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Lisore a écrit :Par contre, les Néandertaliens "modernes" étaient devenus trop différents pour être interféconds avec les Sapiens (et là, Jacques Malaterre s'est planté :p)

Proc Natl Acad Sci U S A. 2008 Mar 25;105(12):4650-5. Epub 2008 Mar 20.

The Homo floresiensis cranium (LB1): size, scaling, and early Homo affinities.
Gordon AD, Nevell L, Wood B.

Department of Anthropology, Center for the Advanced Study of Hominid Paleobiology, The George Washington University, 2110 G Street Northwest, Washington, DC 20052, USA. adam.d.gordon@gmail.com

Abstract
The skeletal remains of a diminutive small-brained hominin found in Late Pleistocene cave deposits on the island of Flores, Indonesia were assigned to a new species, Homo floresiensis [Brown P, et al. (2004) A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia. Nature 431: 1055-1061]. A dramatically different interpretation is that this material belongs not to a novel hominin taxon but to a population of small-bodied modern humans affected, or unaffected, by microcephaly. The debate has primarily focused on the size and shape of the endocranial cavity of the type specimen, LB1, with less attention being paid to the morphological evidence provided by the rest of the LB1 cranium and postcranium, and no study thus far has addressed the problem of how scaling would affect shape comparisons between a diminutive cranium like LB1 and the much larger crania of modern humans. We show that whether or not the effects of its small cranial size are accounted for, the external cranial morphology of the LB1 cranium cannot be accommodated within a large global sample of normal modern human crania. Instead, the shape of LB1, which is shown by multivariate analysis to differ significantly from that of modern humans, is similar to that of Homo erectus sensu lato, and, to a lesser extent, Homo habilis. Our results are consistent with hypotheses that suggest the Liang Bua specimens represent a diminutive population closely related to either early H. erectus s. l. from East Africa and/or Dmanisi or to H. habilis.

J Hum Evol. 2009 Nov;57(5):571-96. Epub 2009 Jul 8.

Liang Bua Homo floresiensis mandibles and mandibular teeth: a contribution to the comparative morphology of a new hominin species.

Brown P, Maeda T.


University of New England, Armidale NSW, Australia. pbrown3@une.edu.au

Abstract
In 2004, a new hominin species, Homo floresiensis, was described from Late Pleistocene cave deposits at Liang Bua, Flores. H. floresiensis was remarkable for its small body-size, endocranial volume in the chimpanzee range, limb proportions and skeletal robusticity similar to Pliocene Australopithecus, and a skeletal morphology with a distinctive combination of symplesiomorphic, derived, and unique traits. Critics of H. floresiensis as a novel species have argued that the Pleistocene skeletons from Liang Bua either fall within the range of living Australomelanesians, exhibit the attributes of growth disorders found in modern humans, or a combination of both. Here we describe the morphology of the LB1, LB2, and LB6 mandibles and mandibular teeth from Liang Bua. Morphological and metrical comparisons of the mandibles demonstrate that they share a distinctive suite of traits that place them outside both the H. sapiens and H. erectus ranges of variation. While having the derived molar size of later Homo, the symphyseal, corpus, ramus, and premolar morphologies share similarities with both Australopithecus and early Homo. When the mandibles are considered with the existing evidence for cranial and postcranial anatomy, limb proportions, and the functional anatomy of the wrist and shoulder, they are in many respects closer to African early Homo or Australopithecus than to later Homo. Taken together, this evidence suggests that the ancestors of H. floresiensis left Africa before the evolution of H. erectus, as defined by the Dmanisi and East African evidence.

Nature. 2009 May 7;459(7243):81-4.

The foot of Homo floresiensis.

Jungers WL, Harcourt-Smith WE, Wunderlich RE, Tocheri MW, Larson SG, Sutikna T, Due RA, Morwood MJ.

Department of Anatomical Sciences, Stony Brook University Medical Center, Stony Brook, New York 11794-8081, USA. william.jungers@stonybrook.edu

Comment in:

Nature. 2009 May 7;459(7243):41-2.

Abstract
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.

Lensman a écrit :Merci, Bull!
On voit que ça discute pas mal...
Oncle Joe

Lisore a écrit :La théorie selon laquelle il s'agirait d'homo sapiens atteints de tares diverses (dont le nanisme et la microcéphalie) a été salement mise à mal par plusieurs découvertes anatomiques résumées ici.

Il y a quand même une chose que je ne comprends pas dans le débat qui agite la communauté scientifique à ce sujet : en quoi le fait que l'homme de Florès soit d'une espèce distincte est-il un problème ? Un VRAI problème, j'entends. Parce que je comprends bien que ça puisse remettre en cause le schéma de l'évolution humaine en vigueur jusqu'à présent, mais je serai tentée de dire "et alors" ? Ce n'est pas encore une science exacte, que je sache, tout ce que l'on sait est susceptible d'être remis en cause par de nouvelles découvertes...
'fin bref.