1School of Anthropology and Conservation, University of Kent, 2Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 3Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, 4Department of Anatomy and Neurobiology, College of Medicine, University of Kentucky, 5Department of Anthropology, Lakehead University, 6Human Origins Program, Department of Anthropology, National Museum of Natural History, Smithsonian Institution, 7Department of Cell and Developmental Biology, University of Colorado School of Medicine, 8Anthropological Institute and Museum, University of Zuerich, 9Department of Anthropology, University of Wisconsin-Madison, 10Department of Evolutionary Anthropology, Duke University
April 16, 2016 9:15, Imperial Ballroom A
Over 150 hand bones of Homo naledi, including a complete hand – missing only the pisiform – found in semi-articulation, have been uncovered from the Dinaledi Chamber of the Rising Star cave system, South Africa. These remains are from at least six adult and two juvenile individuals and offer a rare opportunity to investigate overall hand function in a fossil hominin. We conducted linear and 3D morphometric analyses of the wrist bones, metacarpals and phalanges in comparison to extant apes and fossil hominins. The morphology of the H. naledi thumb bones indicates powerful grasping combined with a distinctly small trapezium-first metacarpal joint that differs from other fossil hominins. The radial carpal bones demonstrate changes in shape and orientation that are known only in Neandertals and modern humans and have been interpreted as adaptations to tool-related behaviours. In contrast to the derived wrist morphology, the phalanges are remarkably curved, more so than most australopiths, indicating H. naledi used its hands for climbing. This combination of later Homo-like and australopith-like features in H. naledi suggests that the hominin hand could be both specialised for complex manipulative tasks but also be functionally proficient for locomotion. Within the context of the remainder of the skeleton, including an australopith-like shoulder and pelvis, but Homo-like foot, H. naledi was an efficient biped that still spent a significant amount of time in the trees.
Research supported by the National Geographic Society, National Research Foundation, European Research Council #336301 (TLK), Max Planck Society (TLK) Smithsonian Scholarly Studies Program (MWT) and Canada Research Chairs Program (MWT).