25 August 2006
'Hobbit' was a disabled caveman?
The remains of a fossilised stone age pygmy, hailed as a new species of human when it was found two years ago, probably belonged to a disabled but otherwise normal caveman, researchers have claimed. The discovery of the 18,000-year-old 'homo floresiensis' on the Indonesian island of Flores was thought to be a major development in tracing human evolution when it was announced in 2004. However, a new analysis of the 3ft skeleton, nicknamed the 'hobbit', along with other remains found at the site, has indicated they probably belonged to an early human suffering from microcephaly, a condition that causes an abnormally small head and other deformities.
"The skeletal remains do not represent a new species, but some of the ancestors of modern human pygmies who live on the island today," concludes a report in the Proceedings of the National Academy of Sciences. "The individual exhibits a combination of characteristics that are not primitive but instead regional and not unique but found in other modern human populations." The team of researchers from the U.S., Indonesia and Australia conclude that the so-called hobbit isn't a separate species, but just an unfortunate pygmy with a form of microcephaly, a developmental disorder that shrinks the head and the brain.
The PNAS team closely examined the one almost complete skull unearthed at Flores and say they found no evidence that it was belonged to anyone but a modern human. The skull was shaped asymmetrically, which the researchers argued was due to the effects of microcephaly. They also say that many of the features of the jaw and teeth cited as evidence that it belonged to a separate species-such as the lack of a chin-could be seen among modern Flores pygmies.
The controversy began in October 2004 when Nature, a leading British science journal, published what appeared to be a groundbreaking paper about a new species of human. The original team, co-directed by Michael Morwood from the University of New England in Australia and Professor Radien Soejono of the Indonesian Research Centre for Archeology, made the discovery in the Liang Bua cave. "Here we have a creature that is substantially different from modern humans, a totally new species of our genus, that lived almost into historical times. This has a number of startling implications," said Henry Gee, Nature’s senior editor for biological science, at the time.
Nature has confirmed that it subjected the manuscript to the normal scientific review process in which it was scrutinised by outside experts who approved its contents. The new study suggests, however, that the initial evaluation of the remains was flawed. Robert Eckhardt, professor of developmental genetics and evolutionary morphology at Pennsylvania State University, who was part of the new team, criticises the original study for comparing the skeleton with those of homo sapiens primarily from Europe. A more accurate understanding of the 'hobbit', he says, emerges when comparing the bones against humans from the same region.
However, the original authors of the Nature paper-Peter Brown and Michael Morwood aren't about to surrender their belief in a new species. In an email, Brown says that the PNAS paper "provides absolutely no evidence that the unique combination of features found in Homo floresiensis are found in any modern human." Morwood points out that supporting papers have previously been published in elite journals like Science and Nature, while Brown argues that the asymmetry in the skull was due to the fact that the original skeleton was buried in 30 ft. of sediment, which deformed the fossil.
The one definitive piece of evidence could be DNA tests of the original skeleton that might prove for sure whether the hobbit belonged to Homo sapiens or something else, but such samples will be difficult to recover, because DNA doesn't keep long in a tropical environment.
Sources: The Sunday Times (20 August 2006), Time Magazine (22 August 2006), The Independent (23 August 2006)