1
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Lee ECS, Young NM, Rainbow MJ. A comparative approach for characterizing the relationship among morphology, range-of-motion and locomotor behaviour in the primate shoulder. Proc Biol Sci 2023; 290:20231446. [PMID: 37848066 PMCID: PMC10581761 DOI: 10.1098/rspb.2023.1446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 09/08/2023] [Indexed: 10/19/2023] Open
Abstract
Shoulder shape directly impacts forelimb function by contributing to glenohumeral (GH) range-of-motion (ROM). However, identifying traits that contribute most to ROM and visualizing how they do so remains challenging, ultimately limiting our ability to reconstruct function and behaviour in fossil species. To address these limitations, we developed an in silico proximity-driven model to simulate and visualize three-dimensional (3D) GH rotations in living primate species with diverse locomotor profiles, identify those shapes that are most predictive of ROM using geometric morphometrics, and apply subsequent insights to interpret function and behaviour in the fossil hominin Australopithecus sediba. We found that ROM metrics that incorporated 3D rotations best discriminated locomotor groups, and the magnitude of ROM (mobility) was decoupled from the anatomical location of ROM (e.g. high abduction versus low abduction). Morphological traits that enhanced mobility were decoupled from those that enabled overhead positions, and all non-human apes possessed the latter but not necessarily the former. Model simulation in A. sediba predicted high mobility and a ROM centred at lower abduction levels than in living apes but higher than in modern humans. Together these results identify novel form-to-function relationships in the shoulder and enhance visualization tools to reconstruct past function and behaviour.
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Affiliation(s)
- Erin C. S. Lee
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada K7L 2V9
| | - Nathan M. Young
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94110, USA
| | - Michael J. Rainbow
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada K7L 2V9
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2
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Meyer MR, Jung JP, Spear JK, Araiza IF, Galway-Witham J, Williams SA. Knuckle-walking in Sahelanthropus? Locomotor inferences from the ulnae of fossil hominins and other hominoids. J Hum Evol 2023; 179:103355. [PMID: 37003245 DOI: 10.1016/j.jhevol.2023.103355] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 03/03/2023] [Accepted: 03/03/2023] [Indexed: 04/03/2023]
Abstract
Because the ulna supports and transmits forces during movement, its morphology can signal aspects of functional adaptation. To test whether, like extant apes, some hominins habitually recruit the forelimb in locomotion, we separate the ulna shaft and ulna proximal complex for independent shape analyses via elliptical Fourier methods to identify functional signals. We examine the relative influence of locomotion, taxonomy, and body mass on ulna contours in Homo sapiens (n = 22), five species of extant apes (n = 33), two Miocene apes (Hispanopithecus and Danuvius), and 17 fossil hominin specimens including Sahelanthropus, Ardipithecus, Australopithecus, Paranthropus, and early Homo. Ulna proximal complex contours correlate with body mass but not locomotor patterns, while ulna shafts significantly correlate with locomotion. African apes' ulna shafts are more robust and curved than Asian apes and are unlike other terrestrial mammals (including other primates), curving ventrally rather than dorsally. Because this distinctive curvature is absent in orangutans and hylobatids, it is likely a function of powerful flexors engaged in wrist and hand stabilization during knuckle-walking, and not an adaptation to climbing or suspensory behavior. The OH 36 (purported Paranthropus boisei) and TM 266 (assigned to Sahelanthropus tchadensis) fossils differ from other hominins by falling within the knuckle-walking morphospace, and thus appear to show forelimb morphology consistent with terrestrial locomotion. Discriminant function analysis classifies both OH 36 and TM 266 with Pan and Gorilla with high posterior probability. Along with its associated femur, the TM 266 ulna shaft contours and its deep, keeled trochlear notch comprise a suite of traits signaling African ape-like quadrupedalism. While implications for the phylogenetic position and hominin status of S. tchadensis remain equivocal, this study supports the growing body of evidence indicating that S. tchadensis was not an obligate biped, but instead represents a late Miocene hominid with knuckle-walking adaptations.
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Affiliation(s)
- Marc R Meyer
- Department of Anthropology, Chaffey College, Rancho Cucamonga, CA 91737, USA.
