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Rowan J, Wood B. Dart and the Taung juvenile: making sense of a century-old record of hominin evolution in Africa. Biol Lett 2024; 20:20240185. [PMID: 39045658 PMCID: PMC11267397 DOI: 10.1098/rsbl.2024.0185] [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: 04/10/2024] [Revised: 06/06/2024] [Accepted: 06/17/2024] [Indexed: 07/25/2024] Open
Abstract
The announcement in 1925 by Raymond Dart of the discovery of the Taung juvenile's skull in a quarry in sub-Saharan Africa is deservedly a classic publication in the history of palaeoanthropology. Dart's paper-which designated Taung as the type specimen of the early hominin species Australopithecus africanus-provided the first fossil evidence supporting Charles Darwin's 1871 prediction that Africa was where the human lineage originated. The Taung juvenile's combination of ape and human characteristics eventually led to a paradigm shift in our understanding of human evolution. This contribution focuses on the milieu in which Dart's paper appeared (i.e. what was understood in 1925 about human evolution), the fossil evidence as set out by Dart, his interpretation of how a species represented by a fossilized juvenile's skull fitted within prevailing narratives about human evolution and the significance of the fossil being found in an environment inferred to be very different from that occupied by living apes. We also briefly review subsequent fossil finds that have corroborated the argument Dart made for having discovered evidence of a hitherto unknown close relative of humans, and summarize our current understanding of the earliest stages of human evolution and its environmental context.
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Affiliation(s)
- John Rowan
- Department of Archaeology, University of Cambridge, CambridgeCB2 3DZ, UK
| | - Bernard Wood
- CASHP, Department of Anthropology, George Washington University, Washington, DC20052, USA
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2
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Rodríguez L, García-González R, Arsuaga JL, Carretero JM. Exploring the morphology of adult tibia and fibula from Sima de los Huesos site in sierra de Atapuerca, Burgos, Spain. Anat Rec (Hoboken) 2024; 307:2606-2634. [PMID: 37792425 DOI: 10.1002/ar.25336] [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: 06/02/2023] [Revised: 09/19/2023] [Accepted: 09/19/2023] [Indexed: 10/05/2023]
Abstract
The analysis of the locomotor anatomy of Late Pleistocene Homo has largely focused on changes in proximal femur and pelvic morphologies, with much attention centered on the emergence of modern humans. Although much of the focus has been on changes in the proximal femur, some research has also been conducted on tibiae and, to a lesser extent, fibulae. With this in mind, we present one of the largest samples of the same population of human tibiae and fibulae from the Middle Pleistocene to determine their main characteristic traits and establish similarities and differences, primarily with those of Neanderthals and modern humans, but also with other Middle Pleistocene specimens in the fossil record. Through this study, we established that the Middle Pleistocene population from the Sima de los Huesos (Atapuerca, Burgos, Spain) had lower leg long bones similar to those of Neanderthals, although there were some important differences, such as bone length, which this fossil individuals resembled those of modern humans and not to Neanderthals. This fact is related to the crural index and leg length, even though we do not have any true association between femora and tibiae yet, it has implications for establishing locomotor efficiency and climate adaptation.
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Affiliation(s)
- Laura Rodríguez
- Area de Antropología Física. Departamento de Biodiversidad y Gestión Ambiental, Universidad de León. Facultad de Ciencias Biológicas y Ambientales. Campus De Vegazana, León, España
- Laboratorio de Evolución Humana, Universidad de Burgos, Burgos, España
| | | | - Juan Luis Arsuaga
- Departamento de Geodinámica, Estratigrafía y Paleontología, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, Madrid, Spain
- Centro UCM-ISCIII de Investigación sobre Evolución y Comportamiento Humanos, Madrid, Spain
| | - José-Miguel Carretero
- Laboratorio de Evolución Humana, Universidad de Burgos, Burgos, España
- Centro UCM-ISCIII de Investigación sobre Evolución y Comportamiento Humanos, Madrid, Spain
- Unidad Asociada de I+D+i al CSIC Vidrio y Materiales del Patrimonio Cultural (VIMPAC), Universidad de Burgos, Burgos, España
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O'Neill MC, Nagano A, Umberger BR. A three-dimensional musculoskeletal model of the pelvis and lower limb of Australopithecus afarensis. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24845. [PMID: 37671481 DOI: 10.1002/ajpa.24845] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 07/08/2023] [Accepted: 08/17/2023] [Indexed: 09/07/2023]
Abstract
OBJECTIVES Musculoskeletal modeling is a powerful approach for studying the biomechanics and energetics of locomotion. Australopithecus (A.) afarensis is among the best represented fossil hominins and provides critical information about the evolution of musculoskeletal design and locomotion in the hominin lineage. Here, we develop and evaluate a three-dimensional (3-D) musculoskeletal model of the pelvis and lower limb of A. afarensis for predicting muscle-tendon moment arms and moment-generating capacities across lower limb joint positions encompassing a range of locomotor behaviors. MATERIALS AND METHODS A 3-D musculoskeletal model of an adult A. afarensis pelvis and lower limb was developed based primarily on the A.L. 288-1 partial skeleton. The model includes geometric representations of bones, joints and 35 muscle-tendon units represented using 43 Hill-type muscle models. Two muscle parameter datasets were created from human and chimpanzee sources. 3-D muscle-tendon moment arms and isometric joint moments were predicted over a wide range of joint positions. RESULTS Predicted muscle-tendon moment arms generally agreed with skeletal metrics, and corresponded with human and chimpanzee models. Human and chimpanzee-based muscle parameterizations were similar, with some differences in maximum isometric force-producing capabilities. The model is amenable to size scaling from A.L. 288-1 to the larger KSD-VP-1/1, which subsumes a wide range of size variation in A. afarensis. DISCUSSION This model represents an important tool for studying the integrated function of the neuromusculoskeletal systems in A. afarensis. It is similar to current human and chimpanzee models in musculoskeletal detail, and will permit direct, comparative 3-D simulation studies.
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Affiliation(s)
- Matthew C O'Neill
- Department of Anatomy, Midwestern University, Glendale, Arizona, USA
| | - Akinori Nagano
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Brian R Umberger
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, USA
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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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Kralick AE, Zemel BS, Nolan C, Lin P, Tocheri MW. Relative leg-to-arm skeletal strength proportions in orangutans by species and sex. J Hum Evol 2024; 188:103496. [PMID: 38412694 DOI: 10.1016/j.jhevol.2024.103496] [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: 04/25/2023] [Revised: 01/02/2024] [Accepted: 01/05/2024] [Indexed: 02/29/2024]
Abstract
Among extant great apes, orangutans climb most frequently. However, Bornean orangutans (Pongo pygmaeus) exhibit higher frequencies of terrestrial locomotion than do Sumatran orangutans (Pongo abelii). Variation in long bone cross-sectional geometry is known to reflect differential loading of the limbs. Thus, Bornean orangutans should show greater relative leg-to-arm strength than their Sumatran counterparts. Using skeletal specimens from museum collections, we measured two cross-sectional geometric measures of bone strength: the polar section modulus (Zpol) and the ratio of maximum to minimum area moments of inertia (Imax/Imin), at the midshaft of long bones in Bornean (n = 19) and Sumatran adult orangutans (n = 12) using medical CT and peripheral quantitative CT scans, and compared results to published data of other great apes. Relative leg-to-arm strength was quantified using ratios of femur and tibia over humerus, radius, and ulna, respectively. Differences between orangutan species and between sexes in median ratios were assessed using Wilcoxon rank sum tests. The tibia of Bornean orangutans was stronger relative to the humerus and the ulna than in Sumatran orangutans (p = 0.008 and 0.025, respectively), consistent with behavioral studies that indicate higher frequencies of terrestrial locomotion in the former. In three Zpol ratios, adult female orangutans showed greater leg-to-arm bone strength compared to flanged males, which may relate to females using their legs more during arboreal locomotion than in adult flanged males. A greater amount of habitat discontinuity on Borneo compared to Sumatra has been posited as a possible explanation for observed interspecific differences in locomotor behaviors, but recent camera trap studies has called this into question. Alternatively, greater frequencies of terrestriality in Pongo pygmaeus may be due to the absence of tigers on Borneo. The results of this study are consistent with the latter explanation given that habitat continuity was greater a century ago when our study sample was collected.
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Affiliation(s)
- Alexandra E Kralick
- Studies of Women, Gender, and Sexuality, Harvard University, Cambridge, 02138, USA; Department of Anthropology, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
| | - Babette S Zemel
- Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; Department of Pediatrics, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Clara Nolan
- Fine Arts Department, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Computer and Information Science, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Phillip Lin
- Stockdale High School, Bakersfield, CA, 93311, USA
| | - Matthew W Tocheri
- Department of Anthropology, Lakehead University, Thunder Bay, Ontario, P7B 5E1, Canada; Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, D.C., 20013, USA; Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales, NSW, 2522, Australia
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6
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Koneru MC, Harper CM. Comparing lateral plantar process trabecular structure to other regions of the human calcaneus. Anat Rec (Hoboken) 2024. [PMID: 38357839 DOI: 10.1002/ar.25406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/22/2024] [Accepted: 01/28/2024] [Indexed: 02/16/2024]
Abstract
Investigating skeletal adaptations to bipedalism informs our understanding of form-function relationships. The calcaneus is an important skeletal element to study because it is a weight-bearing bone with a critical locomotor role. Although other calcaneal regions have been well studied, we lack a clear understanding of the functional role of the lateral plantar process (LPP). The LPP is a bony protuberance on the inferolateral portion of the calcaneus thought to aid the tuberosity in transmission of ground reaction forces during heel-strike. Here, we analyze LPP internal trabecular structure relative to other calcaneal regions to investigate its potential functional affinities. Human calcanei (n = 20) were micro-CT scanned, and weighted spherical harmonic analysis outputs were used to position 251 volumes of interest (VOI) within each bone. Trabecular thickness (Tb.Th), spacing (Tb.Sp), degree of anisotropy (DA), and bone volume fraction (BV/TV) were calculated for each VOI. Similarities in BV/TV and DA (p = 0.2741) between the LPP and inferior tuberosity support suggestions that the LPP is a weight-bearing structure that may transmit forces in a similar direction. The LPP significantly differs from the inferior tuberosity in Tb.Th and Tb.Sp (p < 0.05). Relatively thinner, more closely spaced trabeculae in the LPP may serve to increase internal surface area to compensate for its relatively small size compared to the tuberosity. Significant differences in all parameters between LPP and joint articular surfaces indicate that trabecular morphology is differently adapted for the transmission of forces associated with body mass through joints.
