Radiocarbon Dating of the Piltdown Skull and Jaw
By Prof. H. De Vries, Naturrkundig Laboratorium, Rijks-Universitelt, Groningen
and Dr. K. P. Oakley, F.B.A., British Museum (Natural History)
Nature 1959 ss
(K. P. Oakley)
 IN 1950 it was shown 1 by the fluorine method of relative dating that the Piltdown mandible and cranial bones were considerably younger geologically than the Lower and Middle Pleistocene fossils said to have been found at the same site. Assuming that they were genuine finds, the hominoid remains were not older than Upper Pleistocene, but it was noted that drill-holes into the teeth revealed that they were "apparently no more altered than the dentine of recent teeth from the soil." 2 In 1963, Dr. J. S. Weiner, reviewing this evidence in the light of anatomical considerations, suggested that the mandible was that of a recent ape which had been broken and stained to resemble a fossil, and the teeth artificially abraded to suggest wear through the human type of mastication. According to his hypothesis, the fraudulent jaw-bone had been placed in the Piltdown gravel pit so as to appear associated with fragments of a thick human cranium of presumed antiquity.
Determination of the organic content and re-determination of the fluorine content of these specimens, together with evidence obtained from a detailed anatomical analysis of the teeth, confirmed this hypothesis 3 (Table 1). The mandible had the composition of modern bone, whereas the cranial fragments were very slightly 'fossilized'.
In 1953-55, the possibility of dating the Piltdown bones absolutely by the radiocarbon method was not seriously considered because it would have involved total destruction of the specimens to provide the minimum quanity of carbon (2 gm.) then demanded by radiocarbon laboratories for a single determination. During the past four years, improvement of technique has made it possible to attempt radiocarbon dating on the basis of much smaller quantities. With the agreement of Dr. E. I. White, keeper of palaeontology, powder samples of the Piltdown mandible and right parietal bone were submitted to Prof. H. de Vries after repeated washing in acetone and then in warm water (at 70o C.) which was carried out under rigorous oonditions in the Department of the Government Chemist. The nitrogen content of powder samples of these bones proved to be the same before and after submission to this extraction treatnent, proving their freedom from nitrogengous contaminants (for example, glue, gelatine, celluloid}. Their nitrogen content represents the bone protein (collagen). This is the material which provided the carbon the radioactivity of which has now been measured.
Fluorine Fluorine Nitrogen Carbon
(per cent) (per cent ) (per cent) (per cent)
Piltdown Mandible 0.2 ± 0.2 < 0.03 3.9 14.5
Piltdown Cranium 0.2 ± 0.1 0.10 ± 0.0l 1.4 5.3
Fresh bone 0.03 ± 0.01 4.0 14.0
The Radiocarbon Results
(H. de Vries)
The sample of Piltdown mandible was burnt vithout any further pretreatment. The sample of ihe Piltdown skull (right parietal) was given a treatment which will be described in more detail elsewhere. It was dissolved in hydrochloric aoid: the fraction vhich was not precipitated by alkali was dated. Both samples gave a very small amount of carbon dioxide, corresponding to about 0.1 gm. of carbon. Therefore, the precision is not what it oould have been, but oertainly good enough for the present purpose. Though oontroversia1 dates on bone have been published, our recent experience indicates that ihe conclusions drawn from the present results are trustworthy (Table 2).
 Table 2
Piltdown mandible (GRO 2204) 500 ± 100 years *
Piltdown skull (GRO 2203) 620 ± 100 years*
Expressed in terms of statistical probability, there is 1 chance in 3 that the ages of these specimens lie outside the stated limits, but only 1 chance in 20 that they lie outside the ranges 500 ± 200 and 620 ± 200 years, respectively.
* Allowance has been made for the Suess effect (that is the age was calibrated against nineteenth -century wood.
Comments on the Results
(K. P. Oakley)
The results are satisfactory. In the first place rhey confirm that the Piltdo\vn jaw is geologically quite recent. (Even since the exposure of the hoax in 1953 and 1955, statements have appeared in print maintaining that it is a Pleistocene fossil, considerably more ancient than the cranial bones.) The indication that this mandible is a few centuries old raises the question of its origin. When Sir Wilfrid Le Gros Clark established that it was the jaw-bone of a moderrn orang-utan (and therefore came from Borneo or Sumatra), it was assumed to be a zoologioal collector's piece. Is it not very unlikely that an orang-utan jaw-bone falling into the hands of a collector would prove to be several centuries old? In fact, this is not so improbable as might be supposed. One possibility is that the specimen was obtained from a dealer in ethnographical material. Prof. G.H.R. von Koeningswald has pointed out that the Dyaks of Borneo have been known to keep orang-utan skulls as fetishes or trophies 4 in their long-houses for many generations. Mr. Tom Harrison, curator of the Sarawak Museum, recently sent to the British Museum (Natural History), a photograph of an orang-utan skull, with mandible, which is said to have been preserved for twenty generationsabout 400 years (Fig. 1). However, the chances of an ethnographical dealer obtaining such a highly treasured object directly from living Dyaks are regarded by Mr. Harrison as negligible. On the other hand, he has pointed out that a number of sub-recent bones of orang-utan, obtained in Sarawak in various circumstances, were brought back to Britain in 1875 by A. H. Everett and briefly described. 5 Some were obtained from caves the contents of which were washed by Chinese gold workers. At least one of the specimens (No. 55) appears to have been a trophy skull. Part of Everett's collection (including the last specimen) was preented to the British Museum (Natural History). All the orang-utan skulls and jaws listed as received by the Museum in 1879 can be accounted for; but Mr. Harrison believes that Everett brought much more material to Britain, and what became of it is unknown. Did it pass into the hands of dealers?
