Alvan T. Marston, F.D.S.R.C.S. Eng., L.D.S. Edin.

British Dental Journal 1952

[1] In a previous article (Marston, 1950) I discussed the geological age of the Piltdown skull, then still being considered to be 600,000 years old, and showed that it could not be earlier than the latter part of the Last or Riss-Wurm Interglacial Period, and emphasised that the survival of the turbinal bone might suggest a post-Wurm age—a view consistent with the low fluorine content.

The object of this paper is to present the evidence to show that the canine tooth and mandible belonged to an ape, to give reasons why they could not have belonged to Piltdown Man, and also to demonstrate by very simple tests, which may be confirmed by anyone who goes to the trouble of acquiring casts of the Piltdown fragments, the truly modern man characters of the skull, especially of the temporo-mandibular joint, and of the occipital and frontal regions.

I wish to express my acknowledgements to the Trustees and to the Keeper of Geology of the British Museum (Natural History) for permission to publish reproductions taken from Sir Arthur Smith-Woodward’s lantern slides of the radiographs of the Piltdown canine tooth and mandible.

Fig. 1. Fig. 2.

Figs. 1 and 2. Cast of the Piltdown canine tooth in the socket of the left upper canine in a female orang-outang skull.

The Canine Tooth

The most simple way of demonstrating that the Piltdown canine came from an ape is by fitting it into an ape skull.

Figs. 1 and 2 show the tooth simply inserted into the socket of the left upper canine in the skull of a female orang-outang. There it fits, and it harmonises closely with the canine of the opposite side, and with the remaining teeth. This shows it to be the left upper canine.

[2] The tooth is 3.1 cm. in length, but the end of the root is missing, and judging by the orang canine which it replaces the full length might have been 3.6 cm.

The curvature, thickness, length, and D-shaped transverse section of the root prevent its being fitted into a human skull. While the lingual surface of the root is more definitely flattened than in the existing orang, yet the convexity of the labial surfaces of both Piltdown and orang teeth are the same. The harmonious alignment of the Piltdown crown shows that not only must the curvature of the roots of both teeth have been the same–upwards, inwards, and backwards–an astonishing agreement, but the crown of the Piltdown tooth was set on the root in the same way as in the orang tooth which is deflected slightly outwards towards the cheek, and, projecting downwards below the level of the incisor and cheek teeth, closes down the antero-external surface of the first lower premolar.

The crown is pointed and conoidal, and is longer than in the human tooth; is not mesio-distally compressed as in man, but is narrower in the labio-lingual direction. In the true sense it was not compressed at all, but was preserved from compression by the diastema between it and the lateral incisor. Whereas the crown of the human canine continues to widen from the neck for about two-thirds of its length and then converges to an obtuse point, that of Piltdown narrows from the neck and thus retains the primitive anthropoid character.

The root does not taper sharply from the neck as in man, but the thickness at its apical end is still three-fourths of that at the neck. Of definite diagnostic importance is the D-shaped cross-section with the major axis in the mesio-distal direction, the opposite to that of man (fig. 3).

On the lingual surface of the crown an articular facet extends from the point of the cusp to the cervical margin, and from the distal border obliquely forwards and inwards to the mesial border. The facet is concave from above downwards, and when tested by a "straight-edge" is uniformly flat in the antero-posterior direction. As seen in the ape skull the manner in which it was worn is adequately explained by the overlap of the canine down the flattened antero-external surface of the lower premolar which, in mandibular movement, cannot move outwards much owing to the restraint on lateral movement imposed by projecting canines, and so works from the forward biting position backwards to the position of rest. The antero-posterior flatness thus marks the direction of wear,

the mandibular movement along a relatively flat plane associated with the relatively flat ape type of temporomandibular joint.

Morphological and functional characters of the tooth will be discussed later.

Fig. 3. The Piltdown (upper row) and human (lower row) canine teeth compared. Note the difference in the shape and direction of the transverse section at the cervical margin of the root: the major axis of the Piltdown tooth is in the mesio-distal direction, whereas in the human tooth it is in the opposite or labio-lingual direction. Scale 1 in 2.

The Mandible

The ape characters of the Piltdown mandible were recognised from the outset (Dawson and Smith-Woodward, 1913-14; Keith, 1913; Waterston, 1913). Sir Arthur Smith-Woodward used the mandible of a young chimpanzee and not a human jaw as his pattern in restoring the missing parts, and he cited the following of its features as characters in apes but not in man:

(1) The absence of the eminence of the chin.

(2) The presence of the simian shelf.

(3) The absence of the genial tubercles.

(4) The feebleness of the mylohyoid ridge.

(5) The position of the mylohyoid groove.

(6) The parallelism of the molar-premolar series.

(7) And the great width of the insertion of the temporal muscle as far downwards as the

alveolar margin.

There are other ape characters about this mandible which I do not at the moment intend to discuss, wishing to concentrate attention upon fig. 4.

Vertical sections through the mandible between the first molar and the second premolar disclose a radical distinction between the mandible in man and ape. As figs. 1 and 2 show that the canine tooth belonged to an ape skull, just as definitely does fig. 4 make clear that the Piltdown mandible belonged to an ape and not to a human skull.

In man, whether fossil or recent, the lower portion of the lingual surface slopes outwards and the mandible widens interiorly in this region, [3] whereas in apes it curves inwards to the tongue, and the mandible narrows inferiorly. The issue is clear cut. In man the mandible widens inferiorly;

in apes it narrows inferiorly. What answer does the Piltdown mandible supply? (fig. 4.)