| | - Jason P Jung
- Department of Biology, California State University, San Bernardino, CA 92407, USA
| | - Jeffrey K Spear
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY 10024, USA
| | - Isabella Fx Araiza
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY 10024, USA
| | - Julia Galway-Witham
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY 10024, USA
| | - Scott A Williams
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY 10024, USA
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3
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Cazenave M, Kivell TL. Challenges and perspectives on functional interpretations of australopith postcrania and the reconstruction of hominin locomotion. J Hum Evol 2023; 175:103304. [PMID: 36563461 DOI: 10.1016/j.jhevol.2022.103304] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 12/24/2022]
Abstract
In 1994, Hunt published the 'postural feeding hypothesis'-a seminal paper on the origins of hominin bipedalism-founded on the detailed study of chimpanzee positional behavior and the functional inferences derived from the upper and lower limb morphology of the Australopithecus afarensis A.L. 288-1 partial skeleton. Hunt proposed a model for understanding the potential selective pressures on hominins, made robust, testable predictions based on Au. afarensis functional morphology, and presented a hypothesis that aimed to explain the dual functional signals of the Au. afarensis and, more generally, early hominin postcranium. Here we synthesize what we have learned about Au. afarensis functional morphology and the dual functional signals of two new australopith discoveries with relatively complete skeletons (Australopithecus sediba and StW 573 'Australopithecus prometheus'). We follow this with a discussion of three research approaches that have been developed for the purpose of drawing behavioral inferences in early hominins: (1) developments in the study of extant apes as models for understanding hominin origins; (2) novel and continued developments to quantify bipedal gait and locomotor economy in extant primates to infer the locomotor costs from the anatomy of fossil taxa; and (3) novel developments in the study of internal bone structure to extract functional signals from fossil remains. In conclusion of this review, we discuss some of the inherent challenges of the approaches and methodologies adopted to reconstruct the locomotor modes and behavioral repertoires in extinct primate taxa, and notably the assessment of habitual terrestrial bipedalism in early hominins.
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Affiliation(s)
- Marine Cazenave
- Division of Anthropology, American Museum of Natural History, New York, USA; Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK; Department of Anatomy, Faculty of Health Sciences, University of Pretoria, South Africa.
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK; Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
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4
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de Diego M, Casado A, Gómez M, Ciurana N, Rodríguez P, Avià Y, Cuesta-Torralvo E, García N, San José I, Barbosa M, de Paz F, Pastor JF, Potau JM. Elbow Extensor Muscles in Humans and Chimpanzees: Adaptations to Different Uses of the Upper Extremity in Hominoid Primates. Animals (Basel) 2022; 12:ani12212987. [PMID: 36359111 PMCID: PMC9655010 DOI: 10.3390/ani12212987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 11/29/2022] Open
Abstract
Simple Summary Chimpanzees and humans are both species of hominoid primates that are closely related phylogenetically. One of the key differences between these two species is their use of their upper extremities. Humans use this limb mainly in manipulative tasks, while chimpanzees also use it during locomotion. In this study, we have analyzed the muscle architecture and the expression of the myosin heavy chain isoforms in the two elbow extensor muscles, the triceps brachii and the anconeus, in humans and chimpanzees, in order to find differences that could be related to the different uses of the upper extremities in these species. We have found that the triceps brachii of chimpanzees is more prepared for strength and power as an adaptation to locomotion, while the same muscle in humans is more prepared for speed and resistance to fatigue as an adaptation to manipulative activities. Our results increase the knowledge we have of the musculoskeletal system of chimpanzees and can be applied in various fields, such as comparative anatomy, evolutionary anatomy or anthropology. Abstract The anatomical and functional characteristics of the elbow extensor muscles (triceps brachii and anconeus) have not been widely studied in non-human hominoid primates, despite their great functional importance. In the present study, we have analyzed the muscle architecture and the expression of the myosin heavy chain (MHC) isoforms in the elbow extensors in humans and chimpanzees. Our main objective was to identify differences in these muscles that could be related to the different uses of the upper extremity in the two species. In five humans and five chimpanzees, we have analyzed muscle mass (MM), muscle fascicle length (MFL), and the physiological cross-sectional area (PCSA). In addition, we have assessed the expression of the MHC isoforms by RT-PCR. We have found high MM and PCSA values and higher expression of the MHC-IIx isoform in the triceps brachii of chimpanzees, while in humans, the triceps brachii has high MFL values and a higher expression of the MHC-I and MHC-IIa isoforms. In contrast, there were no significant differences between humans and chimpanzees in any of the values for the anconeus. These findings could be related to the participation of the triceps brachii in the locomotion of chimpanzees and to the use of the upper extremity in manipulative functions in humans. The results obtained in the anconeus support its primary function as a stabilizer of the elbow joint in the two species.
