The Sussex Gravel-Pit Skull That Was the Missing Link for Forty Years and Was Actually an Orangutan Jaw Stained with Iron and Filed Down

On 18 December 1912 the amateur antiquary Charles Dawson and the British Museum’s keeper of geology Arthur Smith Woodward presented to the Geological Society of London a partial human skull and jaw recovered from a gravel pit at Barkham Manor, Piltdown, Sussex. The skull was largely modern in form. The jaw was apelike, with two molars that were ape-like in shape but worn down flat in the human pattern. Together, the bones appeared to be the long-predicted intermediate species — the missing link between ape and human.

Smith Woodward named it Eoanthropus dawsoni (“Dawson’s dawn-man”). The British scientific community accepted it. For the next forty years it dominated British palaeoanthropology textbooks as the earliest known human ancestor.

Why it persisted

The Piltdown find fitted the early-20th-century British expectation of what human evolution should look like: a large brain (modern-shaped cranium) had developed before the human jaw structure. This was the opposite of what the early 20th-century African finds — Raymond Dart’s 1924 Australopithecus africanus from Taung — were showing, which was that the small-brained, human-jawed intermediates had come first. The Piltdown find made the African fossils look like a deviant evolutionary side-branch and the European fossils look like the genuine line.

That was, in the early 20th century, an institutionally appealing conclusion. It meant the British finds were central and the African finds were marginal.

The Piltdown find also fitted Smith Woodward’s career. He had defended it for forty years. So had Sir Arthur Keith, the period’s most prominent British anatomist. By 1940 it would have required a generational shift to reconsider it.

November 1953

The shift came when the British Museum’s Kenneth Oakley applied the new fluorine-dating technique to the Piltdown bones. Fluorine accumulates in buried bones at a rate set by local groundwater chemistry. Two bones found in the same gravel deposit should have closely matched fluorine concentrations.

Oakley’s 1949 first test had already produced a problem: the Piltdown skull and jaw had fluorine concentrations consistent with a few thousand years rather than the half-million expected. In autumn 1953 Oakley, the anatomist Wilfrid Le Gros Clark, and the dental researcher Joseph Weiner ran a comprehensive battery of tests: fluorine, nitrogen, chromium staining analysis, and detailed dental microscopy.

The results, published in the Bulletin of the British Museum (Natural History) on 21 November 1953, demolished the case. The skull was a modern human cranium, probably a few hundred years old. The jaw was a modern orangutan jaw, perhaps fifty years old. Both had been deliberately stained with potassium dichromate and iron sulphate to produce a uniform gravel-pit colour. The orangutan molars had been filed flat with a fine metal file to simulate human wear, then re-stained.

The Piltdown skull was a deliberate forgery.

Who did it

Charles Dawson had died of septicaemia in August 1916. He was the only person continuously present at every Piltdown find. The 2016 reanalysis by De Groote and colleagues — applying ancient-DNA and high-resolution CT imaging — confirmed that the orangutan jaw came from a single specimen, and so did the other “Piltdown II” fragments Dawson supplied in 1915. The forger was working from one orangutan source, and that source was in Dawson’s hands.

Modern consensus is that Dawson was the perpetrator. The motive was professional reputation: he had been campaigning since 1909 for election as a Fellow of the Royal Society. The Piltdown discovery made him, for the four years he lived after it, the most internationally famous British amateur antiquary of the early 20th century. He was elected to the Geological Society of London council on the strength of it.

He died before the election to the Royal Society came up.