Up From the Ape 1931

Earnest Hooton

[302] England and France produce great amateurs of science. An English parson or a French priest is more than likely to be an authority on local antiquities or upon butterflies or moths; the town clerk may have an international reputation as a folk-lorist. Nor are these interests confined to the educated and well-to-do classes. The pioneer student of the earliest implements of man was a petty customs house official in France, and the discoverer of the most ancient human artifacts in England was a grocer. Born and raised on the soil which has been the seat of their ancestors for thousands of years, surrounded by the monuments of the past, and limited in their opportunities for material advancement by the rigid economic system and scanty resources of their countries, intelligent Europeans of small means and humble situation often turn their energies toward intellectual pursuits. Here in the United States comparative wealth is within the reach of every ambitious and industrious boy. Our citizens enrich themselves, [303] but we have few amateurs who in their leisure time enrich the world by scientific investigations. We do have inventors, but we lack self-trained experimenters in the realms of unapplied science.

Mr. Charles Dawson was a lawyer who lived in the historic town of Lewes Sussex, where the river Ouse flows through a gap in the South Downs to empty its waters into the English Channel at Newhaven. For more than twenty years, Dawson employed his leisure time in searching the strata of the Weald for finds of interest to natural science. On the high chalk plateau of the Sussex Weald, Benjamin Harrison, the grocer archaeologist, had long ago found the first English eoliths –"stones of the dawn"–crude flint implements which man used before the glacial epoch and at the very outset of human culture. About eight miles to the north of Lewes is a fertile wooded land with quaint villages and comfortable farms. In this charming Sussex country is Piltdown Common, a moorland tract lying one hundred and twenty feet above the sea. About a mile west flows the Ouse, which has cut its valley eighty feet below the level of the Common.

In 1908 Mr. Dawson was walking near Piltdown Common along a road which had been mended with some peculiar brown flints, unusual in the district. He learned that these flints were dug from a gravel bed in a nearby farm, and shortly afterward visited the place. There he inquired for bones and fossils and urged the workmen to keep a lookout for such finds. Sometime later, one of the laborers handed Mr. Dawson an unusually thick piece of human parietal bone, but many searches failed to reveal any further animal remains. Mr. Dawson, with true British perseverance continued at intervals to visit the pit and in the autumn of 1911 picked up, on one of the rain-washed dumps, another and larger piece of the same skull including a part of the left brow ridge. He then enlisted the cooperation of Sir Arthur Smith-Woodward, the great palaeontologist of the British Museum, and together they made a systematic search among the spoil heaps of the gravel, be rewarded in the spring of 1912 by the finding of the larger portion of a fossil human skull.

The gravel pit lies by the side of the road in the lane leading up to Barkham Manor, an English farmhouse. It is a most unimpressive hole, not more than four feet deep and of no great ex[304]tent. It is, in fact, a mere shallow trench between the roadway and the hedge. The gravel has been laid down in strata by running water; its sand and stones are cemented together by iron oxide and everything in it is stained a deep brown Underneath the gravel deposit is a thin layer of yellow clay and below that the Hastings Beds, ancient rock deposits of the Weald. The human remains came from the lower and darker layer of the gravel just above the clay. Here were also found dark brown eoliths– crudely worked implements which had been washed into the ancient bed of the Ouse–some of them with rolled and abraded edges, and some with the cutting edges still sharp. Battered fragments of the teeth of Miocene and Pliocene forms of elephant, of the hippopotamus, and of a beaver came out of the same fossil bed. The upper stratum of the gravel, which is lighter in color, yielded up some flint implements which were not stained as dark as the eoliths and the animal remains. These upper implements are better chipped and shaped than the eoliths and have been attributed to the pre-Chellean industry, a vaguely characterized class of flint work which occurs in the early Pleistocene period, succeeding the formless eoliths. But the most remarkable artifact which was found in the Piltdown pit is a sixteen inch piece of the femur of an extinct elephant (Elephas meridionis) which had been pointed at the end and shows the part of a hole bored through it, some of the margin having been broken away. This great slab of elephant bone came from the yellow clay at the very base of the deposit and must have been contemporary with the human remains.

As usual the geologists have disagreed about the age of the Piltdown deposit. Sir Arthur Smith Woodward considers it to be of early Pleistocene date (i.e. the beginning of the glacial period). Mr. Dawson, the discoverer, thought that the lower dark stratum was composed of Pliocene drift reconstructed in Pleistocene times. Mr. Lewis Abbott, an authority on the geology of the Weald, is of the opinion that the lower stratum which contained the human remains and the carved bone is Pliocene.

