The "Hobbit" Debate Continues

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May 09, 2009

The puzzling fossils known as Homo floresiensis, nicknamed “Hobbit”, continue to provoke discussion.  (See the story “Hobbit Symposium Held”, below)  Although given the genus name Homo, the fossils found a few years ago in Indonesia exhibit many traits, especially in the hands and feet, of much earlier members of the hominin lineage, particularly Australopithecus afarensis, which lived three million years ago and is not thought to have migrated out of Africa.

Whether H. floresiensis is correctly attributed to the genus Homo; if actually a member of an earlier member of the hominin lineage, such as H. erectus; could Hobbit belong to A. afarensis and if so how did Honnit’s ancestors get to Indonesia; these are all questions difficult to answer on the evidence currently available.  These and other questions are likely to be with us for a while.

The paleoanthropological community does agree, broadly, the H. floresiensis small brain size is not due to a pathological condition, as was previously suggested by some. ”Island dwarfism”, the tendency for animals to reduce their size as a means of adapting to a severely constricted environment, such as an island, is thought to explain Hobbit’s small size

The article appearing in Nature this week poems with these sentences:

"Homo floresiensis is an endemic hominin species that occupied
Liang Bua, a limestone cave on Flores in eastern Indonesia, during
the Late Pleistocene epoch. The skeleton of the type specimen
(LB1) of H. floresiensis includes a relatively complete left foot and
parts of the right foot. These feet provide insights into the evolution
of bipedalism and, together with the rest of the skeleton, have
implications for hominin dispersal events into Asia. Here we show
that LB1’s foot is exceptionally long relative to the femur and tibia,
proportions never before documented in hominins but seen in
some African apes. Although the metatarsal robusticity sequence
is human-like and the hallux is fully adducted, other intrinsic
proportions and pedal features are more ape-like. The postcranial
anatomy of H. floresiensis is that of a biped, but the unique
lower-limb proportions and surprising combination of derived
and primitive pedal morphologies suggest kinematic and biomechanical
differences from modern human gait. Therefore, LB1
offers the most complete glimpse of a bipedal hominin foot that
lacks the full suite of derived features characteristic of modern
humans and whose mosaic design may be primitive for the genus
Homo. These new findings raise the possibility that the ancestor of
H. floresiensis was not Homo erectus but instead some other, more
primitive, hominin whose dispersal into southeast Asia is still
undocumented."

Additionally we have a video of a discussion with Nature article author Bill Jungers on this subject, taken from the radio porogram Science Friday, May 8, 2009.

Read the full Nature article.