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Nalley TK, Scott JE, McGechie F, Grider-Potter N. Comparative ontogeny of functional aspects of human cervical vertebrae. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24788. [PMID: 37283367 DOI: 10.1002/ajpa.24788] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 05/15/2023] [Accepted: 05/24/2023] [Indexed: 06/08/2023]
Abstract
OBJECTIVES Differences between adult humans and great apes in cervical vertebral morphology are well documented, but the ontogeny of this variation is still largely unexplored. This study examines patterns of growth in functionally relevant features of C1, C2, C4, and C6 in extant humans and apes to understand the development of their disparate morphologies. MATERIALS AND METHODS Linear and angular measurements were taken from 530 cervical vertebrae representing 146 individual humans, chimpanzees, gorillas, and orangutans. Specimens were divided into three age-categories based on dental eruption: juvenile, adolescent, and adult. Inter- and intraspecific comparisons were evaluated using resampling methods. RESULTS Of the eighteen variables examined here, seven distinguish humans from apes at the adult stage. Human-ape differences in features related to atlantoaxial joint function tend to be established by the juvenile stage, whereas differences in features related to the nuchal musculature and movement of the subaxial elements do not fully emerge until adolescence or later. The orientation of the odontoid process-often cited as a feature that distinguishes humans from apes-is similar in adult humans and adult chimpanzees, but the developmental patterns are distinct, with human adultlike morphology being achieved much earlier. DISCUSSION The biomechanical consequences of the variation observed here is poorly understood. Whether the differences in growth patterns represent functional links to cranial development or postural changes, or both, requires additional investigation. Determining when humanlike ontogenetic patterns evolved in hominins may provide insight into the functional basis driving the morphological divergence between extant humans and apes.
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Affiliation(s)
- Thierra K Nalley
- Medical Anatomical Sciences Department, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA
| | - Jeremiah E Scott
- Medical Anatomical Sciences Department, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA
| | - Faye McGechie
- Department of Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, Arizona, USA
| | - Neysa Grider-Potter
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, Texas, USA
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2
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Tarquini J, Mosto MC, Ercoli MD. Functional and phylogenetic interpretation of the forelimb myology of two South American carnivorans, the ring-tailed coati (Nasua nasua) and crab-eating raccoon (Procyon cancrivorus). J Morphol 2023; 284:e21587. [PMID: 37183491 DOI: 10.1002/jmor.21587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/27/2023] [Accepted: 04/05/2023] [Indexed: 05/16/2023]
Abstract
A comparative analysis of the forelimb myology of two neotropical procyonids (Nasua nasua and Procyon cancrivorus) was performed to assess how observed differences in their myological configuration would be related to their diverse ecological behaviors and phylogeny. Although both species are associated with the arboreal substrate, N. nasua is a more agile climber that usually digs; whereas P. cancrivorus spends most of its time on the ground foraging, climbing on the trees as shelter and is a good swimmer. Here, myological descriptions, muscle maps, phylogenetic optimizations, and muscle mass data of the forelimb of these two procyonids are presented. The main functional muscular groups are discussed in a comparative framework with other carnivorans that present a wide ecological diversity. Also, muscular characters were mapped onto a phylogeny to explore their evolution and to obtain ancestral state reconstructions. Results indicate clear myological differences among the two neotropical procyonids associated with their ecological preferences. One of the most remarkable anatomical differences is the arrangement and relative mass of the extrinsic musculature, mainly the musculus rhomboideus and the delto-pectoral complexes. In Nasua nasua, these suggested a greater stability in their shoulder girdle for climbing and digging and probably would provide stronger neck and head movements when they use them for foraging on the ground. Conversely, P. cancrivorus has a different extrinsic muscular configuration, which would allow an increment on the stride length and faster movements of the forelimb associated with more frequent terrestrial gaits. Also, significant differences are observed in the distal musculature, associated with strong movements of forepaws when climbing and digging in N. nasua; whereas, P. cancrivorus configuration suggested precise forearm and digits movements, related to manipulation of food items when they are catching prey or feeding. Most of the codified features of P. cancrivorus would reflect retention of plesiomorphies acquired in the common ancestor of caniforms or arctoids, whereas N. nasua shows derived traits, particularly in the proximal forelimb region. The present work increases the information available on the myology of these particular taxa and extant generalized arctoid models in general. The analyses presented here will be useful both for other comparative myological studies (morpho-functional and phylogenetic) and for muscular reconstruction in extinct procyonids, as well as other carnivorans.
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Affiliation(s)
- Juliana Tarquini
- Laboratorio de Paleontología de Vertebrados, Centro de Investigación Científica y de Transferencia Tecnológica a la Producción (CICYTTP, CONICET-Prov. ER-UADER), Diamante, Entre Ríos, Argentina
| | - M Clelia Mosto
- División Zoología Vertebrados, CONICET, Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Buenos Aires, Argentina
| | - Marcos D Ercoli
- Instituto de Ecorregiones Andinas (INECOA, UNJu-CONICET), Jujuy, Argentina
- Laboratorio de Paleontología de Vertebrados, Instituto de Geología y Minería UNJu-CONICET, San Salvador de Jujuy, Argentina
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3
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Monroy-Cendales MJ, Vélez-García JF, Castañeda-Serrano RD, Miglino MA. Gross anatomical description of the extrinsic and intrinsic scapular and brachial muscles of Sapajus apella (Linnaeus, 1758). J Med Primatol 2023; 52:3-16. [PMID: 36156802 DOI: 10.1111/jmp.12619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 09/06/2022] [Accepted: 09/08/2022] [Indexed: 01/10/2023]
Abstract
BACKGROUND The robust brown capuchin monkey (Sapajus apella) is a South American primate with preferences for arboreal locomotion, which requires specific thoracic limb muscle adaptations. The present investigation studied the gross anatomy of the extrinsic and intrinsic scapular and brachial muscles. METHODS Gross dissections were performed in both thoracic limbs of four formaldehyde-fixed specimens. RESULTS Three rhomboideus muscles were present (capitis, cervicis, and thoracis). The trapezius muscle was divided into two parts (cervicis and thoracis). The pectoralis abdominalis and omotransversarius muscles were present. The anconeus muscle was found as an individual muscle or fused to the caput mediale of the triceps brachii muscle. The brachialis muscle had among one and two heads. The anconeus epitrochlearis was absent. CONCLUSION These muscles of Sapajus apella are adapted for arboreal locomotion and some terrestrial habits, since these have many similarities with other primates with a similar locomotor patterns.
