As previously stated, the sequence of strata is visible only in regions of outcrop, and nowhere are we able to see more than mere parts of two or, at most, three systems associated together in a single locality. Moreover, each set of beds is of limited areal extent, and the limits are frequently visible to the eye of the observer. In any case, their visible extent is necessarily limited. It is impossible, therefore, to correlate the strata of one continent with those of another continent by tracing stratigraphic continuity. Hence, in comparing particular horizons of various ages and in distinguishing them from other horizons over large areas, we are obliged to substitute induction for direct observation. Scientific induction, however, is only valid when it rests upon some universal uniformity or invariable sequence of nature. Hence, to be specific, the assumption that the time-scale based on the European classification of fossiliferous strata is applicable to the entire globe as a whole, is based on the further assumption that we are sure of the universality of fossiliferous stratification over the face of the earth, and that, as a matter of fact, fossils are always and everywhere found in the same order of invariable sequence.
But this is tantamount to reviving, under what Spencer calls “a transcendental form,” the exploded “onion-coat” hypothesis of Werner (1749-1817). Werner conceived the terrestrial globe as encircled with successive mineral envelopes, basing his scheme of universal stratification upon that order of sequence among rocks, which he had observed within the narrow confines of his native district in Germany. His hypothesis, after leading many scientists astray, was ultimately discredited and laughed out of existence. For it finally became evident to all observers that Werner’s scheme did not fit the facts, and men were able to witness with their own eyes the simultaneous deposition, in separate localities, of sediments which differed radically in their mineral contents and texture. Thus it came to pass that this classification of strata according to their mineral nature and physical appearance lost all value as an absolute time-scale, while the theory itself was relegated to the status of a curious and amusing episode in the history of scientific fiascos.
Thanks, however, to Wm. Smith and to Cuvier, the discarded onion-coat hypothesis did not perish utterly, but was rehabilitated and bequeathed to us in a new and more subtle form. Werner’s fundamental idea of the universality of a given kind of deposit was retained, but his mineral strata were replaced by fossiliferous strata, the lithological onion-coats of Werner being superseded by the biological onion-coats of our modern theory. The geologist of today discounts physicalappearance, and classifies strata according to their fossil, rather than their mineral, contents, but he stands committed to the same old postulate of universal deposits. He has no hesitation in synchronizing such widely-scattered formations as the Devonian deposits of New York State, England, Germany, and South America. He pieces them all together as parts of a single system of rocks. He has no misgiving as to the universal applicability of the European scheme of stratigraphic classification, but assures us, in the words of the geologist, Wm. B. Scott, that: “Even the minuter divisions, the subdivisions and zones of the European Jura, are applicable to the classification of the South American beds.” (“Introduction to Geology,” p. 681f.) The limestone and sandstone strata of Werner are now things of the past, but, in their stead, we have, to quote the criticism of Herbert Spencer, “groups of formations which everywhere succeed each other in a given order, and are severally everywhere of the same age. Though it may not be asserted that these successive systems are universal, yet it seems to be tacitly assumed that they are so.... Though probably no competent geologist would contend that the European classification of strata is applicable to the globe as a whole, yet most, if not all geologists, write as though it were so.... Must we not say that though the onion-coat hypothesis is dead, its spirit is traceable, under a transcendental form, even in the conclusions of its antagonists.” (“Illustrations of Universal Progress,” pp. 329-380, ed. of 1890.)
But overlooking, for the moment, the mechanical absurdity involved in the notion of a regular succession of universal layers of sediment, and conceding, for the sake of argument, that the substitution of fossiliferous, for lithological, strata may conceivably have remedied the defects of Werner’s geological time-scale, let us confine ourselves to the one question, which, after all, is of prime importance, whether, namely, without the aid of Procrustean tactics, the actual facts of geology can be brought into alignment with the doctrine ofan invariable order of succession among fossil types, and its sequel, the intrinsic time-value of index fossils. The question, in other words, is whether or not a reliable time-scale can be based on the facts of fossiliferous stratification as they are observed to exist in the concrete. Price’s answer is negative, and he formulates several empirical laws to express the concrete facts, on which he bases his contention. The laws and facts to which he appeals may be summarized as follows:
1. The concrete facts of geology do not warrant our singling out any fossiliferous deposit as unquestionably the oldest, and hence we have no reliablestarting-pointfor our time-scale, because:
(a) We may lay it down as an empirical law that “any kind of fossiliferous rock (even the ‘youngest’), that is, strata belonging to any of the systems or other subdivisions, may rest directly upon the Archæan or primitive crystalline rocks, without any other so-called ‘younger’ strata intervening; also these rocks, Permian, Cretaceous, Tertiary, or whatever thus reposing directly on the Archæan may be themselves crystalline or wholly metamorphic in texture. And this applies not alone to small points of contact, but to large areas.”
(b) Conversely: any kind of fossiliferous strata (even the “oldest”) may not only constitute the surface rocks over wide areas,[8]but may consist of loose, unconsolidated materials, thus in both position and texture resembling the “late” Tertiaries or the Pleistocene—“In some regions, notably in the Baltic province and in parts of the United States,” says John Allen Howe, alluding to the Cambrian rocks around the BalticSea and in Wisconsin, “the rocks still retain their original horizontality of deposition, the muds are scarcely indurated, and the sands are incoherent.” (Encycl. Brit., vol. V, p. 86.)
