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Drummond-Clarke RC, Kivell TL, Sarringhaus L, Stewart FA, Piel AK. Sex differences in positional behavior of chimpanzees (Pan troglodytes schweinfurthii) living in the dry and open habitat of Issa Valley, Tanzania. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024:e25007. [PMID: 39056239 DOI: 10.1002/ajpa.25007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 06/20/2024] [Accepted: 07/09/2024] [Indexed: 07/28/2024]
Abstract
OBJECTIVES Many early fossil hominins are associated with savanna-mosaic paleohabitats, and high sexual dimorphism that may reflect differences in positional behavior between sexes. However, reconstructions of hominin behavior and the selective pressures they faced in an open habitat are limited by a lack of studies of extant apes living in contemporary, analogous habitats. Here, we describe adult chimpanzee positional behavior in the savanna-mosaic habitat of the Issa Valley, Tanzania, to test whether Issa chimpanzees show larger sex-differences in positional behavior than their forest-dwelling counterparts. MATERIALS AND METHODS We quantified and compared adult locomotor and postural behavior across sexes (6 females, 7 males) in the riparian forest (closed) and miombo woodland (open) vegetation types at Issa Valley (13,743 focal observations). We then compared our results to published data of chimpanzee communities living in more forested habitats. RESULTS Issa females and males both spent less time arboreally in open vegetation and showed similar locomotor and postural behavior on the same substrates, notably using a high level of suspensory locomotion when arboreal. Females were, however, more arboreal than males during locomotor behavior, as well as compared with females from other communities. Issa males behaved similarly to males from other communities. CONCLUSION Results suggest that open habitats do not elicit less arboreal behaviors in either sex, and may even select for suspensory locomotion to effectively navigate an open canopy. An open habitat may, however, increase sex differences in positional behavior by driving female arboreality. We suggest this is because of higher energetic demands and predator pressures associated with open vegetation, which are likely exaggerated for reproducing females. These results have implications for the interpretation of how sexual dimorphism may influence reconstructions of hominin positional behavior.
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Affiliation(s)
| | - Tracy L Kivell
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
| | | | - Fiona A Stewart
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Department of Anthropology, University College London, London, UK
| | - Alex K Piel
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Department of Anthropology, University College London, London, UK
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2
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Gómez-Olivencia A, Arsuaga JL. The Sima de los Huesos thorax and lumbar spine: Selected traits and state-of-the-art. Anat Rec (Hoboken) 2024; 307:2465-2490. [PMID: 38450997 DOI: 10.1002/ar.25414] [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: 10/15/2023] [Revised: 02/02/2024] [Accepted: 02/07/2024] [Indexed: 03/08/2024]
Abstract
Information on the evolution of the thorax and lumbar spine in the genus Homo is hampered by a limited fossil record due to the inherent fragility of vertebrae and ribs. Neandertals show significant metric and morphological differences in these two anatomical regions, when compared to Homo sapiens. Thus, the important fossil record from the Middle Pleistocene site of Sima de los Huesos (SH) not only offers important information on the evolution of these anatomical regions within the Neandertal lineage but also provides important clues to understand the evolution of these regions at the genus level. We present the current knowledge of the costal skeleton, and the thoracic and lumbar spine anatomy of the hominins found in Sima de los Huesos compared to that of Neandertals and modern humans. The current SH fossil record comprises 738 vertebral specimens representing a minimum of 70 cervical, 95 thoracic and 47 lumbar vertebrae, 652 rib fragments representing a minimum of 118 ribs, and 26 sternal fragments representing 4 sterna. The SH hominins exhibit a morphological pattern in their thorax and lumbar spine more similar to that of Neandertals than to that of H. sapiens, which is consistent with the phylogenetic position of these hominins. However, there are some differences between the SH hominins and Neandertals in these anatomical regions, primarily in the orientation of the lumbar transverse processes and in the robusticity of the second ribs. The presence of some but not all of the suite of Neandertal-derived features is consistent with the pattern found in the cranium and other postcranial regions of this population.