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Affiliation(s)
- María José Monroy-Cendales
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Programa de pós-graduação em Anatomia dos Animais Domésticos e Silvestres, Universidade de São Paulo, São Paulo, Brasil.,Grupo de Investigación BIOECOS, Institución Universitaria Visión de las Américas, Sede Pereira, Pereira, Colombia
| | - Juan Fernando Vélez-García
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Programa de pós-graduação em Anatomia dos Animais Domésticos e Silvestres, Universidade de São Paulo, São Paulo, Brasil.,Departamento de Sanidad Animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad del Tolima, Ibagué, Colombia
| | - Román David Castañeda-Serrano
- Departamento de Producción Pecuaria, Facultad de Medicina Veterinaria y Zootecnia, Universidad del Tolima, Ibagué, Colombia
| | - Maria Angélica Miglino
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Programa de pós-graduação em Anatomia dos Animais Domésticos e Silvestres, Universidade de São Paulo, São Paulo, Brasil
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4
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Agosto ER, Auerbach BM. Morphological integration and evolutionary potential of the primate shoulder: Variation among taxa and implications for genetic covariances with the basicranium, pelvis, and arm. J Hum Evol 2022; 169:103221. [PMID: 35772227 DOI: 10.1016/j.jhevol.2022.103221] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/12/2022] [Accepted: 05/14/2022] [Indexed: 11/24/2022]
Abstract
Within the primate order, the morphology of the shoulder girdle is immensely variable and has been shown to reflect the functional demands of the upper limb. The observed morphological variation among extant primate taxa consequently has been hypothesized to be driven by selection for different functional demands. Evolutionary analyses of the shoulder girdle often assess this anatomical region, and its traits, individually, therefore implicitly assuming independent evolution of the shoulder girdle. However, the primate shoulder girdle has developmental and functional covariances with the basicranium and pelvic girdle that have been shown to potentially influence its evolution. It is unknown whether these relationships are similar or even present across primate taxa, and how they may affect morphological variation among primates. This study evaluates the strength of covariance and evolutionary potential across four anatomical regions: shoulder girdle, basicranium, pelvis, and distal humerus. Measures of morphological integration and evolutionary potential (conditioned covariance and evolutionary flexibility) are assessed across eight anthropoid primate taxa. Results demonstrate a consistent pattern of morphological constraint within paired anatomical regions across primates. Differences in evolutionary flexibility are observed among primate genera, with humans having the highest evolutionary potential overall. This pattern does not follow functional differences, but rather a separation between monkeys and apes. Therefore, evolutionary hypotheses of primate shoulder girdle morphological variation that evaluate functional demands alone may not account for the effect of these relationships. Collectively, our findings suggest differences in genetic covariance among anatomical regions may have contributed to the observable morphological variation among taxa.
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Affiliation(s)
- Elizabeth R Agosto
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 5035, Indianapolis, IN 46202, USA.
| | - Benjamin M Auerbach
- Department of Anthropology, The University of Tennessee, 1621 Cumberland Ave., Room 502A, Knoxville, TN 37996, USA; Department of Ecology and Evolutionary Biology, The University of Tennessee, Dabney Hall, 1416 Circle Dr, Knoxville, TN 37996, USA
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5
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Carlson KJ, Green DJ, Jashashvili T, Pickering TR, Heaton JL, Beaudet A, Stratford D, Crompton R, Kuman K, Bruxelles L, Clarke RJ. The pectoral girdle of StW 573 ('Little Foot') and its implications for shoulder evolution in the Hominina. J Hum Evol 2021; 158:102983. [PMID: 33888323 DOI: 10.1016/j.jhevol.2021.102983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 02/20/2021] [Accepted: 02/23/2021] [Indexed: 10/21/2022]
Abstract
The ca. 3.67 Ma adult skeleton known as 'Little Foot' (StW 573), recovered from Sterkfontein Member 2 breccia in the Silberberg Grotto, is remarkable for its morphology and completeness. Preservation of clavicles and scapulae, including essentially complete right-side elements, offers opportunities to assess morphological and functional aspects of a nearly complete Australopithecus pectoral girdle. Here we describe the StW 573 pectoral girdle and offer quantitative comparisons to those of extant hominoids and selected homininans. The StW 573 pectoral girdle combines features intermediate between those of humans and other apes: a long and curved clavicle, suggesting a relatively dorsally positioned scapula; an enlarged and uniquely proportioned supraspinous fossa; a relatively cranially oriented glenoid fossa; and ape-like reinforcement of the axillary margin by a stout ventral bar. StW 573 scapulae are as follows: smaller than those of some homininans (i.e., KSD-VP-1/1 and KNM-ER 47000A), larger than others (i.e., A.L. 288-1, Sts 7, and MH2), and most similar in size to another australopith from Sterkfontein, StW 431. Moreover, StW 573 and StW 431 exhibit similar structural features along their axillary margins and inferior angles. As the StW 573 pectoral girdle (e.g., scapular configuration) has a greater affinity to that of apes-Gorilla in particular-rather than modern humans, we suggest that the StW 573 morphological pattern appears to reflect adaptations to arboreal behaviors, especially those with the hand positioned above the head, more than human-like manipulatory capabilities. When compared with less complete pectoral girdles from middle/late Miocene apes and that of the penecontemporaneous KSD-VP-1/1 (Australopithecus afarensis), and mindful of consensus views on the adaptiveness of arboreal positional behaviors soliciting abducted glenohumeral joints in early Pliocene taxa, we propose that the StW 573 pectoral girdle is a reasonable model for hypothesizing pectoral girdle configuration of the crown hominin last common ancestor.
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Affiliation(s)
- Kristian J Carlson
- Department of Integrative Anatomical Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa.
| | - David J Green
- Department of Anatomy, Campbell University School of Osteopathic Medicine, Buies Creek, NC 27506, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa
| | - Tea Jashashvili
- Department of Integrative Anatomical Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; Department of Geology and Paleontology, Georgian National Museum, Tbilisi 0105, Georgia
| | - Travis R Pickering
- Department of Anthropology, University of Wisconsin, Madison, WI 53706, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa; Plio-Pleistocene Palaeontology Section, Department of Vertebrates, Ditsong National Museum, Pretoria 0001, South Africa
| | - Jason L Heaton
- Department of Biology, Birmingham-Southern College, Birmingham, AL 35254, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa; Plio-Pleistocene Palaeontology Section, Department of Vertebrates, Ditsong National Museum, Pretoria 0001, South Africa
| | - Amélie Beaudet
- School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050 South Africa; Department of Anatomy, University of Pretoria, PO Box 2034, Pretoria 0001, South Africa
| | - Dominic Stratford
- School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050 South Africa
| | - Robin Crompton
- Department of Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L7 8TX, UK
| | - Kathleen Kuman
- School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050 South Africa
| | - Laurent Bruxelles
- TRACES, UMR 5608 of the French National Centre for Scientific Research, Jean Jaurès University, 31058 Toulouse, France; French National Institute for Preventive Archaeological Researches (INRAP), 30900 Nîmes, France; School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050 South Africa
| | - Ronald J Clarke
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa
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6
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van Beesel J, Hutchinson JR, Hublin JJ, Melillo SM. Exploring the functional morphology of the Gorilla shoulder through musculoskeletal modelling. J Anat 2021; 239:207-227. [PMID: 33629406 PMCID: PMC8197971 DOI: 10.1111/joa.13412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 01/27/2021] [Accepted: 02/02/2021] [Indexed: 12/11/2022] Open
Abstract
Musculoskeletal computer models allow us to quantitatively relate morphological features to biomechanical performance. In non‐human apes, certain morphological features have long been linked to greater arm abduction potential and increased arm‐raising performance, compared to humans. Here, we present the first musculoskeletal model of a western lowland gorilla shoulder to test some of these long‐standing proposals. Estimates of moment arms and moments of the glenohumeral abductors (deltoid, supraspinatus and infraspinatus muscles) over arm abduction were conducted for the gorilla model and a previously published human shoulder model. Contrary to previous assumptions, we found that overall glenohumeral abduction potential is similar between Gorilla and Homo. However, gorillas differ by maintaining high abduction moment capacity with the arm raised above horizontal. This difference is linked to a disparity in soft tissue properties, indicating that scapular morphological features like a cranially oriented scapular spine and glenoid do not enhance the abductor function of the gorilla glenohumeral muscles. A functional enhancement due to differences in skeletal morphology was only demonstrated in the gorilla supraspinatus muscle. Contrary to earlier ideas linking a more obliquely oriented scapular spine to greater supraspinatus leverage, our results suggest that increased lateral projection of the greater tubercle of the humerus accounts for the greater biomechanical performance in Gorilla. This study enhances our understanding of the evolution of gorilla locomotion, as well as providing greater insight into the general interaction between anatomy, function and locomotor biomechanics.
