But once fixism assumes the simultaneousness of organic origins, it encounters, in the absence of modern organic types from ancient geological strata, a new and formidable difficulty. Cuvier’s theory of numerous catastrophes followed by wholesale migrations of the forms, which had escaped extinction, is tantamount to an appeal to the extraordinary and the improbable for purposes of explanation, and this, as we have seen, is an expedient, which natural science is justified in refusing to sanction. Nor does the appeal to the incompleteness of the geological record offer a more satisfactory solution. It is tax enough, as we shall see, upon our credulity, when the transformist seeks to account thereby for the absence of intermediate types, but to account in this fashion for the absence of palæozoic Angiosperms and mammals is asking us to believe the all-but-incredible. It would not, therefore, be advisable for the fixist to appropriate the line of defense suggested for him by Bateson—“It has been asked how do you know for instance that there were no mammals in Palæozoic times? May there not have been mammals somewhere on the earth though no vestige of them has come down to us? We may feel confident there were no mammals then, but are we sure? In very ancient rocks most of the great orders of animals are represented. The absence of the others might by no great stress of imagination be ascribed to accidental circumstances.” But the sudden rise of the Angiosperms in the early part of the Mesozoic era is an instance of de novo origin that is not so easily explained away. Hence Bateson continues: “Happily, however, there is one example of which we can be sure. There were no Angiosperms—that is to say ‘higher plants’ with protected seeds—in the carboniferous epoch. Of that age we have abundant remains of a worldwide and rich flora. The Angiosperms are cosmopolitan. By their means of dispersal they must immediately have become so. Their remains are very readily preserved. If they had been in existence on the earth in carboniferous times they must have been present with the carboniferous plants, and must have been preserved with them. Hence we may be sure that they did appear on earth since those times. We are not certain, using certain in the strict sense, that Angiosperms are the lineal descendants of the carboniferous plants, but it is much easier to believe that they are than that they are not.” (Science, Jan. 20, 1922, p. 58.)
It would thus appear, that not all the organic types of either the plant, or the animal, kingdom are of equal antiquity, and that the belated rise of unprecedented forms has the status of an approximate certainty, wherewith every theory of origins must inevitably reckon. How, then, is the fixist to reconcile this successive appearance of organisms with the simultaneous “creation” advocated by St. Augustine and St. Thomas of Aquin? Unless there be some other gradual process besides transmutation, to bridge the interval between the creative fiat and the eventual appearance of modern types, there seems to be no escape from the dilemma.
This brings us to St. Augustine’s theory of the evolution of organic life from inorganic matter, which Dorlodot sophistically construes as supporting the theory of descent. According to St. Augustine, for whose view the Angelic Doctor expressed a deliberate preference, the creation of the corporeal world was the result of a single creative act, having an immediate effect in the case of minerals, and a remote or postponed effect in the case of plants and animals (cf. “De Genesi ad litteram,” lib. V, c. 5). Living beings, therefore, were created, not in actuality, but in germ. God imparted to the elements the power of producing the various plants and animals in their proper time and place. Hence living beings were created causally rather than formally, by the establishment of causal mechanisms or natural agencies especially ordained to bring about the initial formation of the ancestral forms of life. The Divine act initiating these “natural processes” (rationes seminales, rationes causales) in inorganic, and not in living, matter, was instantaneous, but the processes, which terminated in the formation of plants and animals, in their appointed time and place, were in themselves gradual and successive. Thus by an influx of Divine power the earth was made pregnant with the promise of every form of life—“Sicut matres gravidae sunt foetibus, sic ipse mundus est gravidus causis nascentium.” (Augustine, lib. III, “de Trinitate,” c. 9.)
By reason of this doctrine, the Louvain professor claims that St. Augustine was an evolutionist, and so, indeed, he was, if by evolution is meant a gradual production of organisms from inorganic matter. But if, on the contrary, by evolution is meant a progressive differentiation and multiplication of organic species by transmutation of preëxistent forms of life, or, in other words, if evolution is taken in its usual sense as synonym for transformism, then nothing could be more absurdly anachronistic than to ascribe the doctrine to St. Augustine. The subject of the gradual process postulated by the latter was, not living, but inorganic, matter, and the process was conceived as leading to the formation, and not the transformation, of species. The idea of variable inheritance did not occur to St. Augustine, and he conceived organisms, once they were in existence, as being propagated exclusively by univocal reproduction (generatio univoca). It is the fixist, therefore, rather than the transformist, who is entitled to exploit the Augustinian hypothesis. In fact, it is only the vicious ambiguity and unlimited elasticity of the term evolution, which avail to extenuate the astounding confusion of ideas and total lack of historic sense, that can bracket together under a common term the ideology of Darwin and the view of St. Augustine.
§ 2. The Argument in the Concrete
But it is our task to criticize the theory of transformism, and not to throw a life-line to fixism, by advocating gradual formation of species as the only feasible alternative to gradual transformation of species. Perhaps, this particular life-line will not be appreciated any way; for the fixist may, not without reason, prefer to rest his case on the contention that the intrinsic time-value of geological formations is far too problematic for certain conclusions of any sort. In maintaining this position, he will have the support of some present-day geologists, and can point, as we shall see, to facts that seem to bear out his contention. In fact, the cogency of the palæontological argument appears to be at its maximum in the abstract, and to evaporate the moment we carry it into the concrete. The lute seems perfect, until we begin to play thereon, and then we discover certain rifts that mar the effect. It is to these rifts that our attention must now be turned.