A large number of striking instances are cited by Price to substantiate the foregoing rule and its converse. The impression left is that not only is the starting-point of the time-scale in doubt, but that, if we were to judge the age of the rocks by their physical appearance and position, we could not accept the conventional verdicts of modern geology, which makes fossil evidence prevail over every other consideration.
2. When two contiguous strata are parallel to each other, and there is no indication of disturbance in the lower bed, nor any evidence of erosion along the plane of contact, the two beds are said to exhibit conformity, and this is ordinarily interpreted by geologists as a sign that the upper bed has been laid down in immediate sequence to the lower, and that there has been a substantial continuity of deposition, with no long interval during which the lower bed was exposed as surface to the agents of erosion. When such a conformity exists, as it frequently does, between a “recent” stratum, above, and what is said (according to the testimony of the fossils) to be a very “ancient” stratum, below, and though the two are so alike lithologically as to be mistaken for one and the same formation, nevertheless, such a conformity is termed a “non-evident disconformity,” or “deceptive conformity,” implying that, inasmuch as the “lost interval,” representing, perhaps, a lapse of “several million years,” is entirely unrecorded by any intervening deposition, or any erosion, or any disturbance of the lower bed, we should not have suspected that so great a hiatus had intervened, were it not for the testimony of the fossils. Price cites innumerable examples, and sums them up in the general terms of the following empirical law: “Any sort of fossiliferous formation may occur on top of any other ‘older’ fossiliferous formation, with all the physical evidences of perfect conformity, justas if these alleged incongruous or mismated formations had in reality followed one another in quick succession.”
A quotation from Schuchert’s “Textbook of Geology,” (1920), may be given by way of illustration: “The imperfection,” we read, “of the geologic column is greatest in the interior of North America and more so in the north than in the south. This imperfection is in many places very marked, since an entire period or several periods may be absent. With such great breaks in the local sections the natural assumption is that these gaps are easily seen in the sequence of the strata, but in many places the beds lie in such perfect conformity upon one another that the breaks are not noticeable by the eye and can be proved to exist only by the entombed fossils on each side of a given bedding plane.... Stratigraphers are, as a rule, now fully aware of the imperfections in the geologic record, but the rocks of two unrelated formations may rest upon each other with such absolute conformability as to be completely deceptive. For instance, in the Bear Grass quarries at Louisville, Ky., a face of limestone is exposed in which the absolute conformability of the beds can be traced for nearly a mile, and yet within 5 feet of vertical thickness is found a Middle Silurian coral bed overlain by another coral zone of Middle Devonian. The parting between these two zones is like that between any two limestone beds, but this insignificant line represents a stratigraphic hiatus the equivalent of the last third of Silurian and the first of Devonian time. But such disconformities are by no means rare, in fact are very common throughout the wide central basin area of North America.” (Op. cit., II, pp. 586-588.)
In such cases, the stratigraphical relations give no hint of any enormous gap at the line of contact. On the contrary, there is every evidence of unbroken sequence, and the physical appearances are as if these supposed “geological epochs” had never occurred in the localities, of which there is question. Everything points to the conclusion that the alleged long intervals of time between such perfectly conformable, and,often, lithologically identical, formations are a pure fiction elaborated for the purpose of bolstering up the dogma of the universal applicability of the European classification of fossiliferous rocks. Why not take the facts as we find them? Why resort to tortuous explanations for the mere purpose of saving an arbitrary time-scale? Why insist on a definite time-value for fossils, when it drives us to the extremity of discrediting the objective evidence of physical facts in deference to the preconceptions of orthodox geology? Were it not for theoretical considerations, these stratigraphic facts would be taken at their face value, and the need of saving the reputation of the fossil as an infallible time index is not sufficiently imperative to warrant so drastic a revision of the physical evidence.
3. The third class of facts militating against the time-value of index fossils, are what Price describes as “deceptive conformities turned upside down,” and what orthodox geology tries to explain away as “thrusts,” “thrust faults,” “overthrusts,” “low-angle faulting,” etc.[9]In instances of this kind we find the accepted order of the fossiliferous strata reversed in such a way that the “younger” strata are conformably overlain by “older” strata, and the “older” strata are sometimes interbedded between “younger” strata. “In many places all over the world,” says Price, “fossils have been found in a relative order which was formerly thought to be utterly impossible. That is, the fossils have been found in the ‘wrong’ order, and on such a scale that there can be no mistake about it. For when an area 500 miles longand from 20 to 50 miles wide is found with Palæozoic rocks on top, or composing the mountains, and with Cretaceous beds underneath, or composing the valleys, and running under these mountains all around, as in the case of the Glacier National Park and the southern part of Alberta, the old notion about the exact and invariable order of the fossils has to be given up entirely.”
Price formulates his third law as follows: “Any fossiliferous formation, ‘old’ or ‘young,’ may occur conformably on any other fossiliferous formation, ‘younger’ or ‘older.’” The corollary of this empirical law is that we are no longer justified in regarding any fossils as intrinsically older than other fossils, and that our present classification of fossiliferous strata has ataxonomic, rather than ahistorical, value.
