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No skeletal dysplasia in the Nariokotome boy KNM-WT 15000 (Homo erectus): a reassessment of congenital pathologies of the vertebral column

By Regula Schiess and Martin Häusler

Abstract

The Nariokotome boy skeleton KNM-WT 15000 is the most complete Homo erectus fossil and therefore is key for understanding human evolution. Yet, since Latimer and Ohman (2001, Axial dysplasia in Homo erectus. J Hum Evol 40:A12) reported on severe congenital pathology in KNM-WT 15000, it is questionable whether this skeleton can still be used as reference for Homo erectus skeletal biology. The asserted pathologies include platyspondylic and diminutive vertebrae implying a disproportionately short stature; spina bifida; condylus tertius; spinal stenosis; and scoliosis. Based on this symptom complex, the differential diagnosis of spondyloepiphyseal dysplasia tarda, an extremely rare form of skeletal dysplasia, has been proposed. Yet, our reanalysis of these pathologies shows that the shape of the KNM-WT 15000 vertebrae matches that of normal modern human adolescents. The vertebrae are not abnormally flat, show no endplate irregularities, and thus are not platyspondylic. As this is the hallmark of spondyloepiphyseal dysplasia tarda and related forms of skeletal dysplasia, the absence of platyspondyly refutes axial dysplasia and disproportionate dwarfism. Furthermore, we neither found evidence for spina bifida occulta nor manifesta, whereas the condylus tertius, a developmental anomaly of the cranial base, is not related to skeletal dysplasias. Other fossils indicate that the relatively small size of the vertebrae and the narrow spinal canal are characteristics of early hominins rather than congenital pathologies. Except for the recently described signs of traumatic lumbar disc herniation, the Nariokotome boy fossil therefore seems to belong to a normal Homo erectus youth without pathologies of the axial skeleton

Topics: Institute of Anatomy, Department of Anthropology, Institute of Evolutionary Medicine, 570 Life sciences; biology, 610 Medicine & health, 300 Social sciences, sociology & anthropology
Publisher: Wiley-Blackwell
Year: 2013
DOI identifier: 10.1002/ajpa.22211
OAI identifier: oai:www.zora.uzh.ch:76649
Provided by: ZORA
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