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Affiliation(s)
- Marina de Diego
- Unit of Human Anatomy and Embryology, University of Barcelona, 08036 Barcelona, Spain
| | - Aroa Casado
- Unit of Human Anatomy and Embryology, University of Barcelona, 08036 Barcelona, Spain
- Institut d’Arqueologia de la Universitat de Barcelona (IAUB), Faculty of Geography and History, University of Barcelona (UB), 08001 Barcelona, Spain
| | - Mónica Gómez
- Unit of Human Anatomy and Embryology, University of Barcelona, 08036 Barcelona, Spain
| | - Neus Ciurana
- Unit of Human Anatomy and Embryology, University of Barcelona, 08036 Barcelona, Spain
| | - Patrícia Rodríguez
- Unit of Human Anatomy and Embryology, University of Barcelona, 08036 Barcelona, Spain
| | - Yasmina Avià
- Institut d’Arqueologia de la Universitat de Barcelona (IAUB), Faculty of Geography and History, University of Barcelona (UB), 08001 Barcelona, Spain
- Biological Anthropology Unit, Department of Animal Biology, Autonomous University of Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Elisabeth Cuesta-Torralvo
- Institut d’Arqueologia de la Universitat de Barcelona (IAUB), Faculty of Geography and History, University of Barcelona (UB), 08001 Barcelona, Spain
- Biological Anthropology Unit, Department of Animal Biology, Autonomous University of Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Natividad García
- Department of Anatomy and Radiology, University of Valladolid, 47005 Valladolid, Spain
| | - Isabel San José
- Department of Anatomy and Radiology, University of Valladolid, 47005 Valladolid, Spain
| | - Mercedes Barbosa
- Department of Anatomy and Radiology, University of Valladolid, 47005 Valladolid, Spain
| | - Félix de Paz
- Department of Anatomy and Radiology, University of Valladolid, 47005 Valladolid, Spain
| | - Juan Francisco Pastor
- Department of Anatomy and Radiology, University of Valladolid, 47005 Valladolid, Spain
| | - Josep Maria Potau
- Unit of Human Anatomy and Embryology, University of Barcelona, 08036 Barcelona, Spain
- Institut d’Arqueologia de la Universitat de Barcelona (IAUB), Faculty of Geography and History, University of Barcelona (UB), 08001 Barcelona, Spain
- Correspondence: ; Tel.: +34-9-3402-1906
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5
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Marchi D, Rimoldi A, García‐Martínez D, Bastir M. Morphological correlates of distal fibular morphology with locomotion in great apes, humans, and Australopithecus afarensis. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 178:286-300. [PMID: 36790753 PMCID: PMC9314891 DOI: 10.1002/ajpa.24507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/15/2022] [Accepted: 02/22/2022] [Indexed: 01/27/2023]
Abstract
OBJECTIVES Recent studies highlighted the importance of the fibula to further our understanding of locomotor adaptations in fossil hominins. In this study, we present a three-dimensional geometric morphometric (3D-GM) investigation of the distal fibula in extant hominids and Australopithecus afarensis with the aim of pointing out morphological correlations to arboreal behavior. METHODS Three-dimensional surface meshes of the distal fibula were obtained using computer tomography for 40 extant hominid specimens and laser scanner for five A. afarensis specimens. Distal fibula morphology was quantified positioning 11 fixed landmarks, 40 curve semilandmarks, and 20 surface landmarks on each specimen. A generalized Procrustes analysis (GPA) was carried out on all landmark coordinates followed by Procrustes ANOVA. Principal component analysis (PCA) was performed on the GPA-aligned shape coordinates. Kruskal-Wallis tests and Mann-Whitney test were performed on scores along PCs. RESULTS Great apes are characterized by a shorter subcutaneous triangular surface (STS), more downward facing fibulotalar articular facets, more anteriorly facing lateral malleolus and wider/deeper malleolar fossa than humans. Within great apes, orangutans are characterized by more medially facing fibulotalar articular facets. Australopithecus afarensis shows a unique distal fibular morphology with several traits that are generally associated more to arboreality and less to bipedalism such as a short STS, a more anteriorly facing, laterally pointing malleolus and deeper and larger malleolar fossa. CONCLUSIONS The distal fibula morphology is indicative of locomotor patterns within extant hominids. The 3D-GM method presented here can be successfully used to further our understanding of arboreal adaptations in fossil hominins.