Fig. 4.–Vertical sections through the mandible between the second premolar and the first molar, in:

1. Sinanthropus child. (Locus B) cast

2. Sinanthropus adult. (Locus G/1) cast

3. Heidelberg cast

4. Modern man actual specimen

5. Piltdown mandible cast

6. Chimpanzee actual specimen

7. Orang-outang, female actual specimen

8. Specimen 7 through the second premolar actual specimen

9. Orang-outang, male actual specimen

Specimen 1, 3 and 5 are taken from the right and 3 through the left side of the jaw owing to the incompleteness of these specimens, and the slices mesial and distal to the cutting are opposed. In the actual specimens, 4, 6, 7, 8, both sides of the jaw are opposed. The mandible widens inferiorly in man, but in the apes it curves inwards under the tongue. In Piltdown it curves inwards as in the apes.

In Piltdown, the lower border of the mandible curves inwards to the tongue, as in apes, and particularly in the female orang. This clearly indicates that it belongs to the ape group and not to the human group.

It should be noted that in the Sinanthropus child–a most significant human fossil since it represents the precursive form of Early Pleistocene Man–the mandible in this respect makes no approach to the ape condition, but on the contrary exemplifies the form leading up to modern man.

Method of Demonstrating that the Two Molars in the Piltdown Mandible are Ape Teeth

Much controversy has ranged over the molar teeth. Smith-Woodward and Keith said they were human. Gerrit Miller (1920) said they resembled those of an old chimpanzee. Ramstrom (1919) said:

"The jaw and cheek teeth have no human characters whatever, they represent a Chimpanzee whose peculiarities so far as they are shown by the specimen, come within the range of the genus Pan. The breadth-length index of the Piltdown teeth he assessed as 83; that of Man 90 to 113; and of the Chimpanzee 74.6 to 90.

"Thus the Piltdown teeth come within the range of Chimpanzee and not of man.

"In actual measurements the length of the crown exceeds the width in Chimpanzee by 1 to 3-4 mm.; in Man rarely by as much as 1, while not infrequently the width was equal to or greater than the length. Neither in their crown outline, hypsodonty, form of the pulp chamber, or in the structure of the cusps, are the Piltdown teeth to be considered as human."

William K. Gregory (1922) said:

"The two molar teeth, although greatly worn, show the primitive Dryopithecus pattern which is

disguised in all the hominidae; the molars appear to agree generically with those of the very old Chimpanzee figure by Miller. They differ from all human molars that I have seen in being relatively long and narrow, and in having the posterior moiety less widened transversely."

Hrdickla (1923) said:

"The Piltdown teeth, primitive as they are in some respects, are already human or close to human, and suggested the close relation of the Piltdown molars to some of the late Miocene as early Pliocene human-like teeth attributed to Dryopithecus rhenanus."

Tomes (1923) said:

"The contour of the front of the mandible is exactly that of a young chimpanzee. The teeth, however, are quite human, both having five well-defined cusps, and two normal well-separated root."

My approach has been to make plaster casts from actual ape molars (orang-outang); dip them in wax to prevent stain from penetrating the plaster; cover the crowns with a thin black lacquer; and file down the occlusal surfaces to the same flat condition as the Piltdown molars. After filing, the worn down cusps show up white in contrast with the black unworn-fissures and depressions.

Fig. 5 shows the casts of two orang-outang molars so prepared, mounted by the side of the Piltdown mandible.

Note 1. Same form of crown outline;

2. Concave and not convex lingual margin;

3. Position and size of the five cusps;

4. Same relative antero-posterior length to transverse breadth index.

[4[ 5. The less widened posterior moiety;

6. The shape and size of the talonid valley on the posterior part of the crown.

The Piltdown molars can thus be shown to be as ape-like as the teeth of orang-outang with which they were compared, and in the light of fig. 4 this should occasion no surprise.

Fig. 5. Plaster casts of orang-outang molars treated as described in text, and mounted alongside the Piltdown molars.

The Radiographic Evidence

X-ray examination of the cranial fragments and of the mandible and canine tooth reveals in two ways that the mandible and canine tooth could not belong to the same head. Keith (1925) said:

"When the architecture of the Piltdown mandible is revealed by the use of X-rays, the arrangement of the trabeculae and lines of bone then seen within the mandible is reminiscent of the anthropoid than of the human form."

Clearly bone of anthropoid structure had no place in a human head.

The second discordance between the mandible and canine tooth, on the one hand, and the skull, revealed by the radiographs is that the end of the root of the third lower molar had not finished forming; that the upper canine tooth also, whose apical end was incomplete and pulp chamber widely open, was an immature tooth; and that these would be out of place in a human skull in which the coronal and sagittal sutures were completely closed, the upper part of the lambdoidal suture closed, and the squamous suture of the temporal bone was not fused, representing an age of not less than 40 years for the Piltdown Man.