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Affiliation(s)
- Julia van Beesel
- Department of Human Evolution, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany
| | - John R Hutchinson
- Structure & Motion Laboratory, The Royal Veterinary College, Hatfield, UK
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany.,Collège de France, Paris, France
| | - Stephanie M Melillo
- Department of Human Evolution, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany
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7
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Spear JK, Williams SA. Mosaic patterns of homoplasy accompany the parallel evolution of suspensory adaptations in the forelimb of tree sloths (Folivora: Xenarthra). Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Abstract
We examine how derived functional signal and phylogenetic inheritance interact in the forelimb of tree sloths, to understand the relative contribution of each in the evolution of a novel morphobehavioural suite. Molecular and craniodental data demonstrate that extant tree sloths evolved suspensory behaviours and associated morphologies from a non-suspensory ancestor independently of one another, making them a useful model system. We find that convergence in univariate traits is expressed mosaically, although the signal is largely functional. Three-dimensional analyses suggest there is greater conservatism of gross morphology in more proximal bones than in more distal elements. Convergence in some univariate scapular traits is independent of the gross morphology of the scapula itself, demonstrating that functionally relevant morphologies were mapped on to a more conserved scapular shape. Our results suggest that morphological homoplasy is expressed in a mosaic manner. The relationship between homoplasy and trait integration may be more nuanced than previously thought, even within a single adaptive system.
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Affiliation(s)
- Jeffrey K Spear
- Center for the Study of Human Origins & Department of Anthropology, New York University, New York, USA
- New York Consortium in Evolutionary Primatology, New York, USA
| | - Scott A Williams
- Center for the Study of Human Origins & Department of Anthropology, New York University, New York, USA
- New York Consortium in Evolutionary Primatology, New York, USA
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8
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MacLean KFE, Dickerson CR. Development of a comparative chimpanzee musculoskeletal glenohumeral model: implications for human function. J Exp Biol 2020; 223:jeb225987. [PMID: 33071220 DOI: 10.1242/jeb.225987] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 10/01/2020] [Indexed: 11/20/2022]
Abstract
Modern human shoulder function is affected by the evolutionary adaptations that have occurred to ensure survival and prosperity of the species. Robust examination of behavioral shoulder performance and injury risk can be holistically improved through an interdisciplinary approach that integrates anthropology and biomechanics. Coordination of these fields can allow different perspectives to contribute to a more complete interpretation of biomechanics of the modern human shoulder. The purpose of this study was to develop a novel biomechanical and comparative chimpanzee glenohumeral model, designed to parallel an existing human glenohumeral model, and compare predicted musculoskeletal outputs between the two models. The chimpanzee glenohumeral model consists of three modules - an external torque module, a musculoskeletal geometric module and an internal muscle force prediction module. Together, these modules use postural kinematics, subject-specific anthropometrics, a novel shoulder rhythm, glenohumeral stability ratios, hand forces, musculoskeletal geometry and an optimization routine to estimate joint reaction forces and moments, subacromial space dimensions, and muscle and tissue forces. Using static postural data of a horizontal bimanual suspension task, predicted muscle forces and subacromial space were compared between chimpanzees and humans. Compared with chimpanzees, the human model predicted a 2 mm narrower subacromial space, deltoid muscle forces that were often double those of chimpanzees and a strong reliance on infraspinatus and teres minor (60-100% maximal force) over other rotator cuff muscles. These results agree with previous work on inter-species differences that inform basic human rotator cuff function and pathology.
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Affiliation(s)
- Kathleen F E MacLean
- Division of Kinesiology, School of Health and Human Performance, Dalhousie University, 6260 South Street, Halifax, NS, Canada B3H 4R2
| | - Clark R Dickerson
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada N2L 3G1
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9
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MacLean KF, Dickerson CR. Kinematic and EMG analysis of horizontal bimanual climbing in humans. J Biomech 2019; 92:11-18. [DOI: 10.1016/j.jbiomech.2019.05.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/26/2019] [Accepted: 05/14/2019] [Indexed: 10/26/2022]
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10
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Kohn LAP, Lubach GR. Postcranial Skeletal Differences in Free-Range and Captive-Born Primates. Anat Rec (Hoboken) 2019; 302:761-774. [PMID: 30312525 PMCID: PMC6461526 DOI: 10.1002/ar.23970] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 05/15/2018] [Accepted: 06/02/2018] [Indexed: 11/07/2022]
Abstract
Skeletal morphology is important in evolutionary, genetic, developmental, physiological, and functional studies. Although samples from free-ranging individuals may be preferable, constraints of sample size, demography, or conservation status may necessitate the inclusion of captive-born individuals. Captivity may be associated with physical, physiological, or behavioral differences that may affect skeletal form. This study assesses differences in postcranial skeletal form between free-range and captive-born Macaca mulatta and Saguinus oedipus. Samples included free-range M. mulatta from Cayo Santiago (Caribbean Primate Research Center) and captive-born macaques from the Wisconsin National Primate Research Center. S. oedipus samples included free-range born and captive-born individuals from the Oak Ridge Associated Universities Marmoset Research Center. Twenty-four dimensions of various bones, including the scapula, upper limb, innominate and lower limb, were recorded for adults. Age of epiphyseal closure was recorded for immature captive-born M. mulatta. Analysis of variance and principal component analyses tested significant differences between free-range born and captive-born individuals in each species. Significant differences were present in size and shape of postcrania between free-range and captive-born within taxa. Free-range macaques were larger than captive-born macaques, but this pattern did not consistently carry over to the Saguinus samples. Shape differences, while present throughout the skeleton, were especially prominent in the scapula. Differences in developmental timing, nutrition, and physical activity can be expected to contribute to the observed differences in postcranial skeletal form. These differences should be considered when captive-born primates are included in morphological or evolutionary studies. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:761-774, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Luci Ann P. Kohn
- Department of Biological Sciences, Campus Box 1651, Southern Illinois University Edwardsville, Edwardsville, IL 62026
| | - Gabriele R. Lubach
- Harlow Center for Biological Psychology, University of Wisconsin, 22 North Charter Street, Madison, WI 53715
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11
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Scapular anatomy of Paranthropus boisei from Ileret, Kenya. J Hum Evol 2018; 125:181-192. [DOI: 10.1016/j.jhevol.2017.06.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 06/23/2017] [Accepted: 06/28/2017] [Indexed: 11/21/2022]
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12
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Thompson NE, Rubinstein D, Larson SG. Great ape thorax and shoulder configuration-An adaptation for arboreality or knuckle-walking? J Hum Evol 2018; 125:15-26. [PMID: 30502892 DOI: 10.1016/j.jhevol.2018.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 09/19/2018] [Accepted: 09/24/2018] [Indexed: 10/28/2022]
Abstract
Great apes exhibit a suite of morphological traits of the shoulder and upper thorax that have traditionally been linked to orthograde arborealism. Recently it has been proposed that these traits are instead adaptations for knuckle-walking, and more broadly, that knuckle-walking itself is an adaptation for shock absorption during terrestriality. Here we test several tenets of these hypotheses using kinematic and kinetic data from chimpanzees and macaques, and electromyographic data of shoulder muscle activity in chimpanzees. We collected 3D kinematic data to quantify motion of the acromion and trunk during quadrupedalism and vertical climbing in chimpanzees as well as ground reaction forces to investigate the presence and magnitude of impact transient forces during terrestrial locomotion in chimpanzees and macaques. We also investigated patterns of recruitment of select forelimb musculature (triceps brachii and serratus anterior) using previously collected data in chimpanzees to determine whether these muscles may function to absorb impact transient forces. We found that the acromion is significantly more elevated in vertical climbing than during knuckle-walking, while dorsoventral ranges and magnitudes of motion were similar between gaits. Ground reaction forces indicate that only a minority of strides in either chimpanzees or macaques have transient forces and, when present, these transient forces as well as loading rates are small. Electromyographic results show that activity of the triceps brachii may facilitate energy absorption while serratus anterior likely functions to support the trunk, as in other primates. Our data suggest there is little to no evidence supporting recent hypotheses that the African ape upper thorax and shoulder configuration is an adaptation for knuckle-walking, or more broadly, that knuckle-walking exists as an adaptation to absorb impact shock during terrestriality. We do however find some evidence that shoulder configuration allows greater scapular elevation in chimpanzees during arboreal behaviors (e.g., vertical climbing).
