“But what,” asked Wasmann, “has palæontology to say concerning this question? It tells us that, up to the present, no connecting link between man and the ape has been found; and, indeed, according to the theory of Klaatsch, it is absurd to speak of a link of direct connection between these two forms, but it tells us much more than this. It shows us, on the basis of the results of the most recent research, that we know the genealogical tree of the various apes, a tree very rich in species, which extends from the present as far back as the hypothetical primitive form assigned to the earliest part of the Tertiary period; and, in fact, in Zittel’s work, “Grundzüge der Paläontologie” (1895), not less than thirty genera of fossil Pro-simiæ and eighteen genera of genuine fossil apes are enumerated, the which have been entombed in those strata of the earth that intervene between the Lower Eocene and the Alluvial epoch, but between this hypothetical primitive form and man of the present time we do not find a single connecting link. The entire genealogical tree of man does not show so much as one fossil genus, or even one fossil species.” (Op. cit., italics his.) A brief consideration of the principal fossil remains, in which certain palæontologists profess to see evidence of a transition between man and the primitive pithecoid stock, will serve to verify Wasmann’s statement, and will reveal the fact that all the alleged connecting links are distinctly human, or purely simian, or merely mismated combinations of human and simian remains.
(1) Pithecanthropus erectus: In 1891 Eugène Dubois, a Dutch army surgeon, discovered in Java, at Trinil, in the Ngawa district of the Madiun Residency, a calvarium (skull-cap), 2 upper molars and a femur, in the central part of an old river bed. The four fragments, however, were not all found in the same year, because the advent of the rainy season compelled him to suspend the work of excavation. “The teeth,” to quote Dubois himself, “were distant from the skull from one to, at most, three meters; the femur was fifteen meters (50 feet) away.” (Smithson. Inst. Rpt. for 1898, p. 447.) Dubois judged the lapilli stratum, in which the bones were found, to be older than the Pleistocene, and older, perhaps, than the most recent zones of the Pliocene series. “The Trinil ape-man,” says Osborn, “ ... is the first of the conundrums of human ancestry. Is the Trinil race prehuman or not?” (Loc. cit., p. 40.) Certainly, Lower Pleistocene, or Upper Pliocene represents too late a time for the appearance of the upright primate, whence we are said to have sprung. Even Miocene would be too late a date for our alleged divergence from the primitive arboreal stock.
Of the capacity of the calvarium, Dubois says: “I found the above-mentioned cavity measured 550 c.cm. The cast of the cavity of the Neanderthal skull taken to the same plane measures 750 c.cm.” (Loc. cit., p. 450, footnote.) His first estimate of the total cranial capacity of Pithecanthropus was 1000 c.cm., but, later on, when he decided to reconstruct the skull on the basis of the cranium of a gibbon (Hylobates agilis) rather than that of a chimpanzee (Troglodytes niger), he reduced his estimate of the cranial capacity to 900 c.cm. Recently, it is rumored, he has increased the latter estimate, as a sequel to his having removed by means of a dentist’s tool all the siliceous matter adhering to the skull-cap. As regards shape, the calvarium seems to resemble most closely the cranial vault of gibbon. This similarity, as we have seen, led Dubois to reconstruct the skull on hylobatic lines—“the skull of Hylobates agilis,” says Dubois, “ ... strikingly resembles that of Pithecanthropus.” (Loc. cit., p. 450, footnote.) The craniologist Macnamara, it is true, claims that the skull-cap most closely approximates the Troglodyte type. Speaking of the calvarium of Pithecanthropus, the latter says: “The cranium of an average adult male chimpanzee and the Java cranium are so closely related that I believe them to belong to the same family of animals—i.e. to the true apes.” (Archiv. für Anthropologie, XXVIII, 1903, pp. 349-360.) The large cranial capacity, however, would seem to favor Dubois’ interpretation, seeing that gibbons have, in proportion to their bodies, twice as large a brain as the huge Troglodyte apes, namely, the chimpanzee and the gorilla. The maximum cranial capacity for any ape is from 500 to 600 c.cm. Hence, with 900 c.cm. of cranial capacity estimated by Dubois, the Pithecanthropus stands midway between the ape and the Neanderthal Man, a human dwarf, whose cranial capacity Huxley estimated at 1,236 c.cm. This consideration, however, does not of itself entitle the Pithecanthropus to be regarded as a connecting link between man and the anthropoid apes. In all such comparisons, it is the relative, and not the absolute, size of the brain, which is important. The elephant for example, has as large a brain as a man, but the elephant’s brain is small, in comparison to its huge body. The brain of a mouse is insignificant, as regards absolute size, but, considered in relation to the size of the mouse’s body, it is as large as, if not larger than, that of an elephant, and hence the elephant, for all the absolute magnitude of its brain, is no more “intelligent” than a mouse. As we have already seen, man’s brain is unique, not for its absolute size, but for its weight and enormous cortical surface, considered with reference to the comparatively small organism controlled by the brain in question. It is this excess in size which manifests the specialization of the human brain for psychic functions. The Weddas, a dwarf race of Ceylon, have a far smaller cranial capacity than the Neanderthal Man, their average cranial capacity being 960 c.cm., but they are human pigmies, whereas the Pithecanthropus, according to Richard Hertwig, was a giant ape. “The fragments,” says Hertwig, “were regarded by some as belonging to a connecting link between apes and man, Pithecanthropus erectus Dubois; by others they were thought to be the remains of genuine apes, and by others those of genuine men. The opinion that is most probably correct is that the fragments belonged to an anthropoid ape of extraordinary size and enormous cranial capacity.” (“Lehrbuch der Zoologie,” 7th ed.)
