TY - JOUR
T1 - Ontogenetic changes in limb bone structural proportions in mountain gorillas (Gorilla beringei beringei)
AU - Ruff, Christopher B.
AU - Burgess, M. Loring
AU - Bromage, Timothy G.
AU - Mudakikwa, Antoine
AU - McFarlin, Shannon C.
N1 - Funding Information:
We gratefully acknowledge the Rwandan government for permission to study skeletal remains curated by the Mountain Gorilla Skeletal Project (MGSP), an effort made possible by funding support from the National Science Foundation ( BCS-0852866 , BCS-0964944 ), National Geographic Society's Committee for Research and Exploration ( NGS-8486-08 ), the Leakey Foundation , George Washington University funding to CASHP, and infrastructural support from the Dian Fossey Gorilla Fund International's Karisoke Research Center. Additional support was provided by a 2010 Max Planck Research Award to TGB, endowed by the German Federal Ministry of Education and Research to the Max Planck Society and the Alexander von Humboldt Foundation in respect of the Hard Tissue Research Program in Human Paleobiomics. The MGSP is indebted to the core research partners, field assistants and other staff of the Rwanda Development Board's Department of Tourism and Conservation, DFGFI's Karisoke Research Center, Gorilla Doctors, The George Washington University's Center for the Advanced Study of Hominid Paleobiology, New York University College of Dentistry, and Institute of National Museums of Rwanda, and the many other contributing students and researchers, for their tireless and continuing efforts to preserve mountain gorilla skeletal remains and generate associated long-term data as a resource for scientific study. For access to specimens curated by the Smithsonian's National Museum of Natural History (USNM) and for making available research space for the pQCT scanner, we thank Kristofer Helgen, Linda Gordon, Darrin Lunde, and David Hunt. We thank the Harvard Museum of Comparative Zoology for previous loans of specimens used in this study. We also thank Matt Tocheri for helpful discussions and for clarifying locality information for several USNM specimens, and Keely Arbenz-Smith for research assistance with MGSP specimens.
PY - 2013/12
Y1 - 2013/12
N2 - Behavioral studies indicate that adult mountain gorillas (Gorilla beringei) are the most terrestrial of all nonhuman hominoids, but that infant mountain gorillas are much more arboreal. Here we examine ontogenetic changes in diaphyseal strength and length of the femur, tibia, humerus, radius, and ulna in 30 Virunga mountain gorillas, including 18 immature specimens and 12 adults. Comparisons are also made with 14 adult western lowland gorillas (Gorilla gorilla gorilla), which are known to be more arboreal than adult mountain gorillas. Infant mountain gorillas have significantly stronger forelimbs relative to hind limbs than older juveniles and adults, but are nonsignificantly different from western lowland gorilla adults. The change in inter-limb strength proportions is abrupt at about two years of age, corresponding to the documented transition to committed terrestrial quadrupedalism in mountain gorillas. The one exception is the ulna, which shows a gradual increase in strength relative to the radius and other long bones during development, possibly corresponding to the gradual adoption of stereotypical fully pronated knuckle-walking in older juvenile gorillas. Inter-limb bone length proportions show a contrasting developmental pattern, with hind limb/forelimb length declining rapidly from birth to five months of age, and then showing no consistent change through adulthood. The very early change in length proportions, prior to significant independent locomotion, may be related to the need for relatively long forelimbs for climbing in a large-bodied hominoid. Virunga mountain gorilla older juveniles and adults have equal or longer forelimb relative to hind limb bones than western lowland adults. These findings indicate that both ontogenetically and among closely related species of Gorilla, long bone strength proportions better reflect actual locomotor behavior than bone length proportions.
AB - Behavioral studies indicate that adult mountain gorillas (Gorilla beringei) are the most terrestrial of all nonhuman hominoids, but that infant mountain gorillas are much more arboreal. Here we examine ontogenetic changes in diaphyseal strength and length of the femur, tibia, humerus, radius, and ulna in 30 Virunga mountain gorillas, including 18 immature specimens and 12 adults. Comparisons are also made with 14 adult western lowland gorillas (Gorilla gorilla gorilla), which are known to be more arboreal than adult mountain gorillas. Infant mountain gorillas have significantly stronger forelimbs relative to hind limbs than older juveniles and adults, but are nonsignificantly different from western lowland gorilla adults. The change in inter-limb strength proportions is abrupt at about two years of age, corresponding to the documented transition to committed terrestrial quadrupedalism in mountain gorillas. The one exception is the ulna, which shows a gradual increase in strength relative to the radius and other long bones during development, possibly corresponding to the gradual adoption of stereotypical fully pronated knuckle-walking in older juvenile gorillas. Inter-limb bone length proportions show a contrasting developmental pattern, with hind limb/forelimb length declining rapidly from birth to five months of age, and then showing no consistent change through adulthood. The very early change in length proportions, prior to significant independent locomotion, may be related to the need for relatively long forelimbs for climbing in a large-bodied hominoid. Virunga mountain gorilla older juveniles and adults have equal or longer forelimb relative to hind limb bones than western lowland adults. These findings indicate that both ontogenetically and among closely related species of Gorilla, long bone strength proportions better reflect actual locomotor behavior than bone length proportions.
KW - Diaphyseal strength
KW - Locomotion
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U2 - 10.1016/j.jhevol.2013.06.008
DO - 10.1016/j.jhevol.2013.06.008
M3 - Article
C2 - 24129040
AN - SCOPUS:84887612508
SN - 0047-2484
VL - 65
SP - 693
EP - 703
JO - Journal of Human Evolution
JF - Journal of Human Evolution
IS - 6
ER -