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Wiles CC, Suh SH, Brown KR, Abel RL. The ontogeny of human fetal trabecular bone architecture occurs in a limb-specific manner. Sci Rep 2024; 14:20261. [PMID: 39217219 PMCID: PMC11365959 DOI: 10.1038/s41598-024-67566-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 07/12/2024] [Indexed: 09/04/2024] Open
Abstract
Gestational growth and development of bone is an understudied process compared to soft tissues and has implications for lifelong health. This study investigated growth and development of human fetal limb bone trabecular architecture using 3D digital histomorphometry of microcomputed tomography data from the femora and humeri of 35 skeletons (17 female and 18 male) with gestational ages between 4 and 9 months. Ontogenetic data revealed: (i) fetal trabecular architecture is similar between sexes; (ii) the proximal femoral metaphysis is physically larger, with thicker trabeculae and greater bone volume fraction relative to the humerus, but other aspects of trabecular architecture are similar between the bones; (iii) between 4 and 9 months gestation there is no apparent sexual or limb dimorphism in patterns of growth, but the size of the humerus and femur diverges early in development. Additionally, both bones exhibit significant increases in mean trabecular thickness (and for the femur alone, bone volume fraction) but minimal trabecular reorganisation (i.e., no significant changes in degree of anisotropy, connectivity density, or fractal dimension). Overall, these data suggest that in contrast to data from the axial skeleton, prenatal growth of long bones in the limbs is characterised by size increase, without major reorganizational changes in trabecular architecture.
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Affiliation(s)
- Crispin Charles Wiles
- MSk Laboratory, Sir Michael Uren Hub, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, W12 7ED, UK.
- Centre for Blast Injury Studies, Department of Bioengineering, Faculty of Engineering, Imperial College London, London, SW7 2AZ, UK.
- Warwick Medical School, University of Warwick, Coventry, CV4 8JE, UK.
| | - Sarah Holly Suh
- MSk Laboratory, Sir Michael Uren Hub, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, W12 7ED, UK
| | - Katharine Robson Brown
- Jean Golding Institute for Data Science, University of Bristol, Bristol, BS8 IUU, UK
- School of Engineering, University of Bristol, Bristol, BS8 1UU, UK
- Department of Mechanical Engineering, University of Bristol, Bristol, BS8 1UB, UK
| | - Richard Leslie Abel
- MSk Laboratory, Sir Michael Uren Hub, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, W12 7ED, UK
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2
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Barak MM. Cortical and Trabecular Bone Modeling and Implications for Bone Functional Adaptation in the Mammalian Tibia. Bioengineering (Basel) 2024; 11:514. [PMID: 38790379 PMCID: PMC11118124 DOI: 10.3390/bioengineering11050514] [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: 04/23/2024] [Revised: 05/14/2024] [Accepted: 05/17/2024] [Indexed: 05/26/2024] Open
Abstract
Bone modeling involves the addition of bone material through osteoblast-mediated deposition or the removal of bone material via osteoclast-mediated resorption in response to perceived changes in loads by osteocytes. This process is characterized by the independent occurrence of deposition and resorption, which can take place simultaneously at different locations within the bone due to variations in stress levels across its different regions. The principle of bone functional adaptation states that cortical and trabecular bone tissues will respond to mechanical stimuli by adjusting (i.e., bone modeling) their morphology and architecture to mechanically improve their mechanical function in line with the habitual in vivo loading direction. This principle is relevant to various research areas, such as the development of improved orthopedic implants, preventative medicine for osteopenic elderly patients, and the investigation of locomotion behavior in extinct species. In the present review, the mammalian tibia is used as an example to explore cortical and trabecular bone modeling and to examine its implications for the functional adaptation of bones. Following a short introduction and an exposition on characteristics of mechanical stimuli that influence bone modeling, a detailed critical appraisal of the literature on cortical and trabecular bone modeling and bone functional adaptation is given. By synthesizing key findings from studies involving small mammals (rodents), large mammals, and humans, it is shown that examining both cortical and trabecular bone structures is essential for understanding bone functional adaptation. A combined approach can provide a more comprehensive understanding of this significant physiological phenomenon, as each structure contributes uniquely to the phenomenon.
