The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

Hand and foot proportions of the mountain gorilla, Gorilla beringei beringei


1Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, 2Archeology and Forensics Laboratory, University of Indianapolis, 3Rwanda Development Board, Tourism and Conservation, 4Human Origins Program, Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington DC, USA

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Hand and foot proportions vary with locomotion, posture, and manipulative behaviors across primates. However, reliable information is often lacking about ray identity of disarticulated phalanges in museum collections, hampering efforts to investigate cheiridial proportions in many primates. Here, we report new data on hand and foot proportions of mountain gorillas (Gorilla beringei beringei) based on skeletons recovered by the Mountain Gorilla Skeletal Project in Rwanda using controlled procedures. We calculated maximum length proportions for metatarsals, metacarpals, and phalanges of 3 adult males and 7 females.

Our results generally agree with hand proportions reported for gorillas by Susman (1979, AJPA 50, 215), with some notable exceptions. While six individuals showed a II>III>IV>V metacarpal length sequence, four individuals displayed a III>II>IV>V sequence. All individuals exhibited a III>IV>II>V manual proximal phalanx sequence; all but one showed a III>IV>II>V intermediate phalanx sequence; and the distal phalangeal sequence varied.

Within the foot, seven individuals displayed a II>V>III>IV metatarsal length sequence, two showed a V>II>III>IV sequence, and one showed a II>V>III=IV sequence. While seven individuals displayed a IV>III>II>V proximal phalanx sequence, three displayed a III>IV>II>V sequence. The sequence of intermediate phalanx length was IV>III>V>II in eight individuals, and IV>III>II>V and III>IV>V>II in the remaining two. Pedal distal phalangeal sequence was variable.

Our results show some important differences in hand proportions between G. b. berengei and other gorillas, and provide much-needed data on pedal proportions, that may be linked to hand and foot function involved in the high levels of terrestriality practiced by mountain gorillas.

This project has received funding support from the National Geographic’s Committee for Research and Exploration, Leakey Foundation, National Science Foundation grants BCS-0852866, BCS -964944, DGE-0801634, and GW's Academic Excellence funding to the Center for the Advanced Study of Hominid Paleobiology.

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