The gravel deposit on Piltdown Common was laid down when the river Ouse was meandering over the plateau which is now one hundred and twenty feet above sea level. Since then it has cut its valley down eighty feet and the great expanse of gravel, almost [305] a hundred square miles, has been elevated. When the Ouse flowed over the Piltdown plateau the English Channel was the bed of a great river which drained the southern area of the Weald and of which the Somme and Seine were probably tributaries. There is little reason for doubting that the Piltdown man lived near the beginning of the glacial period or at the end of the preceding period. His age is estimated from 200,000 years to a million years. For the moment we need concern ourselves no further with the prodigal drafts upon time made by geologists.

The fragments of the Piltdown skull recovered include the larger part of the left side of the frontal bone with the outer portion of the orbit, almost the whole of the left parietal bone and [306] the entire left temporal bone, the nasal bones, the right half of the mandible, and a lower canine tooth. Since one half of the skull is almost an exact duplicate of the other half, it is possible to reconstruct the missing side from the corresponding parts of the side found. All of the skull bones are very thick, averaging from eight to twelve millimeters as against a modern range of four to eight millimeters. There is no question of a pathological thickening.

Each half of a lower jaw or mandible consists of the horizontal tooth-bearing part–the body–and the portion which extends up to the temporal bone and articulates with it, called the ascending ramus. The latter terminates in a knob or condyle which fits into the articular socket of the skull base. In the half of the Piltdown jaw recovered the condyle and a portion of the chin region are missing. The rest of the jaw with the second and third molar teeth is intact. It is almost indistinguishahle from that of a young chimpanzee. The chin region does not jut out in human style, but falls away as in apes. We have discussed the evolution of the human jaw in a previous section (page 170) and the reader will do well to refresh his memory on these points. In the Piltdown mandible the origins of the genio-glossal muscles which work the tongue are in a pit, behind which there projects a simian plate or shelf. The canine tooth, found some time after the rest of the mandible, is a massive projecting tusk much like that of a female chimpanzee. The molar teeth are, however, within the human range, and the jaw, while large, is not enormous. Keith estimates the area of the palate constructed to fit this jaw at 53.2 centimeters, as contrasted with 26.6 centimeters, the average of twenty-two British medical students, 36.5 centimeters in a female chimpanzee and about 70 centimeters in male orangs and gorillas.

When compared with the completely ape-like jaw, the brain case of the Piltdown specimen is not at all anthropoidal. In the fitting together of the fragments and the parts restored from the opposite side, there developed a notable controversy between Sir Arthur Keith and other anatomists. The original reconstruction of Sir Arthur Smith-Woodward had a contracted and ape-like forehead and an ill-filled and roof-shaped cranial vault with enor[307]mous projecting face and jaws. The brain case was also markedly lopsided. Dr. Smith Woodward called the new specimen, Eoanthropus dawsoni, "dawn man."

Keith objected to the Smith-Woodward reconstruction of Eoanthropus on the ground that the right side was markedly smaller than the left, whereas we expect primitive men and apes to have notably symmetrical skulls. He maintained that the middle line of the skull vault had been incorrectly identified in that a portion of the left parietal had been pushed over the median line to the right side so as to thrust both of the lateral skull walls inward toward the center line, thus reducing the height and breadth of the vault. Keith re-identified the center line, pulling both parietals outward. The resulting restoration yielded a much more capacious brain case with a cubical content of 1500 cubic centimeters, as against the 1070 cubic centimeters of the original Smith-Woodward restoration.

Thus Smith-Woodward attributed to Eoanthropus a brain of infra-human size while Keith credited him with a cranial capacity equal to the average of adult male Europeans. Challenged as to the correctness of his restoration, Keith accepted a proposal that certain anatomists cut up a modern skull, give him fragments of it corresponding to those found at Piltdown, and that he then attempt from these fragments to reconstruct the skull. From this trial Keith emerged triumphant, having succeeded in reproducing the model skull as to general form and dimensions and returning an estimate of its brain capacity correct within 20 cubic centimeters. Sir Arthur made but one error: he mistook the sex of the skull, which was female, and provided it with masculine and projecting brow ridges.⁴ Later restorations both by Keith and by Smith-Woodward have tended to make the cranial capacity a little smaller than the first restoration of the former and much larger than the original effort of the latter. It is now agreed that the correct capacity must have been about 1400 cubic centimeters. Since Eoanthropus is reckoned to have been a female, the estimated capacity is somewhat above the average of modern European fe[308]males (1350 cubic centimeters). If we accept Keith's restoration as mainly correct, we may then follow him in the interpretation of the brain cast.

