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Monday, 6 January 2014

Homo Floresiensis: Facts About the 'Hobbit'

Homo Floresiensis: Facts About the 'Hobbit'

The hobbit, Homo floresiensis, lived on the island of Flores some 18,000 years ago, and now researchers have more evidence (its relatively large brain) the diminutive creature was a unique human species. 
Credit: © National Museum of Nature and Science, Tokyo View full size image
Homo floresiensis, dubbed "the Hobbit," lived about 18,000 years ago. Several fossils of the hominid have been found, though the first female skeleton (called LB1) is the most complete. Scientists discovered the remains of a 3-foot-tall (1 meter), 30-year-old adult female hominid in 2003 in the Liang Bua (LB) cave on the remote Indonesian island of Flores.

LB1's diminutive build — Homo floresiensis likely weighed between 66 and 77 pounds (30 and 35 kilograms) — earned the species the nickname of "the Hobbit," after the tiny folk in J.R.R. Tolkien's book of the same name. LB1 includes a nearly complete skull, a partial pelvis, several limb bones and hand and foot bones, according to the journal Nature. The other H. floresiensis fossils include the lower jaw and various skeletal specimens from another hobbit individual dubbed LB6, and fossils from at least four other individuals, according to Nature.

The species lived between 95,000 and 17,000 years ago, according to the Smithsonian Institution. Scientists have debated whether the Hobbit specimens represent an extinct species in the human family tree, perhaps a squat offshoot of Homo erectus, a 1.8-million-year-old hominid and the first to have body proportions comparable to those of modern Homo sapiens. (Hominids include humans, chimpanzees, gorillas and their extinct ancestors, whereas hominins include those species that evolved after the human lineage (of the genus Homo) split from the chimpanzees.)

Was Homo floresiensis a separate species?

Critics have argued the specimen belonged to an extinct human with microcephalia, a pathological condition characterized by a small head (the Hobbit is estimated to have a brain about one-third the size of modern humans), short stature and intellectual disabilities.

To tease out pathological human from newfound human offshoot, researchers created endocasts of the brains of healthy humans and those with microcephalia, finding two skull ratios that distinguished the two. After applying this method to the skull of Homo floresiensis, the team concluded in 2007 in the journal Proceedings of the National Academy of Sciences that the Hobbit's features were closer to a typical modern human than a microcephalic person.

A study published online April 17 in the journal Proceedings of the Royal Society B, revealed Homo floresiensis had a larger brain than once thought. The CT scan of the hobbit skull suggested its brain was about 426 cubic centimeters (nearly 26 cubic inches), instead of the commonly cited 400 cubic cm. That's more than one-third the size of the modern human brain, which boasts an average volume of about 1,300 cubic cm, or 79 cubic inches. The findings suggest Homo erectus may indeed be the ancestor of Homo floresiensis, as Javanese specimens of Homo erectus had brains about 860 cubic cm (52 cubic inches) in size.

"Another possibility is that the hobbit evolved from Homo habilis, whose brains were only about 600 cubic cm (37 cubic inches)," LiveScience Contributor Charles Choi writes.

To look into microencephaly, a team of scientists led by Dean Falk, a paleoneurologist at Florida State University, compared computer-generated three-dimensional reconstructions, called "endocasts," of brains from nine microcephalic modern humans with those of 10 normal modern-human brains. They found two ratios created using different skull measurements could accurately distinguish the normal humans (skull, right) from the microcephalics. When Falk's team applied this classification system to a virtual endocast the Hobbit's skull (left), they found its features more closely resembled that of a normal human than a microcephalic.
Credit: Professor Peter Brown, University of New EnglandView full size image
What else do we know about Homo floresiensis?

Inside the Liang Bua cave, where Homo floresiensis fossils were discovered, scientists also found several bird fossils, including wing and leg bones from what appears to have been a stork nearly 6 feet tall (1.8 meters). The marabou stork (Leptoptilos robustus), which lived some time between 20,000 and 50,000 years ago, would've fed on fishes, lizards, other birds … and possibly even juvenile Hobbits, though there is no direct evidence for that sort of feasting.

Three wrist bones have also suggested Homo floresiensis was its own hominid species. Researchers, reporting in the Sept. 21, 2007, issue of the journal Science, found hobbit wrist bones resembled those of apes more than those found in modern humans.

What did the hobbit look like?

Susan Hayes, a senior research fellow at University of Wollongong, New South Wales, Australia, fleshed out the female hobbit's face by uploading information from 3D imaging scans of its skull into a computer graphics program. Compared with portraits of the hobbit by paleo-artists, Hayes' facial depiction of Homo floresiensis showed more modern human features instead of monkey-like traits. The hobbit, in this depiction, doesn't have feminine doe eyes, and she lacks much of a forehead.

Debate continues over whether Homo floresiensis was indeed a separate hominid species and scientists continue to collect and analyze specimens.

by Jeanna Bryner, LiveScience Managing Editor   |   April 26, 2013 06:18pm ETHomo Floresiensis: Facts About the 'Hobbit'

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