Low-angle faulting is the phenomenon devised by geologists to meet the difficulty of “inverted sequence,” when all other explanations fail. Immense mountain masses are said to have been detached from their roots and pushed horizontally over the surface (without disturbing it in the least), until they came finally to rest in perfect conformity upon “younger” strata, so that the plane of slippage ended by being indistinguishable from an ordinary horizontal bedding plane. These gigantic “overthrusts” or “thrust faults” are a rather unique phenomenon. Normal faulting is always at a high angle closely approaching the vertical, but “thrust faults” are at a low angle closely approximating the horizontal, and there is enormous displacement along the plane of slippage. The huge mountain masses are said to have been first lifted up and then thrust horizontally for vast distances, sometimes for hundreds of miles, over the face of the land, being thus pushed over on top of “younger” rocks, so as to repose upon the latter in a relation of perfectly conformable superposition. R. G. McConnell, of the Canadian Survey, comments on the remarkable similarity between these alleged “thrust planes” and ordinary stratification planes, and he is at a loss to know why the surface soilwas not disturbed by the huge rock masses which slid over it for such great distances. Speaking of the Bow River Gap, he says: “The fault plane here is nearly horizontal, and the two formations, viewed from the valley appear to succeed one another conformably,” and then having noted that the underlying Cretaceous shales are “very soft,” he adds that they “have suffered little by the sliding of the limestones over them.” (An. Rpt. 1886, part D., pp. 33, 34, 84.)Credat Iudaeus Apella, non ego!
Schuchert describes the Alpine overthrust as follows: “The movement was both vertical and thrusting from the south and southeast, from the southern portion of Tethys, elevating and folding the Tertiary and older strata of the northern areas of this mediterranean into overturned, recumbent, and nearly horizontal folds, and pushing the southern or Lepontine Alps about 60 miles to the northward into the Helvetic region. Erosion has since carved up these overthrust sheets, leaving remnants lying on foundations which belong to a more northern portion of the ancient sea. Most noted of these residuals of overthrust masses is the Matterhorn, a mighty mountain without roots, a stranger in a foreign geologic environment,” (Pirsson & Schuchert’s “Textbook of Geology,” 1920, II, p. 924.)
With such a convenient device as the “overthrust” at his disposal, it is hard to see how any possible concrete sequence of fossiliferous strata could contradict the preconceptions of an evolutionary geologist. The hypotheses and assumptions involved, however, are so tortuous and incredible, that nothing short of fanatical devotion to the theory of transformism can render them acceptable. “Examples,” says Price, “of strata in the ‘wrong’ order were first reported from the Alps nearly half a century ago. Since that time, whole armfuls of learned treatises in German, in French, and in English have been written to explain the wonderful conditions there found. The diagrams that have been drawn to account for the strange order of the strata are worthy to rank with the similar onesby the Ptolemaic astronomers picturing the cycles and epicycles required to explain the peculiar behavior of the heavenly bodies in accordance with the geocentric theory of the universe then prevailing.... In Scandinavia, a district some 1,120 miles long by 80 miles wide is alleged to have been pushed horizontally eastward ‘at least 86 miles.’ (Schuchert.) In Northern China, one of these upside down areas is reported by the Carnegie Research Expedition to be 500 miles long.” (“The New Geology,” 1923, pp. 633, 634.)
Nor are the epicyclic subterfuges of the evolutionary geologist confined to “deceptive conformities” and “overthrusts.” His inventive genius has hit upon other methods of explaining away inconvenient facts. When, for example, “younger” fossils are found interbedded with “older” fossils, and the discrepancy in time is not too great, he rids himself of the difficulty of their premature appearance by calling them a “pioneer colony.” Similarly, when a group of “characteristic” fossils occur in one age, skip another “age,” and recur in a third, he recognizes the possibility of “recurrent faunas,” some of these faunas having as many as five successive “recurrences.” Clearly, the assumption of gradual approximation and the dogma that the lower preceded the higher forms of life are things to be saved at all costs, and it is a foregone conclusion that no facts will be suffered to conflict with these irrevisable articles of evolutionary faith. “What is the use,” exclaims Price, “of pretending that we are investigating a problem of natural science, if we already know beforehand that the lower and more generalized forms of animals and plants came into existence first, and the higher and the more specialized came only long afterwards, and that specimens of all these successive types have been pigeonholed in the rocks in order to help us illustrate this wonderful truth?” (Op. cit., pp. 667, 668.)
The predominance of extinct species in certain formations is said to be an independent argument of their great age. Most of the species of organisms found as fossils in Cambrian,Ordovician, and Silurian rocks are extinct, whereas modern types abound in Cretaceous and Tertiary rocks. Hence it is claimed that the former must be vastly older than the latter. But this argument gratuitously assumes the substantial perfection of the stone record of ancient life and unwarrantedly excludes the possibility of a sudden impoverishment of the world’s flora and fauna as the result of a sweeping catastrophe, of which our present species are the fortunate survivors. Now the fact that certain floras and faunas skip entire systems of rocks to reappear only in later formations is proof positive that the record of ancient life is far from being complete, and we have in the abundant fossil remains of tropical plants and animals, found in what are now the frozen arctic regions, unmistakable evidence of a sudden catastrophic change by which a once genial climate “was abruptly terminated. For carcasses of the Siberian elephants were frozen so suddenly and so completely that the flesh has remained untainted.” (Dana.) Again, the merefactof extinction tells us nothing about thetimeof the extinction. For this we are obliged to fall back on the index fossil whose inherent time-value is based on the theory of evolution and not on stratigraphy. Hence the argument from extinct species is not an independent argument.
