Homo floresiensis

Homo floresiensis skull, American Museum of Natural History.

Homo floresiensis ("Flores Man", nicknamed Hobbit) is a species in the genus Homo, remarkable for its small body and brain and for its survival until relatively recent times. It was named after the Indonesian island of Flores on which the remains were found. One largely complete subfossil skeleton (named LB1, because it was the first specimen found in the Liang Bua cave) and a complete jawbone from a second individual (LB2), dated at 18,000 years old, were discovered in deposits in Liang Bua Cave on Flores in 2003. Parts of seven other individuals (LB3–LB9; the most complete is LB6), all diminutive, have been recovered as well as similarly small stone tools from horizons ranging from 94,000 to 13,000 years ago. Descriptions of the remains were first published in October 2004. To date, the only complete cranium is that of LB1.

The discoverers (anthropologists Peter Brown, Michael Morwood and their colleagues) have argued that a variety of features, both primitive and derived, identified the skeleton of LB1 as that of a new species of hominin, H. floresiensis. They argued that it lived contemporaneously with modern humans (Homo sapiens) on Flores.

Doubts that the remains constitute a new species were soon voiced by the Indonesian anthropologist Teuku Jacob, who suggested that the skull of LB1 was a microcephalic modern human. A controversy developed, leading to the publication of a number of studies which supported or rejected claims for species status. In March 2005 scientists who published details of the brain of Flores Man in Science supported species status. Several researchers, including one scientist who worked on the initial study, have disputed the 2005 study, supporting the conclusion that the skull is microcephalic. The original discoverers have argued against these interpretations and maintain that H. floresiensis is a distinct species. This is supported by a recent study published by paleoneurologist Dean Falk and his colleagues that disputes the possibility of microcephaly. They compared the H. floresiensis brain to ten microcephalic brains, and revealed distinct differences that have so far gone unanswered by critics. In addition, a 2007 study of carpal bones of H. floresiensis found similarities to those of a chimpanzee or early hominin such as Australopithecus and significant differences from the bones of modern humans. Studies of the bones and joints of the arm and shoulder have also suggested that H. floresiensis was more similar to early humans and apes than modern humans. However, critics of the claim to species status continue to suggest alternative explanations. One recent hypothesis is that the individuals were born without a functioning thyroid, resulting from a type of endemic cretinism (myxoedematous, ME). This idea has been dismissed by members of the original discovery team as based on a misinterpretation of the data.

Discovery

The specimens were discovered on the Indonesian island of Flores in 2003 by a joint Australian-Indonesian team of archaeologists looking for evidence of the original human migration of Homo sapiens from Asia to Australia.[1][3] They were not expecting to find a new species, and were surprised at the recovery of a nearly complete skeleton of a hominin they dubbed LB1 because it was unearthed inside the Liang Bua Cave. Subsequent excavations recovered seven additional skeletons, dating from 38,000 to 13,000 years ago.[2] An arm bone provisionally assigned to H. floresiensis is about 74,000 years old. The specimens are not fossilized and have been described as having "the consistency of wet blotting paper"; once exposed, the bones had to be left to dry before they could be dug up.