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Affiliation(s)
- Meir M Barak
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, NY 11548, USA
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3
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Bird EE, Kivell TL, Dunmore CJ, Tocheri MW, Skinner MM. Trabecular bone structure of the proximal capitate in extant hominids and fossil hominins with implications for midcarpal joint loading and the dart-thrower's motion. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24824. [PMID: 37493308 DOI: 10.1002/ajpa.24824] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 05/05/2023] [Accepted: 07/10/2023] [Indexed: 07/27/2023]
Abstract
OBJECTIVES This research examines whether the distribution of trabecular bone in the proximal capitates of extant hominids, as well as several fossil hominin taxa, is associated with the oblique path of the midcarpal joint known as the dart-thrower's motion (DTM). MATERIALS AND METHODS We analyzed proximal capitates from extant (Pongo n = 12; Gorilla n = 11; Pan n = 10; fossil and recent Homo sapiens n = 29) and extinct (Australopithecus sediba n = 2; Homo naledi n = 1; Homo floresiensis n = 2; Neandertals n = 3) hominids using a new canonical holistic morphometric analysis, which quantifies and visualizes the distribution of trabecular bone using relative bone volume as a fraction of total volume (rBV/TV). RESULTS Homo sapiens and Neandertals had a continuous band of high rBV/TV that extended across the scaphoid, lunate, and hamate subarticular regions, but other fossil hominins and extant great apes did not. A. sediba expressed a distinct combination of human-like and Pan-like rBV/TV distribution. Both H. floresiensis and H. naledi had high rBV/TV on the ulnar-side of the capitate but low rBV/TV on the radial-side. CONCLUSION The proximal capitates of H. sapiens and Neandertals share a distinctive distribution of trabecular bone that suggests that these two species of Homo regularly load(ed) their midcarpal joints along the full extent of the oblique path of the DTM. The observed pattern in A. sediba suggests that human-like stress at the capito-scaphoid articular surface was combined with Pan-like wrist postures, whereas the patterns in H. floresiensis and H. naledi suggest their midcarpal joints were loaded differently from that of H. sapiens and Neandertals.
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Affiliation(s)
- Emma E Bird
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
- Centre for Human Evolution Research, Natural History Museum, London, UK
| | - 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
| | - Christopher J Dunmore
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Matthew W Tocheri
- Department of Anthropology, Lakehead University, Thunder Bay, Ontario, Canada
- Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
- Australian Research Council, Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales, Australia
| | - Matthew M Skinner
- 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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Skedros JG, Cronin JT, Dayton MR, Bloebaum RD, Bachus KN. Exploration of the synergistic role of cortical thickness asymmetry ("Trabecular Eccentricity" concept) in reducing fracture risk in the human femoral neck and a control bone (Artiodactyl Calcaneus). J Theor Biol 2023; 567:111495. [PMID: 37068584 DOI: 10.1016/j.jtbi.2023.111495] [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: 01/19/2023] [Revised: 03/24/2023] [Accepted: 04/10/2023] [Indexed: 04/19/2023]
Abstract
The mechanobiology of the human femoral neck is a focus of research for many reasons including studies that aim to curb age-related bone loss that contributes to a near-exponential rate of hip fractures. Many believe that the femoral neck is often loaded in rather simple bending, which causes net tension stress in the upper (superior) femoral neck and net compression stress in its inferior aspect ("T/C paradigm"). This T/C loading regime lacks in vivo proof. The "C/C paradigm" is a plausible alternative simplified load history that is characterized by a gradient of net compression across the entire femoral neck; action of the gluteus medius and external rotators of the hip are important in this context. It is unclear which paradigm is at play in natural loading due to lack of in vivo bone strain data and deficiencies in understanding mechanisms and manifestations of bone adaptation in tension vs. compression. For these reasons, studies of the femoral neck would benefit from being compared to a 'control bone' that has been proven, by strain data, to be habitually loaded in bending. The artiodactyl (sheep and deer) calcaneus model has been shown to be a very suitable control in this context. However, the application of this control in understanding the load history of the femoral neck has only been attempted in two prior studies, which did not examine the interplay between cortical and trabecular bone, or potential load-sharing influences of tendons and ligaments. Our first goal is to compare fracture risk factors of the femoral neck in both paradigms. Our second goal is to compare and contrast the deer calcaneus to the human femoral neck in terms of fracture risk factors in the T/C paradigm (the C/C paradigm is not applicable in the artiodactyl calcaneus due to its highly constrained loading). Our third goal explores interplay between dorsal/compression and plantar/tension regions of the deer calcaneus and the load-sharing roles of a nearby ligament and tendon, with insights for translation to the femoral neck. These goals were achieved by employing the analytical model of Fox and Keaveny (J. Theoretical Biology 2001, 2003) that estimates fracture risk factors of the femoral neck. This model focuses on biomechanical advantages of the asymmetric distribution of cortical bone in the direction of habitual loading. The cortical thickness asymmetry of the femoral neck (thin superior cortex, thick inferior cortex) reflects the superior-inferior placement of trabecular bone (i.e., "trabecular eccentricity," TE). TE helps the femoral neck adapt to typical stresses and strains through load-sharing between superior and inferior cortices. Our goals were evaluated in the context of TE. Results showed the C/C paradigm has lower risk factors for the superior cortex and for the overall femoral neck, which is clinically relevant. TE analyses of the deer calcaneus revealed important synergism in load-sharing between the plantar/tension cortex and adjacent ligament/tendon, which challenges conventional understanding of how this control bone achieves functional adaptation. Comparisons with the control bone also exposed important deficiencies in current understanding of human femoral neck loading and its potential histocompositional adaptations.
