The skullduggery of Piltdown Man

EVER since Charles Darwin claimed we came down from the trees, it has been the Holy Grail for evolutionary scientists: finding the 'missing link' between humans and apes. While there was never any problem finding fossils of apes or of recognisable humans, evidence of early man has proved frustratingly elusive.

So, when amateur geologist Charles Dawson unveiled his latest find to a meeting of the Geological Society in London, on December 18, 1912, there were gasps of astonishment, the nearest scientists ever get to hysteria.

For there, in front of them, was what looked like a vital piece in the human jigsaw - a skull with both human and ape characteristics. Piltdown Man, named after the Sussex village where it was discovered, was the scientific sensation of the age.

With a large, human-like braincase but the jaw of an ape, Piltdown Man, also known as eothanropus dawsoni - Dawn Man of Dawson - perfectly matched predictions of what our earliest ancestors would look like. At an estimated 500,000 years old, there was no doubt this was the missing link.

It was also a matter of enormous national pride, a triumph for the British Empire at a time when the European powers were jockeying for position which would culminate in the Great War. Previously, the only fossil of such antiquity was a jaw found in Heidelberg in Germany in 1907.

So not only was the most complete specimen of our most ancient ancestors a subject of the British Empire, he was from the Home Counties. He even had a cricket bat, in the form of a tool carved from an elephant bone found nearby. All he lacked was a bowler hat.

Piltdown Man duly took pride of place at the British Museum, now the Natural History Museum. Further finds at the site, including other bones, stone tools and a second skull, seemed to confirm its authenticity. Even the discovery of other fossils which did not have any of Piltdown's characteristics were not enough to dent the confidence of the British archaeological establishment. For them, the cradle of mankind was not Africa, but East Sussex.

For 20 years, Piltdown Man was an important plank of the theory of human evolution. Even when it became something of an anomaly, an unexplained deviation from the otherwise accepted progression from apes to humans, it was still a prized exhibit. Piltdown also dictated subsequent study of human evolution, its high forehead and heavy jaw reinforcing the belief that human brains became larger at an early stage in our development.

But in July 1953, South African physiologist Joe Weiner, a man who had been harbouring doubts about Piltdown Man's authenticity, decided to act on his suspicions. He asked to view the remains, and concluded that the reason they were out of place in the human evolutionary tree was because they were fakes.

After testing the jawbone, he found it came not from an early human, but from a female orang-utan. The teeth of the herbivorous ape had been filed to make them look like those of an omnivore, and the entire skull had been painted with potassium dichromate to stain it a suitably ancient looking mahogany brown. Radiocarbon dating suggested the human part of the skull was not 500,000 years old, but less than 1,000.

On November 21, 1953, Weiner, along with Oxford Professor of Anatomy Le Gros Clerk and the Natural History Museum's Dr Kenneth Oakley, revealed their findings in The Times. Once again, Piltdown Man caused an international sensation, only this time it was very different. One of the greatest treasures in the study of evolution was a fake. Not only were the bones not authentic, they did not even come from Piltdown. They had been planted.

The immediate furore revolved around the damage which had been done to the science of evolution, which had been thrown off course by 40 years, but attention swiftly turned to who had been responsible. The fossils had been deliberately placed in a strata of rock which would lend evidence to their ancient origins.

And there were further signs that the hoaxer was no amateur. Filing the teeth had removed what would have been obvious traits of orang-utan molars, and the staining suggested someone had gone to great lengths to carry out their fraud. The skull was also unusually thick - taken as evidence that it was a part-way stage in the evolution of apes to man, but later shown to suggest Paget's disease, a hereditary thickening of the bone.

But there had been mistakes. In altering the teeth, the hoaxer had been unaware that human teeth wear down quicker on the outside than the inside, and the only reason the chemical staining had not been uncovered was that trust in the fossils was so complete they had never properly been tested. The cricket bat is thought to have been a joke.

Chief suspect was Charles Dawson, the man who found the fossils. After his death in 1915, finds at the site mysteriously ended and he was no stranger to archaeological frauds, having previously put fake fossil toads on show, as well as forged Roman tiles. A skull affected by Paget's disease went missing in the 1900s from Hastings Museum, where Dawson had strong connections.

For Dawson, it may have been a desire for personal glory, combined with an ambition to be a Fellow of the Royal Society. The exact location of his discovery of the second skull was also never made clear, which had first aroused Weiner's suspicions.

Also in the frame was Martin Hinton, a volunteer in the museum's geology department. In 1976, a canvas trunk belonging to Hinton was found in the museum, containing mammal bones and teeth stained using the same method as the skull and jawbone. Hinton would also have had access to specimens at the museum - in 1911 the museum bought a collection of animal remains from Borneo. An inventory found the lower jawbone from an orang-utan was missing.

Hinton's motivation may have been his dislike of Arthur Smith Woodward, the museum's Keeper of Geology and a man whose treatment of his staff inspired resentment. Smith Woodward was one of the first to hail Piltdown Man as an important discovery, and was subsequently feted as a pioneer in his field. Exposing such a man as a fool would have been a big temptation for Hinton.

A third key suspect was Charles Chatwin, an assistant to Smith Woodward, who may also have harboured a grudge against his superior. Chatwin was named as the culprit by Kenneth Oakley at a dinner party in 1975, shortly before Oakley himself died. A plethora of other suspects have also been cited, including Sherlock Holmes creator Arthur Conan-Doyle, a spiritualist who may have wanted to discredit the scientific view of evolution, but gradually the field has been whittled away to those three contenders.

But conclusive proof of the guilt, or otherwise, of any one of them has yet to emerge. Dawson died in 1915, nearly 40 years before the hoax was exposed. By then, the other two suspects had reached such a position that to have admitted their involvement would have left their reputations in ruins. Hinton went on to become Keeper of Zoology at the Natural History Museum before retiring in 1945, and Chatwin became Chief Palaeontologist of the Geological Survey. Both were still highly respected when Weiner made his revelation.

Hinton told a BBC producer in 1954 that the fraud had been an inside job, but he denied responsibility and refused to reveal the perpetrator's name because he was still alive. Hinton himself died in 1961. Chatwin died in 1971, four years before he was named by Oakley. Whoever was responsible, their secret is buried as deep as Piltdown Man's remains.

Piltdown Man: The Context and Exposure, Scientific Forgery runs at the Natural History Museum from November 25.

Timewatch: Britain's Greatest Hoax, BBC2, Friday, November 21, 9pm.