The frontal region of Eoanthropus is high and vaulted; the retread is neither low nor receding, but broad. The outer angle of the orbit shows only a moderate development of the brow ridge. The dimensions of the Keith restoration are: length, 194 millimeters; breadth, 150 millimeters; height from ear lobes, 117 millimeters. These are common measurements in modern skulls of a good size. The line of the temporal crest from the external corner of the orbit extends vertically upward for some distance before turning backward–an ultra-human feature. The occipital markings show that the skull was poised on the spinal column in an essentially modern style. There is little or nothing of the simian in this brain case. Its most outstanding feature is the extraordinary thickness of the bones.

The third frontal convolution, which is concerned with speech, shows essentially human development, and is little if any inferior to that of a native Australian of today. Speech was certainly at least a potential ability. The convolutions of the temporal lobe are simple; the auditory center is plainly indicated. Keith cannot detect any feature in the frontal, parietal, or occipital areas which clearly differentiates this brain cast from modern ones, although the convolutionary arrangements lead him to the conclusion that he is dealing with a simple and primitive arrangement of parts.

The brain case of Eoanthropus may then be said to conform to human standards in size and in configuration. But we are now faced by the same difficulty which confronted us in the case of Pithecanthropus. For with the human brain case of Eoanthropus was found an almost completely ape-like jaw. Just as there is nothing clearly diagnostic of the anthropoid condition in the brain case, so there is nothing that is distinctively human about the jaw fragments. Again, as in the case of Pithecanthropus, some students have sought to solve this difficulty by assigning the jaw to a chimpanzee and the brain case to a man. Such attempts to reconstruct two animals of widely different types out of complementary parts from the same deposit, and presumably belonging to one [309] individual are the result of a misconception of human evolution. Evolution is not a harmonious steady progression of all parts of the organism; it is a jerky and asymmetrical transformation. Some parts of the body, such as the upper limb, remain much as they are in primitive reptiles; others, such as the foot and lower limb, evolve rapidly to adapt themselves to a new function. The human body is like an old house which has been modernized only where modernization is necessary. It has a new foundation and the topmost story is greatly enlarged, but the wings are old. Only a few readjustments have been made in the plumbing, wiring, and lighting.

It is quite wrong to expect all forms of fossil man to display the same balance in the development of their bodily parts. If the brain of your great-grandfather is fifteen per cent smaller than yours, you must not conclude that his jaws should be fifteen per cent larger, his arms fifteen per cent longer, and his legs fifteen per cent shorter. The fact that a Pithecanthropus had a half human brain and a fully human lower limb does not mean that every later human form should show the same precocity of leg evolution as compared with cerebral development. Human stocks did not evolve along the lines of one fixed and immutable pattern any more than have the anthropoid apes. The association of a simian jaw with a human brain case need not disturb us more than the association of a human thigh with an apish skull cap in the Java fossil.

The lower jaw articulates with the skull base in the temporal region. In modern mandibles the condyles or knobs of the ascending branches of the jaw fit into deep hollows in the temporal bones, called the glenoid fossae. In front of these fossae are rounded elevations, the articular eminences. The hind walls of the glenoid fossae are formed mainly by the tympanic plates which encircle the entrances into the bony ear. When you move your jaw in opening your mouth or in chewing, the condyles slip forward onto the summits of the articular eminences. In the lateral movements of chewing one condyle is somewhat in advance of the other and slips back into its socket before the other comes to rest. The pulling forward of the mandible in opening the jaws is accomplished by he action of the pterygoid muscles which have their origin in bony [310] plates running upward behind the hard palate and are inserted inside the angles of the ascending branches of the jaw. The closing movements are accomplished by the temporal and masseter muscles which originate on the sides of the skull vault and the lower borders of the zygomatic arches, and are also attached to the ascending branches, the temporals along the internal and anterior face, and the masseters on the outside. The rotary chewing movements are directed toward the center line; that is in masticating food on the left side, the lower jaw grinds toward the right, and vice versa. These inward grinding movements tend to wear the crowns of the teeth in a slope toward the center line of the palate, so that the crowns of the lower left molars slope upward and inward when deeply worn; and those of the left upper molars have a corresponding inclination. On the right side, the slopes are reversed. The "tripping" of the condylar knobs against tile articular eminences accelerates the opening of tile jaws. The condyles of the jaws slipping forward upon the articular eminences give more room between the molar teeth for the grinding of food.