Prof. J. H. McGregor essays to make a gradational series out of conjectural brain casts of a large ape, the Pithecanthropus and the Neanderthal Man, in the ratio of 6: 9: 12, this ratio being based upon the estimated cranial capacities of the skulls in question. In a previous chapter, we have seen that such symmetrically graded series have little force as an argument for common descent. In the present instance, however, the gradation gives a wrong impression of the real state of affairs. If Doctor McGregor had taken into account the all-important consideration of relative size, he would not have been able to construct this misleading series. This consideration, however, did not escape Dubois himself, and in his paper of Dec. 14, 1896, before the Berlin Anthropological Society, he confessed that a gigantic ape of hylobatic type would have a cranial capacity close to that of Pithecanthropus, even if we suppose it to have been no taller than a man. (Cf. Smithson. Inst. Rpt. for 1898, p. 350.) The admission is all the more significant in view of the fact that Dubois was then endeavoring to exclude the possibility of regarding Pithecanthropus as an anthropoid ape.
The teeth, according to Dubois, are unlike the teeth of either men or apes, but according to Virchow and Hrdlička, they are more ape-like than human. The femur, though unquestionably man-like, might conceivably belong to an ape of the gibbon type, inasmuch as the upright posture is more normal to the long-armed gibbon than to any other anthropoid ape, and its thighbone, for this reason, bears the closest resemblance to that of man. According to the “Text-Book of Zoölogy” by Parker and Haswell, the gibbon is the only ape that can walk erectly, which it does, not like other apes, with the fore-limbs used as crutches, but balanced exclusively upon its hind-limbs, with its long arms dangling to the ground—“The Gibbons can walk in an upright position without the assistance of the fore-limbs; in the others, though, in progression on the surface of the ground, the body may be held in a semi-erect position with the weight resting on the hind-limbs, yet the assistance of the long fore-limbs acting as crutches is necessary to enable the animal to swing itself along.” (Op. cit., 3rd ed., 1921, vol. II, p. 494.) The Javanese femur is rounder than in man, and is, in this, as well as other respects, more akin to the thighbone of the gibbon. “After examining hundreds of human femora,” says Dubois, “Manouvrier could find only two that had a somewhat similar shape. It is therefore a very rare form in man. With the gibbon a similar form normally occurs.” (Loc. cit., pp. 456, 457.) Whether the thighbone really belonged to an erectly walking animal has not yet been definitely settled. To decide this matter, it would be necessary to apply the Walkhoff x-ray method, which determines the mode of progression from the arrangement of the bone fibers in frontal, or other, sections from the femur. This test, however, has not hitherto been made. Nor should the significance of the fact that the thighbone was found at a distance of some fifty feet away from the skull-cap be overlooked, seeing that this fact destroys, once and for all, any possibility of certainty that both belonged to the same animal.
In conclusion, therefore, we may say that the remains of Pithecanthropus are so scanty, fragmentary, and doubtful, as to preclude a reliable verdict on their true significance. As Virchow pointed out, the determination of their correct taxonomic position is impossible, in the absence of a complete skeleton. Meanwhile, the most probable opinion is that they represent the remains of a giant ape of the hylobatic type. In other words, the Pithecanthropus belongs to the genealogical tree of the apes, and not to that of man. In fact, he has been excluded from the direct line of human descent by Schwalbe, Alsberg, Kollmann, Haacke, Hubrecht, Klaatsch, and all the foremost protagonists of the theory of collateral descent. (Cf. Dwight, op. cit., ch. VIII.) Professor McGregor’s series consisting of an ape, the Pithecanthropus, Homo neanderthalensis, and the Crô-Magnon Man fails as an argument, not only for the general reason we have discussed in our third chapter, but also for two special reasons, namely: (1) that he completely ignores the chronological question of the comparative age of the fossils in his series, and (2) that he has neglected to take into account the consideration of the body-brain ratio. For as Prof. G. Grant MacCurdy puts it, “We must distinguish between relative (cranial) capacity and absolute capacity.” (Smithson. Inst. Rpt. for 1909, p. 575.) In justice to Professor McGregor, however, it should be noted that he proposes his interpretation in a purely provisory and tentative sense, and does not dogmatize after the fashion of Osborn and Gregory.
