Just half a century after Darwin’s controversial claim that humans and apes were linked, proof appeared in Piltdown, England: A paleontologist named Charles Dawson claimed to have found the fossilized skull of a creature with the large brain case of a human and the jaw of a great ape. The missing link was real. Unfortunately, it was a hoax—but whose hoax, and why? Researchers say they have a pretty good idea: Dawson himself. They published their report in the journal Royal Society Open Science

The first fossil, recovered in 1912, seemed to raise as many questions as it answered. The skull was clearly old, but it looked an awful lot like somebody had just glued fragments of several animals together. Yet Dawson insisted it was the real deal, and found vindication when his subsequent digs uncovered another, similar skull, along with additional teeth, stone tools, and the fossilized remains of other mammals from around the same projected time period. "Piltdown Man"—a.k.a. Eoanthropus dawsoni, or "Dawson's dawn man"—became the toast of British scientific society. In your face, Dawson told his detractors. (He's the smug-looking gent in the top row of the painting above.) And then he died.

Image credit: Mike Peel via Wikimedia Commons // CC BY-SA 4.0

Less than a half-century after that, scientists confirmed what the skeptics had been saying from the beginning: The remains of Piltdown Man were just a patchwork of primate parts. But the details of the hoax remained unclear, and to this day scientists are still trying to pick apart the forger’s identity, technique, and motivations.

The most recent investigation had several aims: to identify exactly how many animal skulls went into the two Piltdown Man “fossils,” to trace the origin of those skulls, and to determine if all the forgeries were made by the same person. Researchers measured the fakes and scanned them using radiography and computed tomography (CT). They took DNA samples and used radiocarbon dating to determine the age of all the fragments.

Their results indicated that the skulls were made from the remains of one orangutan and at least two medieval humans. All of the bone fragments had been manipulated the same way: stained brown with chromic acid and iron, loaded with little pieces of gravel, and held in place with putty. That’s not a coincidence, the researchers write; the same person must have been responsible for all of it. 

For all of his suspicious behavior, Dawson was far from the only suspect. Since the first skull appeared in 1912, at least 20 other men have been accused of fraud. Suspects included Dawson’s collaborator Arthur Smith Woodward, paleontologist and Jesuit priest Teilhard de Chardin, and Sir Arthur Conan Doyle (who was himself bamboozled by children just a few years later).

Still, through it all, Dawson remained the most likely culprit, and the researchers believe he still is. “Not only did Dawson have the access and connections necessary to obtain the specimens, he was also a great networker,” the authors write. More importantly, he “would have known what the British scientific community was anticipating in a missing link between apes and humans: a large brain, an ape-like face and jaws, and heavily fossilized materials that indicated great antiquity.” And Dawson’s experience as a fossil collector would have made it relatively easy for him to figure out how to make it look real. Then, of course, there’s the fact that the fossils stopped turning up after Dawson died in 1916. 

But why? The authors’ best guess is that Dawson’s ambition got the best of him. He wanted desperately to be named a Fellow of the Royal Society, but the Society wasn’t playing along. In a 1909 letter to Smith Woodward, he complained, “I have been waiting for the big ‘find’ which never seems to come along …” 

It seems he got tired of waiting.

Yet even forgeries have lessons to impart. “The Piltdown hoax stands as a cautionary tale to scientists not to be led by preconceived ideas,” the authors write, “but to use scientific integrity and rigour in the face of novel discoveries.”

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