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Affiliation(s)
- Manisha C Koneru
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey, USA
| | - Christine M Harper
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey, USA
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Miller CK, DeSilva JM. A review of the distal femur in Australopithecus. Evol Anthropol 2024; 33:e22012. [PMID: 38009942 DOI: 10.1002/evan.22012] [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: 07/22/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/29/2023]
Abstract
In 1938, the first distal femur of a fossil Australopithecus was discovered at Sterkfontein, South Africa. A decade later, another distal femur was discovered at the same locality. These two fossil femora were the subject of a foundational paper authored by Kingsbury Heiple and Owen Lovejoy in 1971. In this paper, the authors discussed functionally relevant anatomies of these two fossil femora and noted their strong affinity to the modern human condition. Here, we update this work by including eight more fossil Australopithecus distal femora, an expanded comparative dataset, as well as additional linear measurements. Just as Heiple and Lovejoy reported a half-century ago, we find strong overlap between modern humans and cercopithecoids, except for inferiorly flattened condyles and a high bicondylar angle, both of which characterize modern humans and Australopithecus and are directly related to striding bipedalism. All other measured aspects of the femora are by-products of these key morphological traits. Additional fossil material from the early Pliocene will help to inform the evolution of the hominin distal femur and its condition in the Pan-Homo common ancestor that preceded bipedal locomotion.
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Affiliation(s)
- Catherine K Miller
- Department of Anthropology, Dartmouth College, Hanover, New Hampshire, USA
- Ecology, Evolution, Ecosystems, and Society Graduate Program, Dartmouth College, Hanover, New Hampshire, USA
| | - Jeremy M DeSilva
- Department of Anthropology, Dartmouth College, Hanover, New Hampshire, USA
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
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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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Wiseman AL, Charles JP, Hutchinson JR. Static versus dynamic muscle modelling in extinct species: a biomechanical case study of the Australopithecus afarensis pelvis and lower extremity. PeerJ 2024; 12:e16821. [PMID: 38313026 PMCID: PMC10838096 DOI: 10.7717/peerj.16821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 01/02/2024] [Indexed: 02/06/2024] Open
Abstract
The force a muscle generates is dependent on muscle structure, in which fibre length, pennation angle and tendon slack length all influence force production. Muscles are not preserved in the fossil record and these parameters must be estimated when constructing a musculoskeletal model. Here, we test the capability of digitally reconstructed muscles of the Australopithecus afarensis model (specimen AL 288-1) to maintain an upright, single-support limb posture. Our aim was to ascertain the influence that different architectural estimation methods have on muscle specialisation and on the subsequent inferences that can be extrapolated about limb function. Parameters were estimated for 36 muscles in the pelvis and lower limb and seven different musculoskeletal models of AL 288-1 were produced. These parameters represented either a 'static' Hill-type muscle model (n = 4 variants) which only incorporated force, or instead a 'dynamic' Hill-type muscle model with an elastic tendon and fibres that could vary force-length-velocity properties (n = 3 variants). Each muscle's fibre length, pennation angle, tendon slack length and maximal isometric force were calculated based upon different input variables. Static (inverse) simulations were computed in which the vertical and mediolateral ground reaction forces (GRF) were incrementally increased until limb collapse (simulation failure). All AL 288-1 variants produced somewhat similar simulated muscle activation patterns, but the maximum vertical GRF that could be exerted on a single limb was not consistent between models. Three of the four static-muscle models were unable to support >1.8 times body weight and produced models that under-performed. The dynamic-muscle models were stronger. Comparative results with a human model imply that similar muscle group activations between species are needed to sustain single-limb support at maximally applied GRFs in terms of the simplified static simulations (e.g., same walking pose) used here. This approach demonstrated the range of outputs that can be generated for a model of an extinct individual. Despite mostly comparable outputs, the models diverged mostly in terms of strength.
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Affiliation(s)
- Ashleigh L.A. Wiseman
- McDonald Institute for Archaeological Research, University of Cambridge, Cambridge, United Kingdom
| | - James P. Charles
- Evolutionary Morphology and Biomechanics Lab, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - John R. Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, United Kingdom
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10
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Harper CM, Roach CS, Goldstein DM, Sylvester AD. Morphological variation of the Pan talus relative to that of Gorilla. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023. [PMID: 37300336 DOI: 10.1002/ajpa.24796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 03/27/2023] [Accepted: 05/27/2023] [Indexed: 06/12/2023]
Abstract
OBJECTIVES Differences in talar articular morphology relative to locomotion have recently been found within Pan and Gorilla. Whole-bone talar morphology within, and shared variation among, Pan and Gorilla (sub)species, however, has yet to be investigated. Here we separately analyze talar external shape within Pan (P. t. troglodytes, P. t. schweinfurthii, P. t. verus, P. paniscus) and Gorilla (G. g. gorilla, G. b. beringei, G. b. graueri) relative to degree of arboreality and body size. Pan and Gorilla are additionally analyzed together to determine if consistent shape differences exist within the genera. MATERIALS AND METHODS Talar external shape was quantified using a weighted spherical harmonic analysis. Shape variation both within and among Pan and Gorilla was described using principal component analyses. Root mean square distances were calculated between taxon averages, and resampling statistics conducted to test for pairwise differences. RESULTS P. t. verus (most arboreal Pan) talar shape significantly differs from other Pan taxa (p < 0.05 for pairwise comparisons) driven by more asymmetrical trochlear rims and a medially-set talar head. P. t. troglodytes, P. t. schweinfurthii, and P. paniscus do not significantly differ (p > 0.05 for pairwise comparisons). All gorilla taxa exhibit significantly different talar morphologies (p < 0.007 for pairwise comparisons). The more terrestrial subspecies of G. beringei and P. troglodytes exhibit a superoinferiorly taller talar head/neck complex. DISCUSSION P. t. verus exhibits talar morphologies that have been previously related to more frequent arboreality. The adaptations in the more terrestrial G. beringei and P. troglodytes subspecies may serve to facilitate load transmission.
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Affiliation(s)
- Christine M Harper
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey, USA
| | - Caleigh S Roach
- Krieger School of Arts and Sciences, The Johns Hopkins University, Baltimore, Maryland, USA
| | - Deanna M Goldstein
- Department of Anatomical Sciences, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, USA
| | - Adam D Sylvester
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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11
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Wiseman ALA. Three-dimensional volumetric muscle reconstruction of the Australopithecus afarensis pelvis and limb, with estimations of limb leverage. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230356. [PMID: 37325588 PMCID: PMC10265029 DOI: 10.1098/rsos.230356] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 05/24/2023] [Indexed: 06/17/2023]
Abstract
To understand how an extinct species may have moved, we first need to reconstruct the missing soft tissues of the skeleton, which rarely preserve, with an understanding of segmental volume and muscular composition within the body. The Australopithecus afarensis specimen AL 288-1 is one of the most complete hominin skeletons. Despite 40+ years of research, the frequency and efficiency of bipedal movement in this specimen is still debated. Here, 36 muscles of the pelvis and lower limb were reconstructed using three-dimensional polygonal modelling, guided by imaging scan data and muscle scarring. Reconstructed muscle masses and configurations guided musculoskeletal modelling of the lower limb in comparison with a modern human. Results show that the moment arms of both species were comparable, hinting towards similar limb functionality. Moving forward, the polygonal muscle modelling approach has demonstrated promise for reconstructing the soft tissues of hominins and providing information on muscle configuration and space filling. This method demonstrates that volumetric reconstructions are required to know where space must be occupied by muscles and thus where lines of action might not be feasible due to interference with another muscle. This approach is effective for reconstructing muscle volumes in extinct hominins for which musculature is unknown.
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12
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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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Longman DP, Dolan E, Wells JCK, Stock JT. Patterns of energy allocation during energetic scarcity; evolutionary insights from ultra-endurance events. Comp Biochem Physiol A Mol Integr Physiol 2023; 281:111422. [PMID: 37031854 DOI: 10.1016/j.cbpa.2023.111422] [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: 01/30/2023] [Revised: 04/06/2023] [Accepted: 04/06/2023] [Indexed: 04/11/2023]
Abstract
Exercise physiologists and evolutionary biologists share a research interest in determining patterns of energy allocation during times of acute or chronic energetic scarcity.. Within sport and exercise science, this information has important implications for athlete health and performance. For evolutionary biologists, this would shed new light on our adaptive capabilities as a phenotypically plastic species. In recent years, evolutionary biologists have begun recruiting athletes as study participants and using contemporary sports as a model for studying evolution. This approach, known as human athletic palaeobiology, has identified ultra-endurance events as a valuable experimental model to investigate patterns of energy allocation during conditions of elevated energy demand, which are generally accompanied by an energy deficit. This energetic stress provokes detectable functional trade-offs in energy allocation between physiological processes. Early results from this modelsuggest thatlimited resources are preferentially allocated to processes which could be considered to confer the greatest immediate survival advantage (including immune and cognitive function). This aligns with evolutionary perspectives regarding energetic trade-offs during periods of acute and chronic energetic scarcity. Here, we discuss energy allocation patterns during periods of energetic stress as an area of shared interest between exercise physiology and evolutionary biology. We propose that, by addressing the ultimate "why" questions, namely why certain traits were selected for during the human evolutionary journey, an evolutionary perspective can complement the exercise physiology literature and provide a deeper insight of the reasons underpinning the body's physiological response to conditions of energetic stress.
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Affiliation(s)
- Daniel P Longman
- School of Sport, Health and Exercise Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom.
| | - Eimear Dolan
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Rheumatology Division, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil
| | - Jonathan C K Wells
- Childhood Nutrition Research Centre, UCL Institute of Child Health, London WC1N 1EH, United Kingdom
| | - Jay T Stock
- Department of Archaeology, University of Cambridge, Cambridge CB2 3QG, United Kingdom; Department of Anthropology, University of Western Ontario, Ontario, Canada
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Meyer MR, Jung JP, Spear JK, Araiza IF, Galway-Witham J, Williams SA. Knuckle-walking in Sahelanthropus? Locomotor inferences from the ulnae of fossil hominins and other hominoids. J Hum Evol 2023; 179:103355. [PMID: 37003245 DOI: 10.1016/j.jhevol.2023.103355] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 03/03/2023] [Accepted: 03/03/2023] [Indexed: 04/03/2023]
Abstract
Because the ulna supports and transmits forces during movement, its morphology can signal aspects of functional adaptation. To test whether, like extant apes, some hominins habitually recruit the forelimb in locomotion, we separate the ulna shaft and ulna proximal complex for independent shape analyses via elliptical Fourier methods to identify functional signals. We examine the relative influence of locomotion, taxonomy, and body mass on ulna contours in Homo sapiens (n = 22), five species of extant apes (n = 33), two Miocene apes (Hispanopithecus and Danuvius), and 17 fossil hominin specimens including Sahelanthropus, Ardipithecus, Australopithecus, Paranthropus, and early Homo. Ulna proximal complex contours correlate with body mass but not locomotor patterns, while ulna shafts significantly correlate with locomotion. African apes' ulna shafts are more robust and curved than Asian apes and are unlike other terrestrial mammals (including other primates), curving ventrally rather than dorsally. Because this distinctive curvature is absent in orangutans and hylobatids, it is likely a function of powerful flexors engaged in wrist and hand stabilization during knuckle-walking, and not an adaptation to climbing or suspensory behavior. The OH 36 (purported Paranthropus boisei) and TM 266 (assigned to Sahelanthropus tchadensis) fossils differ from other hominins by falling within the knuckle-walking morphospace, and thus appear to show forelimb morphology consistent with terrestrial locomotion. Discriminant function analysis classifies both OH 36 and TM 266 with Pan and Gorilla with high posterior probability. Along with its associated femur, the TM 266 ulna shaft contours and its deep, keeled trochlear notch comprise a suite of traits signaling African ape-like quadrupedalism. While implications for the phylogenetic position and hominin status of S. tchadensis remain equivocal, this study supports the growing body of evidence indicating that S. tchadensis was not an obligate biped, but instead represents a late Miocene hominid with knuckle-walking adaptations.