To sum up, therefore, the aprioristic evolutional series of fossils is not a genuine time-scale. The only safe criterion of comparative age is that of stratigraphic superposition, and this is inapplicable outside of limited local areas.[10]The index fossil is a reliable basis for the chronological correlation of beds only in case one is already convinced on other grounds of the actuality of evolution, but for the unbiased inquirer it is destitute of any inherent time-value. In other words, we can no longer be sure that a given formation is old merely because it happens to contain Cambrian fossils, nor that a rock is young merely because it chances to contain Tertiaryfossils. Our present classification of rocks according to their fossil contents is purely arbitrary and artificial, being tantamount to nothing more than a mere taxonomical classification of the forms of ancient life on our globe, irrespective of their comparative antiquity. This scheme of classification is, indeed, universally applicable, and places can usually be found in it for new fossiliferous strata, whenever and wherever discovered. Its universal applicability, however, is due not to any prevalent order of invariable sequence among fossiliferous strata, but solely to the fact that the laws of biological taxonomy and ecology are universal laws which transcend spatial and temporal limitation. If a scheme of taxonomy is truly scientific, all forms of life, whether extant or extinct, will fit into it quite readily.
The anomalies of spatial distribution constitute a sixth difficulty for transformistic palæontology. In constructing a phylogeny the most diverse and widely-separated regions are put under tribute to furnish the requisite fossils, no heed being paid to what are now at any rate impassable geographical barriers, not to speak of the climatic and environmental limitations which restrict the migrations of non-cosmopolitan species within the boundaries of narrow habitats. Hypothetical lineages of a modern form of life are frequently constructed from fossil remains found in two or more continents separated from one another by immense distances and vast oceanic expanses. When taxed with failure to plausibleize this procedure, the evolutionist meets the difficulty by hypothecating wholesale and devious migrations to and fro, and by raising up alleged land bridges to accommodate plants and animals in their suppositional migrations from one continent to another, etc.
The European horse, with his so-called ancestry interred, partly in the Tertiary deposits of Europe, but mostly in those of North America, is a typical instance of these anomalies in geographical distribution. It would, of course, be preposterous to suppose that two independent lines of descent couldhave fortuitously terminated in the production of one and the same type, namely, the genusEquus. Moreover, to admit for a moment that the extinct AmericanEquusand the extant EuropeanEquushad converged by similar stages from distinct origins would be equivalent, as we have seen, to a surrender of the basic postulate that structural similarity rests on the principle of inheritance. Nothing remains, therefore, but to hypothecate a Tertiary land bridge between Europe and North America.
Modern geologists, however, are beginning to resent these arbitrary interferences with their science in the interest of biological theories. Land bridges, they rightly insist, should be demonstrated by means of positive geological evidence and not by the mere exigencies of a hypothetical genealogy. Whosoever postulates a land bridge between continents should be able to adduce solid reasons, and to assign a mechanism capable of accomplishing the five-mile uplift necessary to bring a deep-sea bottom to the surface of the hydrosphere. Such an idea is extravagant and not to be easily entertained in our day, when geologists are beginning to understand the principle ofisostasy. To-day, the crust of the earth, that is, the entire surface of the lithosphere, is conceived as being constituted of earth columns, all of which rest with equal weight upon the level of complete compensation, which exists at a depth of some 76 miles below land surfaces. At this depth viscous flows and undertows of the earth take place, compensating all differences of gravitational stress. Hence the materials constituting a mountain column are thought to be less dense than those constituting the surrounding lowland columns, and for this reason the mountains are buoyed up above the surrounding landscape. The columns under ocean bottoms, on the contrary, are thought to consist of heavy materials like basalt, which tend to depress the column. To raise a sea floor, therefore, some means of producing a dilatation of these materials would have to be available. Arthur B. Coleman called attention to this difficulty in his PresidentialAddress to the Geological Society of America (December 29, 1915), and we cannot do better than quote his own statement of the matter here:
“Admitting,” he says, “that in the beginning the lithosphere bulged up in places, so as to form continents, and sagged in other places, so as to form ocean beds, there are interesting problems presented as to the permanence of land and seas. All will admit marginal changes affecting large areas, but these encroachments of the sea on the continents and the later retreats may be of quite a subordinate kind, not implying an interchange of deep-sea bottoms and land surfaces. The essential permanence of continents and oceans has been firmly held by many geologists, notably Dana among the older ones, and seems reasonable; but there are geologists, especially palæontologists, who display great recklessness in rearranging land and sea. The trend of a mountain range, or the convenience of a running bird, or a marsupial afraid to wet his feet seems sufficient warrant for hoisting up any sea bottom to connect continent with continent. A Gondwana Land arises in place of an Indian Ocean and sweeps across to South America, so that a spore-bearing plant can follow up an ice age; or an Atlantis ties New England to Old England to help out the migrations of a shallow-water fauna; or a ‘Lost Land of Agulhas’ joins South Africa and India.
