Friday, December 15, 2006
An open access/free PLoS Biology article by the science writer Tabitha M. Powledge**.
Citation: Powledge TM (2006) What Is the Hobbit? PLoS Biol 4(12): e440 DOI: 10.1371/journal.pbio.0040440
Who - or what - is Homo floresiensis? (Wiki) The tiny hominid bones, which a joint Australian-Indonesian team unearthed in 2003 on the Indonesian island of Flores, have quickly become as celebrated (and derided) as any find in the tempestuous history of human paleontology. The mystery that shrouds these ancient skeletons, nicknamed hobbits after the diminutive characters in J. R. R. Tolkien's novels, seems to deepen with every study published. Two main camps have emerged, each certain they can settle the question. But many other paleoanthropologists confess they still have no idea.
H. floresiensis Discovered
The discovery team declared their find a new human species, H. floresiensis, based primarily on a single near-complete skeleton of one very small individual with a very small brain, known as LB1. Compared to H. sapiens, LB1, whose age was estimated from tooth wear at about 30 years, was only one meter tall - about the size of a 4-year-old H. sapiens child - with a brain the size of a newborn's. Although there are also fragments of eight other small individuals, they provide no information about brain size, nor is much skeleton preserved. Nonetheless, they possess a combination of features never before seen in human fossils, which makes it credible that a previously unknown population of people smaller than today's pygmies lived on Flores between 90,000 and 12,000 years ago.
Stone tools found at the site raise the possibility that hobbits had culture, even though LB1's brain size would make a chimpanzee sneer. H. floresiensis, the discovery team claimed, could be the first human example of island dwarfing. This phenomenon, thought to be evolution's response to limited resources, is known for other mammals, including dwarf elephants from Flores itself. But this is not the only possible conclusion. A long-awaited paper*, which appeared online in Proceedings of the National Academy of Sciences of the United States of America (PNAS) on August 23, 2006, offers a radically different interpretation of these skeletal remains.
Continued at "What Is the Hobbit?"
*An open access/free paper. Full text (pdf) available via the Abstract link:
"Pygmoid Australomelanesian Homo sapiens skeletal remains from Liang Bua, Flores: Population affinities and pathological abnormalities"
Liang Bua 1 (LB1) exhibits marked craniofacial and postcranial asymmetries and other indicators of abnormal growth and development. Anomalies aside, 140 cranial features place LB1 within modern human ranges of variation, resembling Australomelanesian populations. Mandibular and dental features of LB1 and LB6/1 either show no substantial deviation from modern Homo sapiens or share features (receding chins and rotated premolars) with Rampasasa pygmies now living near Liang Bua Cave. We propose that LB1 is drawn from an earlier pygmy H. sapiens population but individually shows signs of a developmental abnormality, including microcephaly. Additional mandibular and postcranial remains from the site share small body size but not microcephaly.
The discovery of an unusual human skeleton has broad implications
When a team of Indonesian and Australian palaeontologists discovered a nearly complete but very strange 18,000-year-old human skeleton in an Indonesian cave in 2003, the find provoked questions about modern human origins. Do these ancient bones belong to a new human species? Are they, as many have claimed, the most important find in hominid palaeontology for decades? Or is this creature - indelibly christened 'the Hobbit' because it is so tiny - simply one of an isolated people who suffered from a deforming malady? The huge stakes in this competitive, caustic debate can be summed up succinctly: money and fame. But Hobbit investigations may eventually have less impact on the study of human evolution than they do on the standing of palaeoanthropology, and on the continuing crusade against the Darwinian account of how life on Earth evolved.