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Pruning the Human Family Tree August 24, 2006
by Zach Zorich

New doubts are cast on the existence of a "hobbit" species.


To illustrate the deformities in the "hobbit" skull, David Frayer at the University of Kansas took an image of one half of the skull, created a mirror image of it and spliced them together to show how different the skull would look if it were symmetrical. The photo on the left shows the actual "Hobbit" skull. The photo in the center shows the right half of the skull spliced together with its mirror image, and the photo on the right shows the left half of the skull with its mirror image. (Courtesy of David Frayer, Etty Indriati, and PNAS) [LARGER IMAGE]

A discovery that has been hailed as the most important development in human evolution in the last 50 years has formally come under scientific attack this week, as a draft of a study to be published in the Proceedings of the National Academy of Sciences (PNAS) has begun circulating among scientists and journalists. The study provides scientific evidence that the so-called "hobbit" bones found in 2003 on the Indonesian island of Flores belonged to a pygmy with a skull-deforming condition called microcephaly, not a member of a previously unknown species of human being,


These "hobbit" femurs may look sturdy, but they have only a thin outer layer of cortical bone, which would have made them brittle--possibly because of a growth disorder. (Courtesy of David Frayer and PNAS) [LARGER IMAGE]

The controversial bones were excavated by a joint Australian and Indonesian research team led by Mike Morwood, an archaeologist at Australia's University of New England. The excavations uncovered the remains of up to seven individuals, but only one skull with a receding chin, strangely shaped premolar teeth, and a brain size measured at 380 ccs--less than a third the size of a modern human brain. Some of the 18,000-year-old skull's other traits seemed to resemble Australopithecus or Homo erectus. The researchers claimed it was a new species, which they named Homo floresiensis (see Indonesia's Lost World: Shaking Up the Family Tree).


These dental casts taken from two women who live in a village near the site where the "hobbit" was found show that they share a common dental trait--premolar teeth that have rotated 90 degrees from the normal position (see arrows in larger image). (Courtesy of Etty Indriati and PNAS) [LARGER IMAGE]

Soon after Morwood's team published their results in the October 28, 2004, edition of Nature, the bones were--depending on whom you ask--either appropriated by or loaned to Teuku Jacob, a senior paleoanthropologist at Indonesia's Gadjah Mada University. Jacob, who has always maintained that the bones were from a very small Homo sapiens (modern human) suffering from microcephaly, is one of the authors of the new study in PNAS. His main arguments against calling the "hobbit" a new species are summarized below.

  • Pygmies living in a village near Liang Bua cave where the bones were found display many of the distinctive dental traits used to define the new species.
  • The hobbit's leg bones are abnormally thick and round, and have very weak muscle attachments, probably indicating some kind of growth disorder.
  • The "hobbit's" skull is deformed in a way that makes it less symmetrical than a healthy human skull, a strong indicator that the individual suffered from a pathological condition like microcephaly.
  • The lack of a chin was also used a defining characteristic for Homo floresiensis, but some of the local pygmies also lack chins.

"From the very beginning the scientific case for Homo floresiensis being a new species was very weak on the evidence and very implausible on the science," said Robert Eckhart a paleoanthropologist at Penn State University, one of the study's authors. Jacob's group plans to follow this study with a series of articles presenting additional evidence to support their case.

Zach Zorich is is an associate editor at ARCHAEOLOGY.

© 2006 by the Archaeological Institute of America