“It is curious to find these revolutionary suggestions made at a time when geodesists are demonstrating that the earth’s crust over large areas, and perhaps everywhere, approaches a state of isostatic equilibrium, and that isostatic compensation is probably complete at a depth of only 76 miles” ... and (having noted the difference of density that must exist between the continental, and submarine, earth columns) Coleman would have us bear in mind “that to transform great areas of sea bottom into land it would be necessary either to expand the rock beneath by several per cent or to replace heavy rock, such as basalt, by lighter materials, such as granite. There is no obvious way in which the rock beneath asea bottom can be expanded enough to lift it 20,000 feet, as would be necessary in parts of the Indian Ocean, to form a Gondwana land; so one must assume that light rocks replace heavy ones beneath a million square miles of ocean floor. Even with unlimited time, it is hard to imagine a mechanism that could do the work, and no convincing geological evidence can be brought forward to show that such a thing ever took place.... The distribution of plants and animals should be arranged for by other means than by the wholesale elevation of ocean beds to make dry land bridges for them.” (Smithson. Inst. Rpt. for 1916, pp. 269-271.)
A seventh anomaly of palæontological phylogeny is what may be described as contrariety of direction. We are asked to believe, for example, that in mammals racial development resulted in dimensional increase. The primitive ancestor of mammoths, mastodons, and elephants is alleged to have been theMoeritherium, “a small tapirlike form, from the Middle Eocene Qasr-el-Sagha beds of the Fayûm in Egypt....Moeritheriummeasured about 3½ feet in height.” (Lull: Smithson. Inst. Rpt. for 1908, pp. 655, 656.) The ancestor of the modern horse, we are told, was “a little animal less than a foot in height, known asEohippus, from the rocks of the Eocene age.” (Woodruff: “Foundations of Biology,” p. 361.) In the case of insects, on the other hand, we are asked to believe the exact reverse, namely, that racial development brought about dimensional reduction. “In the middle of the Upper Carboniferous periods,” says Anton Handlirsch, “the forest swamps were populated with cockroaches about as long as a finger, dragonfly-like creatures with a wing spread of about 2½ feet, while insects that resemble our May flies were as big as a hand.” (“Die fossilen Insekten, und die Phylogenie der recenten Formen,” 1908, L. c., p. 1150.) Contrasting one of these giant palæozoic dragonflies,Meganeura monyiBrongn., with the largest of modern dragonflies,Aeschna grandisL., Chetverikov exclaims with reference to the latter: “What a pitiful pigmy it is and its specific name (grandis) sounds likesuch a mockery.” (Smithson. Inst. Rpt. for 1918, p. 446.) Chetverikov, it is true, proposes a teleological reason for this progressive diminution, but the fact remains that for dysteleological evolutionism, which dispenses with the postulate of a Providential coördination and regulation of natural agencies, thisdiminuendoof the “evolving” insects stands in irreconcilable opposition to thecrescendoof the “evolving” mammals, and constitutes a difficulty which a purely mechanistic philosophy can never surmount.
Not to prolong excessively this already protracted enumeration of discrepancies between fossil fact and evolutionary assumption, we shall mention, as an eighth and final difficulty, the indubitable persistence ofunchangedorganic types from the earliest geological epochs down to the present time. This phenomenon is all the more wonderful in view of the fact that the decision as to which are to be the “older” and which the “younger” strata rests with the evolutionary geologist, who is naturally disinclined to admit the antiquity of strata containing modern types, and whose position as arbiter enables him to date formations aprioristically, according to the exigencies of the transformistic theory. Using, as he does, the absence of modern types as an express criterion of age, and having, as it were, his pick among the various fossiliferous deposits, one would expect him to be eminently successful in eliminating from the stratigraphic groups selected for senior honors all strata containing fossil types identical with modern forms. Since, however, even the most ingenious sort of geological gerrymandering fails to make this elimination complete, we must conclude that the evidence for persistence of type is inescapable and valid under any assumption.
When we speak of persistent types, we mean generic and specific, rather than phyletic, types, although it is assuredly true that the persistence of the great phyla, from their abrupt and contemporaneous appearance in Cambrian and pre-Cambrian rocks down to the present day, constitutes a grave difficulty for progressive evolution in general and monophyletic evolution in particular. All the great invertebrate types, such as the protozoa, the annelida, the brachiopoda, and large crustaceans called eurypterids, are found in rocks of the Proterozoic group, despite the damaged condition of the Archæan record, while in the Cambrian they are represented by a great profusion of forms. “The Lower Cambrian species,” says Dana, “have not the simplicity of structure that would naturally be looked for in the earliest Palæozoic life. They are perfect of their kind and highly specialized structures. No steps from simple kinds leading up to them have been discovered; no line from the protozoans up to corals, echinoderms, or worms, or from either of these groups up to brachiopods, mollusks, trilobites, or other crustaceans. This appearance of abruptness in the introduction of Cambrian life is one of the striking facts made known by geology.” (“Manual,” p. 487.) Thus, as we go backward in time, we find the great organic phyla retaining their identity and showing no tendency to converge towards a common origin in one or a few ancestral types. For this reason, as we shall see presently, geologists are beginning to relegate the evolutionary process to unknown depths below the explored portion of the “geological column.” What may lurk in these unfathomed profundities, it is, of course, impossible to say, but, if we are to judge by that part of the column which is actually exposed to view, there is no indication whatever of a steady progression from lower, to higher, degrees of organization, and it takes all the imperturbable idealism of a scientific doctrinaire to discern in such random, abrupt, and unrelated “origins” any evidence of what Blackwelder styles “a slow but steady increase in complexity of structure and in function.” (Science, Jan. 27, 1922, p. 90.)