Fig. 6.–Radiograph of the Piltdown canine tooth to show details of the apical end of the root. For description see text. Enlarged about twice natural size. ¹

The Radiograph of the Canine Tooth.–The apical end of the root is incomplete, and the widely open pulp-chamber is filled with grains of iron-stone and sand. A larger heart-shaped piece of stone blocks the open end of the pulp-chamber, to which attention is now drawn (fig. 6). In the sketch drawing which I have prepared by projecting Sir Arthur Smith Woodward’s lantern slide of the canine on to a sheet of paper (fig. 7) this stone is wider at b-b¹ than at a-a¹. Between a and b and a ¹ and b¹ the tooth wall diminishes in thickness from within outwards, or, in other words, the pulp chamber is dilating towards its open end. The extent of the dilatation is shown by the presence of three small granules at c, which are wedged in between the wider end of the heart-shaped stone and the tooth wall at b. This evidence permits the interpretation that the end of the root had not finished forming when the tooth found its way into the gravels. The apical end of the pulp chamber was sufficiently widely open for the grains of sand and stone, but not for the heart-shaped wedge to enter. Abrasion in the gravel would round off the thin wall of the dilating extremity.

The human equivalent to this stage of canine development is shown in "Atlas of Skiagrams Illustrating the Development of the Teeth" (Symington and Rankin (1908) Plate VIII, [5] figs. 1 and 2 representing a boy of 9 years old, or Plate XII, fig. 1, that of a girl 13 years old).

Fig. 7.–Drawing taken from the radiograph of the open apical end of the Piltdown canine. The pulp chamber is filled with grains of sand and granules of stone. A larger heart-shaped piece of stone blocks the entrance to the pulp-chamber. This stone is wider at b b¹ than at a a¹. In other words the pulp chamber is dilating towards the open end, as is also shown by the presence of the three small grains of sand at c which are wedged in between the wider end of the larger stone and the tooth wall at be.

This indicates that the Piltdown canine was not fully calcified: it was an immature tooth belonging to a young adult ape and not to an aged specimen. On the grounds of individual-life-age this tooth could not have belonged to the Piltdown human skull of over 40 years of age.

The Radiograph of the Mandibular Third Molar Socket.–The roots of M₁ and M₂ are well formed and pointed. The empty socket of M₃ shows that the roots of this tooth were blunt and the base of the sockets not only descend to a lower level than the roots of the first and second molars but also occupy the same low relationship to the inferior dental canal which is the normal developmental position in apes. The long axes of the sockets tilt forwards, and the thickness of bone between the base of the mesial socket of M₃ and M₂ should be noted as evidence of incompleted rotation from the developmental to the final position (see fig. 8).

Thus the condition of the socket of the third molar indicates a root which had not finished forming, a tooth not yet tightly set. The immaturity of the tooth agrees with that of the upper canine tooth as further evidence that the mandible, as well as the canine, belonged to an ape skull.

Fig. 8.–Radiograph of the mandible to show the socket of the third molar. A, the inferior dental-canal. B, the empty sockets of the roots of the third molar.

Ape Order of Eruption

Apes not only acquire their teeth at an earlier age than man, for by the time the human child has cut its first two milk teeth, the young chimpanzee may have as many as sixteen, but the order in which the permanent teeth make their appearance is different.

In apes the order of eruption is, generally speaking, 6, 1, 2, 7, 4, 5, 8 - 3, that is, the second molar erupts early–after the second incisor and before the premolars; and t he canine late–at about the same time or even later than the third molar. Whereas in man there is an interval of about six years between the eruption of the first and second molars, in the apes the second molar comes into wear soon after the first molar. Although some authorities state that the hominids up to Neanderthal man followed the ape order of eruption (Bennejeant, 1936), it is significant that in Sinanthropus and in Heidelberg the first molar is markedly more worn than the second, possibly being due to the whole range of the eruptive period being spread over a longer time. Man arrives at maturity later.

In the Piltdown molars wear has affected both teeth to about the same extent, indicating that the second molar erupted, as in the apes, fairly soon after the first, and without the more prolonged time interval of man. Linked with the immaturity of the roots of the canine and third molar, it may be concluded that the Piltdown teeth followed the ape order of eruption.

The Evolutionary Gap Between the Piltdown Canine Tooth and the Human Canine

The short-obtused-pointed crown of the human canine is something not seen in any [6] apes, and is one of its characters which suggests that the human stem did not pass through the anthropoid stage. The nearest approach to man in respect of the short crown is found not in the apes, but nearer the base of the Primate stem (Mivart, 1873).

Fig. 9.–To illustrate the essential difference in the form of the ape and human canine (see text).

Ordinarily speaking, the primitive generalised mammalian canine was a sharp-pointed conical tooth aligned with the cheek teeth, and from this primitive form the human canine and the anthropoid canine have developed along divergent lines. The essential difference in crown form may be illustrated by drawing a pointed ovoid, as in fig. 9A, to represent the crown as seen from the labial aspect. If to the blunt end, and from the maximum width a thick and only slightly tapering and recurved root is added, the result gives the shape of the Piltdown canine (fig. 9b). If, in contrast, a thinner, straighter tapering root is added to the pointed end of such an ovoid, the result conveys the general idea of the blunt human canine (fig. 9c).

In non-human canines, the root is more or less curved, and from the neck a conical crown converges to a point. This conical character is enhanced in the males. In male apes, cf. orang-outang, the tooth, owing to its hypertrophied point, has more resemblance to that of a carnivore (cf. Hyaena) than to a human tooth. Similarly the monkey canine resembles a carnivore canine more than that of man.

Thus, in its evolution, the anthropoid canine by retaining the conoidal crown, by being aligned with the cheek teeth and separated by a diastema from the incisor teeth has undergone less modification from the generalised mammalian canine form than has the human tooth. The human tooth is not a reduction from the anthropoid type of canine, but its specialised form characterised by the addition of mesial and distal cuspules to the primitive central point, which has remained short, witnesses a break-away from the way of life of other primates, in a very remote past, influenced by the advantages which hand and foot specialisation conferred. As I have pointed out elsewhere (Marston, 1946), where the prehensile role of the anterior teeth is diminished by being taken over by other organs, as by the hand in Man, the premaxillary region undergoes reduction.