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Affiliation(s)
- Damiano Marchi
- Department of BiologyUniversity of PisaPisa,Centre for the Exploration of the Deep Human JourneyUniversity of the WitwatersrandWits
| | | | - Daniel García‐Martínez
- Centre for the Exploration of the Deep Human JourneyUniversity of the WitwatersrandWits,Centro Nacional de Investigación sobre la Evolución Humana (CENIEH)BurgosSpain,Paleoanthropology GroupMuseo Nacional de Ciencias Naturales (MNCN‐CSIC)MadridSpain
| | - Markus Bastir
- Centre for the Exploration of the Deep Human JourneyUniversity of the WitwatersrandWits,Paleoanthropology GroupMuseo Nacional de Ciencias Naturales (MNCN‐CSIC)MadridSpain
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6
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Williams SA, Prang TC, Meyer MR, Nalley TK, Van Der Merwe R, Yelverton C, García-Martínez D, Russo GA, Ostrofsky KR, Spear J, Eyre J, Grabowski M, Nalla S, Bastir M, Schmid P, Churchill SE, Berger LR. New fossils of Australopithecus sediba reveal a nearly complete lower back. eLife 2021; 10:70447. [PMID: 34812141 PMCID: PMC8610421 DOI: 10.7554/elife.70447] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 10/19/2021] [Indexed: 01/16/2023] Open
Abstract
Adaptations of the lower back to bipedalism are frequently discussed but infrequently demonstrated in early fossil hominins. 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. 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’). 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. 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. Additionally, it bears long, cranially and ventrally oriented costal (transverse) processes, implying powerful trunk musculature. We interpret this combination of features to indicate that A. 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. sediba. One of the defining features of humans is our ability to walk comfortably on two legs. To achieve this, our skeletons have evolved certain physical characteristics. 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. 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. Australopithecus sediba was a close-relative of modern humans that lived about two million years ago. In 2008, fossils from an adult female were discovered at a cave site in South Africa called Malapa. However, the fossils of the lower back region were incomplete, so it was unclear whether the female – referred to as Malapa Hominin 2 (MH2) – had a forward-curving spine and other adaptations needed to walk on two legs. Here, Williams et al. report the discovery of new A. sediba fossils from Malapa. The new fossils are mainly bones from the lower back, and they fit together with the previously discovered MH2 fossils, providing a nearly complete lower spine. Analysis of the fossils suggested that MH2 would have had an upright posture and comfortably walked on two legs, and the curvature of their lower back was similar to modern females. However, other aspects of the bones’ shape suggest that as well as walking, A. sediba probably spent a significant amount of time climbing in trees. The findings of Williams et al. provide new insights in to our evolutionary history, and ultimately, our place in the natural world around us. Our lower back is prone to injury and pain associated with posture, pregnancy and exercise (or lack thereof). Therefore, understanding how the lower back evolved may help us to learn how to prevent injuries and maintain a healthy back.
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Affiliation(s)
- Scott A Williams
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, United States.,New York Consortium in Evolutionary Primatology, New York, United States.,Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Thomas Cody Prang
- Department of Anthropology, Texas A&M University, College Station, United States
| | - Marc R Meyer
- Department of Anthropology, Chaffey College, Rancho Cucamonga, United States
| | - Thierra K Nalley
- Western University of Health Sciences, College of Osteopathic Medicine of the Pacific, Department of Medical Anatomical Sciences, Pomona, United States
| | - Renier Van Der Merwe
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
| | - Christopher Yelverton
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Chiropractic, Faculty of Health Sciences, University of Johannesburg, Johannesburg, South Africa
| | - Daniel García-Martínez
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa.,Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain.,Departamento de Biodiversidad, Ecología y Evolución, Universidad Complutense de Madrid (UCM), Madrid, Spain
| | - Gabrielle A Russo
- Department of Anthropology, Stony Brook University, Stony Brook, United States
| | - Kelly R Ostrofsky
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, United States
| | - Jeffrey Spear
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, United States.,New York Consortium in Evolutionary Primatology, New York, United States
| | - Jennifer Eyre
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, United States.,Department of Anthropology, Bryn Mawr College, Bryn Mawr, United States
| | - Mark Grabowski
- Research Centre in Evolutionary Anthropology and Palaeoecology, Liverpool John Moores University, Liverpool, United Kingdom
| | - Shahed Nalla
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa.,Department of Human Anatomy and Physiology, Faculty of Health Sciences, University of Johannesburg, Johannesburg, South Africa
| | - Markus Bastir
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa.,Departamento de Paleobiología, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain
| | - Peter Schmid
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa.,Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland
| | - Steven E Churchill
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa.,Department of Evolutionary Anthropology, Duke University, Durham, United States
| | - Lee R Berger
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
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7
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Harper CM, Ruff CB, Sylvester AD. Calcaneal shape variation in humans, nonhuman primates, and early hominins. J Hum Evol 2021; 159:103050. [PMID: 34438297 DOI: 10.1016/j.jhevol.2021.103050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 06/29/2021] [Accepted: 06/29/2021] [Indexed: 01/08/2023]
Abstract
The foot has played a prominent role in evaluating early hominin locomotion. The calcaneus, in particular, plays an important role in weight-bearing. Although the calcanei of early hominins have been previously scrutinized, a three-dimensional analysis of the entire calcaneal shape has not been conducted. Here, we investigate the relationship between external calcaneal shape and locomotion in modern Homo sapiens (n = 130), Gorilla (n = 86), Pan (n = 112), Pongo (n = 31), Papio (n = 28), and hylobatids (Hylobates, Symphalangus; n = 32). We use these results to place the calcanei attributed to Australopithecus sediba, A. africanus, A. afarensis, H. naledi, and Homo habilis/Paranthropus boisei into a locomotor context. Calcanei were scanned using either surface scanning or micro-CT and their external shape analyzed using a three-dimensional geometric morphometric sliding semilandmark analysis. Blomberg's K statistic was used to estimate phylogenetic signal in the shape data. Shape variation was summarized using a principal components analysis. Procrustes distances between all taxa as well as distances between each fossil and the average of each taxon were calculated. Blomberg's K statistic was small (K = 0.1651), indicating weak phylogenetic effects, suggesting variation is driven by factors other than phylogeny (e.g., locomotion or body size). Modern humans have a large calcaneus relative to body size and display a uniquely convex cuboid facet, facilitating a rigid midfoot for bipedalism. More arboreal great apes display relatively deeper cuboid facet pivot regions for increased midfoot mobility. Australopithecus afarensis demonstrates the most human-like calcaneus, consistent with obligate bipedalism. Homo naledi is primarily modern human-like, but with some intermediate traits, suggesting a different form of bipedalism than modern humans. Australopithecus africanus, A. sediba, and H. habilis/P. boisei calcanei all possess unique combinations of human and nonhuman ape-like morphologies, suggesting a combination of bipedal and arboreal behaviors.