But, while the permanence of phyletic types excludes progress, that of generic and specific types excludes change, and hence it is in the latter phenomenon, especially, that the theory of transformism encounters a formidable difficulty. Palæobotany furnishes numerous examples of the persistence of unchanged plant forms. Ferns identical with the modern genusMarattiaoccur in rocks of the Palæozoic group. Cycads indistinguishable from the extant generaZamiaandCycasare found in strata belonging to the Triassic system, etc., etc.
The same is true of animal types. In all the phyla some genera and even species have persisted unchanged from the oldest strata down to the present day. Among the Protozoa, for example, we have the genusGlobigerina(one of the Foraminifera), some modern species of which are identical with those found in the Cretaceous. To quote the words of the Protozoologist, Charles A. Kofoid: “The Protozoa are found in the oldest fossiliferous rocks and the genera ofRadiolariatherein conform rather closely to genera living today, while the fossilDinoflagellataof the flints of Delitzsch are scarcely distinguishable from species living in the modern seas. The striking similarities of the most ancient fossil Protozoa to recent ones afford some ground for the inference that the Protozoa living today differ but little from those when life was young.” (Science, April 6, 1923, p. 397.)
The Metazoa offer similar examples of persistence. Among the Cœlenterata, we have the genusSpringopora, whose representatives from the Carboniferous limestones closely resemble some of the present-day reef builders of the East Indies. Species of the brachiopod generaLingulaandCraniaoccurring in the Cambrian rocks are indistinguishable from species living today, while two other modern genera of the Brachiopoda, namely,RhynchonellaandDiscina, are represented among the fossils found in Mesozoic formations.Terebratulina striata, a fossil species of brachiopod occurring in the rocks belonging to the Cretaceous system, is identical with our modern speciesTerebratulina caput serpentis. Among the Mollusca such genera asArca,Nucula,Lucina,Astarte, andNautilushave had a continuous existence since the Silurian, while the generaLimaandPectencan be traced to the Permian. One genusPleurotomariagoes back to pre-Cambrian times. As to Tertiary fossils, Woods informs us that “in some of the later Cainozoic formations as many as 90 per cent of the species of mollusks are still living.” (“Palæontology,” 1st ed., p. 2.) Among the Echinodermata, two genera,Cidaris(a sea urchin) andPentacrinus(a crinoid) may be mentioned as being persistent since the Triassic (“oldest” system of the Mesozoic group). Among the Arthropoda, the horseshoe crabLimulus polyphemushas had a continuous existence since the Lias (i.e.the lowest series of the Jurassic system). Even among the Vertebrata we have instances of persistence. The extant Australian genusCeratodus, a Dipnoan, has been in existence since the Triassic. Among the fossils of the Jurassic (middle system of the Mesozoic group),Sharks,Rays, andChimaeroidsoccur in practically modern forms, while some of the so-called “ganoids” are extremely similar to our present sturgeons and gar pikes—“Some of the Jurassic fishes approximate the teleosts so closely that it seems arbitrary to call them ganoids.” (Scott.)
The instances of persistence enumerated above are those acknowledged by evolutionary palæontologists themselves. This list could be extended somewhat by the addition of several other examples, but even so, it would still be small and insufficient to tip the scales decisively in favor of fixism. On the other hand, we must not forget that the paucity of this list is due in large measure to the fact that our present method of classifying fossiliferous strata was deliberately framed with a view to excluding formations containing modern types from the category of “ancient” beds. Moreover, orthodox palæontology has minimized the facts of persistence to an extent unwarranted even by its own premises. As the following considerations indicate, the actual number of persistent types is far greater, even according to the evolutionary time-scale, than the figure commonly assigned.
First of all, we must take into account the deplorable, if not absolutely dishonest, practice, which is in vogue, of inventing new names for the fossil duplicates of modern species, in order to mask or obscure an identity which conflicts withevolutionary preconceptions. When a given formation fails to fit into the accepted scheme by reason of its fossil anachronisms, or when, to quote the words of Price, “species are found in kinds of rock where they are not at all expected, and where, according to the prevailing theories, it is quite incredible that they should be found ... the not very honorable expedient is resorted to of inventing a new name, specific or even generic, to disguise and gloss over the strange similarity between them and the others which have already been assigned to wholly different formations.” (“The New Geology,” p. 291.) The same observation is made by Heilprin. “It is practically certain,” says the latter, “that numerous forms of life, exhibiting no distinctive characters of their own, are constituted into distinct species for no other reason than that they occur in formations widely separated from those holding their nearest kin.” (“Geographical and Geological Distribution of Animals,” pp. 183, 184.) An instance of this practice occurs in the foregoing list, where a fossil brachiopod identical with a modern species receives the new specific name “striata.” Its influence is also manifest in the previously quoted apology of Scott for calling teleost-like fish “ganoids.”
We must also take into account the imperfection of the fossil record, which is proved by the fact that most of the acknowledged “persistent types” listed above “skip” whole systems and even groups of “later” rocks (which are said to represent enormous intervals of time), only to reappear, at last, in modern times. It is evident that their existence has been continuous, and yet they are not represented in the intervening strata. Clearly, then, the fossil record is imperfect, and we must conclude that many of our modern types actually did exist in the remote past, without, however, leaving behind any vestige of their former presence.
