Next week is the 100-year anniversary of the Piltdown Man announcement - that the evolutionary 'missing link' between humans and apes had been found. This was a hoax, and someone, or some people, went to great lengths to try to fool the scientific world. The hoax was discovered but the culprit wasn't, and scientists are now trying to solve this real-life whodunnit once and for all.
A team of 15 scientists, including the Natural History Museum's human origins expert Chris Stringer, are using the latest techniques on the Piltdown material, to reveal the hoaxer and add more concrete evidence to that which was collected over 50 years ago.
Prime suspect for Piltdown hoax Charles Dawson, and Arthur Smith Woodward, sieving excavated material at Piltdown in Sussex.
There are many suspects but the favourite is Charles Dawson, who was a solicitor and amateur fossil hunter. He 'found' pieces of a thick human-like skull in gravel beds at Piltdown in Sussex, and supposedly made further finds at a second site two miles away in 1915.
In 1912, he wrote a letter to the then Keeper of Geology at the Museum, Arthur Smith Woodward, and they joined forces to unearth more skull pieces, and an ape-like jaw fragment containing 2 teeth.
Woodward named the new species, 'Eoanthropus dawsoni' (Dawson's Dawn Man) and he and Dawson announced the find on 18 Dec 1912. This meant that Woodward himself later became a suspect too.
There are others, such as the Museum curator Martin Hinton, Jesuit priest Teulhard de Chardin, and the famous author Arthur Conan Doyle.
Piltdown jawbone with 2 teeth - later found to have probably belonged to a young orangutan.
In the early 1900s, only a few ancient human fossils had been uncovered, and none in England, so Piltdown was an exciting find. However, some scientists doubted its authenticity and by the early 1950s there was plenty of evidence that showed it was a hoax, resulting in the Natural History Museum's historic announcement in 1953.
In 1949, scientists carried out fluorine tests and showed that the remains were probably less than 50,000 years old, much too young to be from a species with ape-like features. Other tests showed that the skull and jawbone came from 2 different species - the skull from a human and the jaw fragments from an ape, most likely an orangutan.
Comparison of reconstructions of, Piltdown skull on left, and a modern human skull on right.
Scratches on the teeth, visible under a microscope, showed they had been filed down to make them look more human. And most of the finds, including stone tools and other animal fossils, were found to have been planted at the site and artificially stained to match the colour of the local gravels.
60 years later, scientists have many more techniques at their fingertips. It is hoped that DNA analysis will allow the team to determine the exact species to which the Piltdown remains belong. For instance, whether the jaw fragments came from an orangutan - scientists now know the genome for this species.
Piltdown skull fragments. They were found to have been deliberately stained to match the local Piltdown gravels.
Studying the isotopes of particular elements in the Piltdown material could reveal exactly where the various specimens originally came from, since different regions of the world have different isotopic compositions in their rocks and groundwater.
And the latest radiocarbon dating methods will show if the real ages of specimens match up with each other.
Spectroscopy is being used to investigate the stains deliberately made to many of the specimens as it provides a kind of fingerprint of the chemicals used. The team hope to be able to find out how many staining methods were used. If material obtained at the 2 Piltdown sites match up, the culprit is most likely Dawson, as only he 'discovered' the remains from the second site.
Another Piltdown specimen is a canine tooth found by the priest Teilhard de Chardin. If if turns out to have been stained differently from the other samples, then he may have been involved in the hoax.
Piltdown canine - if new tests reveal it to have been stained differently to other Piltdown specimens, the priest Teilhard de Chardin may be implicated in the hoax.
And the staining analyses could also reveal whether Museum zoologist Martin Hinton was involved. He was a volunteer in Woodward's department in 1912 and more than a dozen modified bones and teeth supposedly stained in a similar way to the Piltdown remains were discovered among his personal possessions after his death - was he investigating Piltdown or did he create the fakes?
The team still has a few more months of research to do before they announce their results. Whether the culprit is found to be Dawson, or any of the other key suspects, the Piltdown Man hoax has plenty to teach us.
Stringer concludes, 'The hoax is a stark reminder to scientists that if something seems too good to be true then perhaps it is too good to be true.
'It is a warning to scientists to keep their critical guard up, but on the positive side it is also an example of the eventual triumph of the scientific method.'