In anthropoid apes the condyle of the jaw does not fit into a deep glenoid depression but moves

on a slightly convex articular plateau. The back wall of the temporo-mandibular joint is not formed as in man by the tympanic plate but by a bony ridge, called the postglenoid process, running inward in front of the auditory opening. The jaw of the ape does not rotate laterally in the movements of chewing, because the interlocking canines do not permit such movements. The ape chews straight up and down. Hence the wear on the crowns of the teeth tends to cause blunting of the cusps and pitting of the indentations between the cusps as the upper and lower teeth interlock. For each conical cusp fits into an inter-cusp depression in the opposing tooth above or below. Thus the teeth of an old gorilla show wear on the molar crowns in the form of hills and hollows.

The crowns are not worn flat or sloping as in man.

Now the temporo-mandibular joint in Eoanthropus is a deeply excavated glenoid cavity with a high articular eminence before it as in modern man. Condyles of the human shape are required to fit into the glenoid fossae. Unfortunately the condyle is missing from the half of the mandible recovered. So it cannot be proved [311] that the jaw belongs with the skull by fitting it to the temporo-mandibular joint. This has afforded yet another opportunity for the separatists to affirm the lack of kinship between mandible and brain case They allege that the lower jaw, being almost wholly simian in shape, should be equipped with an ape-like condyle which would not fit the modern type of glenoid fossa present in the temporal bone. A further difficulty lies in the fact that a long projecting canine tooth, evidently a lower canine, has been recovered, and we should expect jaws with protruding ape-like canines to be fitted to the shallow articular plateaus of the anthropoid rather than to the deeply excavated glenoid fossae of modern man. In order to fit the simian jaw to the human socket we must model upon the mandible a humanly shaped condyle which is incongruous with the rest of the bone. This little difficulty need not, however, embarrass us. If nature puts conjoined human and anthropoid parts into the same organism, some compromise has to be made at the junctures.

Because the skull base of Eoanthropus, as reconstructed by Keith, is of considerable breadth and the sockets of the mandibular condyles are far apart, the two halves of the lower jaw must be spread posteriorly in order to articulate the jaw to the skull. This necessitates a departure from anthropoid jaw proportions. For the great apes have long narrow jaws in which the molar tooth rows converge toward the rear, so that the space between the molars is actually less than between the canines. In conformity with this narrow U-shaped dental arcade the ascending rami of the anthropoid jaws are moderately close together. The narrow skull base makes the distance between the glenoid fossae relatively small. Thus the Piltdown jaw cannot be fitted to the skull without modelling the missing side and the symphysis in such a way as to cause the tooth rows to diverge posteriorly, and the condyles to be spread far apart, thus imparting to the whole jaw approximately human shape and proportions in bicondylar breadth and hinder spread of the dental arch. Such a restoration increases the tongue space and provides for its movements in speech.

The association of the long canine tooth with a deep glenoid fossa and a pronounced articular eminence, creates, as we have said, a dilemma. The crown of the tooth in question rises about fourteen [312] millimeters above the neck and is pointed. In female anthropoids, whose canines are much smaller than those of males, the canine crowns rise from sixteen to twenty millimeters above the neck. In human races of today this elevation is rarely more than twelve or thirteen millimeters (Keith). The greatest diameter of the crown of the Piltdown canine also exceeds that found in modern man and the broken root was probably of more than human length. The crown of the tooth is hollowed by the grinding on it of an opposed tooth of the upper series, but the way in which it is worn differ from that found either in anthropoid apes or in man. In anthropoid apes the canine teeth are in the lateral or side series, but in man they have become reduced in size and are rather a part of the front or incisor series. In the chimpanzee the lower canine crown fits into a V-shaped gap between the-upper lateral incisor and the upper canine, which latter tooth is farther back in the upper jaw than the opposing mandibular canine. Thus in the chimpanzee the canines act as shears, the point of the lower one impinging against the outer edge of the upper lateral incisor and the anterior edge of the upper canine, while the upper canine fits into the gap between the lower canine and the first premolar and grinds against both of their edges. Since the lower canine of a chimpanzee is worn both anteriorly by the upper lateral incisor and posteriorly by the upper canine, its inner or lingual aspect presents two worn surfaces separated by a ridge, showing the areas abraded by the opposing upper teeth. In the Piltdown tooth there is no ridge delimiting the areas of incisor and canine wear, but the whole inner surface is deeply excavated. Keith thinks that this wear is due to the upper lateral incisor alone, and that the missing upper canine ground only against the lower first premolar. He explains this condition by the inference that in Piltdown man the lower canines had already been displaced from the lateral series to the front series and that by their approximation the chief tooth opposing the lower canine became the upper lateral incisor instead of the upper canine.