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Affiliation(s)
- Nathan E Thompson
- Department of Anatomy, NYIT College of Osteopathic Medicine, Old Westbury, NY 11568, USA.
| | - Danielle Rubinstein
- New York Institute of Technology, College of Osteopathic Medicine, NY 11568 USA
| | - Susan G Larson
- Department of Anatomical Sciences, Stony Brook University School of Medicine, Stony Brook, NY 11794-8081, USA
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13
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Larson SG. Nonhuman Primate Locomotion. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 165:705-725. [DOI: 10.1002/ajpa.23368] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 11/05/2022]
Affiliation(s)
- Susan G. Larson
- Department of Anatomical Sciences; Stony Brook University School of Medicine; Stony Brook New York 11794-8081
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The cervical spine of Australopithecus sediba. J Hum Evol 2017; 104:32-49. [DOI: 10.1016/j.jhevol.2017.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 12/31/2016] [Accepted: 01/04/2017] [Indexed: 11/22/2022]
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Selby MS, Lovejoy CO. Evolution of the hominoid scapula and its implications for earliest hominid locomotion. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2017; 162:682-700. [PMID: 28128440 DOI: 10.1002/ajpa.23158] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 11/06/2016] [Accepted: 12/08/2016] [Indexed: 11/06/2022]
Abstract
OBJECTIVES The higher primate scapula has been subject to many explanations of the putative "adaptive value" of its individual traits. However, the shift from the bone's position in above branch quadrupeds to its more posterolateral position in recent hominoids obviously required fundamental changes to its general form. We hypothesize that most features argued to be individually adaptive are more likely secondary consequences of changes in its fundamental bauplan, a view more consistent with modern developmental biology. MATERIALS AND METHODS We tested this hypothesis with scapular metrics and angles from a broad anthropoid sample. RESULTS Our results support our hypothesis. Contrary to earlier predictions, vertebral border length differs little relative to body size in anthropoids, inferior angle position primarily reflects mediolateral scapular breadth, and supraspinous and infraspinous fossa sizes largely reflect scapular spine orientation. Suspensory taxa have cranially oriented glenoids, whereas slow clamberers and humans do not. Australopithecus most closely resembles the latter. DISCUSSION Most scapular features can be explained by only two primary changes: (1) reduction in mediolateral breadth and (2) change in the glenoid position relative to the vertebral border with increased reliance on suspension, which led to a more cranially angled scapular spine. Virtually all other scapular traits appear to be byproducts of these two changes. Based on fossil morphology, hominids1 were derived from a last common ancestor primarily adapted for clambering and not for suspension. Scapular form in early hominids such as Australopithecus is therefore primitive and largely reflects the genus's general clambering heritage.
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Affiliation(s)
- Michael S Selby
- Department of Biomedical Sciences, Georgia Campus - Philadelphia College of Osteopathic Medicine, Suwanee, Georgia, 30024-2937
| | - C Owen Lovejoy
- Department of Anthropology, School of Biomedical Sciences, Kent State University, Kent, Ohio, 44242-0001
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Scapular shape of extant hominoids and the African ape/modern human last common ancestor. J Hum Evol 2016; 94:1-12. [DOI: 10.1016/j.jhevol.2016.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 01/08/2016] [Accepted: 01/14/2016] [Indexed: 02/01/2023]
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17
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Hunt KD. Why are there apes? Evidence for the co-evolution of ape and monkey ecomorphology. J Anat 2016; 228:630-85. [PMID: 27004976 PMCID: PMC4804131 DOI: 10.1111/joa.12454] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2016] [Indexed: 11/28/2022] Open
Abstract
Apes, members of the superfamily Hominoidea, possess a distinctive suite of anatomical and behavioral characters which appear to have evolved relatively late and relatively independently. The timing of paleontological events, extant cercopithecine and hominoid ecomorphology and other evidence suggests that many distinctive ape features evolved to facilitate harvesting ripe fruits among compliant terminal branches in tree edges. Precarious, unpredictably oriented, compliant supports in the canopy periphery require apes to maneuver using suspensory and non-sterotypical postures (i.e. postures with eccentric limb orientations or extreme joint excursions). Diet differences among extant species, extant species numbers and evidence of cercopithecoid diversification and expansion, in concert with a reciprocal decrease in hominoid species, suggest intense competition between monkeys and apes over the last 20 Ma. It may be that larger body masses allow great apes to succeed in contest competitions for highly desired food items, while the ability of monkeys to digest antifeedant-rich unripe fruits allows them to win scramble competitions. Evolutionary trends in morphology and inferred ecology suggest that as monkeys evolved to harvest fruit ever earlier in the fruiting cycle they broadened their niche to encompass first more fibrous, tannin- and toxin-rich unripe fruits and later, for some lineages, mature leaves. Early depletion of unripe fruit in the central core of the tree canopy by monkeys leaves a hollow sphere of ripening fruits, displacing antifeedant-intolerant, later-arriving apes to small-diameter, compliant terminal branches. Hylobatids, orangutans, Pan species, gorillas and the New World atelines may have each evolved suspensory behavior independently in response to local competition from an expanding population of monkeys. Genetic evidence of rapid evolution among chimpanzees suggests that adaptations to suspensory behavior, vertical climbing, knuckle-walking, consumption of terrestrial piths and intercommunity violence had not yet evolved or were still being refined when panins (chimpanzees and bonobos) and hominins diverged.