Again, we must frankly confess our profound ignorance with respect to the total number and kinds of species living in our modern seas. Hence our conventional distinction between “extinct” and “extant” species has only a provisory value. Futurediscoveries will unquestionably force us to admit that many of the species now classed as “extinct” are in reality living forms, which must be added to our list of “persistent types.” “It is by no means improbable,” says Heilprin, “that many of the older genera, now recognized as distinct by reason of our imperfect knowledge concerning their true relationships, have in reality representatives in the modern sea.” (Op. cit.pp. 203, 204.)
Finally, the whole of our present taxonomy of plants and animals, both living and fossil, stands badly in need of revision. Systematists, as we have seen in the second chapter, base their classifications mainly on what they regard as basic or homologous structures, in contradistinction to superficial or adaptive characters. Both kinds of structure, however, are purely somatic, and somatic characters, as previously observed, are not, by themselves, a safe criterion for discriminating between varieties and species. In the light of recent genetical research, we cannot avoid recognizing that there has been far too much “splitting” of organic groups on the basis of differences that are purely fluctuational, or, at most, mutational. Moreover, the distinction between homologous and adaptive structures is often arbitrary and largely a matter of personal opinion, especially when numerous specimens are not available. What the “Cambridge Natural History” says in allusion to the Asteroidea is of general application. “While there is considerable agreement,” we read, “amongst authorities as to the number of families, or minor divisions of unequivocal relationship, to be found in the class Asteroidea, there has been great uncertainty both as to the number and limits of the orders into which the class should be divided, and also as to the limits of the various species. The difficulty about the species is by no means confined to the group Echinodermata; in all cases where the attempt is made to determine species by an examination of a few specimens of unknown age there is bound to be uncertainty; the more so, as it becomes increasingly evident that there is nosharp line to be drawn between local varieties and species. In Echinodermata, however, there is the additional difficulty that the acquisition of ripe genital cells does not necessarily mark the termination of growth; the animals can continue to grow and at the same time slightly alter their characters. For this reason many of the species described may be merely immature forms....
“The disputes, however, as to the number of orders included in the Asteroidea proceed from a different cause. The attempt to construct detailed phylogenies involves the assumption that one set of structures, which we take as the mark of the class, has remained constant, whilst the others which are regarded as adaptive, may have developed twice or thrice. As the two sets of structures are about of equal importance it will be seen to what an enormous extent the personal equation enters in the determination of these questions.” (Op. cit., vol. I, pp. 459, 460.)
In dealing with fossil forms, these difficulties of the taxonomist are intensified: (1) by the sparse, badly-preserved, and fragmentary character of fossil remains; (2) by the fact that here breeding experiments are impossible, and hence the diagnosis based on external characters cannot be supplemented by a diagnosis of the germinal factors. Fossil taxonomy is, in consequence, extremely arbitrary and unreliable. Many fossil forms classed as distinct species, or even as distinct genera, may be nothing more than fluctuants, mutants, hybrids, or immature stages of well-known species living today. Again, many fossils mistaken for distinct species are but different stages in the life-history of a single species, a mistake, which is unavoidable, when specimens are few and the age of the specimens unknown. The great confusion engendered in the classification of the hydrozoa by nineteenth-century ignorance of the alternation of hydroid and medusoid generations is a standing example of the danger of classifying forms without a complete knowledge of the entire life-cycle. When due allowance is made for mutation, hybridization, metagenesis, polymorphism,age and metamorphosis, the number of distinct fossil species will undergo considerable shrinkage. Nor must we overlook the possibility of environmentally-induced modifications. Many organisms, such as mollusks, undergo profound alteration as a result of some important, and, perhaps, relatively permanent, change in their environmental conditions, though such alterations affect only the phenotype, and do not involve a corresponding change in the specific genotype,i.e.the germinal constitution of the race.
In the degree that these considerations are taken into account the number of “extinct” fossil species will diminish and the number of “persistent” species will increase. This is a consummation devoutly to be wished for, but it means that hundreds of thousands of described species must needs be reviewed for the purpose of weeding out the duplicates, and who will have the knowledge, the courage, or even the span of life, necessary to accomplish so gigantic a task?
But so far as the practical purposes of our argument are concerned, the accepted list of persistent types needs no amplification. It suffices, as it stands, to establish the central fact (which, for the rest, is admitted by everyone) that some generic and even specific types have remained unchanged throughout the enormous lapse of time which has intervened between the deposition of the oldest strata and the advent of the present age. Our current theories, far from diminishing the significance of this fact, tend to intensify it by computing the duration of such persistence in millions, rather than in thousands, of years. Now, whatever one’s views may be on the subject of transformism, this prolonged permanence of certain genera and species is an indubitablefact, which is utterly irreconcilable with auniversal lawof organic evolution. The theory of transformism is impotent to explain an exception so palpable as this; for persistence and transmutation cannot be subsumed under one and the same principle. That which accounts for change cannot account forunchange. Yet unchange is an observed fact, while the change, in this case, is an inferredhypothesis. Hence, even if we accept the principle of transformism, there will always be scope for the principle of permanence. The extraordinary tenacity of type manifested by persistent genera and species is a phenomenon deserving of far more careful study and investigation than the evolutionally-minded scientist of today deigns to bestow upon it. To the latter it may seem of little consequence, but, to the genuine scientist, the actual persistence of types should be of no less interest than their possible variability.
