Anthropology, Chaffey College
Saturday 147, Plaza Level
Several features of the human thoracic vertebrae confer greater flexibility, load bearing, and neurological capacity than is seen in australopithecines and apes. The Dmanisi and Nariokotome fossil vertebrae provide a window into the evolution of these features in early genus Homo.
The thoracic articular complex in early Homo differs somewhat from modern humans, with a small articular facet size and more horizontal orientation that would have allowed more physiologic motion in the sagittal plane. Short laminae as the posterior component of the articular functional complex in the upper thoracic region may have also contributed to conferred an increased range of movement in the sagittal plane, allowing more freedom in the incidence of vertebral imbrication. Thus, Homo erectus appears to have a slightly more flexible thoracic spine than is seen in humans, australopithecines and especially the apes. Vertebral bodies in the Dmanisi Homo erectus differ from earlier hominids and apes in their configuration to bear forces from vertical and anterior load vectors. The size of the spinal cord in the Dmanisi hominid is fully modern in contrast to Nariokotome.
Taken as a functional whole, the thoracic region in early Homo is typical of the derived human morpho-functional complex, and possess the anatomical hallmarks of modern erect posture and a modern sized thoracic spinal cord.