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Affiliation(s)
- Kevin D Hunt
- Department of Anthropology, Indiana University, Bloomington, IN, USA
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Püschel TA, Sellers WI. Standing on the shoulders of apes: Analyzing the form and function of the hominoid scapula using geometric morphometrics and finite element analysis. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 159:325-41. [DOI: 10.1002/ajpa.22882] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 09/02/2015] [Accepted: 10/01/2015] [Indexed: 12/30/2022]
Affiliation(s)
- Thomas A. Püschel
- Computational and Evolutionary Biology Group, Faculty of Life Sciences; University of Manchester; Manchester M13 9PT UK
| | - William I. Sellers
- Computational and Evolutionary Biology Group, Faculty of Life Sciences; University of Manchester; Manchester M13 9PT UK
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Larson SG. Rotator cuff muscle size and the interpretation of scapular shape in primates. J Hum Evol 2015; 80:96-106. [PMID: 25681014 DOI: 10.1016/j.jhevol.2015.01.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 09/19/2014] [Accepted: 01/08/2015] [Indexed: 12/11/2022]
Abstract
Scapular shape variation among primates is widely viewed as being strongly related to locomotor differences. The relative importance of overhead forelimb elevation in the locomotor repertoire of a species, as reflected in muscular leverage for scapular rotation or in the sizes of attachment areas for muscles involved in glenohumeral elevation, has proven to be a useful organizing principle for understanding this variation. While generally successful in sorting primate scapulae into functional groups, the scapulae of some species do not entirely match predictions based on the perceived importance of forelimb elevation. A recent study has shown that scapular fossa sizes in apes are not as accurate predictors of the sizes of the muscles arising from them as has been assumed. To further explore the degree of correspondence between actual and predicted muscle size based on the perceived importance of forelimb elevation, the current study examines the relative sizes of the rotator cuff muscles in a wider sample of primate taxa using published data on muscle mass and cross-sectional area. The results do not support some of the accepted generalizations about the relative sizes of members of the rotator cuff based on measurements of the sizes of scapular fossae. For example, orthograde apes do not display enlarged supraspinatus muscles compared to pronograde monkeys. Differences in assessments of relative muscle size based on mass compared to those based on cross-sectional area suggest that poor correspondence between muscle size predicted from scapular fossa size and actual muscle size may be related to constraints on scapular form associated with muscular leverage for scapular rotation and with scapular position on the thorax.
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Affiliation(s)
- Susan G Larson
- Department of Anatomical Sciences, Stony Brook University School of Medicine, Stony Brook, NY 11794-8081, USA.
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Green DJ. Ontogeny of the hominoid scapula: The influence of locomotion on morphology. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 152:239-60. [PMID: 24000155 DOI: 10.1002/ajpa.22353] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 07/17/2013] [Accepted: 07/18/2013] [Indexed: 12/18/2022]
Abstract
Primate shoulder morphology has been linked with locomotor habits, oftentimes irrespective of phylogenetic heritage. Among hominoids, juvenile African apes are known to climb more frequently than adults, while orangutans and gibbons maintain an arboreal lifestyle throughout ontogeny. This study examined if these ontogenetic locomotor differences carry a morphological signal, which should be evident in the scapulae of chimpanzees and gorillas but absent in taxa that do not display ontogenetic behavioral shifts. The scapular morphology of five hominoid primates and one catarrhine outgroup was examined throughout ontogeny to evaluate if scapular traits linked with arboreal activities are modified in response to ontogenetic behavioral shifts away from climbing. Specifically, the following questions were addressed: 1) which scapular characteristics distinguish taxa with different locomotor habits; and 2) do these traits show associated changes during development in taxa known to modify their behavioral patterns? Several traits characterized suspensory taxa from nonsuspensory forms, such as cranially oriented glenohumeral joints, obliquely oriented scapular spines, relatively narrow infraspinous fossae, and inferolaterally expanded subscapularis fossae. The relative shape of the dorsal scapular fossae changed in Pan, Gorilla, and also Macaca in line with predictions based on reported ontogenetic changes in locomotor behavior. These morphological changes were mostly distinct from those seen in Pongo, Hylobates, and Homo and imply a unique developmental pattern, possibly related to ontogenetic locomotor shifts. Accordingly, features that sorted taxa by locomotor habits and changed in concert with ontogenetic behavioral patterns should be particularly useful for reconstructing the locomotor habits of fossil forms.
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Affiliation(s)
- David J Green
- Department of Anatomy, Midwestern University, Downers Grove, IL, 60515; Center for the Advanced Study of Hominid Paleobiology, The George Washington University, NW, 20052
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Bello-Hellegouarch G, Potau JM, Arias-Martorell J, Pastor JF, Pérez-Pérez A. Brief communication: Morphological effects of captivity: A geometric morphometric analysis of the dorsal side of the scapula in captive-bred and wild-caught Hominoidea. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 152:306-10. [PMID: 23999861 DOI: 10.1002/ajpa.22356] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 07/22/2013] [Accepted: 07/23/2013] [Indexed: 11/05/2022]
Abstract
Many osteological collections from museums and research institutions consist mainly of remains from captive-bred animals. The restrictions related to the space of their enclosures and the nature of its substrate are likely to affect the locomotor and postural behaviors of captive-bred animals, which are widely considered uninformative regarding bone morphology and anatomical adaptations of wild animals, especially so in the case of extant great apes. We made a landmark-based geometric morphometrics analysis of the dorsal side of the scapular bone of both wild-caught and captive-bred great apes to clarify the effect of captivity on the morphology of a bone greatly involved in locomotion. The comparison suggested that captivity did not have a significant effect on the landmark configuration used, neither on average scapular shape nor shape variability, being impossible to distinguish the scapulae of a captive-bred animal from that of a wild-caught one. This indicates that the analyzed scapulae from captive Hominoidea specimens may be used in morphological or taxonomic analyses since they show no atypical morphological traits caused by living conditions in captivity.
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Affiliation(s)
- Gaëlle Bello-Hellegouarch
- Anthropology Unit, Animal Biology Department, University of Barcelona, Diagonal 643, 08028, Barcelona, Spain
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Larson SG, Stern JT. Rotator cuff muscle function and its relation to scapular morphology in apes. J Hum Evol 2013; 65:391-403. [PMID: 23968682 DOI: 10.1016/j.jhevol.2013.07.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 07/19/2013] [Accepted: 07/20/2013] [Indexed: 10/26/2022]
Abstract
It is widely held that many differences among primate species in scapular morphology can be functionally related to differing demands on the shoulder associated with particular locomotor habits. This perspective is largely based on broad scale studies, while more narrow comparisons of scapular form often fail to follow predictions based on inferred differences in shoulder function. For example, the ratio of supraspinous fossa/infraspinous fossa size in apes is commonly viewed as an indicator of the importance of overhead use of the forelimb, yet paradoxically, the African apes, the most terrestrial of the great apes, have higher scapular fossa ratios than the more suspensory orangutan. The recent discovery of several nearly complete early hominin scapular specimens, and their apparent morphological affinities to scapulae of orangutans and gorillas rather than chimpanzees, has led to renewed interest in the comparative analysis of human and extant ape scapular form. To facilitate the functional interpretation of differences in ape scapulae, particularly in regard to relative scapular fossa size, we used electromyography (EMG) to document the activity patterns in all four rotator cuff muscles in orangutans and gibbons, comparing the results with previously published data for chimpanzees. The EMG results indicate that the distinctive contributions of each cuff muscle to locomotion are the same in the three ape species, failing to support inferences of differences in rotator cuff function based on relative scapular fossa size comparisons. It is also shown that relative scapular fossa size is not in fact a good predictor of either the relative masses or cross-sectional areas of the rotator cuff muscles in apes, and relative fossa size gives a false impression of the importance of individual cuff muscles to locomotor differences among apes. A possible explanation for the disparity between fossa and muscle size relates to the underappreciated role of the scapular spine in structural reinforcement of the blade.
