![]() Studying the fossilized back bones of ancient human remains can help us to understand how we evolved these features, and whether our ancestors moved in a similar way.Īustralopithecus sediba was a close-relative of modern humans that lived about two million years ago. For example, the lower part of the human spine has a forward curve that supports an upright posture whereas the lower backs of chimpanzees and other apes – which walk around on four limbs and spend much of their time in trees – lack this curvature. To achieve this, our skeletons have evolved certain physical characteristics. One of the defining features of humans is our ability to walk comfortably on two legs. sediba used its lower back in both bipedal and arboreal positional behaviors, as previously suggested based on multiple lines of evidence from other parts of the skeleton and reconstructed paleobiology of A. We interpret this combination of features to indicate that A. Additionally, it bears long, cranially and ventrally oriented costal (transverse) processes, implying powerful trunk musculature. Our three-dimensional geometric morphometric (3D GM) analyses show that MH2’s nearly complete middle lumbar vertebra is human-like in overall shape but its vertebral body is somewhat intermediate in shape between modern humans and great apes. These results contrast with some recent work on lordosis in fossil hominins, where MH2 was argued to demonstrate no appreciable lordosis (‘hypolordosis’) similar to Neandertals. We show that MH2 possessed a lower back consistent with lumbar lordosis and other adaptations to bipedalism, including an increase in the width of intervertebral articular facets from the upper to lower lumbar column (‘pyramidal configuration’). Newly discovered lumbar vertebrae contribute to a near-complete lower back of Malapa Hominin 2 (MH2), offering additional insights into posture and locomotion in Australopithecus sediba. Department of Evolutionary Anthropology, Duke University, United States Īdaptations of the lower back to bipedalism are frequently discussed but infrequently demonstrated in early fossil hominins.Anthropological Institute and Museum, University of Zurich, Switzerland.Departamento de Paleobiología, Museo Nacional de Ciencias Naturales (CSIC), Spain.Department of Human Anatomy and Physiology, Faculty of Health Sciences, University of Johannesburg, South Africa. ![]()
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