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Affiliation(s)
- Marc R Meyer
- Department of Anthropology, Chaffey College, Rancho Cucamonga, CA 91737, USA.
| | - Jason P Jung
- Department of Biology, California State University, San Bernardino, CA 92407, USA
| | - Jeffrey K Spear
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY 10024, USA
| | - Isabella Fx Araiza
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY 10024, USA
| | - Julia Galway-Witham
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY 10024, USA
| | - Scott A Williams
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY 10024, USA
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15
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Stamos PA, Alemseged Z. Hominin locomotion and evolution in the Late Miocene to Late Pliocene. J Hum Evol 2023; 178:103332. [PMID: 36947894 DOI: 10.1016/j.jhevol.2023.103332] [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: 05/10/2022] [Revised: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 03/24/2023]
Abstract
In this review, we present on the evolution of the locomotor adaptation of hominins in the Late Miocene to Late Pliocene, with emphasis on some of the prominent advances and debates that have occurred over the past fifty years. We start with the challenging issue of defining hominin locomotor grades that are currently used liberally and offer our own working definitions of facultative, habitual, and obligate bipedalism. We then discuss the nature of the Pan-Homo last common ancestor and characterize the locomotor adaptation of Sahelanthropus, Orrorin, and Ardipithecus-often referred to as facultative bipeds-and examine the debates on the extent of bipedality and arboreality in these taxa. Moreover, the question of Middle Pliocene hominin locomotor diversity is addressed based on information derived from the 'Little Foot' specimen from Sterkfontein, footprints from Laetoli, and the Burtele Foot in Ethiopia. Our review suggests that the most convincing evidence for locomotor diversity comes from Burtele, whereas the evidence from Sterkfontein and Laetoli is unconvincing and equivocal, respectively. Finally, we address the decades old issue of the significance of arboreality in the otherwise habitual biped, Australopithecus, with emphasis on Australopithecus afarensis and its implications for the paleobiology of these creatures. We conclude that many of the apelike features encountered, mostly in the upper part of the Australopithecus skeleton, were retained for their significance in climbing. Approaches that have investigated character plasticity and those exploring internal bone structure have shown that the shoulder and limbs in Au. afarensis and Australopithecus africanus were involved in arboreal activities that are thought to be key for feeding, nesting, and predator avoidance. We conclude that many of the so-called retained ape-like features persisted due to stabilizing selection, that early hominins engaged in a considerable amount of arboreality even after Australopithecus had become a habitual biped, and arboreality only ceased to be an important component of hominin locomotor behavior after the emergence of Homo erectus.
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Affiliation(s)
- Peter A Stamos
- Department of Organismal Biology & Anatomy, The University of Chicago, Anatomy Bldg 201, 1027 E 57th Street, Chicago, IL 60637, USA
| | - Zeresenay Alemseged
- Department of Organismal Biology & Anatomy, The University of Chicago, Anatomy Bldg 201, 1027 E 57th Street, Chicago, IL 60637, USA.
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16
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Avni HL, Shvalb N, Pokhojaev A, Francis S, Pelleg-Kallevag R, Roul V, Hublin JJ, Rühli F, May H. Evolutionary roots of the risk of hip fracture in humans. Commun Biol 2023; 6:283. [PMID: 36932194 PMCID: PMC10023703 DOI: 10.1038/s42003-023-04633-4] [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: 08/14/2022] [Accepted: 02/27/2023] [Indexed: 03/19/2023] Open
Abstract
The transition to bipedal locomotion was a fundamental milestone in human evolution. Consequently, the human skeleton underwent substantial morphological adaptations. These adaptations are responsible for many of today's common physical impairments, including hip fractures. This study aims to reveal the morphological changes in the proximal femur, which increase the risk of intracapsular hip fractures in present-day populations. Our sample includes chimpanzees, early hominins, early Homo Neanderthals, as well as prehistoric and recent humans. Using Geometric Morphometric methods, we demonstrate differences in the proximal femur shape between hominids and populations that practiced different lifestyles. We show that the proximal femur morphology is a risk factor for intracapsular hip fracture independent of osteoporosis. Changes in the proximal femur, such as the shortening of the femoral neck and an increased anterolateral expansion of the greater trochanter, are associated with an increased risk for intracapsular hip fractures. We conclude that intracapsular hip fractures are a trade-off for efficient bipedal walking in humans, and their risk is exacerbated by reduced physical activity.
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Affiliation(s)
- Hadas Leah Avni
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
- The Shmunis Family Anthropology Institute, the Dan David Center for Human Evolution and Biohistory Research, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Nir Shvalb
- Mechanical Engineering Department, Ariel University, Ariel, 40700, Israel
| | - Ariel Pokhojaev
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
- The Shmunis Family Anthropology Institute, the Dan David Center for Human Evolution and Biohistory Research, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
- Department of Oral Biology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Samuel Francis
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
- The Shmunis Family Anthropology Institute, the Dan David Center for Human Evolution and Biohistory Research, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Ruth Pelleg-Kallevag
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
- The Shmunis Family Anthropology Institute, the Dan David Center for Human Evolution and Biohistory Research, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
- Zefat Academic College, Zefat, Israel
| | - Victoria Roul
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
- The Shmunis Family Anthropology Institute, the Dan David Center for Human Evolution and Biohistory Research, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Jean-Jacques Hublin
- Chaire de Paléoanthropologie, CIRB (UMR 7241 - U1050), Collège de France, Paris, 75231, France
- Max-Planck Institute for Evolutionary Anthropology, Leipzig, 04103, Germany
| | - Frank Rühli
- Institute of Evolutionary Medicine, University of Zurich, Zurich, CH-8057, Switzerland
| | - Hila May
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel.
- The Shmunis Family Anthropology Institute, the Dan David Center for Human Evolution and Biohistory Research, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel.
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17
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Hatala KG, Roach NT, Behrensmeyer AK. Fossil footprints and what they mean for hominin paleobiology. Evol Anthropol 2023; 32:39-53. [PMID: 36223539 DOI: 10.1002/evan.21963] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 05/10/2022] [Accepted: 09/18/2022] [Indexed: 11/07/2022]
Abstract
Hominin footprints have not traditionally played prominent roles in paleoanthropological studies, aside from the famous 3.66 Ma footprints discovered at Laetoli, Tanzania in the late 1970s. This contrasts with the importance of trace fossils (ichnology) in the broader field of paleontology. Lack of attention to hominin footprints can probably be explained by perceptions that these are exceptionally rare and "curiosities" rather than sources of data that yield insights on par with skeletal fossils or artifacts. In recent years, however, discoveries of hominin footprints have surged in frequency, shining important new light on anatomy, locomotion, behaviors, and environments from a wide variety of times and places. Here, we discuss why these data are often overlooked and consider whether they are as "rare" as previously assumed. We review new ways footprint data are being used to address questions about hominin paleobiology, and we outline key opportunities for future research in hominin ichnology.
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Affiliation(s)
- Kevin G Hatala
- Department of Biology, Chatham University, Pittsburgh, Pennsylvania, USA
| | - Neil T Roach
- Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Anna K Behrensmeyer
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, USA
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18
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Cazenave M, Kivell TL. Challenges and perspectives on functional interpretations of australopith postcrania and the reconstruction of hominin locomotion. J Hum Evol 2023; 175:103304. [PMID: 36563461 DOI: 10.1016/j.jhevol.2022.103304] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 12/24/2022]
Abstract
In 1994, Hunt published the 'postural feeding hypothesis'-a seminal paper on the origins of hominin bipedalism-founded on the detailed study of chimpanzee positional behavior and the functional inferences derived from the upper and lower limb morphology of the Australopithecus afarensis A.L. 288-1 partial skeleton. Hunt proposed a model for understanding the potential selective pressures on hominins, made robust, testable predictions based on Au. afarensis functional morphology, and presented a hypothesis that aimed to explain the dual functional signals of the Au. afarensis and, more generally, early hominin postcranium. Here we synthesize what we have learned about Au. afarensis functional morphology and the dual functional signals of two new australopith discoveries with relatively complete skeletons (Australopithecus sediba and StW 573 'Australopithecus prometheus'). We follow this with a discussion of three research approaches that have been developed for the purpose of drawing behavioral inferences in early hominins: (1) developments in the study of extant apes as models for understanding hominin origins; (2) novel and continued developments to quantify bipedal gait and locomotor economy in extant primates to infer the locomotor costs from the anatomy of fossil taxa; and (3) novel developments in the study of internal bone structure to extract functional signals from fossil remains. In conclusion of this review, we discuss some of the inherent challenges of the approaches and methodologies adopted to reconstruct the locomotor modes and behavioral repertoires in extinct primate taxa, and notably the assessment of habitual terrestrial bipedalism in early hominins.
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Affiliation(s)
- Marine Cazenave
- Division of Anthropology, American Museum of Natural History, New York, USA; Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK; Department of Anatomy, Faculty of Health Sciences, University of Pretoria, South Africa.
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK; Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
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19
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Figus C, Stephens NB, Sorrentino R, Bortolini E, Arrighi S, Higgins OA, Lugli F, Marciani G, Oxilia G, Romandini M, Silvestrini S, Baruffaldi F, Belcastro MG, Bernardini F, Festa A, Hajdu T, Mateovics‐László O, Pap I, Szeniczey T, Tuniz C, Ryan TM, Benazzi S. Morphologies in-between: The impact of the first steps on the human talus. Anat Rec (Hoboken) 2023; 306:124-142. [PMID: 35656925 PMCID: PMC10083965 DOI: 10.1002/ar.25010] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/15/2022] [Accepted: 05/16/2022] [Indexed: 01/29/2023]
Abstract
OBJECTIVE The development of bipedalism is a very complex activity that contributes to shaping the anatomy of the foot. The talus, which starts ossifying in utero, may account for the developing stages from the late gestational phase onwards. Here, we explore the early development of the talus in both its internal and external morphology to broaden the knowledge of the anatomical changes that occur during early development. MATERIALS AND METHODS The sample consists of high-resolution microCT scans of 28 modern juvenile tali (from 36 prenatal weeks to 2 years), from a broad chronological range from the Late Roman period to the 20th century. We applied geometric morphometric and whole-bone trabecular analysis to investigate the early talar morphological changes. RESULTS In the youngest group (<6 postnatal months), the immature external shell is accompanied by an isotropic internal structure, with thin and densely packed trabeculae. After the initial attempts of locomotion, bone volume fraction decreases, while anisotropy and trabecular thickness increase. These internal changes correspond to the maturation of the external shell, which is now more defined and shows the development of the articular surfaces. DISCUSSION The internal and external morphology of the human talus reflects the diverse load on the foot during the initial phases of the bipedal locomotion, with the youngest group potentially reflecting the lack of readiness of the human talus to bear forces and perform bipedal walking. These results highlight the link between mechanical loading and bone development in the human talus during the acquisition of bipedalism, providing new insight into the early phases of talar development.
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Affiliation(s)
- Carla Figus
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Nicholas B. Stephens
- Department of AnthropologyPennsylvania State UniversityState CollegePennsylvaniaUSA
| | - Rita Sorrentino
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Department of Biological, Geological and Environmental Sciences – BigeaUniversity of BolognaBolognaItaly
| | - Eugenio Bortolini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Human Ecology and Archaeology (HUMANE)IMF, CSI0CBarcelonaSpain
| | - Simona Arrighi
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Owen A. Higgins
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Federico Lugli
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Giulia Marciani
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Research Unit Prehistory and Anthropology, Department of Physical Sciences, Earth and EnvironmentUniversity of SienaSienaItaly
| | - Gregorio Oxilia
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Matteo Romandini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Sara Silvestrini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Fabio Baruffaldi
- Laboratory of Medical TechnologyIRCCS Istituto Ortopedico RizzoliBolognaItaly
| | - Maria Giovanna Belcastro
- Department of Biological, Geological and Environmental Sciences – BigeaUniversity of BolognaBolognaItaly
| | - Federico Bernardini
- Department of Humanistic StudiesUniversità Ca'FoscariVeneziaItaly
- Multidisciplinary LaboratoryAbdus Salam International Centre for Theoretical PhysicsTriesteItaly
| | - Anna Festa
- Laboratory of Medical TechnologyIRCCS Istituto Ortopedico RizzoliBolognaItaly
| | - Tamás Hajdu
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
| | | | - Ildiko Pap
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
- Department of Biological Anthropology, Institute of Biology, Faculty of Science and InformaticsSzeged UniversitySzegedHungary
- Department of AnthropologyHungarian Natural History MuseumBudapestHungary
| | - Tamás Szeniczey
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
| | - Claudio Tuniz
- Multidisciplinary LaboratoryAbdus Salam International Centre for Theoretical PhysicsTriesteItaly
- Centre for Archaeological ScienceUniversity of WollongongWollongongNew South WalesAustralia
| | - Timothy M. Ryan
- Department of AnthropologyPennsylvania State UniversityState CollegePennsylvaniaUSA
| | - Stefano Benazzi
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Department of Human EvolutionMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
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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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21
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Sarringhaus L, Lewton KL, Iqbal S, Carlson KJ. Ape femoral-humeral rigidities and arboreal locomotion. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 179:624-639. [PMID: 36790629 PMCID: PMC9828227 DOI: 10.1002/ajpa.24632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 06/29/2022] [Accepted: 09/13/2022] [Indexed: 11/07/2022]
Abstract
OBJECTIVES This study investigates patterns of bone functional adaptations in extant apes through comparing hindlimb to forelimb bone rigidity ratios in groups with varying levels of arboreality. MATERIALS AND METHODS Using CT scans, bone rigidity (J) was calculated at three regions of interest (ROI) along femoral and humeral diaphyses in Homo, Pongo, Pan, and Gorilla with further comparisons made between species and subspecies divisions within Pan and Gorilla. RESULTS Consistent with previous work on extant hominoids, species exhibited differences in midshaft femoral to humeral (F/H) rigidity ratios. Results of the present study confirm that these midshaft differences extend to 35% and 65% diaphyseal ROIs. Modern humans, exhibiting larger ratios, and orangutans, exhibiting smaller ratios, bracketed the intermediate African apes in comparisons. Within some African apes, limb rigidity ratios varied significantly between taxonomic groups. Eastern gorillas exhibited the highest mean ratios and chimpanzees the lowest at all three ROIs. In posthoc comparisons, chimpanzees and bonobos did not differ in relative limb rigidity ratios at any of the three ROIs. However, western gorillas were more similar to bonobos than eastern gorillas at 50% and 35% ROIs, but not at the 65% ROI. CONCLUSION Species, and to a lesser extent subspecies, can be distinguished by F/H limb rigidity ratios according to broad positional behavior patterns at multiple regions of interest along the diaphyses. Similarity of bonobos and western gorillas is in line with behavioral data of bonobos being the most terrestrial of Pan species, and western gorillas the most arboreal of the Gorilla groups.
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Affiliation(s)
- Lauren Sarringhaus
- Department of Evolutionary AnthropologyDuke UniversityDurhamNorth CarolinaUSA,Department of AnthropologyUniversity of MichiganAnn ArborMichiganUSA,Department of BiologyJames Madison UniversityHarrisonburgVirginiaUSA
| | - Kristi L. Lewton
- Department of Integrative Anatomical Sciences, Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Safiyyah Iqbal
- School of Animal, Plant and Environmental SciencesUniversity of the WitwatersrandJohannesburgSouth Africa
| | - Kristian J. Carlson
- Department of Integrative Anatomical Sciences, Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCaliforniaUSA,Evolutionary Studies InstituteUniversity of the WitwatersrandJohannesburgSouth Africa
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22
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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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23
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Wiseman ALA, Demuth OE, Pomeroy E, De Groote I. Reconstructing Articular Cartilage in the Australopithecus afarensis Hip Joint and the Need for Modeling Six Degrees of Freedom. Integr Org Biol 2022; 4:obac031. [PMID: 36060864 PMCID: PMC9428927 DOI: 10.1093/iob/obac031] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 07/08/2022] [Accepted: 07/26/2022] [Indexed: 11/13/2022] Open
Abstract
Synopsis
The postcranial skeleton of Australopithecus afarensis (AL 288–1) exhibits clear adaptations for bipedality, although there is some debate as to the efficiency and frequency of such upright movement. Some researchers argue that AL 288–1 walked with an erect limb like modern humans do, whilst others advocate for a “bent-hip bent-knee” (BHBK) gait, although in recent years the general consensus favors erect bipedalism. To date, no quantitative method has addressed the articulation of the AL 288–1 hip joint, nor its range of motion (ROM) with consideration for joint spacing, used as a proxy for the thickness of the articular cartilage present within the joint spacing which can affect how a joint moves. Here, we employed ROM mapping methods to estimate the joint spacing of AL 288–1’s hip joint in comparison to a modern human and chimpanzee. Nine simulations assessed different joint spacing and tested the range of joint congruency (i.e., ranging from a closely packed socket to loosely packed). We further evaluated the sphericity of the femoral head and whether three rotational degrees of freedom (DOFs) sufficiently captures the full ROM or if translational DOFs must be included. With both setups, we found that the AL 288–1 hip was unlikely to be highly congruent (as it is in modern humans) because this would severely restrict hip rotational movement and would severely limit the capability for both bipedality and even arboreal locomotion. Rather, the hip was more cartilaginous than it is in the modern humans, permitting the hip to rotate into positions necessitated by both terrestrial and arboreal movements. Rotational-only simulations found that AL 288–1 was unable to extend the hip like modern humans, forcing the specimen to employ a BHBK style of walking, thus contradicting 40+ years of previous research into the locomotory capabilities of AL 288–1. Therefore, we advocate that differences in the sphericity of the AL 288–1 femoral head with that of a modern human necessitates all six DOFs to be included in which AL 288–1 could osteologically extend the hip to facilitate a human-like gait.
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Affiliation(s)
- Ashleigh L A Wiseman
- McDonald Institute for Archaeological Research, University of Cambridge , Cambridge CB2 1TN
- Research Centre in Evolutionary Anthropology and Paleoecology, Liverpool John Moores University , Liverpool, Merseyside L3 5UX
| | - Oliver E Demuth
- Department of Earth Sciences, University of Cambridge , Cambridge CB2 1TN
- Structure and Motion Laboratory , Royal Veterinary College, London NW1 0TU
| | - Emma Pomeroy
- Department of Archaeology, University of Cambridge , Cambridge CB2 1TN
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24
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Marino FE, Sibson BE, Lieberman DE. The evolution of human fatigue resistance. J Comp Physiol B 2022; 192:411-422. [PMID: 35552490 PMCID: PMC9197885 DOI: 10.1007/s00360-022-01439-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 03/28/2022] [Accepted: 04/20/2022] [Indexed: 11/26/2022]
Abstract
Humans differ from African great apes in numerous respects, but the chief initial difference setting hominins on their unique evolutionary trajectory was habitual bipedalism. The two most widely supported selective forces for this adaptation are increased efficiency of locomotion and improved ability to feed in upright contexts. By 4 million years ago, hominins had evolved the ability to walk long distances but extreme selection for endurance capabilities likely occurred later in the genus Homo to help them forage, power scavenge and persistence hunt in hot, arid conditions. In this review we explore the hypothesis that to be effective long-distance walkers and especially runners, there would also have been a strong selective benefit among Homo to resist fatigue. Our hypothesis is that since fatigue is an important factor that limits the ability to perform endurance-based activities, fatigue resistance was likely an important target for selection during human evolution for improved endurance capabilities. We review the trade-offs between strength, power, and stamina in apes and Homo and discuss three biological systems that we hypothesize humans evolved adaptations for fatigue resistance: neurological, metabolic and thermoregulatory. We conclude that the evolution of endurance at the cost of strength and power likely also involved the evolution of mechanisms to resist fatigue.
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Affiliation(s)
- Frank E Marino
- School of Allied Health, Exercise and Sport Science, Charles Sturt University, Bathurst, NSW, 2795, Australia.
| | - Benjamin E Sibson
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Ave, Cambridge, MA, 02138, USA
| | - Daniel E Lieberman
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Ave, Cambridge, MA, 02138, USA
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25
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van Heteren AH, Friess M, Détroit F, Balzeau A. Covariation of proximal finger and toe phalanges in Homo sapiens: A novel approach to assess covariation of serially corresponding structures. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 177:471-488. [PMID: 36787692 DOI: 10.1002/ajpa.24439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 08/13/2021] [Accepted: 10/20/2021] [Indexed: 11/08/2022]
Abstract
OBJECTIVES As hands and feet are serially repeated corresponding structures in tetrapods, the morphology of fingers and toes is expected to covary due to a shared developmental origin. The present study focuses on the covariation of the shape of proximal finger and toe phalanges of adult Homo sapiens to determine whether covariation is different in the first ray relative to the others, as its morphology is also different. MATERIAL AND METHODS Proximal phalanges of 76 individuals of unknown sex (Muséum national d'Histoire naturelle, Paris, and the Natural History Museum, London) were digitized using a surface scanner. Landmarks were positioned on 3D surface models of the phalanges. Generalized Procrustes analysis and two-block partial least squares (PLS) analyses were conducted. A novel landmark-based geometric morphometric approach focusing on covariation is based on a PCoA of the angles between PLS axes in morphospace. The results can be statistically evaluated. RESULTS The difference in PCo scores between the first and the other rays indicates that the integration between the thumb and the big toe is different from that between the lateral rays of the hand and foot. DISCUSSION We speculate that the results are possibly the evolutionary consequence of differential selection pressure on the big toe relative to the other toes related to the rise of bipedalism, which is proposed to have emerged very early in the hominin clade. In contrast, thumb morphology and its precision grip never ceased undergoing changes, suggesting less acute selection pressures related to the evolution of the precision grip.
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Affiliation(s)
- Anneke H van Heteren
- PaleoFED Team, UMR 7194, CNRS, Département Homme et Environnement, Muséum National d'Histoire Naturelle, Musée de l'Homme, 17, Place du Trocadéro, Paris, 75016, France
| | - Martin Friess
- Éco-Anthropologie, UMR 7206, CNRS, Département Homme et Environnement, Muséum National d'Histoire Naturelle, Université de Paris, Paris, 75016, France
| | - Florent Détroit
- PaleoFED Team, UMR 7194, CNRS, Département Homme et Environnement, Muséum National d'Histoire Naturelle, Musée de l'Homme, 17, Place du Trocadéro, Paris, 75016, France
| | - Antoine Balzeau
- PaleoFED Team, UMR 7194, CNRS, Département Homme et Environnement, Muséum National d'Histoire Naturelle, Musée de l'Homme, 17, Place du Trocadéro, Paris, 75016, France.,Department of African Zoology, Royal Museum for Central Africa, Leuvensesteenweg 13, Tervuren, 3080, Belgium
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26
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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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27
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An Unusually Human Time: Effects of the Most Social Stage on the Most Social Species. EVOLUTIONARY PSYCHOLOGY 2022. [DOI: 10.1007/978-3-030-76000-7_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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28
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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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29
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Anaya A, Patel BA, Orr CM, Ward CV, Almécija S. Evolutionary trends of the lateral foot in catarrhine primates: Contextualizing the fourth metatarsal of Australopithecus afarensis. J Hum Evol 2021; 161:103078. [PMID: 34749002 DOI: 10.1016/j.jhevol.2021.103078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 09/02/2021] [Accepted: 09/02/2021] [Indexed: 11/17/2022]
Abstract
In 2000, a complete fourth metatarsal (Mt4) of the ∼3- to 4-Million-year-old hominin Australopithecus afarensis was recovered in Hadar, Ethiopia. This metatarsal presented a mostly human-like morphology, suggesting that a rigid lateral foot may have evolved as early as ∼3.2 Ma. The lateral foot is integral in providing stability during the push off phase of gait and is key in understanding the transition to upright, striding bipedalism. Previous comparisons of this fossil were limited to Pan troglodytes, Gorilla gorilla, and modern humans. This study builds on previous studies by contextualizing the Mt4 morphology of A. afarensis (A.L. 333-160) within a diverse comparative sample of nonhuman hominoids (n = 144) and cercopithecids (n = 138) and incorporates other early hominins (n = 3) and fossil hominoids that precede the Pan-Homo split (n = 4) to better assess the polarity of changes in lateral foot morphology surrounding this divergence. We investigate seven morphological features argued to be functionally linked to human-like bipedalism. Our results show that some human-like characters used to assess midfoot and lateral foot stiffness in the hominin fossil record are present in our Miocene ape sample as well as in living cercopithecids. Furthermore, modern nonhuman hominoids can be generally distinguished from other species in most metrics. These results suggest that the possession of a rigid foot in hominins could represent a conserved trait, whereas the specialized pedal grasping mechanics of extant apes may be more derived, in which case some traits often used to infer bipedal locomotion in early hominins may, instead, reflect a lower reliance on pedal grasping. Another possibility is that early hominins reverted from modern ape Mt4 morphology into a more plesiomorphic condition when terrestrial bipedality became a dominant behavior. More fossils dating around the Pan-Homo divergence time are necessary to test these competing hypotheses.
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Affiliation(s)
- Alisha Anaya
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27705, USA; Division of Anthropology, American Museum of Natural History, New York, NY, 10024, USA.
| | - 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
| | - 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, 80045, USA
| | - Carol V Ward
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, MO, 65212, USA
| | - Sergio Almécija
- Division of Anthropology, American Museum of Natural History, New York, NY, 10024, USA; New York Consortium of Evolutionary Primatology, New York, NY, 10024, USA; Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Spain
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30
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Sylvester AD, Lautzenheiser SG, Kramer PA. A review of musculoskeletal modelling of human locomotion. Interface Focus 2021; 11:20200060. [PMID: 34938430 DOI: 10.1098/rsfs.2020.0060] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2021] [Indexed: 01/07/2023] Open
Abstract
Locomotion through the environment is important because movement provides access to key resources, including food, shelter and mates. Central to many locomotion-focused questions is the need to understand internal forces, particularly muscle forces and joint reactions. Musculoskeletal modelling, which typically harnesses the power of inverse dynamics, unites experimental data that are collected on living subjects with virtual models of their morphology. The inputs required for producing good musculoskeletal models include body geometry, muscle parameters, motion variables and ground reaction forces. This methodological approach is critically informed by both biological anthropology, with its focus on variation in human form and function, and mechanical engineering, with a focus on the application of Newtonian mechanics to current problems. Here, we demonstrate the application of a musculoskeletal modelling approach to human walking using the data of a single male subject. Furthermore, we discuss the decisions required to build the model, including how to customize the musculoskeletal model, and suggest cautions that both biological anthropologists and engineers who are interested in this topic should consider.
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Affiliation(s)
- Adam D Sylvester
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, 1830 E. Monument Street, Baltimore, MD 21205, USA
| | - Steven G Lautzenheiser
- Department of Anthropology, University of Washington, Denny Hall, Seattle, WA 98195, USA.,Department of Anthropology, The University of Tennessee, Strong Hall, Knoxville, TN 37996, USA
| | - Patricia Ann Kramer
- Department of Anthropology, University of Washington, Denny Hall, Seattle, WA 98195, USA
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31
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Harper CM, Ruff CB, Sylvester AD. Calcaneal shape variation in humans, nonhuman primates, and early hominins. J Hum Evol 2021; 159:103050. [PMID: 34438297 DOI: 10.1016/j.jhevol.2021.103050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 06/29/2021] [Accepted: 06/29/2021] [Indexed: 01/08/2023]
Abstract
The foot has played a prominent role in evaluating early hominin locomotion. The calcaneus, in particular, plays an important role in weight-bearing. Although the calcanei of early hominins have been previously scrutinized, a three-dimensional analysis of the entire calcaneal shape has not been conducted. Here, we investigate the relationship between external calcaneal shape and locomotion in modern Homo sapiens (n = 130), Gorilla (n = 86), Pan (n = 112), Pongo (n = 31), Papio (n = 28), and hylobatids (Hylobates, Symphalangus; n = 32). We use these results to place the calcanei attributed to Australopithecus sediba, A. africanus, A. afarensis, H. naledi, and Homo habilis/Paranthropus boisei into a locomotor context. Calcanei were scanned using either surface scanning or micro-CT and their external shape analyzed using a three-dimensional geometric morphometric sliding semilandmark analysis. Blomberg's K statistic was used to estimate phylogenetic signal in the shape data. Shape variation was summarized using a principal components analysis. Procrustes distances between all taxa as well as distances between each fossil and the average of each taxon were calculated. Blomberg's K statistic was small (K = 0.1651), indicating weak phylogenetic effects, suggesting variation is driven by factors other than phylogeny (e.g., locomotion or body size). Modern humans have a large calcaneus relative to body size and display a uniquely convex cuboid facet, facilitating a rigid midfoot for bipedalism. More arboreal great apes display relatively deeper cuboid facet pivot regions for increased midfoot mobility. Australopithecus afarensis demonstrates the most human-like calcaneus, consistent with obligate bipedalism. Homo naledi is primarily modern human-like, but with some intermediate traits, suggesting a different form of bipedalism than modern humans. Australopithecus africanus, A. sediba, and H. habilis/P. boisei calcanei all possess unique combinations of human and nonhuman ape-like morphologies, suggesting a combination of bipedal and arboreal behaviors.
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Affiliation(s)
- Christine M Harper
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States; Cooper Medical School of Rowan University, Department of Biomedical Sciences, 401 S Broadway, Room 453, Camden, NJ 08103, United States.
| | - Christopher B Ruff
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States
| | - Adam D Sylvester
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States
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32
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Raichlen DA, Pontzer H. Energetic and endurance constraints on great ape quadrupedalism and the benefits of hominin bipedalism. Evol Anthropol 2021; 30:253-261. [PMID: 34347329 DOI: 10.1002/evan.21911] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 01/13/2021] [Accepted: 05/12/2021] [Indexed: 11/10/2022]
Abstract
Bipedal walking was one of the first key behavioral traits that defined the evolution of early hominins. While it is not possible to identify specific selection pressures underlying bipedal evolution, we can better understand how the adoption of bipedalism may have benefited our hominin ancestors. Here, we focus on how bipedalism relaxes constraints on nonhuman primate quadrupedal limb mechanics, providing key advantages during hominin evolution. Nonhuman primate quadrupedal kinematics, especially in our closest living relatives, the great apes, are dominated by highly flexed limb joints, often associated with high energy costs, and are constrained by the need to reduce loads on mobile, but less stable forelimb joints. Bipedal walking would have allowed greater hind limb joint extension, which is associated with reduced energy costs and increased endurance. We suggest that relaxing these constraints provided bipedal hominins important benefits associated with long distance foraging and mobility.
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Affiliation(s)
- David A Raichlen
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Herman Pontzer
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA.,Duke Global Health Institute, Duke University, Durham, North Carolina, USA
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33
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Get a Grip: Variation in Human Hand Grip Strength and Implications for Human Evolution. Symmetry (Basel) 2021. [DOI: 10.3390/sym13071142] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Although hand grip strength is critical to the daily lives of humans and our arboreal great ape relatives, the human hand has changed in form and function throughout our evolution due to terrestrial bipedalism, tool use, and directional asymmetry (DA) such as handedness. Here we investigate how hand form and function interact in modern humans to gain an insight into our evolutionary past. We measured grip strength in a heterogeneous, cross-sectional sample of human participants (n = 662, 17 to 83 years old) to test the potential effects of age, sex, asymmetry (hand dominance and handedness), hand shape, occupation, and practice of sports and musical instruments that involve the hand(s). We found a significant effect of sex and hand dominance on grip strength, but not of handedness, while hand shape and age had a greater influence on female grip strength. Females were significantly weaker with age, but grip strength in females with large hands was less affected than those with long hands. Frequent engagement in hand sports significantly increased grip strength in the non-dominant hand in both sexes, while only males showed a significant effect of occupation, indicating different patterns of hand dominance asymmetries and hand function. These results improve our understanding of the link between form and function in both hands and offer an insight into the evolution of human laterality and dexterity.
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34
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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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35
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Almécija S, Hammond AS, Thompson NE, Pugh KD, Moyà-Solà S, Alba DM. Fossil apes and human evolution. Science 2021; 372:372/6542/eabb4363. [DOI: 10.1126/science.abb4363] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Humans diverged from apes (chimpanzees, specifically) toward the end of the Miocene ~9.3 million to 6.5 million years ago. Understanding the origins of the human lineage (hominins) requires reconstructing the morphology, behavior, and environment of the chimpanzee-human last common ancestor. Modern hominoids (that is, humans and apes) share multiple features (for example, an orthograde body plan facilitating upright positional behaviors). However, the fossil record indicates that living hominoids constitute narrow representatives of an ancient radiation of more widely distributed, diverse species, none of which exhibit the entire suite of locomotor adaptations present in the extant relatives. Hence, some modern ape similarities might have evolved in parallel in response to similar selection pressures. Current evidence suggests that hominins originated in Africa from Miocene ape ancestors unlike any living species.
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Affiliation(s)
- Sergio Almécija
- Division of Anthropology, American Museum of Natural History (AMNH), New York, NY 10024, USA
- New York Consortium in Evolutionary Primatology at AMNH, New York, NY 10024, USA
- Institut Català de Paleontologia Miquel Crusafont (ICP), Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
| | - Ashley S. Hammond
- Division of Anthropology, American Museum of Natural History (AMNH), New York, NY 10024, USA
- New York Consortium in Evolutionary Primatology at AMNH, New York, NY 10024, USA
| | - Nathan E. Thompson
- Department of Anatomy, New York Institute of Technology (NYIT) College of Osteopathic Medicine, Old Westbury, NY 11568, USA
| | - Kelsey D. Pugh
- Division of Anthropology, American Museum of Natural History (AMNH), New York, NY 10024, USA
- New York Consortium in Evolutionary Primatology at AMNH, New York, NY 10024, USA
| | - Salvador Moyà-Solà
- Institut Català de Paleontologia Miquel Crusafont (ICP), Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
- Unitat d’Antropologia Biològica, Departament de Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
| | - David M. Alba
- Institut Català de Paleontologia Miquel Crusafont (ICP), Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
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Bird EE, Kivell TL, Skinner MM. Cortical and trabecular bone structure of the hominoid capitate. J Anat 2021; 239:351-373. [PMID: 33942895 PMCID: PMC8273598 DOI: 10.1111/joa.13437] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 01/02/2023] Open
Abstract
Morphological variation in the hominoid capitate has been linked to differences in habitual locomotor activity due to its importance in movement and load transfer at the midcarpal joint proximally and carpometacarpal joints distally. Although the shape of bones and their articulations are linked to joint mobility, the internal structure of bones has been shown experimentally to reflect, at least in part, the loading direction and magnitude experienced by the bone. To date, it is uncertain whether locomotor differences among hominoids are reflected in the bone microarchitecture of the capitate. Here, we apply a whole‐bone methodology to quantify the cortical and trabecular architecture (separately and combined) of the capitate across bipedal (modern Homo sapiens), knuckle‐walking (Pan paniscus, Pan troglodytes, Gorilla sp.), and suspensory (Pongo sp.) hominoids (n = 69). It is hypothesized that variation in bone microarchitecture will differentiate these locomotor groups, reflecting differences in habitual postures and presumed loading force and direction. Additionally, it is hypothesized that trabecular and cortical architecture in the proximal and distal regions, as a result of being part of mechanically divergent joints proximally and distally, will differ across these portions of the capitate. Results indicate that the capitate of knuckle‐walking and suspensory hominoids is differentiated from bipedal Homo primarily by significantly thicker distal cortical bone. Knuckle‐walking taxa are further differentiated from suspensory and bipedal taxa by more isotropic trabeculae in the proximal capitate. An allometric analysis indicates that size is not a significant determinate of bone variation across hominoids, although sexual dimorphism may influence some parameters within Gorilla. Results suggest that internal trabecular and cortical bone is subjected to different forces and functional adaptation responses across the capitate (and possibly other short bones). Additionally, while separating trabecular and cortical bone is normal protocol of current whole‐bone methodologies, this study shows that when applied to carpals, removing or studying the cortical bone separately potentially obfuscates functionally relevant signals in bone structure.
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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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Cazenave M, Oettlé A, Pickering TR, Heaton JL, Nakatsukasa M, Francis Thackeray J, Hoffman J, Macchiarelli R. Trabecular organization of the proximal femur in Paranthropus robustus: Implications for the assessment of its hip joint loading conditions. J Hum Evol 2021; 153:102964. [PMID: 33713985 DOI: 10.1016/j.jhevol.2021.102964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 11/19/2022]
Abstract
Reconstruction of the locomotor repertoire of the australopiths (Australopithecus and Paranthropus) has progressively integrated information from the mechanosensitive internal structure of the appendicular skeleton. Recent investigations showed that the arrangement of the trabecular network at the femoral head center is biomechanically compatible with the pattern of cortical bone distribution across the neck, both suggesting a full commitment to bipedalism in australopiths, but associated with a slightly altered gait kinematics compared to Homo involving more lateral deviation of the body center of mass over the stance limb. To provide a global picture in Paranthropus robustus of the trabecular architecture of the proximal femur across the head, neck and greater trochanter compartments, we applied techniques of virtual imaging to the variably preserved Early Pleistocene specimens SK 82, SK 97, SK 3121, SKW 19 and SWT1/LB-2 from the cave site of Swartkrans, South Africa. We also assessed the coherence between the structural signals from the center of the head and those from the trabecular network of the inferolateral portion of the head and the inferior margin of the neck, sampling the so-called vertical bundle, which in humans represents the principal compressive system of the joint. Our analyses show a functionally related trabecular organization in Pa. robustus that closely resembles the extant human condition, but which also includes some specificities in local textural arrangement. The network of the inferolateral portion of the head shows a humanlike degree of anisotropy and a bone volume fraction intermediate between the extant human and the African ape patterns. These results suggest slight differences in gait kinematics between Pa. robustus and extant humans. The neck portion of the vertical bundle revealed a less biomechanically sensitive signal. Future investigations on the australopith hip joint loading environment should more carefully investigate the trabecular structure of the trochanteric region and possible structural covariation between cortical bone distribution across the neck and site-specific trabecular properties of the arcuate bundle.
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Affiliation(s)
- Marine Cazenave
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.
| | - Anna Oettlé
- Department of Anatomy and Histology, Sefako Makgatho Health Sciences University, Ga-Rankuwa, Pretoria, South Africa
| | - Travis Rayne Pickering
- Department of Anthropology, University of Wisconsin, Madison, USA; Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa; Plio-Pleistocene Palaeontology Section, Department of Vertebrates, Ditsong National Museum of Natural History (Transvaal Museum), Pretoria, South Africa
| | - Jason L Heaton
- Department of Biology, Birmingham-Southern College, Birmingham, USA; Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa; Plio-Pleistocene Palaeontology Section, Department of Vertebrates, Ditsong National Museum of Natural History (Transvaal Museum), Pretoria, South Africa
| | - Masato Nakatsukasa
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - J Francis Thackeray
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Jakobus Hoffman
- South African Nuclear Energy Corporation SOC Ltd., Pelindaba, South Africa
| | - Roberto Macchiarelli
- Département Homme & Environnement, UMR 7194 CNRS, Muséum national d'Histoire naturelle, 75116, Paris, France; Unité de Formation Géosciences, Université de Poitiers, Poitiers, France
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Something Scary Is Out There: Remembrances of Where the Threat Was Located by Preschool Children and Adults with Nighttime Fear. EVOLUTIONARY PSYCHOLOGICAL SCIENCE 2021. [DOI: 10.1007/s40806-021-00279-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AbstractYoung children frequently report imaginary scary things in their bedrooms at night. This study examined the remembrances of 140 preschool children and 404 adults selecting either above, side, or below locations for a scary thing relative to their beds. The theoretical framework for this investigation posited that sexual-size dimorphism in Australopithecus afarensis, the presumed human ancestor in the Middle Pliocene, constrained sleeping site choice to mitigate predation. Smaller-bodied females nesting in trees would have anticipated predatory attacks from below, while male nesting on the ground would have anticipated attacks from their side. Such anticipation of nighttime attacks from below is present in many arboreal primates and might still persist as a cognitive relict in humans. In remembrances of nighttime fear, girls and women were predicted to select the below location and males the side location. Following interviews of children and adult questionnaires, multinomial log-linear analyses indicated statistically significant interactions (p < 0.001) of sex by location for the combined sample and each age class driven, in part, by larger frequencies of males selecting the side location and females selecting the below location. Data partitioning further revealed that males selected the side location at larger frequencies (p < 0.001) than the below location, whereas female selection of side and below locations did not differ significantly. While indicative of evolutionary persistence in cognitive appraisal of threat locations, the female hypothesis did not consider natural selection acting on assessment of nighttime terrestrial threats following the advent of early Homo in the Late Pliocene.
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van Beesel J, Hutchinson JR, Hublin JJ, Melillo SM. Exploring the functional morphology of the Gorilla shoulder through musculoskeletal modelling. J Anat 2021; 239:207-227. [PMID: 33629406 PMCID: PMC8197971 DOI: 10.1111/joa.13412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 01/27/2021] [Accepted: 02/02/2021] [Indexed: 12/11/2022] Open
Abstract
Musculoskeletal computer models allow us to quantitatively relate morphological features to biomechanical performance. In non‐human apes, certain morphological features have long been linked to greater arm abduction potential and increased arm‐raising performance, compared to humans. Here, we present the first musculoskeletal model of a western lowland gorilla shoulder to test some of these long‐standing proposals. Estimates of moment arms and moments of the glenohumeral abductors (deltoid, supraspinatus and infraspinatus muscles) over arm abduction were conducted for the gorilla model and a previously published human shoulder model. Contrary to previous assumptions, we found that overall glenohumeral abduction potential is similar between Gorilla and Homo. However, gorillas differ by maintaining high abduction moment capacity with the arm raised above horizontal. This difference is linked to a disparity in soft tissue properties, indicating that scapular morphological features like a cranially oriented scapular spine and glenoid do not enhance the abductor function of the gorilla glenohumeral muscles. A functional enhancement due to differences in skeletal morphology was only demonstrated in the gorilla supraspinatus muscle. Contrary to earlier ideas linking a more obliquely oriented scapular spine to greater supraspinatus leverage, our results suggest that increased lateral projection of the greater tubercle of the humerus accounts for the greater biomechanical performance in Gorilla. This study enhances our understanding of the evolution of gorilla locomotion, as well as providing greater insight into the general interaction between anatomy, function and locomotor biomechanics.
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Affiliation(s)
- Julia van Beesel
- Department of Human Evolution, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany
| | - John R Hutchinson
- Structure & Motion Laboratory, The Royal Veterinary College, Hatfield, UK
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany.,Collège de France, Paris, France
| | - Stephanie M Melillo
- Department of Human Evolution, Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany
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Zelazny KG, Sylvester AD, Ruff CB. Bilateral asymmetry and developmental plasticity of the humerus in modern humans. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 174:418-433. [PMID: 33460465 DOI: 10.1002/ajpa.24213] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/08/2020] [Accepted: 12/08/2020] [Indexed: 11/12/2022]
Abstract
OBJECTIVE This study investigates bilateral asymmetry in the humerus of modern human populations with differing activity patterns to assess the relative plasticity of different bone regions in response to environmental influences, particularly the biomechanical demands of handedness. METHODS External breadths, cross-sectional properties, and centroid sizes were used to quantify directional and absolute asymmetry of humeral diaphyseal, distal periarticular, and articular regions in six populations with differing subsistence strategies (total n = 244). Geometric section properties were measured using computed tomography at six locations along the distal humerus, while centroid sizes of the distal articular and periarticular regions, as well as eight segments of the diaphysis, were extracted from external landmark data. Bilateral asymmetries were compared between populations and sexes. Each property was also tested for correlation with bilateral asymmetry at 40% of bone length, which has been shown to correlate with handedness. RESULTS Asymmetry is highest in the diaphysis, but significant through all distal bone regions. Asymmetry increases in the region of the deltoid tuberosity, and progressively declines distally through the shaft and distal periarticular region. Articular asymmetry is higher than periarticular asymmetry, approaching levels seen just proximal to the olecranon fossa, and is weakly but significantly correlated with diaphyseal asymmetry. Hunter-gatherers from Indian Knoll have significantly higher levels of asymmetry than other groups and are more sexually dimorphic, particularly in cross-sectional properties of the diaphysis. CONCLUSIONS Humeral dimensions throughout the diaphysis, including regions currently used in taxonomic assignments of fossil hominins, likely respond to in vivo use, including population and sex-specific behaviors.
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Affiliation(s)
- Kaya G Zelazny
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Adam D Sylvester
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher B Ruff
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Wind J, Horst F, Rizzi N, John A, Schöllhorn WI. Electrical Brain Activity and Its Functional Connectivity in the Physical Execution of Modern Jazz Dance. Front Psychol 2021; 11:586076. [PMID: 33384641 PMCID: PMC7769774 DOI: 10.3389/fpsyg.2020.586076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/02/2020] [Indexed: 11/16/2022] Open
Abstract
Besides the pure pleasure of watching a dance performance, dance as a whole-body movement is becoming increasingly popular for health-related interventions. However, the science-based evidence for improvements in health or well-being through dance is still ambiguous and little is known about the underlying neurophysiological mechanisms. This may be partly related to the fact that previous studies mostly examined the neurophysiological effects of imagination and observation of dance rather than the physical execution itself. The objective of this pilot study was to investigate acute effects of a physically executed dance with its different components (recalling the choreography and physical activity to music) on the electrical brain activity and its functional connectivity using electroencephalographic (EEG) analysis. Eleven dance-inexperienced female participants first learned a Modern Jazz Dance (MJD) choreography over three weeks (1 h sessions per week). Afterwards, the acute effects on the EEG brain activity were compared between four different test conditions: physically executing the MJD choreography with music, physically executing the choreography without music, imaging the choreography with music, and imaging the choreography without music. Every participant passed each test condition in a randomized order within a single day. EEG rest-measurements were conducted before and after each test condition. Considering time effects the physically executed dance without music revealed in brain activity analysis most increases in alpha frequency and in functional connectivity analysis in all frequency bands. In comparison, physically executed dance with music as well as imagined dance with music led to fewer increases and imagined dance without music provoked noteworthy brain activity and connectivity decreases at all frequency bands. Differences between the test conditions were found in alpha and beta frequency between the physically executed dance and the imagined dance without music as well as between the physically executed dance with and without music in the alpha frequency. The study highlights different effects of a physically executed dance compared to an imagined dance on many brain areas for all measured frequency bands. These findings provide first insights into the still widely unexplored field of neurological effects of dance and encourages further research in this direction.
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Affiliation(s)
- Johanna Wind
- Training and Movement Science, Institute of Sport Science, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Fabian Horst
- Training and Movement Science, Institute of Sport Science, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Nikolas Rizzi
- Training and Movement Science, Institute of Sport Science, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Alexander John
- Training and Movement Science, Institute of Sport Science, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Wolfgang I Schöllhorn
- Training and Movement Science, Institute of Sport Science, Johannes Gutenberg-University Mainz, Mainz, Germany
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Venditti C, Baker J, Benton MJ, Meade A, Humphries S. 150 million years of sustained increase in pterosaur flight efficiency. Nature 2020; 587:83-86. [PMID: 33116315 DOI: 10.1038/s41586-020-2858-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/14/2020] [Indexed: 11/09/2022]
Abstract
The long-term accumulation of biodiversity has been punctuated by remarkable evolutionary transitions that allowed organisms to exploit new ecological opportunities. Mesozoic flying reptiles (the pterosaurs), which dominated the skies for more than 150 million years, were the product of one such transition. The ancestors of pterosaurs were small and probably bipedal early archosaurs1, which were certainly well-adapted to terrestrial locomotion. Pterosaurs diverged from dinosaur ancestors in the Early Triassic epoch (around 245 million years ago); however, the first fossils of pterosaurs are dated to 25 million years later, in the Late Triassic epoch. Therefore, in the absence of proto-pterosaur fossils, it is difficult to study how flight first evolved in this group. Here we describe the evolutionary dynamics of the adaptation of pterosaurs to a new method of locomotion. The earliest known pterosaurs took flight and subsequently appear to have become capable and efficient flyers. However, it seems clear that transitioning between forms of locomotion2,3-from terrestrial to volant-challenged early pterosaurs by imposing a high energetic burden, thus requiring flight to provide some offsetting fitness benefits. Using phylogenetic statistical methods and biophysical models combined with information from the fossil record, we detect an evolutionary signal of natural selection that acted to increase flight efficiency over millions of years. Our results show that there was still considerable room for improvement in terms of efficiency after the appearance of flight. However, in the Azhdarchoidea4, a clade that exhibits gigantism, we test the hypothesis that there was a decreased reliance on flight5-7 and find evidence for reduced selection on flight efficiency in this clade. Our approach offers a blueprint to objectively study functional and energetic changes through geological time at a more nuanced level than has previously been possible.
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Affiliation(s)
- Chris Venditti
- School of Biological Sciences, University of Reading, Reading, UK.
| | - Joanna Baker
- School of Biological Sciences, University of Reading, Reading, UK
| | | | - Andrew Meade
- School of Biological Sciences, University of Reading, Reading, UK
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Torres-Tamayo N, Schlager S, García-Martínez D, Sanchis-Gimeno JA, Nalla S, Ogihara N, Oishi M, Martelli S, Bastir M. Three-dimensional geometric morphometrics of thorax-pelvis covariation and its potential for predicting the thorax morphology: A case study on Kebara 2 Neandertal. J Hum Evol 2020; 147:102854. [PMID: 32805525 DOI: 10.1016/j.jhevol.2020.102854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 07/04/2020] [Accepted: 07/04/2020] [Indexed: 11/18/2022]
Abstract
The skeletal torso is a complex structure of outstanding importance in understanding human body shape evolution, but reconstruction usually entails an element of subjectivity as researchers apply their own anatomical expertise to the process. Among different fossil reconstruction methods, 3D geometric morphometric techniques have been increasingly used in the last decades. Two-block partial least squares analysis has shown great potential for predicting missing elements by exploiting the covariation between two structures (blocks) in a reference sample: one block can be predicted from the other one based on the strength of covariation between blocks. The first aim of this study is to test whether this predictive approach can be used for predicting thorax morphologies from pelvis morphologies within adult Homo sapiens reference samples with known covariation between the thorax and the pelvis. The second aim is to apply this method to Kebara 2 Neandertal (Israel, ∼60 ka) to predict its thorax morphology using two different pelvis reconstructions as predictors. We measured 134 true landmarks, 720 curve semilandmarks, and 160 surface semilandmarks on 60 3D virtual torso models segmented from CT scans. We conducted three two-block partial least squares analyses between the thorax (block 1) and the pelvis (block 2) based on the H. sapiens reference samples after performing generalized Procrustes superimposition on each block separately. Comparisons of these predictions in full shape space by means of Procrustes distances show that the male-only predictive model yields the most reliable predictions within modern humans. In addition, Kebara 2 thorax predictions based on this model concur with the thorax morphology proposed for Neandertals. The method presented here does not aim to replace other techniques, but to rather complement them through quantitative prediction of a virtual 'scaffold' to articulate the thoracic fossil elements, thus extending the potential of missing data estimation beyond the methods proposed in previous works.
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Affiliation(s)
- Nicole Torres-Tamayo
- Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), J.G. Abascal 2, 28006, Madrid, Spain; GIAVAL Research Group, Department of Anatomy and Human Embryology, University of Valencia, Av. Blasco Ibanez, 15, E-46010, Valencia, Spain.
| | - Stefan Schlager
- Biological Anthropology, Faculty of Medicine, University of Freiburg, Hebelstr 29, D-79104, Freiburg, Germany
| | - Daniel García-Martínez
- Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), J.G. Abascal 2, 28006, Madrid, Spain; Centro Nacional de Investigación Sobre La Evolución Humana (CENIEH), Avenida de La Sierra de Atapuerca 3, 09002, Burgos, Spain
| | - Juan Alberto Sanchis-Gimeno
- GIAVAL Research Group, Department of Anatomy and Human Embryology, University of Valencia, Av. Blasco Ibanez, 15, E-46010, Valencia, Spain
| | - Shahed Nalla
- Department of Human Anatomy and Physiology, Faculty of Health Sciences, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg, 2006, Gauteng, South Africa
| | - Naomichi Ogihara
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Motoharu Oishi
- Laboratory of Anatomy 1, School of Veterinary Medicine, Azabu University, Kanagawa, 252-5201, Japan
| | - Sandra Martelli
- UCL Centre for Integrative Anatomy (CIA), Department of Cell and Developmental Biology, Faculty of Life Sciences, Gower Street, WC1E 6BT, London, UK
| | - Markus Bastir
- Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), J.G. Abascal 2, 28006, Madrid, Spain
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Bailey KE, Winking JW, Carlson DL, Tran Van Bang, Ha Thang Long. Arm-Swinging in the Red-Shanked Douc (Pygathrix nemaeus): Implications of Body Mass. INT J PRIMATOL 2020. [DOI: 10.1007/s10764-020-00163-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Morimoto N, Kunimatsu Y, Nakatsukasa M, Ponce de León MS, Zollikofer CPE, Ishida H, Sasaki T, Suwa G. Variation of bony labyrinthine morphology in Mio−Plio−Pleistocene and modern anthropoids. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 173:276-292. [DOI: 10.1002/ajpa.24098] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 03/06/2020] [Accepted: 05/17/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Naoki Morimoto
- Laboratory of Physical Anthropology Graduate School of Science, Kyoto University Kyoto Japan
| | - Yutaka Kunimatsu
- Faculty of Business Administration Ryukoku University Fushimi, Kyoto Japan
| | - Masato Nakatsukasa
- Laboratory of Physical Anthropology Graduate School of Science, Kyoto University Kyoto Japan
| | | | | | | | | | - Gen Suwa
- University Museum, University of Tokyo Hongo, Bunkyo‐ku, Tokyo Japan
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Phalangeal curvature in a chimpanzee raised like a human: Implications for inferring arboreality in fossil hominins. Proc Natl Acad Sci U S A 2020; 117:11223-11225. [PMID: 32393625 PMCID: PMC7260939 DOI: 10.1073/pnas.2004371117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Arboreal primates such as chimpanzees exhibit pronounced curvature in their hand and foot phalanges, which is assumed to develop throughout life in response to mechanical loads produced by grasping and hanging from branches. Intriguingly, ancient fossil hominins also exhibit substantial phalangeal curvature, which, too, has been interpreted as a direct result of habitual arboreality during life. Here, we describe the phalangeal curvature of a chimpanzee who was raised during the 1930s in New York City to live much like a human, including by having very few opportunities to engage in arboreal activities. We show that the degree of hand and foot phalangeal curvature in this individual is indistinguishable from that of wild chimpanzees and distinct from humans. Thus, rather than being a direct effect of mechanical loads produced by lifetime arboreal activities, phalangeal curvature appears to be shaped largely by genetic factors. An important implication of this finding is that phalangeal curvature among fossil hominins is evidently best interpreted as a primitive trait inherited from an arboreal ancestral species rather than proof of engagement in arboreal activities during life.
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Longman DP, Wells JCK, Stock JT. Human athletic paleobiology; using sport as a model to investigate human evolutionary adaptation. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 171 Suppl 70:42-59. [PMID: 31957878 PMCID: PMC7217212 DOI: 10.1002/ajpa.23992] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/29/2019] [Accepted: 12/12/2019] [Indexed: 11/11/2022]
Abstract
The use of sport as a conceptual framework offers unprecedented opportunities to improve our understanding of what the body does, shedding new light on our evolutionary trajectory, our capacity for adaptation, and the underlying biological mechanisms. This approach has gained traction over recent years. To date, sport has facilitated exploration not only of the evolutionary history of our species as a whole, but also of human variation and adaptation at the interindividual and intraindividual levels. At the species level, analysis of lower and upper limb biomechanics and energetics with respect to walking, running and throwing have led to significant advances in the understanding of human adaptations relative to other hominins. From an interindividual perspective, investigation of physical activity patterns and endurance running performance is affording greater understanding of evolved constraints of energy expenditure, thermoregulatory energetics, signaling theory, and morphological variation. Furthermore, ultra-endurance challenges provoke functional trade-offs, allowing new ground to be broken in the study of life history trade-offs and human adaptability. Human athletic paleobiology-the recruitment of athletes as study participants and the use of contemporary sports as a model for studying evolutionary theory-has great potential. Here, we draw from examples in the literature to provide a review of how the use of athletes as a model system is enhancing understanding of human evolutionary adaptation.
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Affiliation(s)
- Daniel P. Longman
- School of Sport, Exercise and Health SciencesLoughborough UniversityLoughboroughUK
| | | | - Jay T. Stock
- Department of AnthropologyUniversity of Western OntarioLondonOntarioCanada
- Department of ArchaeologyMax Planck Institute for the Science of Human HistoryJenaGermany
- Department of ArchaeologyUniversity of CambridgeCambridgeUK
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Morphometric analysis of the hominin talus: Evolutionary and functional implications. J Hum Evol 2020; 142:102747. [PMID: 32240884 DOI: 10.1016/j.jhevol.2020.102747] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 01/07/2020] [Accepted: 01/21/2020] [Indexed: 11/21/2022]
Abstract
The adoption of bipedalism is a key benchmark in human evolution that has impacted talar morphology. Here, we investigate talar morphological variability in extinct and extant hominins using a 3D geometric morphometric approach. The evolutionary timing and appearance of modern human-like features and their contributions to bipedal locomotion were evaluated on the talus as a whole, each articular facet separately, and multiple combinations of facets. Distinctive suites of features are consistently present in all fossil hominins, despite the presence of substantial interspecific variation, suggesting a potential connection of these suites to bipedal gait. A modern human-like condition evolved in navicular and lateral malleolar facets early in the hominin lineage compared with other facets, which demonstrate more complex morphological variation within Homininae. Interestingly, navicular facet morphology of Australopithecus afarensis is derived in the direction of Homo, whereas more recent hominin species such as Australopithecus africanus and Australopithecus sediba retain more primitive states in this facet. Combining the navicular facet with the trochlea and the posterior calcaneal facet as a functional suite, however, distinguishes Australopithecus from Homo in that the medial longitudinal arch had not fully developed in the former. Our results suggest that a more everted foot and stiffer medial midtarsal region are adaptations that coincide with the emergence of bipedalism, whereas a high medial longitudinal arch emerges later in time, within Homo. This study provides novel insights into the emergence of talar morphological traits linked to bipedalism and its transition from a facultative to an obligate condition.
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Abstract
Here we present evidence of hominin locomotor behavior from the trabecular bone of the femur. We show evidence for habitual use of highly flexed hip postures, which could potentially indicate regular climbing in a South African hominin from Sterkfontein, which is either Paranthropus robustus or Homo. Second, we present evidence that Australopithecus africanus likely did not climb at the frequencies seen in extant nonhuman apes, and exhibits a modern, human-like pattern of loading at the hip joint. These results challenge the prevailing view of a single transition to bipedalism within the hominin clade by providing evidence of climbing in a more recent, non-Australopithecus South African hominin, and add to the increasing evidence for locomotor diversity in the hominin clade. Bipedalism is a defining trait of the hominin lineage, associated with a transition from a more arboreal to a more terrestrial environment. While there is debate about when modern human-like bipedalism first appeared in hominins, all known South African hominins show morphological adaptations to bipedalism, suggesting that this was their predominant mode of locomotion. Here we present evidence that hominins preserved in the Sterkfontein Caves practiced two different locomotor repertoires. The trabecular structure of a proximal femur (StW 522) attributed to Australopithecus africanus exhibits a modern human-like bipedal locomotor pattern, while that of a geologically younger specimen (StW 311) attributed to either Homo sp. or Paranthropus robustus exhibits a pattern more similar to nonhuman apes, potentially suggesting regular bouts of both climbing and terrestrial bipedalism. Our results demonstrate distinct morphological differences, linked to behavioral differences between Australopithecus and later hominins in South Africa and contribute to the increasing evidence of locomotor diversity within the hominin clade.
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Harrison SJ, Kinsella-Shaw JM, Dotov D. Effects of footedness and stance asymmetry confirm an inter-leg metastable coordination dynamics of standing posture. J Mot Behav 2020; 53:135-156. [PMID: 32208833 DOI: 10.1080/00222895.2020.1740151] [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: 10/24/2022]
Abstract
We investigated the patterns of coordination between the left and right legs that support the task of maintaining an upright standing posture. We used cross-wavelet analyses to assess coordination between the centers of pressure under the left and right feet. We recruited participants with a lateralized functional preference for their right leg, and we manipulated whether these participants stood with symmetric/asymmetric stances and whether their eyes were open or closed. Our hypotheses were derived from the Haken-Kelso-Bunz (HKB) model of interlimb coordination dynamics. Consistent with HKB model predictions, we observed (1) coordination taking the form of metastable, transient epochs of stable phase relations, (2) preferences for in-phase and anti-phase coordination patterns, and (3) changes in pattern stability and phase leads associated with both stance asymmetry and right-side lateral preference. The form and stability of observed coordination patterns were mediated by the availability of visual information. Our findings confirm the existence of a metastable coordination dynamic associated with the task of maintaining upright stance. We discuss the implications of these findings in the context of evaluating the utility of the HKB model for understanding the functional organization of the posture system.
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Affiliation(s)
- Steven J Harrison
- Doctor of Physical Therapy Program, Department of Kinesiology, University of Connecticut, Mansfield, Connecticut, USA.,Center for the Ecological Study of Perception and Action, Department of Psychological Sciences, University of Connecticut, Mansfield, Connecticut, USA
| | - Jeffrey M Kinsella-Shaw
- Doctor of Physical Therapy Program, Department of Kinesiology, University of Connecticut, Mansfield, Connecticut, USA.,Center for the Ecological Study of Perception and Action, Department of Psychological Sciences, University of Connecticut, Mansfield, Connecticut, USA
| | - Dobromir Dotov
- LIVELab, Psychology, Neuroscience and Behavior, McMaster University, Hamilton, Ontario, Canada.,RHPCS, McMaster University, Hamilton, Ontario, Canada
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