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Affiliation(s)
- Susan G Larson
- Department of Anatomical Sciences, Stony Brook University School of Medicine, Stony Brook, NY 11794-8081, USA.
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Bello-Hellegouarch G, Potau JM, Arias-Martorell J, Pastor JF, Pérez-Pérez A. A Comparison of Qualitative and Quantitative Methodological Approaches to Characterizing the Dorsal Side of the Scapula in Hominoidea and Its Relationship to Locomotion. INT J PRIMATOL 2013. [DOI: 10.1007/s10764-013-9660-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Green DJ, Alemseged Z. Australopithecus afarensis Scapular Ontogeny, Function, and the Role of Climbing in Human Evolution. Science 2012; 338:514-7. [DOI: 10.1126/science.1227123] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Preuschoft H, Hohn B, Scherf H, Schmidt M, Krause C, Witzel U. Functional Analysis of the Primate Shoulder. INT J PRIMATOL 2010; 31:301-320. [PMID: 20495602 PMCID: PMC2860095 DOI: 10.1007/s10764-010-9399-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Accepted: 03/10/2010] [Indexed: 11/30/2022]
Abstract
Studies of the shoulder girdle are in most cases restricted to morphological comparisons and rarely aim at elucidating function in a strictly biomechanical sense. To fill this gap, we investigated the basic functional conditions that occur in the shoulder joint and shoulder girdle of primates by means of mechanics. Because most of nonhuman primate locomotion is essentially quadrupedal walking-although on very variable substrates-our analysis started with quadrupedal postures. We identified the mechanical situation at the beginning, middle, and end of the load-bearing stance phase by constructing force parallelograms in the shoulder joint and the scapulo-thoracal connection. The resulting postulates concerning muscle activities are in agreement with electromyographical data in the literature. We determined the magnitude and directions of the internal forces and explored mechanically optimal shapes of proximal humerus, scapula, and clavicula using the Finite Element Method. Next we considered mechanical functions other than quadrupedal walking, such as suspension and brachiation. Quadrupedal walking entails muscle activities and joint forces that require a long scapula, the cranial margin of which has about the same length as the axillary margin. Loading of the hand in positions above the head and suspensory behaviors lead to force flows along the axillary margin and so necessitate a scapula with an extended axillary and a shorter cranial margin. In all cases, the facies glenoidalis is nearly normal to the calculated joint forces. In anterior view, terrestrial monkeys chose a direction of the ground reaction force requiring (moderate) activity of the abductors of the shoulder joint, whereas more arboreal monkeys prefer postures that necessitate activity of the adductors of the forelimb even when walking along branches. The same adducting and retracting muscles are recruited in various forms of suspension. As a mechanical consequence, the scapula is in a more frontal, rather than parasagittal, position on the thorax. In both forms of locomotion-quadrupedal walking and suspension-the compression-resistant clavicula contributes to keeping the shoulder complex distant from the rib cage. Future studies should consider the consequences for thorax shape. The morphological specializations of all Hominoidea match the functional requirements of suspensory behavior. The knowledge of mechanical functions allows an improved interpretation of fossils beyond morphological similarity.
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Affiliation(s)
- Holger Preuschoft
- Formerly Funktionelle Morphologie, Anatomisches Institut, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Bianca Hohn
- Formerly Funktionelle Morphologie, Anatomisches Institut, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Heike Scherf
- Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany
| | - Manuela Schmidt
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena, 07737 Jena, Germany
| | - Cornelia Krause
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena, 07737 Jena, Germany
| | - Ulrich Witzel
- Subdepartment Biomechanik, Fakultät für Maschinenbau, Ruhr-Universität Bochum, 44780 Bochum, Germany
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Rib orientation and implications for orthograde positional behavior in nonhuman anthropoids. Primates 2009; 50:305-10. [PMID: 19529976 DOI: 10.1007/s10329-009-0147-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Accepted: 04/22/2009] [Indexed: 11/26/2022]
Abstract
Strong caudal obliquity of the lower ribs is one of the assumed characteristics of the thoracic region in hominoids and Ateles. Strong caudal obliquity keeps the scapula of the weight-bearing forelimb on the dorsal surface of the trunk via the serratus anterior muscles during propulsion (Stern et al. 1980). We examined the orientation of odd-numbered ribs in lateral view in remounted thoracic skeletons of fifteen nonhuman anthropoids. Hominoids exhibit pronounced caudal obliquity in the seventh and ninth ribs compared to Old and New World monkeys. The position of the maximum thoracic cage width, which approximates the attachment of the serratus anterior muscle, is more caudally located in Hylobates and Pongo. The overall pattern of rib obliquity is generally similar between New and Old World monkeys, including Ateles. Perhaps not only forelimb suspensory behavior but also various orthograde positional behaviors are related to the strong obliquity of the lower ribs; however, further investigation is necessary.
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Young NM. A comparison of the ontogeny of shape variation in the anthropoid scapula: Functional and phylogenetic signal. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2008; 136:247-64. [DOI: 10.1002/ajpa.20799] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Brindle TJ, Nyland JA, Nitz AJ, Shapiro R. Scapulothoracic latent muscle reaction timing comparison between trained overhead throwers and untrained control subjects. Scand J Med Sci Sports 2006; 17:252-9. [PMID: 16774649 DOI: 10.1111/j.1600-0838.2006.00574.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM This study evaluated select scapulothoracic muscles for training-induced latent muscle reaction timing (LMRT) changes. Comparisons were also made between the dominant and non-dominant upper extremities and between individual muscles. MATERIALS AND METHODS Fifteen male trained overhead throwers (college baseball pitchers) and 15 male untrained, age-matched control subjects participated in this study. Scapulothoracic muscle activation data were collected as subjects attempted to stop a variably timed, sudden glenohumeral joint internal rotation perturbation. RESULTS Training group differences were not evident for LMRT (P=0.56), however upper extremity dominance (P=0.003) and test muscle (P=0.0002) displayed significant differences. Dominant upper extremity upper trapezius muscle LMRT (72.5+/-26 ms) occurred later than non-dominant upper trapezius muscle LMRT (60.0+/-14.1 ms, P=0.001). Dominant upper extremity middle trapezius-rhomboid muscle LMRT (60.0+/-16.2 ms) occurred later than non-dominant middle trapezius-rhomboid muscle LMRT (50.2+/-12.6 ms, P=0.004). Dominant upper extremity upper trapezius muscle LMRT also occurred later than serratus anterior (55.7+/-16.0 ms, P=0.001) and middle trapezius-rhomboid LMRT (60.2+/-16 ms, P=0.003). Mean overall dominant upper extremity LMRT (62.7+/-19.4 ms) was delayed compared with mean overall non-dominant upper extremity LMRT (53.9+/-12.4 ms, P=0.003). CLINICAL CONSEQUENCES Although training was not found to influence scapulothoracic LMRT, differences were observed between the dominant and non-dominant upper extremities. Consistent LMRT delays at the dominant upper extremity suggest possible neuromuscular timing differences to enable prolonged glenohumeral joint and scapulothoracic articulation acceleration before deceleration through eccentric muscle activation. Both trained and untrained overhead throwers displayed this response. Variable perturbation test velocities, and in-season testing of larger subject groups may be needed to better elucidate the more subtle differences associated with training.