With these reflections, our criticism of the palæontological argument terminates. The enumeration of its various deficiencies was not intended as a refutation. To disprove the theory of organic evolution is a feat beyond our power to accomplish. We can only adduce negative evidence, whose scope is to show that the various evolutionary arguments are inconsequential or inconclusive. We cannot rob the theory of its intrinsic possibility, and sheer justice compels us to confess that certain facts, like those of symbiotic preadaptation, lend themselves more readily to a transformistic, than to a fixistic, interpretation. On the other hand, nothing is gained by ignoring flaws so obvious and glaring as those which mar the cogency of palæontological “evidence.” The man who would gloss them over is no true friend either of Science or of the scientific theory of Evolution! They represent so many real problems to be frankly faced and fully solved, before the palæontological argument can become a genuine demonstration. But until such time as a demonstration of this sort is forthcoming, the evolutionist must not presume to cram his unsubstantiated theory down our reasonably reluctant throats. To accept as certain what remains unproved, is to compromise our intellectual sincerity. True certainty, which rests on the recognition of objective necessity, will never be attainable so long as difficulties that sap the very base of evolutionary argumentation are left unanswered; and, as for those who, in the teeth of discordant factual evidence, profess, nevertheless, to have certainty regarding the “fact” of evolution, we canonly say that such persons cannot have a very high or exacting conception of what scientific certainty really means.
For the rest, it cannot even be said that the palæontological record furnishes good circumstantial evidence that our globe has been the scene of a process of organic evolution. In fact, so utterly at variance with this view is the total impression conveyed by the visible portion of the geological column, that the modern geologist proposes, as we have seen, to probe depths beneath its lowest strata for traces of that alleged transmutation, which higher horizons do not reveal. There are six to eight thick terranes below the Cambrian, we are told, and igneous masses that were formerly supposed to be basal have turned out to be intrusions into sedimentary accumulations, all of which, of course, is fortunate for the theory of organic evolution, as furnishing it with a sadly needed new court of appeal. The bottom, so to speak, has dropped out of the geological column, and Prof. T. C. Chamberlin announces the fact as follows: “The sharp division into two parts, a lifeless igneous base and a sedimentary fossiliferous superstructure, has given place to the general concept of continuity with merely minor oscillations in times and regions of major activity. Life has been traced much below the Cambrian, but its record is very imperfect. The recent discoveries of more ample and varied life in the lower Palæozoic, particularly the Cambrian, implies, under current evolutional philosophy, a very great downward extension of life. In the judgment of some biologists and geologists, this extension probably reaches below all the pre-Cambrian terranes as yet recognized, though this pre-Cambrian extension is great. The ‘Azoic’ bottom has retired to depths unknown. This profoundly changes the life aspect of the ‘column.’” (Science, Feb. 8, 1924, p. 128.) All this is doubtless true, but such an appeal, from the known to the unknown, from the actual to the possible, is not far-removed from a confession of scientific insolvency. Life must, of course, have had an earlier history than that recorded in the pre-Cambrian rocks. But even supposing that some portion of anearlier record should become accessible to us, it could not be expected to throw much light on the problem of organic origins. Most of the primordial sediments have long since been sapped and engulfed by fiery magmas, while terranes less deep have, in all probability, been so metamorphosed that every trace of their fossil contents has perished. The sub-Archæan beginnings of life will thus remain shrouded forever in a mystery, which we have no prospect of penetrating. Hence it is the exposed portion of the geological column which continues and will continue to be our sole source of information, and it is preëminently on this basis that the evolutionary issue will have to be decided.
Yet what could be more enigmatic than the rock record as it stands? For in nature it possesses none of that idealized integrity and coherence, with which geology has invested it for the purpose of making it understandable. Rather it is a mighty chaos of scattered and fragmentary fossiliferous formations, whose baffling complexity, discontinuity, and ambiguity tax the ingenuity of the most sagacious interpreters. Transformism is the key to one possible synthesis, which might serve to unify that intricate mass of facts, but it is idle to pretend that this theory is the unique and necessary corollary of the facts as we find them. The palæontological argument is simply a theoretical construction which presupposes evolution instead of proving it. Its classic pedigrees of the horse, the camel, and the elephant are only credible when we have assumed the “fact” of evolution, and even then, solely upon condition that they claim to approximate, rather than assign, the actual ancestry of the animals in question. In palæontology, as in the field of zoölogy, evolution is not a conclusion, but an interpretation. In palæontology, otherwise than in the field of genetics, evolution is not amenable to the check of experimental tests, because here it deals not with that which is, but with that whichwas. Here the sole objective basis is the mutilated and partially obliterated record of a march of events, which no one has observed and which will never be repeated.These obscure and fragmentary vestiges of a vanished past, by reason of their very incompleteness, lend themselves quite readily to all sorts of theories and all sorts of speculations. Of the “Stone Book of the Universe” we may say with truth that which Oliver Wendell Holmes says of the privately-interpreted Bible, namely, that its readers take from it the same views which they had previously brought to it. “I am, however, thoroughly persuaded,” say the late Yves Delage, “that one is or is not a transformist, not so much for reasons deduced from natural history, as for motives based on personal philosophic opinions. If there existed some other scientific hypothesis besides that of descent to explain the origin of species, many transformists would abandon their present opinion as not being sufficiently demonstrated.... If one takes his stand upon the exclusive ground of the facts, it must be acknowledged that the formation of one species from another species has not been demonstrated at all.” (“L’herédité et les grands problèmes de la biologie générale,” Paris, 1903, pp. 204, 322.)