Was the ‘hobbit’ microcephalic?

The discovery in 2004 of the fossilized remains of a small hominid was big news.

The skeleton was found on the Indonesian island of Flores, and belonged to a female who stood 1 metre tall and weighed 25 kilograms. It was nicknamed 'the hobbit' because of its small stature, and given the scientific name Homo floresiensis after the island on which it was found.The original skeleton, called LB1, was 18,000 years old. Since the discovery of LB1, 8 other skeletons, dating from between 90,000 and 12,000 years ago, have also been found.

At the time, researchers concluded that H. floresiensis was a new hominid species, which must have been the ancestor of Homo erectus, the only hominid species known to have existed in Asia at the right time.

The hobbit was considered to be the most exciting discovery in palaeoanthropology for 50 years. Recently, however, H. floresiensis has become the most controversial topic in the field.

Robert Martin, of Chicago's Field Museum, does not believe that H. floresiensis constitutes a new homind species. Instead, he thinks that the hobbits were small modern humans, and that the stone tools found buried with the hobbits were made by Homo sapiens.

Martin points out the size of LB1's brain (400 cubic centimetres) is exactly the same as that of a human with microcephaly, a congenital condition in which brain development is incomplete.

On the other hand, Dean Falk of Florida State Univesity, Tallahassee, argues that the hobbit skull is shaped differently from that of a microcephalic human, and has frontal and temporal lobe features that are missing from Homo sapiens.

It is unfortunate that, of the 9 hobbit skeletons that have been excavated, only the first, LB1, has a skull. The finding of more hobbit skulls may clear up the debate over whether LB1 was microcephalic human or not.

The discovery of stone tools on Flores by Adam Brum and his colleagues, reported in this week's issue of Nature, has implications for the status of H. floresiensis. The 500 blades discovered have been dated to more than 700,000 years ago, and appear to have been made in the same way as more recent tools found with the remains of hobbits.

Brum's team speculates that the tools they have discovered were probably made by H. erectus, and that the skills for making them may have been inherited by H. floreseinsis. (John Hawks discusses the discovery of these tools in detail.)

The hobbit controvery is likely to continue for some time. The discovery of more hobbit artefacts and skeletons, including (hopefully) skulls, should provide more evidence about the status of H. floresiensis and the evolution of our own species.

Until then, says anthropologist Chris Stringer of London's Natural History Museum, "whoever digs in Flores…has to do so with an open mind."

Snakes lost their limbs on land then slithered into the sea

Palaeontologists have discovered the fossil of a 90 million year-old snake which had legs. The fossil, found in the northern Pataganian province of Rio Negro in Argentina, has been named Najash rionegrina and is one of the most primitive snakes ever found.

Najash rionegrina has hind legs and a well-defined sacrum, the triangular bone made from five fused vertebrae, which forms the back of the pelvis. The presence of hind limbs in a primitive snake supports the hypothesis that snakes evolved on land rather than in the sea. 

"This represents an intermediate morphology that has never before been seen,” says research team member Hussam Zaher, who is also herpetology curator at the Sao Paulo Museum in Brazil.The discovery in the last 10 years of fossils of legged snakes in marine deposits in Israel led some to theorize that snakes evolved in the sea from aquatic lizards called mosasaurs.

Najash rionegrina was found in a terrestrial deposit, meaning that it almost certainly lived on land. It also adds more weight to the theory that snakes evolved on land by losing their limbs to enable them to burrow into soil with ease.  

“We can," according to Zaher, "now reject the hypothesis of marine origin." Blair Hedges, an evolutionary biologist at Penn State University, adds that it is difficult to find examples of animals that lost their limbs upon invasion of the sea, as "almost all of them kept their limbs and turned them into fins or paddles". 

The discovery of the Najash fossil may have cleared up the debate about the evolutionary origin of snakes, but it still leaves unanswered questions. For example, it is still not clear which groups of lizards are evolutionarily closest to snakes.