In modern man the blunt conical canines are, as stated, in the front series, and are used for biting in exactly the same way as are the incisors. The lower jaw has receded so that the incisors no longer meet edge-to-edge as in primitive man and the anthropoid [313] apes, but the lower ones bite behind the upper, making what is known as an "over-bite." In Keith's opinion the canine of Eoanthropus represents a transitional stage in the conversion of a projecting, shearing canine of the lateral series to a short, blunt—cusped canine of incisor function in the front series.

The molar teeth of Eoanthropus are longer from back to front than from side to side–an anthropoidal characteristic. Instead of the molars decreasing in size from the first to the third, the second molar is larger than the first and the third as large as the first. In modern men the third molar is the smallest and the first the largest of the series. In the gorilla the molar teeth increase in size from front to back. Thus as regards molar tooth size Eoanthropus is in a class midway between modern man and the apes. The lower molar teeth of modern man often have but four cusps. The fifth hinder cusp belongs to the ancestral Dryopithecus pattern and is preserved in many modern savages. This fifth cusp is well developed in the surviving molars of the Piltdown specimen. Since the molars of Eoanthropus are ground flat, rotary chewing movements must have taken place, as suggested by the character of the glenoid fossae. The canines could not then have interlocked.

The face of the Eoanthropus must be reconstructed from forehead and brow ridges, the nasal bones, and the lower jaw. Fortunately in 1915 Mr. Dawson found three fragments of a second Piltdown skull on the surface of the plateau two miles distant from the site of the first discovery. These were a portion of the frontal carrying the inner side of the right orbit, a portion of the middle of the occipital bone, and a left lower molar. The orbital fragment completes the restoration of the forehead region in the first specimen and clearly shows that only a moderate brow ridge was present. The nasal bones are flat and broad, much like those of modern Negroids or Australians. The external angle of the brow ridge together with the root of the zygomatic arch attached to the temporal bone and the articulated lower jaw, give some idea of the width of the face. This was moderate. When the jaw is articulated to the skull base and the coronoid process put at the correct level with reference to the zygomatic arch, it is seen that the face was not overlong nor remarkably projecting. Details [314] of the nasal aperture are of course impossible of restoration. It seems clear, however, that the nasal bridge was low and broad and the aperture wide. From the heavy but not greatly prognathous jaws the mandible dropped away in chinless fashion.

The finding of fragments of another Piltdown skull of the same type seems to settle the case of the association of the original jaw with the skull, since the second specimen shows the same broad and high vaulted forehead and the molar tooth is declared to be identical with those found implanted in the original jaw. The new fragments could not however, have belonged to the first skull, since they were found at too great a distance from the site of its discovery.

Although we know nothing of the bodily skeletal characters of the Piltdown woman, we are safe in assuming at least that she was an erect walker with a fully human foot.

The Piltdown lady was then provided with a brain a little larger than that of the average English woman and with a respectable forehead. To her capacious but thick walled brain case was attached a face of ordinary dimensions but ending in a massive jaw with projecting, ape-like canine teeth. Her palate and masticatory muscles were enormously larger than those of her modern sisters, and very little different from those of a chimpanzee. She could not have resembled Pithecanthropus of Java much more closely than the latter resembled an anthropoid ape.

If the Piltdown jaw belongs with the skull, and of this there can be little reasonable doubt, we shall have to abandon the old functional theory that the human brain evolved because the jaws atrophied and shrank, as a result of their loss of function through the freeing of the arms for prehension. For the Piltdown lady acquired a big brain without losing anything of her jaw worth mentioning. Was the Dawson Dawn Lady our direct ancestor? Keith thinks not. She represents in his opinion a survival into early Pleistocene times of a primitive offshoot from the human stock which had attained to essentially human status early in the Pliocene period. I am inclined to think. however. that this type more nearly approximates the ancestral form of modern Europeans than any prototype yet discovered.

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4 A detailed and interesting description of this test and a most exhaustive discussion of the Piltdown skull may be found in Keith's great work, the Antiquity of Man, Philadelphia (1925), vol. II, p. 537 sqq.