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Affiliation(s)
- Christine M Harper
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States; Cooper Medical School of Rowan University, Department of Biomedical Sciences, 401 S Broadway, Room 453, Camden, NJ 08103, United States.
| | - Christopher B Ruff
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States
| | - Adam D Sylvester
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States
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8
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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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9
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Cazenave M, Oettlé A, Pickering TR, Heaton JL, Nakatsukasa M, Francis Thackeray J, Hoffman J, Macchiarelli R. Trabecular organization of the proximal femur in Paranthropus robustus: Implications for the assessment of its hip joint loading conditions. J Hum Evol 2021; 153:102964. [PMID: 33713985 DOI: 10.1016/j.jhevol.2021.102964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 11/19/2022]
Abstract
Reconstruction of the locomotor repertoire of the australopiths (Australopithecus and Paranthropus) has progressively integrated information from the mechanosensitive internal structure of the appendicular skeleton. Recent investigations showed that the arrangement of the trabecular network at the femoral head center is biomechanically compatible with the pattern of cortical bone distribution across the neck, both suggesting a full commitment to bipedalism in australopiths, but associated with a slightly altered gait kinematics compared to Homo involving more lateral deviation of the body center of mass over the stance limb. To provide a global picture in Paranthropus robustus of the trabecular architecture of the proximal femur across the head, neck and greater trochanter compartments, we applied techniques of virtual imaging to the variably preserved Early Pleistocene specimens SK 82, SK 97, SK 3121, SKW 19 and SWT1/LB-2 from the cave site of Swartkrans, South Africa. We also assessed the coherence between the structural signals from the center of the head and those from the trabecular network of the inferolateral portion of the head and the inferior margin of the neck, sampling the so-called vertical bundle, which in humans represents the principal compressive system of the joint. Our analyses show a functionally related trabecular organization in Pa. robustus that closely resembles the extant human condition, but which also includes some specificities in local textural arrangement. The network of the inferolateral portion of the head shows a humanlike degree of anisotropy and a bone volume fraction intermediate between the extant human and the African ape patterns. These results suggest slight differences in gait kinematics between Pa. robustus and extant humans. The neck portion of the vertical bundle revealed a less biomechanically sensitive signal. Future investigations on the australopith hip joint loading environment should more carefully investigate the trabecular structure of the trochanteric region and possible structural covariation between cortical bone distribution across the neck and site-specific trabecular properties of the arcuate bundle.
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Affiliation(s)
- Marine Cazenave
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.
| | - Anna Oettlé
- Department of Anatomy and Histology, Sefako Makgatho Health Sciences University, Ga-Rankuwa, Pretoria, South Africa
| | - Travis Rayne Pickering
- Department of Anthropology, University of Wisconsin, Madison, USA; Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa; Plio-Pleistocene Palaeontology Section, Department of Vertebrates, Ditsong National Museum of Natural History (Transvaal Museum), Pretoria, South Africa
| | - Jason L Heaton
- Department of Biology, Birmingham-Southern College, Birmingham, USA; Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa; Plio-Pleistocene Palaeontology Section, Department of Vertebrates, Ditsong National Museum of Natural History (Transvaal Museum), Pretoria, South Africa
| | - Masato Nakatsukasa
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - J Francis Thackeray
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Jakobus Hoffman
- South African Nuclear Energy Corporation SOC Ltd., Pelindaba, South Africa
| | - Roberto Macchiarelli
- Département Homme & Environnement, UMR 7194 CNRS, Muséum national d'Histoire naturelle, 75116, Paris, France; Unité de Formation Géosciences, Université de Poitiers, Poitiers, France
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10
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11
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Rein TR. Comparative analysis of femoral biomechanical neck length in primates. Anat Rec (Hoboken) 2020; 303:2330-2343. [PMID: 31961484 DOI: 10.1002/ar.24377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 12/02/2019] [Accepted: 12/10/2019] [Indexed: 11/10/2022]
Abstract
The unique abductor capability of the human lesser gluteal muscles among extant hominoids has been suggested to be associated, in part, with biomechanical neck length of the femur. Beyond the hominin lineage, the relationship between biomechanical neck length and locomotor performance remains unclear due, in part, to the limited number of primate taxa directly compared and the need to examine species characterized by a wider range of locomotor diversity. Measurements were taken on the proximal femora of 28 extant taxa, with each species being assigned to a locomotor and phylogenetic category. Pairwise comparisons and phylogenetic generalized least-squares analysis were performed to examine the impact of phylogeny and locomotor adaptation on relative biomechanical neck length. Arboreal quadrupeds that perform varying proportions of climbing/clambering versus leaping were characterized by different biomechanical neck lengths, whereas semi-terrestrial anthropoids that perform either knuckle-walking or palmigrade/digitigrade quadrupedalism were found to have similar relative neck lengths. Samples categorized as either orthograde clamberers or bipeds were distinct from all other anthropoid samples and characterized by the relatively shortest and longest biomechanical neck lengths, respectively. Results of additional analyses that included prosimian primates suggest that relatively long biomechanical necks characterize species adapted to hind limb-dominated forms of locomotion (e.g., vertical clinging and leaping and bipedalism). Thus, biomechanical neck length is useful for signaling reliance on bipedalism (as performed by humans) or leaping, including subtle variation in leaping performance among arboreal quadrupeds. Furthermore, this trait is informative regarding reliance on irregular gait clambering as performed by orangutans.