The Piltdown canine with its conoidal crown, which closely parallels the teeth of orangs and chimpanzees which were figured over a hundred years ago by Owen (1845) was the tooth of an animal which still used its forelimbs for walking. The character which most of all distinguishes it from Man is the D-shaped cross-section of its root.

The Cross-Section of the Root of the Upper Canine.–The cross-section of the root of the human canine at its junction with the crown, may be likened to the keystone of an arch, wedged in, as it is, between the lateral incisor and the first premolar. The labial surface is wider than the lingual, both are convex; and the mesial and distal surfaces may both be grooved. The labio-lingual axis is no longer than the mesio-distal. It is the tooth of the closed dental arch, and as such its characters were already established in the earliest known human fossils which have yet come to light.

The Piltdown cross-section is quite different; the tooth is not mesio-distally compressed, as in man, for its shorter axis lies in the opposite or labio-lingual direction. In the true sense it was not compressed at all, but was preserved from compression by a diastema between it and the lateral incisor (see figs. 1 and 2). The deduction made from the character of the lingual facet that the tooth was associated with a fairly wide diastema and with the anthropoid and non-human type of premaxilla, and for this reason did not belong to the human skull, was confirmed by mounting it in the ape skull.

As further evidence of the wide evolutionary gap between this tooth and that of man, man differs from the apes and from all other animals possessing upper incisors in that the bone seen below the level of the nose and forming the anterior walls of the incisor sockets is the maxilla; in all other animals, apes included it is the premaxilla. Man is thus unique in this respect (Wood Jones, 1929). Generally speaking, in Man when the developing child has reached the twelfth week of foetal life, the incisor processes of the maxilla overgrow, absorb and replace the facial premaxilla which appears transitorily only during the tenth and twelfth weeks, and the maxilla thus comes to form the anterior walls, the mesial septal walls, and in the case of the second incisor the medial third of the posterior wall, of the sockets of these teeth (Ashley-Montagu, 1935 and 1936).

[7] In apes the facial premaxilla retains its identity throughout life; it is not replaced by the maxilla. Even when the suture between the premaxilla and maxilla closes, it closes just as in the closure of other cranial sutures, by the process of simple interstitial union, and the bone seen below the level of the nose and forming the incisor sockets still remains the premaxilla.

Professor Wood Jones (1948) has considered that the establishment of this feature as a specific human character at so early a stage in embryonic life suggests that it was rooted in an extremely remote past near to the base of the Primate stem.

The cross-section of the Piltdown canine is a diagnostic ape character, well established in the Miocene apes, and which the passage of thirty million years has done little to change.

The Wear on the Teeth.–The wear on the Piltdown teeth was the result of mandibular movement associated with:

(1) the flat anthropoid type of temporomandibular joint which allows greater antero-posterior

play along a relatively flat occlusal plane,

(2) protruding ape canine teeth whose length restricts lateral movement, especially movement

outwards.

(3) rapid rather than slow wear.

In order to be able to distinguish between what is human and what is anthropoid wear on teeth it is necessary to have a clear idea of underlying principles.

Wear results from movement, and mandibular movement differs in man and ape. Man can move his jaw from side to side. The ape cannot, because the long canines which protrude beyond the occlusal plane prevents lateral movement–especially outward lateral movement. Hence ape movement is from before backwards, or from inwards and forwards back to the position of rest. Examination of the ape temporomandibular joint on the temporal bone shows that it is especially

designed for antero-posterior movement–the articular eminence is shallow, and the articular surface over which the condyle ranges is prolonged anteriorly. The condyle path is thus relatively flat, and the cheek teeth meet and work along a relatively flat occlusal plane. From this movement along a relatively flat plane, flat wear results, which shows on the lower molar teeth as flat or only slightly concave facets.

Fig. 10.–Orang-outang male, lateral view, to show the restraint on outward lateral movement imposed by the long canine teeth. Note also the feeble mastoid process, and the height of the head of the condyle relative to the external auditory meatus.

The highlights of canine restraint are shown in the male orang-outang (fig. 10). Here the hypertrophied canines restrain lateral movement to the extent that it is impossible, when the teeth are in closed sliding occlusion, for the buccal cusps of the lower cheek teeth to cross outside the crests of the buccal cusps of the upper teeth. In this skull, although the distance from the mid-incisor point to the centre of the head of the condyle is 160 mm., and the length of the dental arcade from the mid-incisor point to the hinder margin of the third molar is 90 mm., the maximum lateral movement in the incisor region is only 4 mm. to either side of the middle line–a range of 8 mm. from side to side; on the first molar it is only half that amount. In the much shorter human mandible lateral movement is considerably greater, and it permits the lower cheek teeth to cross (transgress) the buccal cusps of the upper teeth.

One further feature must be noted. It assumes diagnostic importance in deciding between ape and human wear. In all ape mandibular movements, the lingual cusps of the lower molars escape transgression. They cannot be made to cross the crests of the lingual cusps of the upper teeth.

This is the general picture.

Now to come to details. As characters of ape wear may be noted:

(1) Because of the low condyle path the whole trend of ape wear is to produce relatively flat or only slightly concave facets on the lower molars.

