This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
In the early 20th century the search for our ancestors - the supposed "missing links" between man and the animal kingdom - was a crucial task in the new emerging field of human palaeontology. First results came from Germany with the discovery in 1907 of a jaw with mixed characteristics between apes and humans - a good start, but scientists wanted something even better.
Only a year later some workers discovered strange bones in a gravel pit near the village of Piltdown in southern Sussex. They consigned the bones to the local lawyer, antiquarian and amateur geologist Charles Dawson.
Dawson initiated with the help of Arthur Smith Woodward, Keeper of the Geological Department at the British Museum, a private prospection campaign in the gravel pit. Dawson already had experience in digging up fossils, many of which he donated to the museum, and he was a respected fellow of the Geological Society.
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Between June and September 1912 several fragments of a human skull, along with bones of Pleistocene animals, like elephant, mastodon and beaver, were discovered. Finally during a "warm summer evening" (Woodward) the two men found a jaw, fitting to the human skull.
Woodward worked secretly on the reconstruction of the entire skull. It resembled that of modern man, except for the part where the skull is attached to the spinal cord and the slightly smaller cranial capacity, with an estimated brain volume of 1070ccm (about two-third of modern humans). The jaw was indistinguishable from that of a modern, young chimpanzee, except by the presence of two molars identical to human ones.
December 18, 1912 Woodward presented the reconstruction to a large audience and suggested that the fossil - dubbed by the press later Piltdown Man - represents an evolutionary missing link between ape and man, since the combination of a large brain with the jaw of a monkey seemed to support the notion that the main characteristic of human evolution was the early development of a large brain. The reconstruction was harshly criticized, especially by non-british anthropologists and archaeologists.
Many of these experts noted that the fragments didn't fit or even necessarily belonged together. The anatomist Arthur Keith at the Royal College of Surgeons produced a reconstruction quite identical to a modern man (Homo piltdownensis). Marcellin Boule, a French archaeologist, affirmed in 1921 that the remains belong to two different species - if it was not entirely a hoax. This conclusion was supported by the American zoologist Gerrit Smith Miller, who attributed the jaw to a still unknown species of chimpanzee, informally named Pan vetus. The German anthropologist Franz Weidenreich examined the remains and reasserted that the presumed fossil was simply a modern human skull and an orang-utan jaw with manipulated teeth.
But in the end there were no conclusive evidence to assert that the entire story was a fake and the British scientific community accepted the new species as Eoanthropus dawsoni.
Over the years further discoveries were made at Piltdown: bones of animals, a bone tool that resembled a cricket bat (!) and supposedly two more skulls. It was in 1915 that Dawson claimed to have found fragments of a second skull (called Piltdown II) in a not specified locality; however Woodward himself seems never to have visited this supposed site. Dawson died in August 1916, leaving Woodward with the heredity of Piltdown, who in 1917 continued to present material to support the alleged Piltdown Man.
Fig.1. A typical missing link. "The Man of La Chapelle-aux-Saints: an accurate reconstruction of the prehistoric cave man whose skull was found in the Department of Correze." Reconstruction by Frantisek Kupka, published in the journal "L´Illustration" (1909), based on the work of Marcellin Boule on the Neandertal skeleton discovered in 1908 at La Chapelle-aux-Saints (department Corrèze in central France).
In the next three decades discoveries on the African continent seemed to contradict the hypothesis based on the genus Eoanthropus. Ancient biped hominids were found only in Africa and the cranial capacity of these species did not differ significantly from those of chimpanzees - bipedalism evolved before a large brain.
In October 1948 the geologist Kenneth Oakley decided to apply a new dating method and analyzed the fluorine concentration in the bones of the Pleistocene animals found at Piltdown. While the bones contained up to 3% fluorine, the Piltdown skull showed a concentration of just 0,2%, it was not possible that both the bones as the skull lay underground side by side for thousands of years.
This seemed the end of the Piltdown Man, but in light of recent discoveries on the evolution of humans some scientists re-evaluated the status of Eoanthropus dawsoni. The fossil bones of Homo floresiensis of Indonesia, the genetic analysis of the human remains of Denisova in Siberia, controversial early H. sapiens teeth discovered in Israel and bones of an unknown hominid from China have shown that the early model of a unique migration wave out from Africa, which lead to our modern species, was too simple. It is however possible that diverse migration waves occurred over time and that single populations of hominids evolved separately in various forms - this could possibly explain also the repeated sightings of large biped and apelike creatures all around the world in recent times, evolved parallel to - and hiding from - us.
For Eoanthropus this means that it is possibly a descendant of a late migration wave, as supported by the relative young age inferred by the low concentration of fluorine. The strange combination of a large skull and an apelike chin is according to the hypothesis of Professor Shlibovitz, one of the leading experts of missing links, an atavistic phenomenon - "primitive" characteristics of ancestors still encoded in the DNA re-emerging in more recent species, like legs on whales. Absolutely coincidentally today also other important missing links, ignored until now by science, are discussed on "Tetrapod Zoology".
The preliminary results of the new research, announced in February 2012, and the official (re)recognition of the species Eoanthropus dawsoni can be accessed for free following this link.