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Affiliation(s)
- T J Brindle
- Physical Disabilities Branch, National Institutes of Health, Bethesda, Maryland, USA
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Abstract
In an analysis of hominoid postcranial variation, 'Evol. Anthrop. 6 (1998) 87' argued that many purportedly unique features of the hominoid postcranium are actually much more variable than previously reported and in many instances overlap with both suspensory (Ateles) and non-suspensory primates. Based on these results, it was concluded that parallelism in the living ape postcranium was a plausible and even likely possibility given the Miocene hominoid postcranial record. However, this analysis did not distinguish whether within-hominoid variability or overlap with non-hominoids involved one or all ape taxa, a distinction which has potentially important effects on the interpretation of results. To address this issue, primate postcranial morphometric data from the trunk and forelimb were reanalyzed using three techniques: cladistic analysis, principle components analysis, and cluster analysis. Results reveal that these postcranial characters distinguish not only suspensory and quadrupedal primates but also discriminate hominoids and Ateles from all other taxa, great apes from lesser apes and Ateles, cercopithecines from colobines, and cercopithecoids from platyrrhines. The majority of hominoid variability and overlap with Ateles occurs with Hylobates humeral head and shoulder joint characters related to brachiation. This suggests that Hylobates' specializations may skew analyses of hominoid postcranial uniqueness and variability, and that great apes are relatively similar in their postcranium.
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Affiliation(s)
- Nathan M Young
- Harvard University, Department of Anthropology, 11 Divinity Avenue, Cambridge, MA 02138, USA.
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Schmitt D. Insights into the evolution of human bipedalism from experimental studies of humans and other primates. J Exp Biol 2003; 206:1437-48. [PMID: 12654883 DOI: 10.1242/jeb.00279] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An understanding of the evolution of human bipedalism can provide valuable insights into the biomechanical and physiological characteristics of locomotion in modern humans. The walking gaits of humans, other bipeds and most quadrupedal mammals can best be described by using an inverted-pendulum model, in which there is minimal change in flexion of the limb joints during stance phase. As a result, it seems logical that the evolution of bipedalism in humans involved a simple transition from a relatively stiff-legged quadrupedalism in a terrestrial ancestor to relatively stiff-legged bipedalism in early humans. However, experimental studies of locomotion in humans and nonhuman primates have shown that the evolution of bipedalism involved a much more complex series of transitions, originating with a relatively compliant form of quadrupedalism. These studies show that relatively compliant walking gaits allow primates to achieve fast walking speeds using long strides, low stride frequencies, relatively low peak vertical forces, and relatively high impact shock attenuation ratios. A relatively compliant, ape-like bipedal walking style is consistent with the anatomy of early hominids and may have been an effective gait for a small biped with relatively small and less stabilized joints, which had not yet completely forsaken arboreal locomotion. Laboratory-based studies of primates also suggest that human bipedalism arose not from a terrestrial ancestor but rather from a climbing, arboreal forerunner. Experimental data, in conjunction with anatomical data on early human ancestors, show clearly that a relatively stiff modern human gait and associated physiological and anatomical adaptations are not primitive retentions from a primate ancestor, but are instead recently acquired characters of our genus.
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Affiliation(s)
- Daniel Schmitt
- Department of Biological Anthropology and Anatomy, Duke University, Durham NC, USA.
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Gibbs S, Collard M, Wood B. Soft-tissue anatomy of the extant hominoids: a review and phylogenetic analysis. J Anat 2002; 200:3-49. [PMID: 11833653 PMCID: PMC1570881 DOI: 10.1046/j.0021-8782.2001.00001.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2001] [Indexed: 11/20/2022] Open
Abstract
This paper reports the results of a literature search for information about the soft-tissue anatomy of the extant non-human hominoid genera, Pan, Gorilla, Pongo and Hylobates, together with the results of a phylogenetic analysis of these data plus comparable data for Homo. Information on the four extant non-human hominoid genera was located for 240 out of the 1783 soft-tissue structures listed in the Nomina Anatomica. Numerically these data are biased so that information about some systems (e.g. muscles) and some regions (e.g. the forelimb) are over-represented, whereas other systems and regions (e.g. the veins and the lymphatics of the vascular system, the head region) are either under-represented or not represented at all. Screening to ensure that the data were suitable for use in a phylogenetic analysis reduced the number of eligible soft-tissue structures to 171. These data, together with comparable data for modern humans, were converted into discontinuous character states suitable for phylogenetic analysis and then used to construct a taxon-by-character matrix. This matrix was used in two tests of the hypothesis that soft-tissue characters can be relied upon to reconstruct hominoid phylogenetic relationships. In the first, parsimony analysis was used to identify cladograms requiring the smallest number of character state changes. In the second, the phylogenetic bootstrap was used to determine the confidence intervals of the most parsimonious clades. The parsimony analysis yielded a single most parsimonious cladogram that matched the molecular cladogram. Similarly the bootstrap analysis yielded clades that were compatible with the molecular cladogram; a (Homo, Pan) clade was supported by 95% of the replicates, and a (Gorilla, Pan, Homo) clade by 96%. These are the first hominoid morphological data to provide statistically significant support for the clades favoured by the molecular evidence.
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Affiliation(s)
- S Gibbs
- Department of Human Anatomy and Cell Biology, The University of Liverpool, New Medical School, UK
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Richmond FJ, Singh K, Corneil BD. Neck muscles in the rhesus monkey. I. Muscle morphometry and histochemistry. J Neurophysiol 2001; 86:1717-28. [PMID: 11600634 DOI: 10.1152/jn.2001.86.4.1717] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Morphometric methods were used to describe the musculotendinous lengths, fascicle lengths, pennation angles, and cross-sectional areas of neck muscles in adult Macaca mulatta monkeys. Additionally, muscles were frozen, sectioned, and stained for ATPase activity to determine fiber-type composition. Individual rhesus muscles were found to vary widely in their degree of similarity to feline and human muscles studied previously. Suboccipital muscles and muscles supplied by the spinal accessory nerve were most similar to human homologs, whereas most other muscles exhibited architectural specializations. Many neck muscles were architecturally complex, with multiple attachments and internal aponeuroses or tendinous inscriptions that affected the determination of their cross-sectional areas. All muscles were composed of a mixture of type I, IIa, and IIb fiber types the relative proportions of which varied. Typically, head-turning muscles had lower proportions of type II (fast) fibers than homologous feline muscles, whereas extensor muscles contained higher proportions of type II fibers. The physical and histochemical specializations described here are known to have a direct bearing on functional properties, such as force-developing capacity and fatigue-resistance. These specializations must be recognized if muscles are to be modeled accurately or studied electrophysiologically.