(2) Because of the canine restraint these facets first show on the buccal cusps, leaving the

points of the lingual cusps untouched.

(3) The buccal cusps are worn, not by crossing the buccal cusps of the upper teeth, but by

their passage over the median valley and up to the [8] medial slope of the upper lingual cusps whose crests they cannot cross because of the interlock of the upper canine and first lower premolar.

(4) The reduction of the lower lingual cusps is not caused actively by transgression of the

upper lingual cusps, but passively by the general lowering of the whole of the occlusal surface by the extension of the facets which began on the buccal cusps.

When the points of the lingual cusps have been levelled away and the lingual crown outline has been reached and lowered, its surface contour has been forced on it by the contour of the medial valley of the upper teeth.

It is not unevenly worn, as in human attrition, by the opposing upper lingual cusps.

(5) The median valley on orang upper molars is broad and shallow. The oblique ridge is blunt and not high-standing, and when this has been reduced by direct antero-posterior wear, as in nibbling, the lower buccal cusps are thus left to work over an increasingly flat surface becoming themselves flattened in the process.

This flatness, derived from the median valley on the upper teeth, becomes the character of the buccal crown outline on the lower molars and later of the lingual crown outline.

The above reasoning may seem to be unduly labouring a point and making a mountain out of a molehill, but it is by paying attention to details that the wear on the Piltdown tooth, which was said to be human, can be shown to be anthropoid, and that the wear on the left lower molar, found two miles away from Piltdown, which was claimed to be worn in the same manner as the type specimen, can be shown to be human and to differ from the type specimen.

The Piltdown Wear. The character of the lingual facet on the upper canine has already been described. This tooth protruded below the occlusal plane. The flatness of the facet from before backwards when tested with a "straight-edge," and the simple concavity from above downwards, confirm that it was worn by antero-posterior and not by lateral movement, by the antero-external surface of the lower premolar.

When a "straight-edge" is applied to either molar, whether antero-posteriorly along the buccal or lingual margins or transversely across the mesial of distal margins, the wear is flat. On both teeth all five cusps have been removed completely. The first molar has suffered a post-mortem displacement which has caused its lingual margin to stand higher than that of the second molar, and the tooth is slightly displaced buccally, but on neither tooth is there any evidence of the uneven lowering of the crown outline where it could have been expected to show had there been the lateral movement which accompanies human wear.

Visualise a carpenter’s plane being pushed forwards and slightly inwards along these teeth. The result would be the evenly worn buccal and lingual crown outline very like what is seen on the Piltdown teeth. Thus in the Piltdown flatness we can see something more than the effect which has been produced. We can see why and how it has been produced, and know that this human rotary movement which was part and parcel of the joint cavity on the Piltdown temporal bone, but that it was an ape movement.

While there are some, who were formerly skeptics, but who now admit that the canine tooth belonged to an ape, among these are some unwilling to admit that the mandible also belonged to an ape. The fact that the mandibular teeth received their wear from the same cause as the canine tooth should resolve their doubts. Canine and mandible are both linked together by the wear on the teeth.

The heavy wear has often been considered to indicate age. That does not necessarily follow. Here it can be explained as relatively rapid wear, since the enamel and the dentine, the one the hardest tissue in the body, the other softer, are both worn down at the same rate. In slow wear, as in the attrition of the aged, saucer-shaped concavities form in the exposed dentine leaving upstanding rims of the harder enamel. These concavities may even sometimes be seen on deciduous teeth. Although the wear has been heavy on the canine tooth and had nearly reached the pulp chamber, only at the extreme coronal tip of the pulp has secondary dentine been laid down, otherwise there is very little, if any, beneath the facet on the lingual surface.

Note on Human Wear.–As features distinguishing human from anthropoid wear the following may be noted.

The whole trend of human wear as it shows on the first and second lower molars favours

(1) facets which are more concave than those found in anthropoids;

(2) facets which transgress both the buccal and the lingual outlines;

(3) facets which are bi-directional and vary in direction according as to which condyle

swings forwards;

(4) a general oblique concavity which runs from the lingual side of the distal margin to

the buccal side of the mesial margin, related to the parabolic shape of the dental arcades

and the off-centre bias due to the steep condyle path.

[9]

Fig. 11.–The movement of wear on the first and second left lower human molars analysed. The A-lines, continuous, denote movement from without inwards. The B-lines, stippled, denote movement from before backwards. The upper cusps concerned are indicated by A.1, External cusp of PM², B.l; A.2 antero-external of M¹, B.2; A.3, postero-external of M¹, B.3; A.4, antero-external of M², B.4; A.5, postero-external of M², B.5; A.6, internal of PM²,, B.6; A.7, antero-internal of M¹, B.7; A.8, postero-internal of M¹, B.8; A.9, antero-internal of M², B.9.

The bi-directional transgression of human wear is shown in diagram by fig. 11. The lines A denote movements from without inwards; the lines B denote movements from before backwards and outwards back to the position of rest. In the mouth the facets are broadened and blurred by rotary movement combined with direct antero-posterior (nibbling) movement, and this is apt to create the impression that the predominant character of human wear lies in the oblique concavity, noted in (4), running from the lingual side of the distal margin to the buccal side of the mesial margin.

Fig. 11 suggests a method for identifying human wear on the first and second lower molars. it is applicable to Sinanthropus, Heidelberg, as well as to modern man. It can also be applied to the isolated left lower molar which was found on a heap of stones raked off from the surface of a field two miles from Piltdown (Smith-Woodward, 1917). Admittedly it has a striking resemblance to the molars in the mandible, but differs, among other things, in its greater width at the junction of the crown and root but more importantly as concerns this study, in the nature of its wear.

