by way of B, or in some closely analogous fashion; for it is always probable that one may not hit upon the exact line of filiation, and, in dealing with fossils, may mistake uncles and nephews for fathers and sons." Ibid.

Of course, the lecture in which these passages occur was delivered over forty years ago, and the science of paleontology has made great progress in the mean time. It is an important document, however, as showing the confidence with which the evolution — hypothesis was urged, even with "defective evidence" quite as confidently as at the present. It is also valuable as a study, since Huxley was undoubtedly an honest man, and, apart from the inevitable mental bias, due to his "convictions," also a good logician. In spite of all the advances made since his day, the general conditions remain about the same as stated above. The greater percentage of sunno^ed "links" and "evidences" are still drawn from the tvpes of the higher vertebrates, and the larger proportion o+* these, in turn, are nreciselv what Huxley would have called "intercalary tvoes." Thev admit of inference and presumption, to be sure, but not of sufficientlv complete "demonstration" to warrant the corollaries so nlentifully drawn from the variation, supposedly established by them. Another matter which is quite often forgotten in this connection is that, while pigs, ruminants and Anoplothcridac may represent so many "stations" in a line of constant variation in form and function, which may be held to be established (for the sake of argument, if nothing more), the bearing of such examples of modification, like that of the horses from their supposed five-toed ancestors, is not immediate upon the Spencerian hypothesis of organic evolution from the simplest possible form of living organism to the most complex. They example merely that there is such a thing as variation in nature or, at least, that we may assume that there is —and leaves us at a very long distance away from any idea of the origin of life on earth, or even of the genus, order, family or class in which the examples of variation are assumed to have occurred. In fact, even admitting all the variations that zoologists and paleontologists claim to have demonstrated, the process by which they attempt to place them in line on the "upward road" of organic evolution is logic, and not natural science. We find our evolutionists, accordingly, still arguing, with Huxley, as to what "might" or "may" have happened, but still furnishing very defective "proof" of the. main contention of organic evolution of the Spencerian type. They also fail to remember that their "doctrine," in all its essential features, was propounded before most of the facts and alleged facts were known, and that the best of them are still using the arguments originated, apparently, by Robert Chambers (in his Vestiges of the Natural History of Creation) in 1845.