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Affiliation(s)
- John G Skedros
- University of Utah, Department of Orthopaedics, Salt Lake City, UT, USA; Research Service, Veterans Affairs Medical Center, Salt Lake City, UT, USA.
| | - John T Cronin
- University of Utah, Department of Orthopaedics, Salt Lake City, UT, USA
| | - Michael R Dayton
- University of Colorado, Department of Orthopedics, Aurora, CO, USA
| | - Roy D Bloebaum
- University of Utah, Department of Orthopaedics, Salt Lake City, UT, USA; Research Service, Veterans Affairs Medical Center, Salt Lake City, UT, USA
| | - Kent N Bachus
- University of Utah, Department of Orthopaedics, Salt Lake City, UT, USA; Research Service, Veterans Affairs Medical Center, Salt Lake City, UT, USA
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5
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Korpinen N. Comparison of bone density patterns of the subaxial spine between chimpanzees and gorillas - A case study. J Med Primatol 2023; 52:85-91. [PMID: 36420796 DOI: 10.1111/jmp.12627] [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: 09/20/2022] [Revised: 11/02/2022] [Accepted: 11/10/2022] [Indexed: 11/25/2022]
Abstract
Case study on the bone density pattern of subaxial vertebral column in African apes. INTRODUCTION African apes have been noted to experience fewer back ailments than humans and to have higher vertebral bone density. Yet, research on the subject is quite limited and has usually included only one or few vertebrae. However, to understand vertebral column as whole and how posture and locomotion might have affected it, we need to know how bone density varies between adjacent vertebrae. MATERIALS AND METHODS Bone density in the vertebral body was measured for all subaxial vertebrae of five specimens including two Pan troglodytes (1 male and 1 female) and three Gorilla gorilla (2 males and 1 female) using peripheral quantitative computed tomography (pQCT). RESULTS The results tentatively indicated differences between species, especially in the trabecular density of the cervical segment and support the need for further studies on this subject.
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Affiliation(s)
- Niina Korpinen
- Department of Archaeology, Faculty of Humanities, University of Oulu, Oulu, Finland
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6
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Deckers K, Tsegai ZJ, Skinner MM, Zeininger A, Kivell TL. Ontogenetic changes to metacarpal trabecular bone structure in mountain and western lowland gorillas. J Anat 2022; 241:82-100. [PMID: 35122239 PMCID: PMC9178373 DOI: 10.1111/joa.13630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 11/28/2022] Open
Abstract
The trabecular bone morphology of adult extant primates has been shown to reflect mechanical loading related to locomotion. However, ontogenetic studies of humans and other mammals suggest an adaptive lag between trabecular bone response and current mechanical loading patterns that could result in adult trabecular bone morphology reflecting juvenile behaviours. This study investigates ontogenetic changes in the trabecular bone structure of the third metacarpal of mountain gorillas (Gorilla beringei beringei; n = 26) and western lowland gorillas (Gorilla gorilla gorilla; n = 26) and its relationship to expected changes in locomotor loading patterns. Results show that trabecular bone reflects predicted mechanical loading throughout ontogeny. Bone volume fraction, trabecular thickness and trabecular number are low at birth and increase with age, although degree of anisotropy remains relatively stable throughout ontogeny. A high concentration of bone volume fraction can be observed in the distopalmar region of the third metacarpal epiphysis in early ontogeny, consistent with the high frequency of climbing, suspensory and other grasping behaviours in young gorillas. High trabecular bone concentration increases dorsally in the epiphysis during the juvenile period as terrestrial knuckle-walking becomes the primary form of locomotion. However, fusion of the epiphysis does not take place until 10-11 years of age, and overall trabecular structure does not fully reflect the adult pattern until 12 years of age, indicating a lag between adult-like behaviours and adult-like trabecular morphology. We found minimal differences in trabecular ontogeny between mountain and western lowland gorillas, despite presumed variation in the frequencies of arboreal locomotor behaviours. Altogether, ontogenetic changes in Gorilla metacarpal trabecular structure reflect overall genus-level changes in locomotor behaviours throughout development, but with some ontogenetic lag that should be considered when drawing functional conclusions from bone structure in extant or fossil adolescent specimens.
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Affiliation(s)
- Kim Deckers
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, UK
| | - Zewdi J Tsegai
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Matthew M Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Angel Zeininger
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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7
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Chirchir H. Trabecular bone in domestic dogs and wolves: Implications for understanding human self‐domestication. Anat Rec (Hoboken) 2020; 304:31-41. [DOI: 10.1002/ar.24510] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 05/13/2020] [Accepted: 05/13/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Habiba Chirchir
- Department of Biological Sciences Marshall University Huntington West Virginia USA
- Human Origins Program, Department of Anthropology National Museum of Natural History, Smithsonian Institution Washington District of Columbia USA
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8
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Human manual distal phalanges from the Middle Stone Age deposits of Klasies River Main Site, Western Cape Province, South Africa. J Hum Evol 2020; 146:102849. [PMID: 32721654 DOI: 10.1016/j.jhevol.2020.102849] [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: 02/10/2020] [Revised: 06/11/2020] [Accepted: 06/11/2020] [Indexed: 11/23/2022]
Abstract
Two new distal manual phalanges from the Middle Stone Age deposits of Klasies River Main Site are described. One (SAM-AP 6387) likely derives from ray II or ray III, whereas the other (SAM-AP 6388) is from the thumb. Both derive from a late adolescent or fully adult individual. They were recovered by H. Deacon from the same stratigraphic unit (submember W or possibly submember R) of the Shell and Sand Member of Cave 1, which places them between 100 and 90 ka. Both are comparatively small elements, and the possibility that they came from the same hand cannot be discounted at this time. These bones add to the meager and all too fragmentary postcranial human fossil sample from the Late Pleistocene of South Africa. These two specimens provide some additional evidence pertaining to the morphological attributes of the distal phalanges of the Middle Stone Age inhabitants of South Africa. Together with the distal pollical phalanx from Die Kelders (SAM-AP 6402), they are relatively small in comparison with homologs from recent human samples as well as Late Pleistocene specimens from Eurasia. Given their small sizes, the distal pollical phalanges from Klasies and Die Kelders are not dissimilar to Holocene Khoesan homologs. As expected, the Klasies elements differ noticeably from Neandertal homologs, especially in the narrowness of their shafts and distal tuberosities.
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9
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Thompson NE. The biomechanics of knuckle-walking: 3-D kinematics of the chimpanzee and macaque wrist, hand and fingers. J Exp Biol 2020; 223:jeb224360. [PMID: 32554524 DOI: 10.1242/jeb.224360] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/05/2020] [Indexed: 08/26/2023]
Abstract
The origin and evolution of knuckle-walking has long been a key focus in understanding African ape, including human, origins. Yet, despite numerous studies documenting morphological characteristics potentially associated with knuckle-walking, little quantitative three-dimensional (3-D) data exist of forelimb motion during knuckle-walking. Nor do any comparative 3-D data exist for hand postures used during quadrupedalism in monkeys. This lack of data has limited the testability of proposed adaptations for knuckle-walking in African apes. This study presents the first 3-D kinematic data of the wrist, hand and metacarpophalangeal joints during knuckle-walking in chimpanzees and in macaques using digitigrade and palmigrade hand postures. These results clarify the unique characteristics of, and commonalities between, knuckle-walking and digitigrady/palmigrady in multiple planes of motion. Notably, chimpanzees utilized more wrist ulnar deviation than any macaque hand posture. Maximum extension of the chimpanzee wrist was slight (5-20 deg) and generally overlapped with macaque digitigrady. Metacarpophalangeal joint motion displayed distinct differences between digits in both species, likely related to the timing of force application. These data also reveal that maximum metacarpophalangeal extension angles during knuckle-walking (26-59 deg) were generally higher than previously considered. In macaques, maximum metacarpophalangeal extension during digitigrady and palmigrady overlapped for most digits, highlighting additional complexity in the interpretation of skeletal features that may be related to limiting metacarpophalangeal motion. Most importantly, however, these new 3-D data serve as a fundamental dataset with which evaluation of proposed musculoskeletal adaptations for knuckle-walking can be tested.
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Affiliation(s)
- Nathan E Thompson
- Department of Anatomy, NYIT College of Osteopathic Medicine, Old Westbury, NY 11568, USA
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10
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Dunmore CJ, Skinner MM, Bardo A, Berger LR, Hublin JJ, Pahr DH, Rosas A, Stephens NB, Kivell TL. The position of Australopithecus sediba within fossil hominin hand use diversity. Nat Ecol Evol 2020; 4:911-918. [PMID: 32424278 DOI: 10.1038/s41559-020-1207-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 04/15/2020] [Indexed: 11/09/2022]
Abstract
The human lineage is marked by a transition in hand use, from locomotion towards increasingly dexterous manipulation, concomitant with bipedalism. The forceful precision grips used by modern humans probably evolved in the context of tool manufacture and use, but when and how many times hominin hands became principally manipulative remains unresolved. We analyse metacarpal trabecular and cortical bone, which provide insight into behaviour during an individual's life, to demonstrate previously unrecognized diversity in hominin hand use. The metacarpals of the palm in Australopithecus sediba have trabecular morphology most like orangutans and consistent with locomotor power-grasping with the fingers, while that of the thumb is consistent with human-like manipulation. This internal morphology is the first record of behaviour consistent with a hominin that used its hand for both arboreal locomotion and human-like manipulation. This hand use is distinct from other fossil hominins in this study, including A. afarensis and A. africanus.
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Affiliation(s)
- Christopher J Dunmore
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.
| | - Matthew M Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Ameline Bardo
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Lee R Berger
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.,Chaire Internationale de Paléoanthropologie, Collège de France, Paris, France
| | - Dieter H Pahr
- TU Wien Institute of Lightweight Design and Structural Biomechanics, Vienna, Austria
| | - Antonio Rosas
- Department of Paleobiology, National Museum of Natural Sciences, CSIC, Madrid, Spain
| | - Nicholas B Stephens
- Department of Anthropology, The Pennsylvania State University, State College, PA, USA
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
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11
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Synek A, Lu SC, Nauwelaerts S, Pahr DH, Kivell TL. Metacarpophalangeal joint loads during bonobo locomotion: model predictions versus proxies. J R Soc Interface 2020; 17:20200032. [PMID: 32126191 DOI: 10.1098/rsif.2020.0032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The analysis of internal trabecular and cortical bone has been an informative tool for drawing inferences about behaviour in extant and fossil primate taxa. Within the hand, metacarpal bone architecture has been shown to correlate well with primate locomotion; however, the extent of morphological differences across taxa is unexpectedly small given the variability in hand use. One explanation for this observation is that the activity-related differences in the joint loads acting on the bone are simply smaller than estimated based on commonly used proxies (i.e. external loading and joint posture), which neglect the influence of muscle forces. In this study, experimental data and a musculoskeletal finger model are used to test this hypothesis by comparing differences between climbing and knuckle-walking locomotion of captive bonobos (Pan paniscus) based on (i) joint load magnitude and direction predicted by the models and (ii) proxy estimations. The results showed that the activity-related differences in predicted joint loads are indeed much smaller than the proxies would suggest, with joint load magnitudes being almost identical between the two locomotor modes. Differences in joint load directions were smaller but still evident, indicating that joint load directions might be a more robust indicator of variation in hand use than joint load magnitudes. Overall, this study emphasizes the importance of including muscular forces in the interpretation of skeletal remains and promotes the use of musculoskeletal models for correct functional interpretations.
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Affiliation(s)
- Alexander Synek
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Szu-Ching Lu
- Animal Postcranial Evolution Laboratory, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Laboratory for Innovation in Autism, School of Education, University of Strathclyde, Glasgow, UK
| | - Sandra Nauwelaerts
- Department of Biology, University of Antwerp, Wilrijk, Belgium.,Center for Research and Conservation KMDA, Astridplein, Antwerpen, Belgium
| | - Dieter H Pahr
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria.,Department of Anatomy and Biomechanics, Karl Landsteiner Private University of Health Sciences, Krems an der Donau, Austria
| | - Tracy L Kivell
- Animal Postcranial Evolution Laboratory, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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12
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Ragni AJ. Trabecular architecture of the capitate and third metacarpal through ontogeny in chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla). J Hum Evol 2019; 138:102702. [PMID: 31805487 DOI: 10.1016/j.jhevol.2019.102702] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 10/16/2019] [Accepted: 10/16/2019] [Indexed: 11/18/2022]
Abstract
Chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla) both knuckle-walk in adulthood but are known to develop their locomotor strategies differently. Using dentally defined age-groups of both Pan and Gorilla and behavioral data from the literature, this study presents an internal trabecular bone approach to better understand the morphological ontogeny of knuckle-walking in these taxa. Capitate and third metacarpal bones were scanned by μCT at 23-43 μm resolution with scaled volumes of interest placed centrally within the head of the capitate and base of the third metacarpal. Trabecular measures related to activity level (size-adjusted bone volume/total volume, trabecular number, and bone surface area/bone volume) met expectations of decreasing through ontogeny in both taxa. Degree of anisotropy did not show statistical support for predicted species differences, but this may be due to the sample size as observed changes through ontogeny reflect expected trends in the capitate. Analyses of principal trabecular orientation corroborated known behavioral differences related to variation of hand use in these taxa, but only Pan showed directional patterning associated with suggested wrist posture. Assessment of allometry showed that the trabecular bone of larger animals is characterized by fewer and thinner trabeculae relative to bone size. In combination, these findings confirm the efficacy of trabecular bone in reflecting locomotor ontogeny differences between closely related taxa. These techniques show promise for use within the hominin fossil record, particularly for taxa hypothesized to be arboreal in some capacity.
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Affiliation(s)
- Anna J Ragni
- Richard Gilder Graduate School, American Museum of Natural History, New York, NY, USA; New York Consortium in Evolutionary Primatology, New York, NY, USA; Department of Anthropology, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA.
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Dunmore CJ, Bardo A, Skinner MM, Kivell TL. Trabecular variation in the first metacarpal and manipulation in hominids. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 171:219-241. [PMID: 31762017 DOI: 10.1002/ajpa.23974] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 10/27/2019] [Accepted: 10/29/2019] [Indexed: 12/14/2022]
Abstract
OBJECTIVES The dexterity of fossil hominins is often inferred by assessing the comparative manual anatomy and behaviors of extant hominids, with a focus on the thumb. The aim of this study is to test whether trabecular structure is consistent with what is currently known about habitually loaded thumb postures across extant hominids. MATERIALS AND METHODS We analyze first metacarpal (Mc1) subarticular trabecular architecture in humans (Homo sapiens, n = 10), bonobos (Pan paniscus, n = 10), chimpanzees (Pan troglodytes, n = 11), as well as for the first time, gorillas (Gorilla gorilla gorilla, n = 10) and orangutans (Pongo sp., n = 1, Pongo abelii, n = 3 and Pongo pygmaeus, n = 5). Using a combination of subarticular and whole-epiphysis approaches, we test for significant differences in relative trabecular bone volume (RBV/TV) and degree of anisotropy (DA) between species. RESULTS Humans have significantly greater RBV/TV on the radiopalmar aspects of both the proximal and distal Mc1 subarticular surfaces and greater DA throughout the Mc1 head than other hominids. Nonhuman great apes have greatest RBV/TV on the ulnar aspect of the Mc1 head and the palmar aspect of the Mc1 base. Gorillas possessed significantly lower DA in the Mc1 head than any other taxon in our sample. DISCUSSION These results are consistent with abduction of the thumb during forceful "pad-to-pad" precision grips in humans and, in nonhuman great apes, a habitually adducted thumb that is typically used in precision and power grips. This comparative context will help infer habitual manipulative and locomotor grips in fossil hominins.
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Affiliation(s)
- Christopher J Dunmore
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Ameline Bardo
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Matthew M Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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14
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Wood Z, Lynn L, Nguyen JT, Black MA, Patel M, Barak MM. Are we crying Wolff? 3D printed replicas of trabecular bone structure demonstrate higher stiffness and strength during off-axis loading. Bone 2019; 127:635-645. [PMID: 31390534 PMCID: PMC6939675 DOI: 10.1016/j.bone.2019.08.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/01/2019] [Accepted: 08/02/2019] [Indexed: 11/18/2022]
Abstract
Roux's principle of bone functional adaptation postulates that bone tissue, and particularly trabecular bone tissue, responds to mechanical stimuli by adjusting (modeling) its architecture accordingly. Hence, it predicts that the new modeled trabecular structure is mechanically improved (stiffer and stronger) in line with the habitual in vivo loading direction. While previous studies found indirect evidence to support this theory, direct support was so far unattainable. This is attributed to the fact that each trabecular bone is unique, and that trabecular bone tissue tends to be damaged during mechanical testing. Consequently, a unique modeled trabecular structure can be mechanically tested only along one direction and a comparison to other directions for that specific structure is impossible. To address this issue, we have 3D printed 10 replicas of a trabecular structure from a sheep talus cropped along the 3 principal axes of the bone and in line with the principal direction of loading (denoted on-axis model). Next, we have rotated the same cropped trabecular structure in increments of 10° up to 90° to the bone principal direction of loading (denoted off-axis models) and printed 10 replicas of each off-axis model. Finally, all on-axis and off-axis 3D printed replicas were loaded in compression until failure and trabecular structure stiffness and strength were calculated. Contrary to our prediction, and conflicting with Roux's principle of bone functional adaptation, we found that a trabecular structure loaded off-axis tended to have higher stiffness and strength values when compared to the same trabecular structure loaded on-axis. These unexpected results may not disprove Roux's principle of bone functional adaptation, but they do imply that trabecular bone adaptation may serve additional purposes than simply optimizing bone structure to one principal loading scenario and this suggests that we still don't fully understand bone modeling in its entirety.
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Affiliation(s)
- Zach Wood
- Department of Biology, Winthrop University, Rock Hill, SC 29733, USA
| | - Lisa Lynn
- Department of Biology, Winthrop University, Rock Hill, SC 29733, USA
| | - Jack T Nguyen
- Department of Biology, Winthrop University, Rock Hill, SC 29733, USA
| | - Margaret A Black
- Department of Biology, Winthrop University, Rock Hill, SC 29733, USA
| | - Meha Patel
- Department of Biology, Winthrop University, Rock Hill, SC 29733, USA
| | - Meir M Barak
- Department of Biology, Winthrop University, Rock Hill, SC 29733, USA; Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, NY 11548, USA.
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15
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Cortical bone distribution in the femoral neck of Paranthropus robustus. J Hum Evol 2019; 135:102666. [DOI: 10.1016/j.jhevol.2019.102666] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 08/20/2019] [Accepted: 08/20/2019] [Indexed: 02/07/2023]
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Saers JP, Ryan TM, Stock JT. Trabecular bone structure scales allometrically in the foot of four human groups. J Hum Evol 2019; 135:102654. [DOI: 10.1016/j.jhevol.2019.102654] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 08/06/2019] [Accepted: 08/07/2019] [Indexed: 11/26/2022]
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Dunmore CJ, Kivell TL, Bardo A, Skinner MM. Metacarpal trabecular bone varies with distinct hand-positions used in hominid locomotion. J Anat 2019; 235:45-66. [PMID: 31099419 PMCID: PMC6580057 DOI: 10.1111/joa.12966] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2019] [Indexed: 12/11/2022] Open
Abstract
Trabecular bone remodels during life in response to loading and thus should, at least in part, reflect potential variation in the magnitude, frequency and direction of joint loading across different hominid species. Here we analyse the trabecular structure across all non-pollical metacarpal distal heads (Mc2-5) in extant great apes, expanding on previous volume of interest and whole-epiphysis analyses that have largely focused on only the first or third metacarpal. Specifically, we employ both a univariate statistical mapping and a multivariate approach to test for both inter-ray and interspecific differences in relative trabecular bone volume fraction (RBV/TV) and degree of anisotropy (DA) in Mc2-5 subchondral trabecular bone. Results demonstrate that whereas DA values only separate Pongo from African apes (Pan troglodytes, Pan paniscus, Gorilla gorilla), RBV/TV distribution varies with the predicted loading of the metacarpophalangeal (McP) joints during locomotor behaviours in each species. Gorilla exhibits a relatively dorsal distribution of RBV/TV consistent with habitual hyper-extension of the McP joints during knuckle-walking, whereas Pongo has a palmar distribution consistent with flexed McP joints used to grasp arboreal substrates. Both Pan species possess a disto-dorsal distribution of RBV/TV, compatible with multiple hand postures associated with a more varied locomotor regime. Further inter-ray comparisons reveal RBV/TV patterns consistent with varied knuckle-walking postures in Pan species in contrast to higher RBV/TV values toward the midline of the hand in Mc2 and Mc5 of Gorilla, consistent with habitual palm-back knuckle-walking. These patterns of trabecular bone distribution and structure reflect different behavioural signals that could be useful for determining the behaviours of fossil hominins.
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Affiliation(s)
- Christopher J. Dunmore
- Skeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Tracy L. Kivell
- Skeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
- Department of Human EvolutionMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
| | - Ameline Bardo
- Skeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Matthew M. Skinner
- Skeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
- Department of Human EvolutionMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
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18
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Synek A, Dunmore CJ, Kivell TL, Skinner MM, Pahr DH. Inverse remodelling algorithm identifies habitual manual activities of primates based on metacarpal bone architecture. Biomech Model Mechanobiol 2019; 18:399-410. [PMID: 30413983 PMCID: PMC6418057 DOI: 10.1007/s10237-018-1091-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 10/29/2018] [Indexed: 12/30/2022]
Abstract
Previously, a micro-finite element (micro-FE)-based inverse remodelling method was presented in the literature that reconstructs the loading history of a bone based on its architecture alone. Despite promising preliminary results, it remains unclear whether this method is sensitive enough to detect differences of bone loading related to pathologies or habitual activities. The goal of this study was to test the sensitivity of the inverse remodelling method by predicting joint loading histories of metacarpal bones of species with similar anatomy but clearly distinct habitual hand use. Three groups of habitual hand use were defined using the most representative primate species: manipulation (human), suspensory locomotion (orangutan), and knuckle-walking locomotion (bonobo, chimpanzee, gorilla). Nine to ten micro-computed tomography scans of each species ([Formula: see text] in total) were used to create micro-FE models of the metacarpal head region. The most probable joint loading history was predicted by optimally scaling six load cases representing joint postures ranging from [Formula: see text] (extension) to [Formula: see text] (flexion). Predicted mean joint load directions were significantly different between knuckle-walking and non-knuckle-walking groups ([Formula: see text]) and in line with expected primary hand postures. Mean joint load magnitudes tended to be larger in species using their hands for locomotion compared to species using them for manipulation. In conclusion, this study shows that the micro-FE-based inverse remodelling method is sensitive enough to detect differences of joint loading related to habitual manual activities of primates and might, therefore, be useful for palaeoanthropologists to reconstruct the behaviour of extinct species and for biomedical applications such as detecting pathological joint loading.
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Affiliation(s)
- Alexander Synek
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9/BE, Vienna, Austria.