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Affiliation(s)
- Thomas R Rein
- Department of Anthropology, Central Connecticut State University, New Britain, Connecticut
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12
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Heaton JL, Pickering TR, Carlson KJ, Crompton RH, Jashashvili T, Beaudet A, Bruxelles L, Kuman K, Heile AJ, Stratford D, Clarke RJ. The long limb bones of the StW 573 Australopithecus skeleton from Sterkfontein Member 2: Descriptions and proportions. J Hum Evol 2019; 133:167-197. [DOI: 10.1016/j.jhevol.2019.05.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 05/30/2019] [Accepted: 05/31/2019] [Indexed: 02/07/2023]
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13
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Three-dimensional geometric morphometric analysis of the first metacarpal distal articular surface in humans, great apes and fossil hominins. J Hum Evol 2019; 132:119-136. [DOI: 10.1016/j.jhevol.2019.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/23/2019] [Accepted: 04/23/2019] [Indexed: 11/18/2022]
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14
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Arias‐Martorell J. The morphology and evolutionary history of the glenohumeral joint of hominoids: A review. Ecol Evol 2019; 9:703-722. [PMID: 30680150 PMCID: PMC6342098 DOI: 10.1002/ece3.4392] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 06/11/2018] [Accepted: 06/18/2018] [Indexed: 11/10/2022] Open
Abstract
The glenohumeral joint, the most mobile joint in the body of hominoids, is involved in the locomotion of all extant primates apart from humans. Over the last few decades, our knowledge of how variation in its morphological characteristics relates to different locomotor behaviors within extant primates has greatly improved, including features of the proximal humerus and the glenoid cavity of the scapula, as well as the muscles that function to move the joint (the rotator cuff muscles). The glenohumeral joint is a region with a strong morphofunctional signal, and hence, its study can shed light on the locomotor behaviors of crucial ancestral nodes in the evolutionary history of hominoids (e.g., the last common ancestor between humans and chimpanzees). Hominoids, in particular, are distinct in showing round and relatively big proximal humeri with lowered tubercles and flattened and oval glenoid cavities, morphology suited to engage in a wide range of motions, which enables the use of locomotor behaviors such as suspension. The comparison with extant taxa has enabled more informed functional interpretations of morphology in extinct primates, including hominoids, from the Early Miocene through to the emergence of hominins. Here, I review our current understanding of glenohumeral joint functional morphology and its evolution throughout the Miocene and Pleistocene, as well as highlighting the areas where a deeper study of this joint is still needed.