The first and most obvious flaw, in the evolutionary interpretation of fossil series, is the confounding of succession with filiation. Thinkers, from time immemorial, have commented on the deep chasm of distinction, which divides historical from causal sequence, and philosophers have never ceased to inveigh against the sophistical snare of: Post hoc, ergo propter hoc. That one form of life has been subsequent in time to another form of life is, in itself, no proof of descent. “Let us suppose,” says Bather, “all written records to be swept away, and an attempt made to reconstruct English history from coins. We could set out our monarchs in true order, and we might suspect that the throne was hereditary; but if on that assumption we were to make James I, the son of Elizabeth—well, but that’s just what palæontologists are constantly doing. The famous diagram of the Evolution of the Horse which Huxley used in his American lectures has had to be corrected in the light of the fuller evidence recently tabulated in a handsome volume by Prof. H. F. Osborn and his coadjutors. Palæotherium, which Huxley regarded as a direct ancestor of the horse, is now held to be only a collateral, as the last of the Tudors were collateral ancestors of the Stuarts. The later Ancitherium must be eliminated from the true line as a side branch—a Young Pretender. Sometimes an apparent succession is due to immigration of a distant relative from some other region—‘The glorious House of Hanover and Protestant Succession.’ It was, you will remember, by such migrations that Cuvier explained the renewal of life when a previous fauna had become extinct. He admitted succession but not descent.” (Science, Sept. 17, 1920, p. 261.)
But, if succession does not imply descent, descent, at least, implies succession, and the fact that succession is the necessary corollary of descent, may be used as a corrective for the erroneous allocations made by neontologists on the basis of purely morphological considerations. The priority of a type is the sine qua non condition of its being accepted as ancestral. It is always embarrassing when, as sometimes happens, a “descendant” turns out to be older than, or even coëval with, his “ancestor.” If, however, the historical position of a form can be made to coincide with its anatomical pretensions to ancestry, then the inference of descent attains to a degree of logical respectability that is impossible in the case of purely zoölogical evidence. Recent years have witnessed a more drastic application of the historical test to morphological speculations, and the result has been a wholesale revision of former notions concerning phylogeny. “I could easily,” says Bather, “occupy the rest of this hour by discussing the profound changes wrought by this conception on our classification. It is not that orders and classes hitherto unknown have been discovered, not that some erroneous allocations have been corrected, but the whole basis of our system is being shifted. So long as we were dealing with a horizontal section across the tree of life—that is to say, with an assemblage of approximately contemporaneous forms—or even with a number of such horizontal sections, so long were we confined to simple description. Any attempt to frame a causal connection was bound to be speculative.” (Ibidem, p. 258.) Whether zoölogists will take kindly to this “shifting of the whole basis” of classification, remains to be seen. Personally, we think they would be very ill-advised to exchange the solid observational basis of homology for the scanty facts and fanciful interpretations of palæontologists.
The second stumbling block in the path of Transformism is the occurrence of convergence. We have seen that, in the palæontological argument, descent is inferred conjointly from similarity and succession, and that, in the abstract, this argument is very persuasive. One of the concrete phenomena, however, that tend to make it inconsequential, is the undoubted occurrence of convergence. Prof. H. Woods of Cambridge, in the Introduction to the 5th edition of his “Palæontology” (1919), speaks of three kinds of convergence (cf., pp. 14, 15, 16), which, as a matter of convenience, we may term the parallelistic, the radical, and the adaptational, types of convergence. A brief description of each type will serve to elucidate its nature and its significance:
(1) Parallelistic convergence implies the appearance of parallel modifications in the homologous parts of organisms regarded as diverging from common stock in two distinct collateral lines, that were independent at the time of the appearance in both of the said parallel modifications. Speaking of the fossil cœlenterates known as Graptolites, Professor Woods says: “In some genera the hydrothecæ of different species show great variety of form, those of one species being often much more like those of a species belonging to another genus than to other species of the same genus.” (“Palæontology,” 5th ed., 1919, p. 69.) As another instance of this phenomenon, the case of the fossil ungulates of South America, spoken of as Litopterna, may be cited, and the case is peculiarly interesting because of its bearing on that pièce de résistance of palæontological evidence, the Pedigree of the Horse. “The second family of Litopterna,” says Wm. B. Scott, “the Proterotheriidæ, were remarkable for their many deceptive resemblances to horses. Even though those who contend that the Litopterna should be included in the Perissodactyla should prove to be in the right, there can be no doubt that the proterotheres were not closely related to the horses, but formed a most striking illustration of the independent acquisition of similar characters through parallel or convergent development. The family was not represented in the Pleistocene, having died out before that epoch, and the latest known members of it lived in the upper Pliocene.... Not that this remarkable character was due to grotesque proportions; on the contrary, they looked far more like the ordinary ungulates of the northern hemisphere than did any of their South American contemporaries; it is precisely this resemblance that is so notable.... The feet were three-toed, except in one genus (Thoatherium) in which they were single-toed, and nearly or quite the whole weight was carried upon the median digit, the laterals being mere dew-claws. The shape of the hoofs and the whole appearance of the foot was surprisingly like those of the three-toed horses, but there were certain structural differences of such great importance, in my judgment, as to forbid the reference of these animals, not merely to the horses, but even to the perissodactyls.” (“A History of Land Mammals in the Western Hemisphere,” p. 499.)