The occlusal surface is heavily worn and the dentine is exposed on all five cusps. Occupying the central area is a smooth concave depression from which all traces of fissure pattern had been worn. In heavy wear, unsuspected details of fine relief and tracks of movement can be brought out by allowing a lightly held soft pencil to find its way guided only by the contours of the surface. In this way, bi-directional lines of movement B.7 and A.7 (see fig. 11), where the antero-internal cusp of the first upper molar occludes, can be traced. This bi-directional track of movement is human and not ape wear. Studied in the light of fig. 11, all the effects of the A and B lines are identifiable. A.1, B.1 on the antero-external cusp; A.6, B.6 on the antero-internal cusp; the distal margin by A.3, B.3, and by A.8, B.8.

When the tooth is held in the hand and moved, the play of light shows a general concavity which runs obliquely forwards and outwards from near the distal border to the antero-external margin, suggesting that the tooth formed part of the human parabolic-shaped dental arch.

When the transverse angle of attrition is measured across the anterior and posterior moieties, the difference discloses the lateral twisting component of the human occlusal plane, the curve of Monson.

Mandibular Width–Sufficient evidence has been produced to show that the Piltdown mandible belonged to an ape. Some workers consider this ape was more like an orang-outang than a chimpanzee. Male and female orang skulls which I have used show a feature which, though not constant in all apes, is certainly present in that shown in figs. 1 and 2. In them, in the mandible three lines are parallel. These, to be referred to as A, B, and C, run antero-posteriorly. They are: A, Through the centre of the head of the condyle and the tip of the coronoid process; B, through the median axis of the molar teeth; C, the sagittal line through the symphysis (fig. 12).

In man the lines A and B diverge, and B and C converge, anteriorly. In the orang shown, all three lines are parallel. Can these observations be applied to estimating the width of the Piltdown jaw? Owing to damage to the specimen, the centre point of the head of the condyle and the centre of the symphysis, are matters of interpretation lacking scientific proof, so that the following hypothesis is not brought forward as proof but only as permissible deductions.

The tip of the condyle is present; the margin of the sigmoid notch and sufficient of the neck of the condyle are present to allow the centre of the head of the condyle to be estimated reasonably, when an ape jaw is used as a control [10] and cognisance is taken of the direction of the posterior border of the ascending ramus. This gives the Piltdown line A.

For the line B I have taken the median long axis of the second molar, thus taking in account the slight buccal displacement of M₁. If, however, the line B is made to pass through the hypoconulids of both molars, the value of the width is diminished by about 1 mm., but this does not detract from the hypothesis since, even with the higher width value, it falls with that for the ape jaw.

In determining the mid-line as the symphysis we are aided by the presence of the outer rim of a foramen usual in ape jaws, in the pit above the simian shelf, and which in the orang is 2.5 mm. on the right side of the mid-symphyseal point. This has been taken to indicate the position of the Piltdown line C.

Application. On paper describe the line C to represent the sagittal line. Fasten thin direction rods, A to the tip of the coronoid process and to the estimated centre of the head of the condyle, and B through the median axis of the second molar. With the mandible mounted on a block of wax for stability, and with the direction of the ascending ramus the same as in the ape, place it on the paper so that the line C passes 2.5 mm. on the left side of the rim of the foramen mentioned, and so that the lines A and B are parallel to C (fig. 12).

Fig. 12.–To illustrate note on estimated mandibular width. Left, Human mandible. Centre, Orang-outang. Right, Piltdown mandible.

By dropping verticals from A and B and marking these positions on the paper, the distance between A and C can be measured.

Sir Arthur Keith (1925) estimated that a bi-condylar width of at least 120 mm. is required to articulate the mandible to the Piltdown skull. The bi-condylar width as used by Keith is the width measured from the outer border of one condyle to the outer border of the other.

Taking a modern mandible with this bi-condylar with of 120 mm., the distance on it between the centre of the heads of the condyles was found to e 101.5 mm.

In Piltdown the distance between A and C, i.e. half the width between the centre of the heads of both condyles, was about 42 mm. when B passed through the hypoconulids of M₁ and M₂ and 43 mm. when the median long axis of M₂ alone was used, and by doubling those amounts we arrive at the values 84 mm. or 86 mm. for Piltdown in contrast with the figure 101.5 for the human mandible.

The actual measurements for the mandibles show in fig. 12 are:

External Inter-centre Internal

bi-condylar condylar bi-condylar

Modern man 120 mm. 101.5 mm. 83 mm.

Orang female 111 mm. 86.3 mm. 62 mm.

Sir Arthur Smith-Woodward in his reconstruction, maintained the parallelism of the molar-premolar series, and widened the mandible at the symphysis.

Sir Arthur Keith recognised the anterior narrowness of the mandible but widened it posteriorly, with tooth rows which widened posteriorly.

The recognition of the rim of the foramen above the simian shelf and its relation to the median line confirm the anterior narrowness. The feebleness of the mylohyoid ridge and muscle witness the lack of response to posterior widening. The greater flatness of the lingual surface of the upper canine, the intrinsic narrowness of the molars when measured at gum-level, and the occurrence of the simian shelf are all indications of a narrow jaw. Fig. 4 shows the mandible to belong to the ape group. In apes, though the dental arch is straight-sided and usually parallel-sided, the tendency is to anterior rather than posterior widening, cf. gorilla, if there is any deviation from the parallelism.