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Affiliation(s)
- Julia Arias‐Martorell
- Animal Postcranial Evolution LabSkeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
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15
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DeSilva J, McNutt E, Benoit J, Zipfel B. One small step: A review of Plio‐Pleistocene hominin foot evolution. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 168 Suppl 67:63-140. [DOI: 10.1002/ajpa.23750] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/01/2018] [Accepted: 10/05/2018] [Indexed: 01/03/2023]
Affiliation(s)
- Jeremy DeSilva
- Department of AnthropologyDartmouth College Hanover New Hampshire
- Evolutionary Studies Institute and School of GeosciencesUniversity of the Witwatersrand Johannesburg South Africa
| | - Ellison McNutt
- Department of AnthropologyDartmouth College Hanover New Hampshire
| | - Julien Benoit
- Evolutionary Studies Institute and School of GeosciencesUniversity of the Witwatersrand Johannesburg South Africa
| | - Bernhard Zipfel
- Evolutionary Studies Institute and School of GeosciencesUniversity of the Witwatersrand Johannesburg South Africa
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16
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Chirchir H. Trabecular Bone Fraction Variation in Modern Humans, Fossil Hominins and Other Primates. Anat Rec (Hoboken) 2018; 302:288-305. [DOI: 10.1002/ar.23967] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 06/04/2018] [Accepted: 06/25/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Habiba Chirchir
- Department of Biological SciencesMarshall University Huntington West Virginia
- Human Origins ProgramNational Museum of Natural History, Smithsonian Institution Washington, D.C
- Department of AnthropologyNew York University New York New York
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17
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Rein TR. A Geometric Morphometric Examination of Hominoid Third Metacarpal Shape and Its Implications for Inferring the Precursor to Terrestrial Bipedalism. Anat Rec (Hoboken) 2018; 302:983-998. [DOI: 10.1002/ar.23985] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 06/07/2018] [Accepted: 06/14/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Thomas R. Rein
- Department of Anthropology Central Connecticut State University New Britain Connecticut
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18
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Ryan TM, Carlson KJ, Gordon AD, Jablonski N, Shaw CN, Stock JT. Human-like hip joint loading in Australopithecus africanus and Paranthropus robustus. J Hum Evol 2018; 121:12-24. [DOI: 10.1016/j.jhevol.2018.03.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 03/22/2018] [Accepted: 03/23/2018] [Indexed: 02/02/2023]
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19
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Boyle EK, McNutt EJ, Sasaki T, Suwa G, Zipfel B, DeSilva JM. A quantification of calcaneal lateral plantar process position with implications for bipedal locomotion in Australopithecus. J Hum Evol 2018; 123:24-34. [PMID: 30075872 DOI: 10.1016/j.jhevol.2018.05.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 05/23/2018] [Accepted: 05/24/2018] [Indexed: 11/25/2022]
Abstract
The evolution of bipedalism in the hominin lineage has shaped the posterior human calcaneus into a large, robust structure considered to be adaptive for dissipating peak compressive forces and energy during heel-strike. A unique anatomy thought to contribute to the human calcaneus and its function is the lateral plantar process (LPP). While it has long been known that humans possess a plantarly positioned LPP and apes possess a more dorsally positioned homologous structure, the relative position of the LPP and intraspecific variation of this structure have never been quantified. Here, we present a method for quantifying relative LPP position and find that, while variable, humans have a significantly more plantar position of the LPP than that found in the apes. Among extinct hominins, while the position of the LPP in Australopithecus afarensis falls within the human distribution, the LPP is more dorsally positioned in Australopithecus sediba and barely within the modern human range of variation. Results from a resampling procedure suggest that these differences can reflect either individual variation of a foot structure/function largely shared among Australopithecus species, or functionally distinct morphologies that reflect locomotor diversity in Plio-Pleistocene hominins. An implication of the latter possibility is that calcaneal changes adaptive for heel-striking bipedalism may have evolved independently in two different hominin lineages.
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Affiliation(s)
- Eve K Boyle
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, 800 22nd St. NW, Suite 6000, Washington, DC 20052, USA.
| | - Ellison J McNutt
- Department of Anthropology, Dartmouth College, Hanover, NH 03755, USA; Ecology, Evolution, Ecosystems, and Society, Dartmouth College, Hanover, NH 03755, USA
| | - Tomohiko Sasaki
- The University Museum, The University of Tokyo, Tokyo, Japan
| | - Gen Suwa
- The University Museum, The University of Tokyo, Tokyo, Japan
| | - Bernhard Zipfel
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa; School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Jeremy M DeSilva
- Department of Anthropology, Dartmouth College, Hanover, NH 03755, USA; Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
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20
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Caley T, Extier T, Collins JA, Schefuß E, Dupont L, Malaizé B, Rossignol L, Souron A, McClymont EL, Jimenez-Espejo FJ, García-Comas C, Eynaud F, Martinez P, Roche DM, Jorry SJ, Charlier K, Wary M, Gourves PY, Billy I, Giraudeau J. A two-million-year-long hydroclimatic context for hominin evolution in southeastern Africa. Nature 2018; 560:76-79. [PMID: 29988081 DOI: 10.1038/s41586-018-0309-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 04/25/2018] [Indexed: 12/21/2022]
Abstract
The past two million years of eastern African climate variability is currently poorly constrained, despite interest in understanding its assumed role in early human evolution1-4. Rare palaeoclimate records from northeastern Africa suggest progressively drier conditions2,5 or a stable hydroclimate6. By contrast, records from Lake Malawi in tropical southeastern Africa reveal a trend of a progressively wetter climate over the past 1.3 million years7,8. The climatic forcings that controlled these past hydrological changes are also a matter of debate. Some studies suggest a dominant local insolation forcing on hydrological changes9-11, whereas others infer a potential influence of sea surface temperature changes in the Indian Ocean8,12,13. Here we show that the hydroclimate in southeastern Africa (20-25° S) is controlled by interplay between low-latitude insolation forcing (precession and eccentricity) and changes in ice volume at high latitudes. Our results are based on a multiple-proxy reconstruction of hydrological changes in the Limpopo River catchment, combined with a reconstruction of sea surface temperature in the southwestern Indian Ocean for the past 2.14 million years. We find a long-term aridification in the Limpopo catchment between around 1 and 0.6 million years ago, opposite to the hydroclimatic evolution suggested by records from Lake Malawi. Our results, together with evidence of wetting at Lake Malawi, imply that the rainbelt contracted toward the Equator in response to increased ice volume at high latitudes. By reducing the extent of woodland or wetlands in terrestrial ecosystems, the observed changes in the hydroclimate of southeastern Africa-both in terms of its long-term state and marked precessional variability-could have had a role in the evolution of early hominins, particularly in the extinction of Paranthropus robustus.
