An international team of scientists led by South African researchers from the University of the Witwatersrand, Johannesburg, South Africa, on Tuesday announced the discovery of an extinct population of small-bodied humans found on the island of Palau, Micronesia, an island in the Pacific Ocean.
The study, funded by the National Geographic Society, is published in this week's edition of the journal PLoS ONE.
The team of researchers led by Professor Lee Berger, a palaeoanthropologist from the University of the Witwatersrand together with colleagues from Duke University and Rutgers University, describe the fossil humans, which lived on the island between 1400 and 3000 years ago, as having some, but not all of the features found in the controversial Homo floresiensis fossils found on the island of Flores in Indonesia.
H. floresiensis, also known as the "Hobbit" has been at the centre of scientific debate as to whether the tiny skeletal remains represent a new species of human or are just the remains of a pathological individual with some type of genetic disorder such as microcephally.
"The Palauen fossils exhibit a surprising number of traits that were originally used to describe the Hobbit as a unique species including, small body size, relatively large teeth, small faces and reduced chins," says Berger who discovered the fossil treasure trove whilst vacationing in Palau in 2006.
The Palauen fossils come from two burial caves in the picturesque Rock Islands of Palau, in the Pacific Ocean.
"We were on a kayak excursion when a guide asked me if I wanted to see a cave with some old bones in it - of course I did!" recounts Berger.
"When I saw a tiny face, part of a fossil skull, I instinctively knew that they were of major importance. I initially thought it was one individual and of course the 'Flores' debate was raging at the time. I used my camera to focus on the tiny bones and snapped some shots so that I could study them in detail at a later stage."
After obtaining an emergency grant from the National Geographic's Mission Programs, Berger and a team of international scientists, including students from the University of the Witwatersrand, returned to Palau a few weeks later.
"What we found astounded our most experienced explorers, even the Palauen officials who accompanied us," explains Berger.
"The cave where Berger had found the original fossils was literally filled with tens of individuals. When excavated, the sand itself was practically made up of ground human bone," adds Bonita De Klerk, a PhD student at the University of the Witwatersrand, one of the initial explorers and co-authors of the paper.
"In a one meter square by 50 centimetre deep test pit, we recovered more than 1200 fragments of human beings - it was remarkable!"
De Klerk is studying the body size of the Palauens and found individuals in Palau that were practically the same height as Flores.
"They were as small as just over a metre," she explains.
"One foot bone is actually almost the same size as the same foot bone of the famous Little Foot skeleton in Sterkfontein, and that's very small."
Little Foot is an australopithecine and early human ancestor that dates to around 2,5 million-years-ago.
The brains of the Palauen humans are thought to be small, at the very bottom or even below modern human variation.
"However, they are not as small as the brains of the Hobbits," clarifies De Klerk.
"We have found some skulls but they are heavily embedded in flowstones and we cannot measure their brain size, only estimate it."
A second cave has revealed an equally large cache of bones indicating to Berger that the islands might be full of surprises.
"Who knows what is out there?" asks Berger.
"It just demonstrates the great need for more exploration to be undertaken in these remote areas."
Berger says the Palauen discovery suggests that given the many characteristics that the Palauen fossils share with Flores (that were typically considered "primitive" to modern humans), that these characters probably should not be used to define a new species, particularly when found in only a single skeleton.
Another fascinating aspect of the find is how quickly the island adaptations may have occurred.
"Our fossils are among the oldest ever found on Palau and may indicate that all of these features evolved very quickly, possibly in just a few generations," speculates Berger.
But how can this be?
Berger explains: "Palau is like a Galapagos for humans. There were at the time no large terrestrial animals so it is likely that the early Palauens had to survive on only near shore marine resources. While this island looks like Paradise these early people, who may have been stranded, were really living under a great deal of dietary stress," notes Berger.
The announcement by Berger and his colleagues falls only a week after the legitimacy of Flores as a unique species came under question once again when Australian researchers presented evidence that the unusual limb morphology of H. floresiensis, which has been held forth by supporters of the unique status of the Hobbit as critical, looks remarkably similar to the limb morphology of individuals who are suffering from a genetic disorder or pathology such as cretinism, which can also effect cranial morphology.
"When you put our two studies together it does make one wonder," says Berger.
"With their big teeth, small faces, reduced chins and small stature, it makes me wonder what a cretin or microcephalic would look like in the Palauen sample. Maybe not identical to, but perhaps a lot like the Hobbit skeleton?"
"When we go back, maybe we will find one!" he adds.
Berger and his colleagues intend to continue work on Palau and neighbouring islands as part of an international expedition to discover more fossils.
Contact and photo information
For interviews with researchers in South Africa or for high resolution pictures, please contact Shirona Patel on +27 11 7171019 or +27 84 619 2646 or firstname.lastname@example.org who will put you in touch with the relevant spokespeople.
Professor Lee Berger is in the United States. He can be reached on +27 83 454 6309 or email@example.com
Bonita de Klerk, co-author of the paper, is in South Africa and is available for interviews. She can be reached at +27 83 268 6225 or firstname.lastname@example.org
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