Like this mandible, some of the bones of small-bodied people found in Omedokel Cave in Palau were embedded in calcite flowstone created by water dripping though limestone. Such embedding can occur quickly, but the older bones in Omedokel Cave were dated by radiocarbon to 2300 years ago. Bones from another cave, Ucheliungs, were dated to 2900 years ago, a time when the Pacific was first being colonized. Photograph by Chris Sloan/© 2008 National Geographic
Peculiarities found in prehistoric human bones discovered in July 2006 on Palau have caused much head-scratching for National Geographic grantee Lee Berger and his colleagues over the last year. See the story at National Geographic News and the scientific paper at PLoSOne.
Berger found the bones, mostly the fragmented skeletons of many individuals, in two island caves, Omedokel and Ucheliungs, not far from Palau’s capital, Koror.
While analysis of these bone caches is still in its early days (it will take decades to complete), Berger thinks it is likely that the bones are the remains of islanders brought into the caves for burial long ago.
One might ask why Berger, an American researcher at Wittswatersrand University in South Africa, is leading a dig in the middle of the Pacific Ocean. It is because it was he who, while on vacation in July 2006, stumbled upon the unusual bones in steamy Ucheliungs Cave. Inside the cave, he flicked on his flashlight. “It illuminated a scene from out of a horror movie or an archaeologist’s dream,” he said. “Thousands of fragmentary human remains were scattered about the cave floor.”
By August of 2006, funded by the National Geographic Society, Berger and a small crew of anthropologists, geologists, and archaeologists, including Palauans, were back in the caves. The team dug a one meter by one meter test pit in the cave floor, and soon realized that the bones were not only spread wide, but deep. They collected almost 1,200 bone samples.
Here are the results: The oldest bones dated (by radiocarbon) were from people that died between 2,900 and 1,400 years ago. They were all tiny humans. Berger and his team were perplexed by the odd mixture of traits they saw. Some of the traits were used by scientists to classify prehumans and others were used to classify Homo sapiens.
To make a long story short, this led the scientists to entertain a maverick idea; the primitive traits in the earliest Palauans are not archaic at all, but rather a consequence of a type of extreme shrinking never observed in humans before.
Small-bodied Homo sapiens abound today in places like the Andaman Islands and the Ituri Forest of Africa. But their heads and faces are large and well within the normal range set for modern humans. Berger and his colleagues suggest that when the early Palauans shrank, their heads and faces shrank in proportion to their bodies, producing faces much smaller than those of living pygmoid groups.
But, according to Berger, this is not the case with the Homo floresiensis, knick-named the hobbit. It may have experienced the same type of shrinking as the Palauans. If Berger and his colleagues are correct, then some small-bodied human ancestors with these “primitive” traits, including the hobbit, may have them because they are small, not because they are primitive.
If these early Palauans turn out to be everything Berger and his colleagues claim they are—and not children, as the report at Nature.com suggests—then either the little folk crossed 370 miles of shark-infested deep ocean to get to Palau or large folk did it and, due perhaps to insular dwarfism, became dwarfed once they arrived. Neither scenario can be proved at this early stage of study, but either way, it was a fantastic voyage.
This photo compares a modern human female mandible with one of the small ones from Palau. The vertical depth of the jaw and the reduced chin are two "archaic" features Berger points to. Photo by Stephen Alvarez/© 2008 National Geographic.