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Affiliation(s)
- Thibaut Caley
- EPOC, UMR 5805, CNRS, University of Bordeaux, Pessac, France.
| | - Thomas Extier
- EPOC, UMR 5805, CNRS, University of Bordeaux, Pessac, France.,Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
| | - James A Collins
- GFZ - German Research Center for Geosciences, Section 5.1 Geomorphology, Organic Surface Geochemistry Laboratory, Potsdam, Germany.,Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Enno Schefuß
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Lydie Dupont
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Bruno Malaizé
- EPOC, UMR 5805, CNRS, University of Bordeaux, Pessac, France
| | - Linda Rossignol
- EPOC, UMR 5805, CNRS, University of Bordeaux, Pessac, France
| | - Antoine Souron
- PACEA, UMR 5199, CNRS, University of Bordeaux, Pessac, France
| | | | | | - Carmen García-Comas
- Research and Development Center for Global Change, (JAMSTEC), Yokohama, Japan.,Ecology Group, University of Vic - Central University of Catalonia, Barcelona, Spain
| | | | | | - Didier M Roche
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France.,Vrije Universiteit Amsterdam, Faculty of Science, Cluster Earth and Climate, Amsterdam, The Netherlands
| | - Stephan J Jorry
- Unité Géosciences Marines, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Plouzané, France
| | - Karine Charlier
- EPOC, UMR 5805, CNRS, University of Bordeaux, Pessac, France
| | - Mélanie Wary
- EPOC, UMR 5805, CNRS, University of Bordeaux, Pessac, France
| | | | - Isabelle Billy
- EPOC, UMR 5805, CNRS, University of Bordeaux, Pessac, France
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Meyer MR, Woodward C, Tims A, Bastir M. Neck function in early hominins and suspensory primates: Insights from the uncinate process. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 166:613-637. [PMID: 29492962 DOI: 10.1002/ajpa.23448] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 02/02/2018] [Accepted: 02/06/2018] [Indexed: 11/11/2022]
Abstract
OBJECTIVES Uncinate processes are protuberances on the cranial surface of subaxial cervical vertebrae that assist in stabilizing and guiding spinal motion. Shallow uncinate processes reduce cervical stability but confer an increased range of motion in clinical studies. Here we assess uncinate processes among extant primates and model cervical kinematics in early fossil hominins. MATERIALS AND METHODS We compare six fossil hominin vertebrae with 48 Homo sapiens and 99 nonhuman primates across 20 genera. We quantify uncinate morphology via geometric morphometric methods to understand how uncinate process shape relates to allometry, taxonomy, and mode of locomotion. RESULTS Across primates, allometry explains roughly 50% of shape variation, as small, narrow vertebrae feature the relatively tallest, most pronounced uncinate processes, whereas larger, wider vertebrae typically feature reduced uncinates. Taxonomy only weakly explains the residual variation, however, the association between Uncinate Shape and mode of locomotion is robust, as bipeds and suspensory primates occupy opposite extremes of the morphological continuum and are distinguished from arboreal generalists. Like humans, Australopithecus afarensis and Homo erectus exhibit shallow uncinate processes, whereas A. sediba resembles more arboreal taxa, but not fully suspensory primates. DISCUSSION Suspensory primates exhibit the most pronounced uncinates, likely to maintain visual field stabilization. East African hominins exhibit reduced uncinate processes compared with African apes and A. sediba, likely signaling different degrees of neck motility and modes of locomotion. Although soft tissues constrain neck flexibility beyond limits suggested by osteology alone, this study may assist in modeling cervical kinematics and positional behaviors in extinct taxa.
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Affiliation(s)
- Marc R Meyer
- Department of Anthropology, Chaffey College, Rancho Cucamonga, California 91737
| | - Charles Woodward
- Department of Anthropology, University of California, Berkeley, California 94720
| | - Amy Tims
- Department of Wildlife, Fish, & Conservation Biology, University of California, Davis, California 95616
| | - Markus Bastir
- Paleoanthropology Group, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid 28006, Spain
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22
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Senut B. 1987-2017 : Regard sur l’évolution de l’histoire des origines. REVUE DE PRIMATOLOGIE 2017. [DOI: 10.4000/primatologie.2787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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