The news is abuzz today as two papers published in this week’s Nature lend support to the theory that the Hobbit represents a new species. One study of the Hobbit’s foot reveals that while the hobbit was bipedal, it did not walk like humans and probably could not run very well. Another study compared the rate of dwarfism among an extinct species of hippos in Madagascar with those of the mainland, with special attention to brain size and found that it is possible for dwarf populations to evolve smaller brains, which means the same principle could be applied to the homo floresiensis. It should be noted though, the mainstream media’s hyping up the “Hobbit is a new species” tune. I certainly think the consensus is forming that way.
Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis
Nature, 07 May 2009
The foot of Homo floresiensis
Nature, 07 May 2009
Hobbits ‘are a separate species’
BBC, 06 May 2009
New analysis shows ‘hobbits’ couldn’t hustle
Physorg.com, 06 May 2009
Hobbit foot, hippo skulls deepen ancestral mystery
Science News, 06 May 2009
‘Hobbits’ Couldn’t Hustle: Feet Of Homo Floresiensis Were Primitive But Not Pathological
Science Daily, 06 May 2009
Ancient ‘hobbit’ humans new species after all
AFP, 06 May 2009
The foot of Homo floresiensis
W. L. Jungers, W. E. H. Harcourt-Smith, R. E. Wunderlich, M. W. Tocheri, S. G. Larson, T. Sutikna,
Rhokus Awe Due & M. J. MorwoodHomo floresiensis is an endemic hominin species that occupied
Liang Bua, a limestone cave on Flores in eastern Indonesia, during the Late Pleistocene epoch1,2. The skeleton of the type specimen (LB1) of H. floresiensis includes a relatively complete left foot and parts of the right foot3. 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 biped1–3, 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.
Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis
Eleanor M. Weston & Adrian M. ListerBody size reduction in mammals is usually associated with only
moderate brain size reduction, because the brain and sensory
organs complete their growth before the rest of the body during ontogeny. On this basis, ‘phyletic dwarfs’ are predicted to have a greater relative brain size than ‘phyletic giants’. However, this trend has been questioned in the special case of dwarfism of mammals on islands. Here we showthat the endocranial capacities of extinct dwarf species of hippopotamus from Madagascar are up to 30%smaller than those of a mainland African ancestor scaled to equivalent body mass. These results show that brain size reduction is much greater than predicted from an intraspecific ‘late ontogenetic’ model of dwarfism in which brain size scales to body size with an exponent of 0.35. The nature of the proportional change or grade shift observed here indicates that selective pressures on brain size are potentially independent of those on body size. This study demonstrates empirically that it is mechanistically possible for dwarf mammals on islands to evolve significantly smaller brains than would be predicted from a model of dwarfing based on the intraspecific scaling of the mainland ancestor. Our findings challenge current understanding of brain–body allometric relationships in mammals and suggest that the process of dwarfism could in principle explain small brain size, a factor relevant to the interpretation of the small-brained hominin found on the Island of Flores, Indonesia.