(Photo: Tom Harrison, Sarawak Museum)
Fig. 1. Orang-utan skull with mandible kept as a fetish in a Dyak long-house seventy miles from Kuching and said to be twenty generations (about 400 years) old.
Comparison between one of the 'sub-recent' orang-utan jaw-bones in the Everett Collection (No. 100 in Everett's list, recorded as "doubtfully from a cave" in Sarawak; registered as ZD.220.127.116.11) and the Piltdown jaw-bone has brought out a number of points of resemblance.
Not only is the nitrogen content of the 'antique' Bornean specimen likewise undiminished (4 6 per cent, determined by Mr. G. Ross in the Central Laboratory, Department of Zoology, British Museum (Natural History); he has reported 4.0-5.3 per oent nitrogen in other recent Hominoid bones) but also the surface of the bone is in the same finely cracked condition, which was diffioult to account for if the Piltdown specimen came from a modern zoological collection. Attempts to reproduce the appearanoe of the Piltdown jaw by artificial treatment of modern bones failed in just this respect The condition of the collagen fibres, revealed by the electron-miorosoope, indicated that it had not been boiled.
The radiocarbon dating of the cranial bones has confirmed that they also are Post-Pleistocene in
age as indicated in the report of 1955 (p. 257). In 1953, it was thought that they might have been genuine finds which had served as the nucleus of the hoax; but as soon as it was proved (as reported by Dr. G.F. Claringbull and Dr. M.H. Hey in 1955) that all the cranial fragments had been artificially stained to match the gravel, it became clear that they were fraudulent introductions at the site, so the possibility of their being of Pleistooene age could be entirely discounted. The phosphatic matter of these cranial bones has been partially altered to gypsum. This is only explicable if they had been artificially stained by an acid iron sulphate solution. Experiments showed that this alteration only occurs if the bone has the porosity due to partial loss of organic matrix. Thus the Piltdown cranial bones are evidently of moderate antiquity. Presumably they were fragments of a skull seleoted on account of its unusual thickness from among a series obtained in the excavation of some ancient burial ground. The fluorine oontent of the unaltered portion of their bone substanoe also indicates that they are of some slight antiquity; but unless one knows the souroe of a bone, precise relative dating by fluorine content is impossible. However, in many British and foreign cemeteries bones less than a thousand years old can be found with the same fluorine oontent (0.1 per cent).
 Although the differenoe in the radiocarbon ages of the cranial bones and mandible is less than might have been expected in view of their contrasting states of preservation, it should be borne in mind that whereas a bone that has been buried in the ground for a few oenturies may have become porous and 'sub-fossil' (with some absorbed fluorine), a bone of equal antiquity that has been preserved in air, for example on the floor of a dry cave, in a building or in a reliquary, may have retained the oomposition of 'recent' bone.
Summary. Radiocarbon dating has confirmed that the Piltdown skull (human) is Post-Pleistooene, probably less than 800 years old; and that the Piltdown mandible (orang-utan) is younger rather than older, although possibly several centuries old. It is shown that these findings are not inconsistent with the skull being in 'sub-fossil' condition whereas the mandible (of very different origin) has the preservation of 'recent' bone.
1 Oakley, K. P., and Hoskins, C. R., Nature, 165, 379 (1950).
2 Oakley. K. P., and Hoskins. C. R., Nature, 165. 351 (1950)
3 Weiner, J. S., Oakley, K. P, and Le Gros Clark, W. E., Bull. Brit. Mus. (Nat. Hist), Geol.,
2, No. 3, 139 (1953), reporting nitrogen determinations by Mrs. A. Foster in the Brit. Mus.
(Nat. Hist) Dept. of Minerals and fluorine determination by Mr. C.F.M. Fry in the Dept.. of
the Government Chemist. Further account in Bull. Brit. Mus. (Nat. Hist.), Geol., 2, No. 6,
4 See, for example, Martin, R., "Uber Skeletkult und verwand Vorstellungen", Mit. Geogr.
Ethnogr. Geselt., Zurich 1920. Tab. 4, Fig. 6.
5 Everett, A. H., Second Quarterly Report on the Bornean Exploration, Rep. Brit. Assoc.,
Sheffield, 144 (1879).