These considerations, and the method of enquiry instanced above, indicate that the Piltdown mandible showed no greater posterior width than that of the female orang, and in so doing failed to meet the width requirements of the Piltdown skull.

The Piltdown Skull: Modern Man Characters

(1) The temporomandibular joint on the Piltdown temporal bone is exactly the same as in man

of today.

If a softened piece of dental impression com[11]position be pressed into the glenoid cavity of the Piltdown temporal bone to cover the articular eminence anteriorly and to reach down the tympanic plate posteriorly, and if trimmed to a convenient thickness of about 5 mm., the templet thus made provides the antero-posterior contour of the joint.

This templet from the Piltdown skull fits perfectly the same region of a modern human skull.

For confirmation see fig. 13, 2.

Fig. 13.–To illustrate modern man characters of the Piltdown skull. 1. Wax templet of the line from the bregma to the external angular process on the Piltdown skull (fronto-parietal fragment) shown fitting a modern skull, 2, X. Templet in dental impression composition of the glenoid cavity of the Piltdown temporal bone, fitting the glenoid cavity of a modern skull. 3. Antero-superior view of the endocranial cast of a modern skull to show the widening of the superior longitudinal sinus and the masking effects of the bregmatic pool. It is suggested that the line A -A was mistakenly adopted as the mid-frontal line on the Piltdown endocranial cast.

As for other characters of the Piltdown temporal: The mastoid process is robustly developed and its size is the same as that in the skull shown. The mastoid plate is well pulled down: the petrous process runs directly inwards and forwards without bending as in the apes; the width of the posterior root of the zygoma, and the distance between the zygomatic arch and the temporal squama are exactly the same as in the modern skull shown in fig. 13, 2. The temporal fossa here, as on the parietal bone I as well filled out as in the modern skull. Lacking any anthropoid feature it shows that the mandible and canine tooth could not have belonged to the same skull.

(2) The characters of the occipital fragment are those of modern man. It has no anthropoid feature.

This may be demonstrated by moulding a thin sheet of dental modelling wax over the external surface of the Piltdown occipital fragment and processing it in transparent acrylic plastic. When this transparent pattern is transposed to a modern skull in my possession, which has a capacity of over 1,600 c.c., it can be seen that not only do the muscle impressions correspond in position, size, and depth, but that the sagittal and lateral curvatures agree.

This may be demonstrated by moulding a thin sheet of dental modelling wax over the external surface of the Piltdown occipital fragment and processing it in transparent acrylic plastic. When this transparent pattern is transposed to a modern skull in my possession, which has a capacity of over 1,600 c.c., it can be seen that not only do the muscle impressions correspond in position, size, and depth, but that the sagittal and lateral curvature agree.

On the endocranial surface there is similar correspondence between the Piltdown and this modern skull. The distance between the lateral sinus and the foramen magnum, the size of the cerebellar fossae, and the relative positions of the internal to the external occipital protuberance are the same in both skulls. In both skills the cerebral hemispheres are symmetrical.

On this modern skull the measured length from the lambda to the opisthion is 123 mm., precisely the same as the value estimated by Sir Arthur Keith (1938) for Piltdown.

(3) If a thick strip of modelling wax stiffened by a wire be fitted along the line from the external angular process to the bregmatic angle of the frontoparietal fragment, this templet fits the same modern skull of over 1,600 c.c. precisely, both in respect to its length and [12] curvature. It fits a great number of modern foreheads on which it has been tested. Figs. 13, 1 shows the templet in position on a modern skull. ²

(4) The Frontal Region of the Endocranial Cast. There was nothing anthropoid about the Piltdown brain. As in the occipital region, so in the frontal region there is little difference when the endocranial cast of the Piltdown frontoparietal fragment is compared with the same region on the cast from this modern skull of 1,600 c.c. which was used for comparing the occipital region. In both the direct measurement from the supraciliary margin to the mid-point of the superior longitudinal sinus is 100 mm.; the depth of the third or inferior frontal convolution is 48 mm. for Piltdown and 50 mm. on the modern cast.

This advanced development of the frontal region of the Piltdown brain, evidently well endowed for speech, contrasts with the lack of provision for articulate language in the mandible.

(5) What applies to the occipital, temporal, and frontal regions applies also to the parietal region. The parietal vault is well domed and filled out. There is no post-orbital constriction comparable with that of the ape nor even of Neanderthal and earlier Man. The temporal lines rise no higher on the side of the vault than in modern man. The unusual thickness of the skull alone is its outstanding character, and this stands out in contrast with the slimness of the mandible.

Summary

In this paper no attempt has been made to describe the Piltdown skull and endocranial cast in detail, it would be out of place, but the demonstration of the four salient modern-man features, those of the back and front of the head, of the frontal development on the brain cast, and the templet of the temporomandibular joint, proves the presence of characters which are the same as in the skulls of man of today.

When one examines the nasal cavity of a modern skull, the realisation of the frailty of the turbinal bones poses the question could such bones survive the conditions under which the Piltdown gravels were formed and the sludging effects of post-glacial cold which afterwards churned them up. The survival of the Piltdown turbinal bone and the retention of the temporal bone suggest that Piltdown man may have lived after the last ice-age–a view supported by the low fluorine content.

Even though the low fluorine content is shared by the mandible and canine tooth, both are incompatible with the human skull.

