Anthropology Research Team Finds That 'Hobbit' Fossil Evidence Is Linked To Human Evolution (3/20/2008)

New Methods To Study and Compare Skull Shapes Illustrate Evolution is Not a Linear Path

Researchers at The George Washington University present new evidence to support the theory that the fossil species Homo floresiensis, known as the "Hobbit," represents a unique human lineage that diverged from our own, possibly as long ago as 1.7 million years ago, and strikes another blow against the idea that human evolution occurred in a linear progression. The research appears in Proceedings of the National Academy of Sciences.

The skeletal remains, found in Indonesia in 2003, have been dubbed "Hobbit" because of their small stature and the small brain size of the one individual with a skull (known as Liang Bua 1, or LB1). The skeleton indicates that it was a full-grown adult female, but stood at only three feet tall and had a brain about one-third the size of modern adult humans. Scientists have debated whether the remains, which cover a span from before 38,000 years ago to at least 18,000 years ago, represent modern human individuals who suffered from a disorder that caused their small build and small brain size, versus a new human species, Homo floresiensis.

"This should be the final nail in the coffin of the exotic pathological explanations of the H. floresiensis material, but doubtless advocates of such explanations will find yet more ingenious ways of explaining away one of the most exciting, if not the most exciting, and intriguing paleoanthropological discoveries," said co-author Bernard Wood, GW University Professor and director of the hominid paleobiology doctoral program. "The thought that these creatures co-existed in time, if not in the same location, with modern humans emphasizes the extent to which evolution can still hold surprises for us."

Previously researchers faced complications, because direct comparisons of the skull shape between the "Hobbit" and modern humans could be misleading. They thought that because the skull of LB1 is so much smaller than those of modern humans that the shapes may differ because of size variations.

GW researchers Adam Gordon, Lisa Nevell, and Bernard Wood developed a novel way to compare the shape of the "Hobbit's" skull with what the shape of modern human skulls would be like in individuals as small as the "Hobbit." Using these new methods, they have shown that the "Hobbit's" skull is shaped nothing like that of a modern human, whether or not size differences are taken into account. Instead, it is similar to our possible ancestors belonging to the species Homo erectus and Homo habilis found in Africa and the Republic of Georgia, which are about 1.7 million years old. This result is consistent with the most recent analyses of the skeleton that also suggest it was similar to older species.

"What's interesting about this is that the 'Hobbit' doesn't closely resemble the younger Homo erectus material from Indonesia, arguing for an ancient divergence of this species from the lineage that produced modern humans," said Gordon, postdoctoral research fellow with GW's Center for the Advanced Study of Hominid Paleobiology. "We're looking at a different human lineage that split from our own possibly as much as 1.7 million years ago or more, and persisted up to the time when modern humans started peopling the Americas. That's pretty exciting."

Nevell, co-lead author and a graduate student in the GW hominid paelobiology program, notes implications of the study for the possibility that the "Hobbits" represent pathological modern human individuals.

"The LB1 and Homo erectus crania differed from scaled modern human skulls in the same way. We are not aware of any inherited genetic condition that would cause modern human crania to so closely resemble the shape of Homo erectus," Nevell said.

Proceedings of the National Academy of Sciences of the United States of America (PNAS) is one of the world's most-cited multidisciplinary scientific serials. Since its establishment in 1914, it continues to publish cutting-edge research reports, commentaries, reviews, perspectives, colloquium papers, and actions of the academy. Coverage in PNAS spans the biological, physical, and social sciences. PNAS is published weekly in print, and daily online in PNAS Early Edition.

Note: This story has been adapted from a news release issued by George Washington University

Post Comments: