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Lukova A, Dunmore CJ, Tsegai ZJ, Bachmann S, Synek A, Skinner MM. Technical note: Does scan resolution or downsampling impact the analysis of trabecular bone architecture? AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024:e25023. [PMID: 39237469 DOI: 10.1002/ajpa.25023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 08/12/2024] [Accepted: 08/18/2024] [Indexed: 09/07/2024]
Abstract
The "gold standard" for the assessment of trabecular bone structure is high-resolution micro-CT. In this technical note, we test the influence of initial scan resolution and post hoc downsampling on the quantitative and qualitative analysis of trabecular bone in a Gorilla tibia. We analyzed trabecular morphology in the right distal tibia of one Gorilla gorilla individual to investigate the impact of variation in voxel size on measured trabecular variables. For each version of the micro-CT volume, trabecular bone was segmented using the medical image analysis method. Holistic morphometric analysis was then used to analyze bone volume (BV/TV), anisotropy (DA), trabecular thickness (Tb.Th), spacing (Tb.Sp), and number (Tb.N). Increasing voxel size during initial scanning was found to have a strong impact on DA and Tb.Th measures, while BV/TV, Tb.Sp, and Tb.N were found to be less sensitive to variations in initial scan resolution. All tested parameters were not substantially influenced by downsampling up to 90 μm resolution. Color maps of BV/TV and DA also retained their distribution up to 90 μm. This study is the first to examine the effect of variation in micro-CT voxel size on the analysis of trabecular bone structure using whole epiphysis approaches. Our results indicate that microstructural variables may be measured for most trabecular parameters up to a voxel size of 90 μm for both scan and downsampled resolutions. Moreover, if only BV/TV, Tb.Sp or Tb.N is measured, even larger voxel sizes might be used without substantially affecting the results.
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Affiliation(s)
- Andrea Lukova
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
- Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Christopher J Dunmore
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Zewdi J Tsegai
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA
| | - Sebastian Bachmann
- Computatioal Biomechanics, Institute of Lightweight Design and Structural Biomechanics, Wien, Austria
| | - Alexander Synek
- Computatioal Biomechanics, Institute of Lightweight Design and Structural Biomechanics, Wien, Austria
| | - Matthew M Skinner
- Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Arlegi M, Lorenzo C. Evolutionary selection and morphological integration in the hand of modern humans. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024:e25024. [PMID: 39228137 DOI: 10.1002/ajpa.25024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Revised: 08/10/2024] [Accepted: 08/18/2024] [Indexed: 09/05/2024]
Abstract
OBJECTIVES To enhance our understanding of the evolutionary dynamics of the modern human hand by analyzing the degree of integration and ability to respond to selection pressures of each phalanx and metacarpal bone. MATERIALS AND METHODS The sample comprised 96 adult individuals, both female and male, from Euro-American, Afro-American, and European populations. We collected 10 linear measurements from the 19 metacarpals and proximal, middle, and distal phalanges that constitute the five digits of the hand. Using these data, we constructed variance/covariance matrices to quantify the degree of integration and assess the hand ability to respond to selective pressures. RESULTS Distal phalanges are the most evolvable and flexible elements, while being the least integrated and constrained. The thumb is similarly integrated as the second and third rays, while medial rays (fourth and fifth digits) are more integrated. However, the thumb presents different integration and response to selection patterns. No significant relationship was found between functionality and the indices of selection and integration. Finally, the correlation between hand and foot indices yielded significant results for conditional evolvability and flexibility. DISCUSSION The findings suggest different evolutionary trajectories for the metacarpal and distal phalanx in the modern human thumb, likely reflecting varying functional and developmental pressures. The first metacarpal, characterized by high flexibility and low evolvability, appears to have reached a stable, optimal morphology, under stabilizing selection. In contrast, the distal phalanx seems to have undergone directional evolution, suggesting specialization for a specific function. Comparisons between hands and feet suggest that these structures evolve differently under directional selection but similarly under stabilizing selection.
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Affiliation(s)
- Mikel Arlegi
- McDonald Institute for Archaeological Research, University of Cambridge, Cambridge, UK
| | - Carlos Lorenzo
- Departament d'Història i Història de l'Art, Universitat Rovira i Virgili, Tarragona, Spain
- Institut Català de Paleoecologia Humana i Evolució Social (IPHES-CERCA), Tarragona, Spain
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Lukova A, Dunmore CJ, Bachmann S, Synek A, Pahr DH, Kivell TL, Skinner MM. Trabecular architecture of the distal femur in extant hominids. J Anat 2024; 245:156-180. [PMID: 38381116 PMCID: PMC11161831 DOI: 10.1111/joa.14026] [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: 07/10/2023] [Revised: 02/01/2024] [Accepted: 02/05/2024] [Indexed: 02/22/2024] Open
Abstract
Extant great apes are characterized by a wide range of locomotor, postural and manipulative behaviours that each require the limbs to be used in different ways. In addition to external bone morphology, comparative investigation of trabecular bone, which (re-)models to reflect loads incurred during life, can provide novel insights into bone functional adaptation. Here, we use canonical holistic morphometric analysis (cHMA) to analyse the trabecular morphology in the distal femoral epiphysis of Homo sapiens (n = 26), Gorilla gorilla (n = 14), Pan troglodytes (n = 15) and Pongo sp. (n = 9). We test two predictions: (1) that differing locomotor behaviours will be reflected in differing trabecular architecture of the distal femur across Homo, Pan, Gorilla and Pongo; (2) that trabecular architecture will significantly differ between male and female Gorilla due to their different levels of arboreality but not between male and female Pan or Homo based on previous studies of locomotor behaviours. Results indicate that trabecular architecture differs among extant great apes based on their locomotor repertoires. The relative bone volume and degree of anisotropy patterns found reflect habitual use of extended knee postures during bipedalism in Homo, and habitual use of flexed knee posture during terrestrial and arboreal locomotion in Pan and Gorilla. Trabecular architecture in Pongo is consistent with a highly mobile knee joint that may vary in posture from extension to full flexion. Within Gorilla, trabecular architecture suggests a different loading of knee in extension/flexion between females and males, but no sex differences were found in Pan or Homo, supporting our predictions. Inter- and intra-specific variation in trabecular architecture of distal femur provides a comparative context to interpret knee postures and, in turn, locomotor behaviours in fossil hominins.
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Affiliation(s)
- Andrea Lukova
- Skeletal Biology Research Centre, School of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Christopher J. Dunmore
- Skeletal Biology Research Centre, School of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Sebastian Bachmann
- Institute of Lightweight Design and Structural BiomechanicsTU WienWienAustria
| | - Alexander Synek
- Institute of Lightweight Design and Structural BiomechanicsTU WienWienAustria
| | - Dieter H. Pahr
- Institute of Lightweight Design and Structural BiomechanicsTU WienWienAustria
- Department of Anatomy and Biomechanics, Division BiomechanicsKarl Landsteiner University of Health SciencesKremsAustria
| | - Tracy L. Kivell
- Department of Human OriginsMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
| | - Matthew M. Skinner
- Department of Human OriginsMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
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Syeda SM, Tsegai ZJ, Cazenave M, Skinner MM, Kivell TL. Cortical bone architecture of hominid intermediate phalanges reveals functional signals of locomotion and manipulation. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 184:e24902. [PMID: 38400773 DOI: 10.1002/ajpa.24902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 11/03/2023] [Accepted: 01/13/2024] [Indexed: 02/26/2024]
Abstract
OBJECTIVES Reconstruction of fossil hominin manual behaviors often relies on comparative analyses of extant hominid hands to understand the relationship between hand use and skeletal morphology. In this context, the intermediate phalanges remain understudied. Thus, here we investigate cortical bone morphology of the intermediate phalanges of extant hominids and compare it to the cortical structure of the proximal phalanges, to investigate the relationship between cortical bone structure and inferred loading during manual behaviors. MATERIALS AND METHODS Using micro-CT data, we analyze cortical bone structure of the intermediate phalangeal shaft of digits 2-5 in Pongo pygmaeus (n = 6 individuals), Gorilla gorilla (n = 22), Pan spp. (n = 23), and Homo sapiens (n = 23). The R package morphomap is used to study cortical bone distribution, cortical thickness and cross-sectional properties within and across taxa. RESULTS Non-human great apes generally have thick cortical bone on the palmar shaft, with Pongo only having thick cortex on the peaks of the flexor sheath ridges, while African apes have thick cortex along the entire flexor sheath ridge and proximal to the trochlea. Humans are distinct in having thicker dorsal shaft cortex as well as thick cortex at the disto-palmar region of the shaft. DISCUSSION Variation in cortical bone distribution and properties of the intermediate phalanges is consistent with differences in locomotor and manipulative behaviors in extant great apes. Comparisons between the intermediate and proximal phalanges reveals similar patterns of cortical bone distribution within each taxon but with potentially greater load experienced by the proximal phalanges, even in knuckle-walking African apes. This study provides a comparative context for the reconstruction of habitual hand use in fossil hominins and hominids.
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Affiliation(s)
- Samar M Syeda
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Zewdi J Tsegai
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA
| | - Marine Cazenave
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Division of Anthropology, American Museum of Natural History (AMNH), New York, USA
| | - Matthew M Skinner
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Tracy L Kivell
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Dunmore CJ, Bachmann S, Synek A, Pahr DH, Skinner MM, Kivell TL. The deep trabecular structure of first metacarpals in extant hominids. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24695. [PMID: 36790736 DOI: 10.1002/ajpa.24695] [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: 07/07/2022] [Revised: 11/07/2022] [Accepted: 01/04/2023] [Indexed: 06/18/2023]
Abstract
OBJECTIVES Recent studies have associated subarticular trabecular bone distribution in the extant hominid first metacarpal (Mc1) with observed thumb use, to infer fossil hominin thumb use. Here, we analyze the entire Mc1 to test for interspecific differences in: (1) the absolute volume of trabecular volume fraction, (2) the distribution of the deeper trabecular network, and (3) the distribution of trabeculae in the medullary cavity, especially beneath the Mc1 disto-radial flange. MATERIALS AND METHODS Trabecular bone was imaged using micro-computed tomography in a sample of Homo sapiens (n = 11), Pan paniscus (n = 10), Pan troglodytes (n = 11), Gorilla gorilla (n = 10) and Pongo sp., (n = 7). Using Canonical Holistic Morphometric Analysis (cHMA), we tested for interspecific differences in the trabecular bone volume fraction (BV/TV) and its relative distribution (rBV/TV) throughout the Mc1, including within the head, medullary cavity, and base. RESULTS P. paniscus had the highest, and H. sapiens the lowest, BV/TV relative to other species. rBV/TV distribution statistically distinguished the radial concentrations and lack of medullary trabecular bone in the H. sapiens Mc1 from all other hominids. H. sapiens and, to a lesser extent, G. gorilla also had a significantly higher trabecular volume beneath the disto-radial flange relative to other hominids. DISCUSSION These results are consistent with differences in observed thumb use in these species and may also reflect systemic differences in bone volume fraction. The trabecular bone extension into the medullary cavity and concentrations beneath the disto-radial flange may represent crucial biomechanical signals that will aid in the inference of fossil hominin thumb use.
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Affiliation(s)
- Christopher J Dunmore
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Sebastian Bachmann
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Alexander Synek
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Dieter H Pahr
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
- Department of Anatomy and Biomechanics, Division Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - 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
| | - 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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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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Cebeiro A, Key A. Captive bonobos (Pan paniscus) apply precision grips when using flaked stone tools. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24759. [PMID: 37218536 DOI: 10.1002/ajpa.24759] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 02/21/2023] [Accepted: 05/08/2023] [Indexed: 05/24/2023]
Abstract
OBJECTIVES Current evidence suggests that flaked stone tool technologies did not emerge until ~3.3-2.6 million-years-ago (Ma). It is often hypothesized that early hominin (principally Ardipithecus and early Australopithecus) manual anatomy may have prevented an earlier emergence, as the forceful precision grips essential to flake tool-use may have been ineffectively performed by these species. Marzke, Marchant, McGrew, and Reece (2015) observed potentially forceful pad-to-side precision grips being recruited by wild chimpanzees (Pan troglodytes) during feeding behaviors, indicating that Pan-like manual anatomy, and therefore potentially early hominin anatomy, may be capable of effectively securing flake stone tools during their use. MATERIALS AND METHODS Here, we report on the grips recruited by four captive, human-trained, bonobos (Pan paniscus) during the use of stone and organic tools, including flake stone tools during cutting behaviors. RESULTS It is revealed that pad-to-side precision grips are frequently recruited by these bonobos when securing stone flakes during cutting actions. In some instances, high forces could have been resisted and applied by the thumb and fingers. DISCUSSION While our analyzes are preliminary and limited to captive individuals, and Pan is not suggested to secure flakes with the same efficacy as Homo or Australopithecus, it points to early hominins potentially being able to perform the precision grips required to use flake stone tools. In turn, the ability to gain tangible benefits from the effective use of flake tools (i.e., gain energetic returns from processing food resources) may have been - at least anatomically - possible in early Australopithecus and other pre-Early Stone Age hominin species. In turn, hominin manual anatomy may not be a leading restriction on the emergence of the earliest stone tool technologies.
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Affiliation(s)
- Adela Cebeiro
- Department of Anthropology, New York University, New York, New York, USA
| | - Alastair Key
- Department of Archaeology, University of Cambridge, Cambridge, UK
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Bardo A, Dunmore CJ, Cornette R, Kivell TL. Morphological integration and shape covariation between the trapezium and first metacarpal among extant hominids. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24800. [PMID: 37377134 DOI: 10.1002/ajpa.24800] [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: 07/16/2022] [Revised: 04/16/2023] [Accepted: 06/04/2023] [Indexed: 06/29/2023]
Abstract
OBJECTIVES The shape of the trapezium and first metacarpal (Mc1) markedly influence thumb mobility, strength, and the manual abilities of extant hominids. Previous research has typically focused solely on trapezium-Mc1 joint shape. Here we investigate how morphological integration and shape covariation between the entire trapezium (articular and non-articular surfaces) and the entire Mc1 reflect known differences in thumb use in extant hominids. MATERIALS AND METHODS We analyzed shape covariation in associated trapezia and Mc1s across a large, diverse sample of Homo sapiens (n = 40 individuals) and other extant hominids (Pan troglodytes, n = 16; Pan paniscus, n = 13; Gorilla gorilla gorilla, n = 27; Gorilla beringei, n = 6; Pongo pygmaeus, n = 14; Pongo abelii, n = 9) using a 3D geometric morphometric approach. We tested for interspecific significant differences in degree of morphological integration and patterns of shape covariation between the entire trapezium and Mc1, as well as within the trapezium-Mc1 joint specifically. RESULTS Significant morphological integration was only found in the trapezium-Mc1 joint of H. sapiens and G. g. gorilla. Each genus showed a specific pattern of shape covariation between the entire trapezium and Mc1 that was consistent with different intercarpal and carpometacarpal joint postures. DISCUSSION Our results are consistent with known differences in habitual thumb use, including a more abducted thumb during forceful precision grips in H. sapiens and a more adducted thumb in other hominids used for diverse grips. These results will help to infer thumb use in fossil hominins.
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Affiliation(s)
- Ameline Bardo
- Département Homme et Environnement, UMR 7194 - HNHP, CNRS-MNHN, Musée de l'Homme, Paris, France
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, UK
| | - Christopher J Dunmore
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, UK
| | - Raphaël Cornette
- Institute of Systematic, Evolution, Biodiversity (ISYEB), UMR 7205-CNRS/MNHN/UPMC/EPHE, National Museum of Natural History, Paris, France
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, UK
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Tanner SB, Bardo A, Davies TW, Dunmore CJ, Johnston RE, Owen NJ, Kivell TL, Skinner MM. Variation and covariation of external shape and cross-sectional geometry in the human metacarpus. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24866. [PMID: 37929663 PMCID: PMC10952563 DOI: 10.1002/ajpa.24866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 09/05/2023] [Accepted: 10/10/2023] [Indexed: 11/07/2023]
Abstract
OBJECTIVES Analyses of external bone shape using geometric morphometrics (GM) and cross-sectional geometry (CSG) are frequently employed to investigate bone structural variation and reconstruct activity in the past. However, the association between these methods has not been thoroughly investigated. Here, we analyze whole bone shape and CSG variation of metacarpals 1-5 and test covariation between them. MATERIALS AND METHODS We analyzed external metacarpal shape using GM and CSG of the diaphysis at three locations in metacarpals 1-5. The study sample includes three modern human groups: crew from the shipwrecked Mary Rose (n = 35 metacarpals), a Pre-industrial group (n = 50), and a Post-industrial group (n = 31). We tested group differences in metacarpal shape and CSG, as well as correlations between these two aspects of metacarpal bone structure. RESULTS GM analysis demonstrated metacarpus external shape variation is predominately related to changes in diaphyseal width and articular surface size. Differences in external shape were found between the non-pollical metacarpals of the Mary Rose and Pre-industrial groups and between the third metacarpals of the Pre- and Post-industrial groups. CSG results suggest the Mary Rose and Post-industrial groups have stronger metacarpals than the Pre-industrial group. Correlating CSG and external shape showed significant relationships between increasing external robusticity and biomechanical strength across non-pollical metacarpals (r: 0.815-0.535; p ≤ 0.05). DISCUSSION Differences in metacarpal cortical structure and external shape between human groups suggest differences in the type and frequency of manual activities. Combining these results with studies of entheses and kinematics of the hand will improve reconstructions of manual behavior in the past.
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Affiliation(s)
- Samuel B. Tanner
- School of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Ameline Bardo
- School of Anthropology and ConservationUniversity of KentCanterburyUK
- UMR 7194 ‐ Histoire Naturelle de l'Homme Préhistorique (HNHP)CNRS‐Muséum National d'Histoire NaturelleParisFrance
| | - Thomas W. Davies
- School of Anthropology and ConservationUniversity of KentCanterburyUK
- Department of Human OriginsMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
| | | | - Richard E. Johnston
- Advanced Imaging of Materials (AIM) Facility, Faculty of Science and Engineering, Bay CampusSwansea UniversitySwanseaUK
| | - Nicholas J. Owen
- Applied Sports Technology Exercise and Medicine Research Centre (A‐STEM), School of Engineering and Applied Sciences, Bay CampusSwansea UniversitySwanseaUK
| | - Tracy L. Kivell
- School of Anthropology and ConservationUniversity of KentCanterburyUK
- Department of Human OriginsMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
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Syeda SM, Tsegai ZJ, Cazenave M, Skinner MM, Kivell TL. Cortical bone distribution of the proximal phalanges in great apes: implications for reconstructing manual behaviours. J Anat 2023; 243:707-728. [PMID: 37358024 PMCID: PMC10557399 DOI: 10.1111/joa.13918] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 06/06/2023] [Accepted: 06/12/2023] [Indexed: 06/27/2023] Open
Abstract
Primate fingers are typically in direct contact with the environment during both locomotion and manipulation, and aspects of external phalangeal morphology are known to reflect differences in hand use. Since bone is a living tissue that can adapt in response to loading through life, the internal bone architecture of the manual phalanges should also reflect differences in manual behaviours. Here, we use the R package Morphomap to analyse high-resolution microCT scans of hominid proximal phalanges of digits 2-5 to determine whether cortical bone structure reflects variation in manual behaviours between bipedal (Homo), knuckle-walking (Gorilla, Pan) and suspensory (Pongo) taxa. We test the hypothesis that relative cortical bone distribution patterns and cross-sectional geometric properties will differ both among extant great apes and across the four digits due to locomotor and postural differences. Results indicate that cortical bone structure reflects the varied hand postures employed by each taxon. The phalangeal cortices of Pongo are significantly thinner and have weaker cross-sectional properties relative to the African apes, yet thick cortical bone under their flexor sheath ridges corresponds with predicted loading during flexed finger grips. Knuckle-walking African apes have even thicker cortical bone under the flexor sheath ridges, as well as in the region proximal to the trochlea, but Pan also has thicker diaphyseal cortices than Gorilla. Humans display a distinct pattern of distodorsal thickening, as well as relatively thin cortices, which may reflect the lack of phalangeal curvature combined with frequent use of flexed fingered hand grips during manipulation. Within each taxon, digits 2-5 have a similar cortical distribution in Pongo, Gorilla and, unexpectedly, Homo, which suggest similar loading of all fingers during habitual locomotion or hand use. In Pan, however, cortical thickness differs between the fingers, potentially reflecting differential loading during knuckle-walking. Inter- and intra-generic variation in phalangeal cortical bone structure reflects differences in manual behaviours, offering a comparative framework for reconstructing hand use in fossil hominins.
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Affiliation(s)
- Samar M. Syeda
- Skeletal Biology Research Centre, School of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Zewdi J. Tsegai
- Department of Organismal Biology and AnatomyUniversity of ChicagoChicagoIllinoisUSA
| | - Marine Cazenave
- Skeletal Biology Research Centre, School of Anthropology and ConservationUniversity of KentCanterburyUK
- Division of AnthropologyAmerican Museum of Natural HistoryNew YorkNew YorkUSA
- Department of Anatomy, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
| | - Matthew M. Skinner
- Skeletal Biology Research Centre, School of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Tracy L. Kivell
- Department of Human OriginsMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
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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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12
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Mika A, Lierenz J, Smith A, Buchanan B, Walker RS, Eren MI, Bebber MR, Key A. Hafted technologies likely reduced stone tool-related selective pressures acting on the hominin hand. Sci Rep 2023; 13:15582. [PMID: 37730739 PMCID: PMC10511494 DOI: 10.1038/s41598-023-42096-z] [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: 05/25/2023] [Accepted: 09/05/2023] [Indexed: 09/22/2023] Open
Abstract
The evolution of the hominin hand has been widely linked to the use and production of flaked stone tool technologies. After the earliest handheld flake tools emerged, shifts in hominin hand anatomy allowing for greater force during precision gripping and ease when manipulating objects in-hand are observed in the fossil record. Previous research has demonstrated how biometric traits, such as hand and digit lengths and precision grip strength, impact functional performance and ergonomic relationships when using flake and core technologies. These studies are consistent with the idea that evolutionary selective pressures would have favoured individuals better able to efficiently and effectively produce and use flaked stone tools. After the advent of composite technologies during the Middle Stone Age and Middle Palaeolithic, fossil evidence reveals differences in hand anatomy between populations, but there is minimal evidence for an increase in precision gripping capabilities. Furthermore, there is little research investigating the selective pressures, if any, impacting manual anatomy after the introduction of hafted composite stone technologies ('handles'). Here we investigated the possible influence of tool-user biometric variation on the functional performance of 420 hafted Clovis knife replicas. Our results suggest there to be no statistical relationships between biometric variables and cutting performance. Therefore, we argue that the advent of hafted stone technologies may have acted as a 'performance equaliser' within populations and removed (or reduced) selective pressures favouring forceful precision gripping capabilities, which in turn could have increased the relative importance of cultural evolutionary selective pressures in the determination of a stone tool's performance.
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Affiliation(s)
- Anna Mika
- Department of Archaeology, University of Cambridge, Cambridge, CB2 3DZ, UK.
- Department of Anthropology, Kent State University, Kent, OH, 44224, USA.
| | - Julie Lierenz
- Department of Anthropology, Kent State University, Kent, OH, 44224, USA
- Department of Anthropology, Ohio State University, Columbus, OH, 43210, USA
| | - Andrew Smith
- Department of Anthropology, Kent State University, Kent, OH, 44224, USA
| | - Briggs Buchanan
- Department of Anthropology, University of Tulsa, Tulsa, OK, 74104, USA
| | - Robert S Walker
- Department of Anthropology, University of Missouri, Columbia, 65211, USA
| | - Metin I Eren
- Department of Anthropology, Kent State University, Kent, OH, 44224, USA
- Department of Archaeology, Cleveland Museum of Natural History, Cleveland, OH, 44106, USA
| | - Michelle R Bebber
- Department of Anthropology, Kent State University, Kent, OH, 44224, USA
| | - Alastair Key
- Department of Archaeology, University of Cambridge, Cambridge, CB2 3DZ, UK
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13
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de Sousa AA, Beaudet A, Calvey T, Bardo A, Benoit J, Charvet CJ, Dehay C, Gómez-Robles A, Gunz P, Heuer K, van den Heuvel MP, Hurst S, Lauters P, Reed D, Salagnon M, Sherwood CC, Ströckens F, Tawane M, Todorov OS, Toro R, Wei Y. From fossils to mind. Commun Biol 2023; 6:636. [PMID: 37311857 PMCID: PMC10262152 DOI: 10.1038/s42003-023-04803-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 04/04/2023] [Indexed: 06/15/2023] Open
Abstract
Fossil endocasts record features of brains from the past: size, shape, vasculature, and gyrification. These data, alongside experimental and comparative evidence, are needed to resolve questions about brain energetics, cognitive specializations, and developmental plasticity. Through the application of interdisciplinary techniques to the fossil record, paleoneurology has been leading major innovations. Neuroimaging is shedding light on fossil brain organization and behaviors. Inferences about the development and physiology of the brains of extinct species can be experimentally investigated through brain organoids and transgenic models based on ancient DNA. Phylogenetic comparative methods integrate data across species and associate genotypes to phenotypes, and brains to behaviors. Meanwhile, fossil and archeological discoveries continuously contribute new knowledge. Through cooperation, the scientific community can accelerate knowledge acquisition. Sharing digitized museum collections improves the availability of rare fossils and artifacts. Comparative neuroanatomical data are available through online databases, along with tools for their measurement and analysis. In the context of these advances, the paleoneurological record provides ample opportunity for future research. Biomedical and ecological sciences can benefit from paleoneurology's approach to understanding the mind as well as its novel research pipelines that establish connections between neuroanatomy, genes and behavior.
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Affiliation(s)
| | - Amélie Beaudet
- Laboratoire de Paléontologie, Évolution, Paléoécosystèmes et Paléoprimatologie (PALEVOPRIM), UMR 7262 CNRS & Université de Poitiers, Poitiers, France.
- University of Cambridge, Cambridge, UK.
| | - Tanya Calvey
- Division of Clinical Anatomy and Biological Anthropology, University of Cape Town, Cape Town, South Africa.
| | - Ameline Bardo
- UMR 7194, CNRS-MNHN, Département Homme et Environnement, Musée de l'Homme, Paris, France
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Julien Benoit
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Christine J Charvet
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, USA
| | - Colette Dehay
- University of Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, F-69500, Bron, France
| | | | - Philipp Gunz
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103, Leipzig, Germany
| | - Katja Heuer
- Institut Pasteur, Université Paris Cité, Unité de Neuroanatomie Appliquée et Théorique, F-75015, Paris, France
| | | | - Shawn Hurst
- University of Indianapolis, Indianapolis, IN, USA
| | - Pascaline Lauters
- Institut royal des Sciences naturelles, Direction Opérationnelle Terre et Histoire de la Vie, Brussels, Belgium
| | - Denné Reed
- Department of Anthropology, University of Texas at Austin, Austin, TX, USA
| | - Mathilde Salagnon
- CNRS, CEA, IMN, GIN, UMR 5293, Université Bordeaux, Bordeaux, France
- PACEA UMR 5199, CNRS, Université Bordeaux, Pessac, France
| | - Chet C Sherwood
- Department of Anthropology, The George Washington University, Washington, DC, USA
| | - Felix Ströckens
- C. & O. Vogt Institute for Brain Research, University Hospital Düsseldorf, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Mirriam Tawane
- Ditsong National Museum of Natural History, Pretoria, South Africa
| | - Orlin S Todorov
- School of Natural Sciences, Macquarie University, Sydney, NSW, Australia
| | - Roberto Toro
- Institut Pasteur, Université Paris Cité, Unité de Neuroanatomie Appliquée et Théorique, F-75015, Paris, France
| | - Yongbin Wei
- Beijing University of Posts and Telecommunications, Beijing, China
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14
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Alemseged Z. Reappraising the palaeobiology of Australopithecus. Nature 2023; 617:45-54. [PMID: 37138108 DOI: 10.1038/s41586-023-05957-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/14/2023] [Indexed: 05/05/2023]
Abstract
The naming of Australopithecus africanus in 1925, based on the Taung Child, heralded a new era in human evolutionary studies and turned the attention of the then Eurasian-centric palaeoanthropologists to Africa, albeit with reluctance. Almost one hundred years later, Africa is recognized as the cradle of humanity, where the entire evolutionary history of our lineage prior to two million years ago took place-after the Homo-Pan split. This Review examines data from diverse sources and offers a revised depiction of the genus and characterizes its role in human evolution. For a long time, our knowledge of Australopithecus came from both A. africanus and Australopithecus afarensis, and the members of this genus were portrayed as bipedal creatures that did not use stone tools, with a largely chimpanzee-like cranium, a prognathic face and a brain slightly larger than that of chimpanzees. Subsequent field and laboratory discoveries, however, have altered this portrayal, showing that Australopithecus species were habitual bipeds but also practised arboreality; that they occasionally used stone tools to supplement their diet with animal resources; and that their infants probably depended on adults to a greater extent than what is seen in apes. The genus gave rise to several taxa, including Homo, but its direct ancestor remains elusive. In sum, Australopithecus had a pivotal bridging role in our evolutionary history owing to its morphological, behavioural and temporal placement between the earliest archaic putative hominins and later hominins-including the genus Homo.
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15
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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: 6] [Impact Index Per Article: 6.0] [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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16
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Drummond-Clarke RC, Kivell TL, Sarringhaus L, Stewart FA, Humle T, Piel AK. Wild chimpanzee behavior suggests that a savanna-mosaic habitat did not support the emergence of hominin terrestrial bipedalism. SCIENCE ADVANCES 2022; 8:eadd9752. [PMID: 36516260 PMCID: PMC9750136 DOI: 10.1126/sciadv.add9752] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 11/08/2022] [Indexed: 06/17/2023]
Abstract
Bipedalism, a defining feature of the human lineage, is thought to have evolved as forests retreated in the late Miocene-Pliocene. Chimpanzees living in analogous habitats to early hominins offer a unique opportunity to investigate the ecological drivers of bipedalism that cannot be addressed via the fossil record alone. We investigated positional behavior and terrestriality in a savanna-mosaic community of chimpanzees (Pan troglodytes schweinfurthii) in the Issa Valley, Tanzania as the first test in a living ape of the hypothesis that wooded, savanna habitats were a catalyst for terrestrial bipedalism. Contrary to widely accepted hypotheses of increased terrestriality selecting for habitual bipedalism, results indicate that trees remained an essential component of the hominin adaptive niche, with bipedalism evolving in an arboreal context, likely driven by foraging strategy.
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Affiliation(s)
| | - Tracy L. Kivell
- 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
| | - Lauren Sarringhaus
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
- Department of Anthropology, University of Michigan, Ann Arbor, MI, USA
| | - Fiona A. Stewart
- Department of Anthropology, University College London, London, UK
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| | - Tatyana Humle
- School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Alex K. Piel
- Department of Anthropology, University College London, London, UK
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17
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Hammond P, Lewis‐Bevan L, Biro D, Carvalho S. Risk perception and terrestriality in primates: A quasi‐experiment through habituation of chacma baboons (
Papio ursinus
) in Gorongosa National Park, Mozambique. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022. [PMCID: PMC9540627 DOI: 10.1002/ajpa.24567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Objectives Habituation is a common pre‐requisite for studying noncaptive primates. Details and quantitative reporting on this process are often overlooked but are useful for measuring human impact on animal behavior, especially when comparing studies across time or sites. During habituation, perceived risk of a stimulus—human observers—is assumed to decline with repeated exposure to that stimulus. We use habituation as a quasi‐experiment to study the landscape of fear, exploring relationships between actual risk, perceived risk, mediating environmental variables, and behavioral correlates. Materials and Methods We recorded vocalizations and observer‐directed vigilance as indicators of perceived risk during habituation of two troops of chacma baboons (Papio ursinus) in Gorongosa National Park, Mozambique. Here, we model changes in these variables as a function of habituation time, troop, time of day, and habitat features. We also model the relationship between each of the anti‐predator behaviors and ground‐use, exploring whether they predict greater terrestriality in the baboons. Results In both troops, vocalization rates and observer‐directed vigilance declined with cumulative exposure to observers, but were heightened later in the day and in denser habitat types. We found that terrestrial activity was negatively related to levels of both vocalizations and observer‐directed vigilance. Discussion This study provides a quantitative assessment of the impact of human observation on primate behavior and highlights environmental variables that influence anti‐predator behaviors, perhaps indicating heightened perception of risk. The relationship between perceived risk and terrestriality is significant for understanding the evolution of this rare trait in primates.
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Affiliation(s)
- Philippa Hammond
- Primate Models for Behavioural Evolution Lab, School of Anthropology and Museum Ethnography University of Oxford Oxford UK
| | | | - Dora Biro
- Department of Zoology University of Oxford Oxford UK
- Department of Brain and Cognitive Sciences University of Rochester Rochester New York USA
| | - Susana Carvalho
- Primate Models for Behavioural Evolution Lab, School of Anthropology and Museum Ethnography University of Oxford Oxford UK
- Paleo‐Primate Project Gorongosa National Park Gorongosa Sofala Mozambique
- Interdisciplinary Center for Archaeology and Evolution of Human Behaviour (ICArEHB) Universidade do Algarve Faro Portugal
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18
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Murray AA. Variability and the form-function framework in evolutionary biomechanics and human locomotion. EVOLUTIONARY HUMAN SCIENCES 2022; 4:e29. [PMID: 37588899 PMCID: PMC10426129 DOI: 10.1017/ehs.2022.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The form-function conceptual framework, which assumes a strong relationship between the structure of a particular trait and its function, has been crucial for understanding morphological variation and locomotion among extant and fossil species across many disciplines. In biological anthropology, it is the lens through which many important questions and hypotheses have been tackled with respect to relationships between morphology and locomotor kinematics, energetics and performance. However, it is becoming increasingly evident that the morphologies of fossil hominins, apes and humans can confer considerable locomotor diversity and flexibility, and can do so with a range of kinematics depending on soft tissue plasticity and environmental and cultural factors. This complexity is not built into traditional biomechanical or mathematical models of relationships between structure and kinematics or energetics, limiting our interpretation of what bone structure is telling us about behaviour in the past. The nine papers presented in this Special Collection together address some of the challenges that variation in the relationship between form and function pose in evolutionary biomechanics, to better characterise the complexity linking structure and function and to provide tools through which we may begin to incorporate some of this complexity into our functional interpretations.
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Affiliation(s)
- Alison A. Murray
- Department of Anthropology, University of Victoria, Cornett Building Room B228, 3800 Finnerty Road, Victoria, BC, CanadaV8P 5C2
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19
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Saers JPP, Gordon AD, Ryan TM, Stock JT. Growth and development of trabecular structure in the calcaneus of Japanese macaques (Macaca fuscata) reflects locomotor behavior, life history, and neuromuscular development. J Anat 2022; 241:67-81. [PMID: 35178713 PMCID: PMC9178394 DOI: 10.1111/joa.13641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 11/30/2022] Open
Abstract
Bone structure dynamically adapts to its mechanical environment throughout ontogeny by altering the structure of trabecular bone, the three-dimensional mesh-like structure found underneath joint surfaces. Trabecular structure, then, can provide a record of variation in loading directions and magnitude; and in ontogenetic samples, it can potentially be used to track developmental shifts in limb posture. We aim to broaden the analysis of trabecular bone ontogeny by incorporating interactions between ontogenetic variation in locomotor repertoire, neuromuscular maturation, and life history. We examine the associations between these variables and age-related variation in trabecular structure in the calcaneus of Japanese macaques (Macaca fuscata). We used high-resolution micro-computed tomography scanning to image the calcaneus in a cross-sectional sample of 34 juvenile M. fuscata aged between 0 and 7 years old at the Primate Research Institute, Japan. We calculated whole bone averages of standard trabecular properties and generated whole-bone morphometric maps of bone volume fraction and Young's modulus. Trabecular structure becomes increasingly heterogeneous in older individuals. Bone volume fraction (BV/total volume [TV]) decreases during the first month of life and increases afterward, coinciding with the onset of independent locomotion in M. fuscata. At birth, primary Young's modulus is oriented orthogonal to the ossification center, but after locomotor onset bone structure becomes stiffest in the direction of joint surfaces and muscle attachments. Age-related variation in bone volume fraction is best predicted by an interaction between the estimated percentage of adult brain size, body mass, and locomotor onset. To explain our findings, we propose a model where interactions between age-related increases in body weight and maturation of the neuromuscular system alter the loading environment of the calcaneus, to which the internal trabecular structure dynamically adapts. This model cannot be directly tested based on our cross-sectional data. However, confirmation of the model by longitudinal experiments and in multiple species would show that trabecular structure can be used both to infer behavior from fossil morphology and serve as a valuable proxy for neuromuscular maturation and life history events like locomotor onset and the achievement of an adult-like gait. This approach could significantly expand our knowledge of the biology and behavior of fossil species.
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Affiliation(s)
- Jaap P P Saers
- Department of Archaeology, Cambridge University, Cambridge, UK
| | - Adam D Gordon
- Department of Anthropology, University at Albany, SUNY, Albany, New York, USA
| | - Timothy M Ryan
- Department of Anthropology, Pennsylvania State University, State College, Pennsylvania, USA
| | - Jay T Stock
- Department of Archaeology, Cambridge University, Cambridge, UK.,Department of Anthropology, Western University, London, Ontario, Canada
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20
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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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21
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Bird EE, Kivell TL, Skinner MM. Patterns of internal bone structure and functional adaptation in the hominoid scaphoid, lunate, and triquetrum. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021. [DOI: 10.1002/ajpa.24449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Emma E. Bird
- Skeletal Biology Research Centre, School of Anthropology and Conservation University of Kent Canterbury UK
| | - 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
| | - 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
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22
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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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23
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Bowland LA, Scott JE, Kivell TL, Patel BA, Tocheri MW, Orr CM. Homo naledi pollical metacarpal shaft morphology is distinctive and intermediate between that of australopiths and other members of the genus Homo. J Hum Evol 2021; 158:103048. [PMID: 34340120 DOI: 10.1016/j.jhevol.2021.103048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 06/25/2021] [Accepted: 06/26/2021] [Indexed: 10/20/2022]
Abstract
Homo naledi fossils from the Rising Star cave system provide important insights into the diversity of hand morphology within the genus Homo. Notably, the pollical (thumb) metacarpal (Mc1) displays an unusual suite of characteristics including a median longitudinal crest, a narrow proximal base, and broad flaring intrinsic muscle flanges. The present study evaluates the affinities of H. naledi Mc1 morphology via 3D geometric morphometric analysis of shaft shape using a broader comparative sample (n = 337) of fossil hominins, recent humans, apes, and cercopithecoid monkeys than in prior work. Results confirm that the H. naledi Mc1 is distinctive from most other hominins in being narrow at the proximal end but surmounted by flaring muscle flanges distally. Only StW 418 (Australopithecus cf. africanus) is similar in these aspects of shape. The gracile proximal shaft is most similar to cercopithecoids, Pan, Pongo, Australopithecus afarensis, and Australopithecus sediba, suggesting that H. naledi retains the condition primitive for the genus Homo. In contrast, Neandertal Mc1s are characterized by wide proximal bases and shafts, pinched midshafts, and broad distal flanges, while those of recent humans generally have straight shafts, less robust muscle flanges, and wide proximal shafts/bases. Although uncertainties remain regarding character polarity, the morphology of the H. naledi thumb might be interpreted as a retained intermediate state in a transformation series between the overall gracility of the shaft and the robust shafts of later hominins. Such a model suggests that the addition of broad medial and lateral muscle flanges to a primitively slender shaft was the first modification in transforming the Mc1 into the overall more robust structure exhibited by other Homo taxa including Neandertals and recent Homo sapiens in whose shared lineage the bases and proximal shafts became expanded, possibly as an adaptation to the repeated recruitment of powerful intrinsic pollical muscles.
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Affiliation(s)
- Lucyna A Bowland
- Department of Anthropology, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Jill E Scott
- Department of Sociology and Anthropology, Metropolitan State University of Denver, Denver, CO, 80217, USA; Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, WITS 2050, Johannesburg, South Africa
| | - Tracy L Kivell
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, WITS 2050, Johannesburg, South Africa; School of Anthropology and Conservation, University of Kent, Canterbury, CT2 7NR, UK; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, 04103, Germany
| | - Biren A Patel
- Department of Integrative Anatomical Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA; Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Matthew W Tocheri
- Department of Anthropology, Lakehead University, Thunder Bay, ON, P7K 1L8, Canada; Human Origins Program, Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington DC, 20560, USA; Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - Caley M Orr
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, 80045, USA; Department of Anthropology, University of Colorado Denver, Denver, CO, 80217, USA.
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24
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Prabhat AM, Miller CK, Prang TC, Spear J, Williams SA, DeSilva JM. Homoplasy in the evolution of modern human-like joint proportions in Australopithecus afarensis. eLife 2021; 10:65897. [PMID: 33978569 PMCID: PMC8116054 DOI: 10.7554/elife.65897] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 04/19/2021] [Indexed: 11/22/2022] Open
Abstract
The evolution of bipedalism and reduced reliance on arboreality in hominins resulted in larger lower limb joints relative to the joints of the upper limb. The pattern and timing of this transition, however, remains unresolved. Here, we find the limb joint proportions of Australopithecus afarensis, Homo erectus, and Homo naledi to resemble those of modern humans, whereas those of A. africanus, Australopithecus sediba, Paranthropus robustus, Paranthropus boisei, Homo habilis, and Homo floresiensis are more ape-like. The homology of limb joint proportions in A. afarensis and modern humans can only be explained by a series of evolutionary reversals irrespective of differing phylogenetic hypotheses. Thus, the independent evolution of modern human-like limb joint proportions in A. afarensis is a more parsimonious explanation. Overall, these results support an emerging perspective in hominin paleobiology that A. afarensis was the most terrestrially adapted australopith despite the importance of arboreality throughout much of early hominin evolution.
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Affiliation(s)
| | - Catherine K Miller
- Anthropology, Dartmouth College, Hanover, United States.,Ecology, Evolution, Ecosystems, and Society, Dartmouth College, Hanover, United States
| | - Thomas Cody Prang
- Department of Anthropology, Texas A&M University, College Station, 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
| | - 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
| | - Jeremy M DeSilva
- Anthropology, Dartmouth College, Hanover, United States.,Ecology, Evolution, Ecosystems, and Society, Dartmouth College, Hanover, United States
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25
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García-Martínez D, Green DJ, Bermúdez de Castro JM. Evolutionary development of the Homo antecessor scapulae (Gran Dolina site, Atapuerca) suggests a modern-like development for Lower Pleistocene Homo. Sci Rep 2021; 11:4102. [PMID: 33602966 PMCID: PMC7892855 DOI: 10.1038/s41598-021-83039-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/25/2021] [Indexed: 01/31/2023] Open
Abstract
Two well-preserved, subadult 800 ky scapulae from Gran Dolina belonging to Homo antecessor, provide a unique opportunity to investigate the ontogeny of shoulder morphology in Lower Pleistocene humans. We compared the H. antecessor scapulae with a sample of 98 P. troglodytes and 108 H. sapiens representatives covering seven growth stages, as well as with the DIK-1-1 (Dikika; Australopithecus afarensis), KNM-WT 15000 (Nariokotome; H. ergaster), and MH2 (Malapa; A. sediba) specimens. We quantified 15 landmarks on each scapula and performed geometric morphometric analyses. H. sapiens scapulae are mediolaterally broader with laterally oriented glenoid fossae relative to Pan and Dikika shoulder blades. Accordingly, H. antecessor scapulae shared more morphological affinities with modern humans, KNM-WT 15000, and even MH2. Both H. antecessor and modern Homo showed significantly more positive scapular growth trajectories than Pan (slopes: P. troglodytes = 0.0012; H. sapiens = 0.0018; H. antecessor = 0.0020). Similarities in ontogenetic trajectories between the H. antecessor and modern human data suggest that Lower Pleistocene hominin scapular development was already modern human-like. At the same time, several morphological features distinguish H. antecessor scapulae from modern humans along the entire trajectory. Future studies should include additional Australopithecus specimens for further comparative assessment of scapular growth trends.
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Affiliation(s)
- Daniel García-Martínez
- Centro Nacional para el Estudio de la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca 3, 09002, Burgos, Spain.
- Departamento de Paleobiología, Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal 2, 28006, Madrid, Spain.
| | - 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
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26
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Karakostis FA, Haeufle D, Anastopoulou I, Moraitis K, Hotz G, Tourloukis V, Harvati K. Biomechanics of the human thumb and the evolution of dexterity. Curr Biol 2021; 31:1317-1325.e8. [PMID: 33513351 PMCID: PMC7987722 DOI: 10.1016/j.cub.2020.12.041] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/26/2020] [Accepted: 12/24/2020] [Indexed: 01/02/2023]
Abstract
Systematic tool production and use is one of humanity's defining characteristics, possibly originating as early as >3 million years ago.1-3 Although heightened manual dexterity is considered to be intrinsically intertwined with tool use and manufacture, and critical for human evolution, its role in the emergence of early culture remains unclear. Most previous research on this question exclusively relied on direct morphological comparisons between early hominin and modern human skeletal elements, assuming that the degree of a species' dexterity depends on its similarity with the modern human form. Here, we develop a new approach to investigate the efficiency of thumb opposition, a fundamental component of manual dexterity, in several species of fossil hominins. Our work for the first time takes into account soft tissue as well as bone anatomy, integrating virtual modeling of musculus opponens pollicis and its interaction with three-dimensional bone shape form. Results indicate that a fundamental aspect of efficient thumb opposition appeared approximately 2 million years ago, possibly associated with our own genus Homo, and did not characterize Australopithecus, the earliest proposed stone tool maker. This was true also of the late Australopithecus species, Australopithecus sediba, previously found to exhibit human-like thumb proportions. In contrast, later Homo species, including the small-brained Homo naledi, show high levels of thumb opposition dexterity, highlighting the increasing importance of cultural processes and manual dexterity in later human evolution.
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Affiliation(s)
- Fotios Alexandros Karakostis
- Paleoanthropology, Senckenberg Centre for Human Evolution and Palaeoenvironment, Eberhard Karls University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
| | - Daniel Haeufle
- Hertie Institute for Clinical Brain Research and Werner Reichardt Centre for Integrative Neuroscience, Eberhard Karls University of Tübingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany; Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Nobelstrasse 15, 70569 Stuttgart, Germany
| | - Ioanna Anastopoulou
- Department of Forensic Medicine and Toxicology, School of Medicine, National and Kapodistrian University of Athens, Mikras Asias Street 75, 11527 Athens, Greece
| | - Konstantinos Moraitis
- Department of Forensic Medicine and Toxicology, School of Medicine, National and Kapodistrian University of Athens, Mikras Asias Street 75, 11527 Athens, Greece
| | - Gerhard Hotz
- Anthropological Collection, Natural History Museum of Basel, Basel 4051, Switzerland
| | - Vangelis Tourloukis
- Paleoanthropology, Senckenberg Centre for Human Evolution and Palaeoenvironment, Eberhard Karls University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
| | - Katerina Harvati
- Paleoanthropology, Senckenberg Centre for Human Evolution and Palaeoenvironment, Eberhard Karls University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany; DFG Centre of Advanced Studies 'Words, Bones, Genes, Tools', Eberhard Karls University of Tübingen, Rümelinstrasse 23, D-72070 Tübingen, Germany.
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27
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The implications of thumb movements for Neanderthal and modern human manipulation. Sci Rep 2020; 10:19323. [PMID: 33244047 PMCID: PMC7692544 DOI: 10.1038/s41598-020-75694-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/15/2020] [Indexed: 11/12/2022] Open
Abstract
Much research has debated the technological abilities of Neanderthals relative to those of early modern humans, with a particular focus on subtle differences in thumb morphology and how this may reflect differences in manipulative behaviors in these two species. Here, we provide a novel perspective on this debate through a 3D geometric morphometric analysis of shape covariation between the trapezial and proximal first metacarpal articular surfaces of Neanderthals (Homo neanderthalensis) in comparison to early and recent humans (Homo sapiens). Results show a distinct pattern of shape covariation in Neanderthals, consistent with more extended and adducted thumb postures that may reflect habitual use of grips commonly used for hafted tools. Both Neanderthals and recent humans demonstrate high intraspecific variation in shape covariation. This intraspecific variation is likely the result of genetic and/or developmental differences, but may also reflect, in part, differing functional requirements imposed by the use of varied tool-kits. These results underscore the importance of holistic joint shape analysis for understanding the functional capabilities and evolution of the modern human thumb.
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28
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Williams-Hatala EM, Hatala KG, Key A, Dunmore CJ, Kasper M, Gordon M, Kivell TL. Kinetics of stone tool production among novice and expert tool makers. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 174:714-727. [PMID: 33107044 DOI: 10.1002/ajpa.24159] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 08/21/2020] [Accepted: 09/15/2020] [Indexed: 12/30/2022]
Abstract
OBJECTIVES As is the case among many complex motor tasks that require prolonged practice before achieving expertise, aspects of the biomechanics of knapping vary according to the relative experience/skill level of the practitioner. In archaeological experiments focused on the production of Plio-Pleistocene stone tools, these skill-mediated biomechanical differences have bearings on experimental design, the interpretation of results, and lithic assemblage analysis. A robust body of work exists on variation in kinematic patterns across skill levels but less is known about potential kinetic differences. The current study was undertaken to better understand kinetic patterns observed across skill levels during "Oldowan," freehand stone tool production. MATERIALS AND METHODS Manual pressure data were collected from 23 novice and 9 expert stone tool makers during the production of simple stone flakes using direct hard hammer percussion. RESULTS Results show that expert tool makers experienced significantly lower cumulative pressure magnitudes and pressure-time integral magnitudes compared with novices. In expert knappers, digits I and II experienced similarly high pressures (both peak pressure and pressure-time integrals) and low variability in pressure relative to digits III-V. Novices, in contrast, tended to hold hammerstones such that pressure patterns were similar across digits II-V, and they showed low variability on digit I only. DISCUSSION The similar and consistent emphasis of the thumb by both skill groups indicates the importance of this digit in stabilizing the hammerstone. The emphasis placed on digit II is exclusive to expert knappers, and so this digit may offer osteological signals diagnostic of habitual expert tool production.
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Affiliation(s)
- Erin Marie Williams-Hatala
- Department of Biology, Chatham University, Pittsburgh, Pennsylvania, USA.,Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, USA
| | - Kevin G Hatala
- Department of Biology, Chatham University, Pittsburgh, Pennsylvania, USA.,Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, USA
| | - Alastair Key
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Christopher J Dunmore
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Margaret Kasper
- Department of Biology, Chatham University, Pittsburgh, Pennsylvania, USA
| | - McKenzie Gordon
- Department of Biology, Chatham University, Pittsburgh, Pennsylvania, 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
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