After the year 1896, Dubois appears to have withdrawn the relics of Pithecanthropus from further inspection on the part of scientific men, and to have kept them securely locked up in his safe at Haarlem, Holland. (Cf. Science, June 15, 1923, suppl. VIII.) Since all existing casts of the skull-cap of Pithecanthropus are inaccurate, according to the measurements originally given by Dubois, anthropologists were anxious to have access to bones, in order to verify his figures and to obtain better casts. (Cf. Hrdlička, Smithson. Inst. Rpt. for 1913, p. 498.) His obstinate refusal, therefore, to place the Javanese remains at the disposal of scientists was bitterly resented by the latter. Some of them accused him of having become “reactionary” and “orthodox” in his later years, and others went so far as to impugn his good faith in the matter of the discovery. (Cf. W. H. Ballou’s article, North American Review, April, 1922.) A writer in Science says: “It has been rumored that he was influenced by religious bigotry” and refers to the bones as a “skeleton in the closet.” (Cf. loc. cit.) Dubois’ own explanation, however, was that he wished to publish his own finds first. Recently, he seems to have yielded to pressure in the matter, since he permitted Hrdlička, McGregor, and others to examine the fragments of Pithecanthropus. (Cf. Science, Aug. 17, 1923, Suppl. VIII.) Meanwhile, too, his opinion has changed with reference to these bones, which he now regards as the remains of a large ape of the hylobatic type, and not of a form intermediate between men and apes. This opinion is, in all likelihood, the correct one.
(2) The Heidelberg Man: In a quarry near Mauer in the Elsenz Valley, Germany, on Oct. 21, 1907, a workman engaged in excavating drove his shovel into a fossilized human jaw, severing it into two pieces. Herr Joseph Rösch, the owner of the quarry, immediately telegraphed the news of the find to Prof. Otto Schoetensack of the neighboring University of Heidelberg. The Professor arrived on the scene the following day, and “once he got hold of the specimen, he would no more let it out of his possession.” (Cf. Smithson. Inst. Rpt. for 1913, p. 510.) He took it back with him to Heidelberg, where he cleaned and repaired it. The crowns of four of the teeth broken by the workman’s shovel were never recovered. The Heidelberg jaw was found at a depth of about 79 feet below the surface (24.1 meters). Fossil bones of Elephas antiquus, Rhinoceros etruscus, Felis leo fossilis, etc., are said to have been discovered at the same level. The layer in which it was found has been classed by some as Middle Pleistocene, by others as Early Quaternary; for “there seems to be some uncertainty as to the exact subdivision of the period to which it should be attributed.” (Hrdlička, loc. cit., p. 516.) No other part of the skeleton except the jaw was discovered.
The teeth are of the normal human pattern, being small and vertical. Prof. Arthur Keith says they have the same shape as those of the specimen found at Spy. The jaw has an ape-like appearance, due to the extreme recessiveness of the chin. It is also remarkable for its massiveness and the broadness of the ascending rami. Its anomalous character is indicated by the manifest disproportion between the powerful jaw and the insignificant teeth. “One is impressed,” says Prof. George Grant MacCurdy of Yale, “by the relative smallness of the teeth as compared with the massive jaw in the case of Homo heidelbergensis.” (Smithson. Inst. Rpt. for 1909, p. 570.) “Why so massive a jaw,” says the late Professor Dwight, former anatomist at Harvard, “should have such inefficient teeth is hard to explain, for the very strength of the jaw implies the fitness of corresponding teeth. Either it is an anomaly or the jaw of some aberrant species of ape.” (Op. cit., p. 164.) This fact alone destroys its evidential force; for, by way of anomaly, almost any sort of feature can appear in apes and men, that is, human characters in apes and simian characters in man. “Thus it is certain,” says Dwight, “that animal features of the most diverse kinds appear in man apparently without rhyme or reason, and also that they appear in precisely the same way in animals far removed from those in which they are normal. It is hopeless to try to account for them by inheritance; and to call them instances of convergence does not help matters.” (Op. cit., pp. 230, 231.)
Kramberger, however, claims that, with the exception of the extremely recessive chin, the features of the Heidelberg jaw are approximated by those which are normal in the modern Eskimo skull. (Cf. Sitzungbericht der Preuss. Akad. der Wissenschaften, 1909.) Prof. J. H. McGregor holds similar views. He claims that the greater use of the jaw in uncivilized peoples, who must masticate tough foods, tends to accentuate and increase the recessiveness of the chin. It is also possible that the backward sloping of the chin may have been intensified in certain primitive races or varieties of the human species as a result of factorial mutation. We would not, however, be justified in segregating a distinct human species on the basis of minor differences, such as the protuberance or recessiveness of chins. On the whole, we are hopelessly at sea with reference to the significance of the Heidelberg mandible. Taxonomic allocation must be grounded on something more than a jaw, otherwise it amounts to nothing more than a piece of capricious speculation.