The sight of the Piltdown canine in the ape skull (figs. 1 and 2), and the vertical section through the mandible (fig. 4) prove that both the canine which is the left upper canine, and the mandible belonged to an ape skull.

The X-ray photographs reveal anthropoid bone structure in the mandible, and disclose the individual-life-age discordance between the human skull of not less than 40 years of age, and the young adult ape to which the immature third molar and canine belonged.

Diagnostic ape characters of the Piltdown canine are:

a. Conoidal, labio-lingually narrow crown, longer than in man.

b. Thick root.

c. Cross-section of the root at junction with crown, with major axis in mesio-distal direction:

semi-lunar or D-shaped and somewhat more lingually flattened in Piltdown.

d. Character of the long lingual facet showing (1) that the crown protruded below the level of

the cheek and incisor teeth, (2) that it was worn by the antero-external surface of the first

lower premolar, (m) the tooth was associated with a diastema, ape premaxilla, and flat

ape temporomandibular join.

The mandible is shown to be anthropoid and not human by:

a. Vertical section between first molar and second premolar.

b. Ape characters of molars.

c. Straight-sided dental arch and narrow bi-condylar width.

d. Simian shelf, feebleness of mylohyoid ridge, position of mylohyoid groove, etc., etc.

e. Low developmental position of roots of third molar.

Agreement between the canine and mandible is instanced by:

a. X-ray evidence of incompleted roots of canine and third lower molar.

b. Wear on the molars and canine of the same type.

c. Labio-lingual narrowness of the molars and canine at the cervical margin which fit both

into the same serial homology.

d. Canine and molars show ape order of eruption.

Discordances between ape characters of mandible and canine, and the human skull are:

a. Individual-life-age difference. The young canine could not belong to the old skull.

[13] b. Difference in bone structure.

c. Difference in attachment of muscles–those of mandible: genioglossus, geniohyoid,

digastric, mylohyoid, temporal, etc. are typically anthropoid; those of skull are typically

human.

d. Bi-condylar width less than bi-glenoid width.

e. Functional. Mandible and canine show lack of rotary movement. Deep-sunk glenoid

indicates normal human rotary movement.

f. Mandible not equipped for articulate language; speech area well developed in brain cast

(Broca’s convolution).

g. Head carriage. The robust mastoid process, the muscles of the occipital region indicate

head carriage as in modern man. The procumbent symphysis, simian shelf, and incurvature of lower border of mandible indicate lack of attainment of the erect posture.

In closing this paper, the writer hopes his readers are now fully convinced that a complete case has been made out for the final rejection of the Piltdown mandible and canine tooth as being human and as having belonged to the Piltdown skull.

References

Ashley-Montague, M. F. (19335) The premaxilla in the Primates, Quart. Rev. Biol., 10, No. 1, 32-50; No. 2, 181-208.

– (1936) The premaxilla in man, J. Amer. dent. Ass., 23, 2045-2057.

Bennejeant, C. (1936) Anomalies et Variations Dentaires chez les Primates. Valliere, Glement-Ferrand.

Clark, W. E. Le Gros (1950) Evolution of the Hominidae, Quart. J. Geol. Soc. Lond. 105, Part 2, 259.

Dawson, C., and Smith-Woodward, A. (1915) On a human skull and mandible discovered at Piltdown. Quart J. geol. Soc. Lond., 69, 117-151.

–. (1914) Supplementary note on the discovery of a palaeolithic human skull and mandible at Piltdown. Quart. J. geol. Soc. Lond., 70, 82-99.

Elliot-Smith, Grafton (1914) On the exact determination of the median plane of the Piltdown skull. Quart J. geol. Soc. Lond., 70, 93-97.

Gregory, W. K. (1922) The Origin and Evolution of the Human Dentine. Williams and Witkin, Baltimore.

Hrdlicka, Ales (1923) The Piltdown Molars, Amer. J. phys. Anthrop., p. 202.

Jones, Frederick Wood. (1929) Man’s Place among the Mammals. Edward Arnold, London.

– (1948) Hallmarks of Mankind. Balliere, Tindall and Cos, London. .

Keith, Sir Arthur (1913) In the discussion on Piltdown, Quart. J. geol. Soc., Lond., 69, 148.

– (1925) The Antiquity of Man, 2, 644. Williams and Norgate, London

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1 Figs. 6 and 8 are photographs taken from the lantern slides of the late Sir Arthur Smith-

Woodward. Published by permission of the Trustees of the British Museum (Natural History)

and the Keeper of Geology.

2 In the restoration of the Piltdown skull in the British Museum (Natural History) by Elliot Smith

(1911) s mistake was made in the choice of the middle line. A feature on the internal surface of the bregmatic angle of the frontoparietal fragment was interpreted as an internal metopic crest, and adopted as the mid-frontal line. But the sulcus for the superior longitudinal sinus, see fig. 13, from below upwards on the frontal bone widens, and it broadens out as it approaches the coronal suture into the bregmatic pool, which severs and masks the mesial margins of both of the cerebral hemispheres. The line adopted as sagittal is the impression of the frontal lobe. The effect of the mistake has been to carry the broken antero-superior or bregmatic angle of the left frontoparietal fragment too far over on to the right side of the left fronto-parietal fragment too far over on to the right side of the head, and so to reduce the frontal height and width to make the restoration less of a contrast with the ape mandible.

When the mistake is corrected, the median line crosses the broken bregmatic angle about 3 mm. on the left side of the projecting point on the external surface.–A. T. M.