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Affiliation(s)
- F J Richmond
- Medical Research Council Group in Sensory-Motor Neuroscience, Queen's University, Kingston, Ontario K7L 3N6, Canada
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Abstract
Gorillas are generating renewed interest as mounting evidence from field and molecular studies strongly suggests the western lowland (Gorilla gorilla gorilla) and eastern mountain (Gorilla gorilla beringei) gorillas are considerably more distinct than has previously been accepted. Schultz (1927, 1930, 1934) was one of the earliest investigators to document morphological differences between the two groups, noting differences in pedal, limb and scapular morphology. These differences led Schultz to conclude that while lowland gorillas retained some features suited to an arboreal habitat, the mountain gorilla had evolved into a specialized terrestrial quadruped. In particular, he noted that mountain gorillas exhibited lower values for the scapular index, higher values for ratios of infraspinous fossa vs. scapula length and spine length vs. scapula length and variability in the extent of curvature of the vertebral border. However, Schultz' observations were based upon small sample sizes of mostly adult specimens. This study extends Schultz' preliminary work by assessing, with appreciably larger sample sizes, patterns of relative growth of the scapula in these two subspecies of Gorilla. Scapula measurements were obtained for ontogenetic series of G.g. gorilla (n = 366) and G. g. beringei (n = 43). Statistical analyses reveal mountain gorillas exhibit significantly (P < 0.05) greater spine lengths and scapula breadths and smaller scapula lengths than lowland gorillas of comparable superior border lengths. However, at comparable body weights, mountain gorillas exhibit significantly shorter spines and superior borders than lowland gorillas. These differences in scapula proportions are evaluated in the context of biomechanical predictions regarding scapula form and locomotion.
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Affiliation(s)
- A B Taylor
- School of Physical Therapy, Slippery Rock University, Pennsylvania 16057, USA
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Larson SG. New characters for the functional interpretation of primate scapulae and proximal humeri. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 1995; 98:13-35. [PMID: 8579188 DOI: 10.1002/ajpa.1330980103] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The study of muscle function in nonhuman primates through the technique of electromyography (EMG) has facilitated the identification of specific functional roles for muscles in particular behaviors. This has led to a more complete understanding of the biomechanics of certain regions of the musculoskeletal system, and should facilitate our ability to identify morphological features useful in the functional interpretation of fossil material. The current paper represents one such investigation of a new set of morphometric characters of the scapula and proximal humerus suggested by EMG analyses of shoulder muscle function. A set of new metric variables were examined on the scapulae and proximal humeri of 25 species of extant anthropoid primates, as well as on casts of scapulae and humeri of three fossil primate taxa. The variables are primarily related to the line of action and attachments of the rotator cuff muscles. The position of the scapular spine, the degree of lateral expansion of the subscapular fossa, the size and shape of the subscapularis insertion facet on the lesser tubercle, and the orientation of the infraspinatus insertion facet on the greater tubercle all appear to successfully sort the extant taxa into locomotor groups. Their appearance on the fossil specimens generally supports previous functional interpretations of each taxon's locomotor abilities based on a variety of other characters, suggesting that these traits are equally applicable to fossil material.
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Affiliation(s)
- S G Larson
- Department of Anatomical Science, School of Medicine, University at Stony Brook, New York 11794-8081, USA
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Wall CE, Larson SG, Stern JT. EMG of the digastric muscle in gibbon and orangutan: functional consequences of the loss of the anterior digastric in orangutans. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 1994; 94:549-67. [PMID: 7977679 DOI: 10.1002/ajpa.1330940408] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Unlike all other primates, the digastric muscle of the orangutan lacks an anterior belly; the posterior belly, while present, inserts directly onto the mandible. To understand the functional consequences of this morphologic novelty, the EMG activity patterns of the digastric muscle and other potential mandibular depressors were studied in a gibbon and an orangutan. The results suggest a significant degree of functional differentiation between the two digastric bellies. In the gibbon, the recruitment pattern of the posterior digastric during mastication is typically biphasic. It is an important mandibular depressor, active in this role during mastication and wide opening. It also acts with the anterior suprahyoid muscles to move the hyoid prior to jaw opening during mastication. The recruitment patterns of the anterior digastric suggest that it is functionally allied to the geniohyoid and mylohyoid. For example, although it transmits the force of the posterior digastric during mandibular depression, it functions independent of the posterior digastric during swallowing. Of the muscles studied, the posterior digastric was the only muscle to exhibit major differences in recruitment pattern between the two species. The posterior digastric retains its function as a mandibular depressor in orangutans, but is never recruited biphasically, and is not active prior to opening. The unique anatomy of the digastric muscle in orangutans results in decoupling of the mechanisms for hyoid movement and mandibular depression, and during unilateral activity it potentially contributes to substantial transverse movements of the mandible. Hypotheses to explain the loss of the anterior digastric should incorporate these functional conclusions.
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Affiliation(s)
- C E Wall
- Doctoral Program in Anthropological Sciences, State University of New York, Stony Brook 11794
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Schmitt D, Larson SG, Stern JT. Serratus ventralis function in vervet monkeys(Cercopithecus aethiops):are primate quadrupeds unique? J Zool (1987) 1994. [DOI: 10.1111/j.1469-7998.1994.tb01570.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hunt KD. Mechanical implications of chimpanzee positional behavior. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 1991; 86:521-36. [PMID: 1776659 DOI: 10.1002/ajpa.1330860408] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Mechanical hypotheses concerning the function of chimpanzee anatomical specializations are examined in light of recent positional behavior data. Arm-hanging was the only common chimpanzee positional behavior that required full abduction of the humerus, and vertical climbing was the only distinctive chimpanzee positional behavior that required forceful retraction of the humerus and flexion of the elbow. Some elements of the chimpanzee anatomy, including an abductible humerus, a broad thorax, a cone-shaped torso, and a long, narrow scapula, are hypothesized to be a coadapted functional complex that reduces muscle action and structural fatigue during arm-hanging. Large muscles that retract the humerus (latissimus dorsi and probably sternocostal pectoralis major and posterior deltoid) and flex the elbow (biceps brachii, probably brachialis and brachioradialis) are argued to be adaptations to vertical climbing alone. A large ulnar excursion of the manus and long, curved metacarpals and phalanges are interpreted as adaptations to gripping vertical weight-bearing structures during vertical climbing and arm-hanging. A short torso, an iliac origin of the latissimus dorsi, and large muscles for arm-raising (caudal serratus, teres minor, cranial trapezius, and probably anterior deltoid and clavicular pectoralis major) are interpreted as adaptations to both climbing and unimanual suspension.
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Affiliation(s)
- K D Hunt
- Department of Anthropology, Indiana University, Bloomington 47405
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