| | - Christopher J Dunmore
- Animal Postcranial Evolution Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Tracy L Kivell
- Animal Postcranial Evolution Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
- Department of Human Evolution, Max Plank Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Matthew M Skinner
- Animal Postcranial Evolution Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
- Department of Human Evolution, Max Plank Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Dieter H Pahr
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9/BE, Vienna, Austria
- Department of Anatomy and Biomechanics, Karl Landsteiner Private University of Health Sciences, Krems an der Donau, Austria
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19
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Sukhdeo S, Parsons J, Niu XM, Ryan TM. Trabecular Bone Structure in the Distal Femur of Humans, Apes, and Baboons. Anat Rec (Hoboken) 2018; 303:129-149. [DOI: 10.1002/ar.24050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 06/27/2018] [Accepted: 08/13/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Simone Sukhdeo
- Department of AnthropologyPennsylvania State University University Park Pennsylvania
| | - Jacob Parsons
- Department of StatisticsPennsylvania State University University Park Pennsylvania
| | - Xiaoyue Maggie Niu
- Department of StatisticsPennsylvania State University University Park Pennsylvania
| | - Timothy M. Ryan
- Department of AnthropologyPennsylvania State University University Park Pennsylvania
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20
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Doershuk LJ, Saers JPP, Shaw CN, Jashashvili T, Carlson KJ, Stock JT, Ryan TM. Complex variation of trabecular bone structure in the proximal humerus and femur of five modern human populations. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 168:104-118. [DOI: 10.1002/ajpa.23725] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 09/17/2018] [Accepted: 09/18/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Lily J. Doershuk
- Department of Anthropology The Pennsylvania State University University Park Pennsylvania
| | - Jaap P. P. Saers
- Department of Archaeology University of Cambridge Cambridge United Kingdom
| | - Colin N. Shaw
- Department of Archaeology University of Cambridge Cambridge United Kingdom
| | - Tea Jashashvili
- Department of Geology and Paleontology Georgian National Museum Tbilisi Georgia
- Molecular Imaging Center, Department of Radiology Keck School of Medicine, University of Southern California Los Angeles California
| | - Kristian J. Carlson
- Department of Integrative Anatomical Sciences, Keck School of Medicine University of Southern California Los Angeles California
- Evolutionary Studies Institute, University of the Witwatersrand Johannesburg South Africa
| | - Jay T. Stock
- Department of Archaeology University of Cambridge Cambridge United Kingdom
- Department of Anthropology Western University London Ontario Canada
| | - Timothy M. Ryan
- Department of Anthropology The Pennsylvania State University University Park Pennsylvania
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21
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Tsegai ZJ, Skinner MM, Pahr DH, Hublin JJ, Kivell TL. Ontogeny and variability of trabecular bone in the chimpanzee humerus, femur and tibia. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 167:713-736. [DOI: 10.1002/ajpa.23696] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/22/2018] [Accepted: 07/23/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Zewdi J. Tsegai
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig Germany
| | - Matthew M. Skinner
- Skeletal Biology Research Center; School of Anthropology and Conservation, University of Kent; Canterbury United Kingdom
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig Germany
| | - Dieter H. Pahr
- Institute for Lightweight Design and Structural Biomechanics; Vienna University of Technology; Wien Austria
| | - Jean-Jacques Hublin
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig Germany
| | - Tracy L. Kivell
- Skeletal Biology Research Center; School of Anthropology and Conservation, University of Kent; Canterbury United Kingdom
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig Germany
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22
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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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23
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Stephens NB, Kivell TL, Pahr DH, Hublin JJ, Skinner MM. Trabecular bone patterning across the human hand. J Hum Evol 2018; 123:1-23. [PMID: 30072187 DOI: 10.1016/j.jhevol.2018.05.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 05/09/2018] [Accepted: 05/10/2018] [Indexed: 02/06/2023]
Abstract
Hand bone morphology is regularly used to link particular hominin species with behaviors relevant to cognitive/technological progress. Debates about the functional significance of differing hominin hand bone morphologies tend to rely on establishing phylogenetic relationships and/or inferring behavior from epigenetic variation arising from mechanical loading and adaptive bone modeling. Most research focuses on variation in cortical bone structure, but additional information about hand function may be provided through the analysis of internal trabecular structure. While primate hand bone trabecular structure is known to vary in ways that are consistent with expected joint loading differences during manipulation and locomotion, no study exists that has documented this variation across the numerous bones of the hand. We quantify the trabecular structure in 22 bones of the human hand (early/extant modern Homo sapiens) and compare structural variation between two groups associated with post-agricultural/industrial (post-Neolithic) and foraging/hunter-gatherer (forager) subsistence strategies. We (1) establish trabecular bone volume fraction (BV/TV), modulus (E), degree of anisotropy (DA), mean trabecular thickness (Tb.Th) and spacing (Tb.Sp); (2) visualize the average distribution of site-specific BV/TV for each bone; and (3) examine if the variation in trabecular structure is consistent with expected joint loading differences among the regions of the hand and between the groups. Results indicate similar distributions of trabecular bone in both groups, with those of the forager sample presenting higher BV/TV, E, and lower DA, suggesting greater and more variable loading during manipulation. We find indications of higher loading along the ulnar side of the forager sample hand, with high site-specific BV/TV distributions among the carpals that are suggestive of high loading while the wrist moves through the 'dart-thrower's' motion. These results support the use of trabecular structure to infer behavior and have direct implications for refining our understanding of human hand evolution and fossil hominin hand use.
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Affiliation(s)
- Nicholas B Stephens
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NZ, United Kingdom; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Dieter H Pahr
- Institute for Lightweight Design and Structural Biomechanics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Matthew M Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NZ, United Kingdom; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
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