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Affiliation(s)
- Asier Gómez-Olivencia
- Dept. Geología, Facultad de Ciencia y Tecnología, Universidad del País Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), Leioa, Spain
- Sociedad de Ciencias Aranzadi, Donostia-San Sebastián, Spain
- Centro UCM-ISCIII de Investigación sobre Evolución y Comportamiento Humanos, Madrid, Spain
| | - Juan Luis Arsuaga
- Centro UCM-ISCIII de Investigación sobre Evolución y Comportamiento Humanos, Madrid, Spain
- Departamento de Geodinámica, Estratigrafía y Paleontología, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, Madrid, Spain
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3
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Villamil CI, Middleton ER. Conserved patterns and locomotor-related evolutionary constraints in the hominoid vertebral column. J Hum Evol 2024; 190:103528. [PMID: 38579429 DOI: 10.1016/j.jhevol.2024.103528] [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: 06/20/2023] [Revised: 03/13/2024] [Accepted: 03/14/2024] [Indexed: 04/07/2024]
Abstract
The evolution of the hominoid lineage is characterized by pervasive homoplasy, notably in regions such as the vertebral column, which plays a central role in body support and locomotion. Few isolated and fewer associated vertebrae are known for most fossil hominoid taxa, but identified specimens indicate potentially high levels of convergence in terms of both form and number. Homoplasy thus complicates attempts to identify the anatomy of the last common ancestor of hominins and other taxa and stymies reconstructions of evolutionary scenarios. One way to clarify the role of homoplasy is by investigating constraints via phenotypic integration, which assesses covariation among traits, shapes evolutionary pathways, and itself evolves in response to selection. We assessed phenotypic integration and evolvability across the subaxial (cervical, thoracic, lumbar, sacral) vertebral column of macaques (n = 96), gibbons (n = 77), chimpanzees (n = 92), and modern humans (n = 151). We found a mid-cervical cluster that may have shifted cranially in hominoids, a persistent thoracic cluster that is most marked in chimpanzees, and an expanded lumbosacral cluster in hominoids that is most expanded in gibbons. Our results highlight the highly conserved nature of the vertebral column. Taxa appear to exploit existing patterns of integration and ontogenetic processes to shift, expand, or reduce cluster boundaries. Gibbons appear to be the most highly derived taxon in our sample, possibly in response to their highly specialized locomotion.
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Affiliation(s)
- Catalina I Villamil
- School of Chiropractic, Universidad Central del Caribe, Puerto Rico, PO Box 60327, Bayamón, USA.
| | - Emily R Middleton
- Department of Anthropology, University of Wisconsin-Milwaukee, 3413 N. Downer Ave., Sabin Hall 390, Milwaukee, WI, USA
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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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Hamilton MI, Copeland SR, Nelson SV. A reanalysis of strontium isotope ratios as indicators of dispersal in South African hominins. J Hum Evol 2024; 187:103480. [PMID: 38159536 DOI: 10.1016/j.jhevol.2023.103480] [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: 04/02/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 01/03/2024]
Abstract
Dispersal patterns in primates have major implications for behavior and sociality but are difficult to reconstruct for fossil species. This study applies novel strontium isotope methodologies that have reliably predicted philopatry and dispersal patterns in chimpanzees and other modern primates to previously published strontium isotope ratios (87Sr/86Sr) of two South African hominins, Australopithecus africanus and Australopithecus robustus. In this study, the difference or 'offset' was calculated between the 87Sr/86Sr of each fossil tooth compared to local bioavailable 87Sr/86Sr as defined by cluster analysis of modern plant isotope ratios. Large teeth (presumably belonging to males) have low offsets from local 87Sr/86Sr proxies, while small teeth (presumably from females) have greater offsets from local 87Sr/86Sr proxies. This supports previous conclusions of male philopatry and female dispersal in both A. africanus and A. robustus. Furthermore, A. robustus shows more extreme differences between presumed males and females compared to A. africanus. This is analogous to differences seen in modern olive baboons compared to chimpanzees and suggests that A. africanus may have had a larger home range than A. robustus. Neither hominin species has 87Sr/86Sr consistent with riparian habitat preferences despite the demonstrated presence of riparian habitats in South Africa at the time.
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Affiliation(s)
- Marian I Hamilton
- University of New Mexico, Department of Anthropology, MSC01-1040 1, Albuquerque, NM, 87131, USA; University of Northern Colorado, Department of Anthropology, Candelaria Hall 2200, Campus Box 90, Greeley, CO, 80639, USA.
| | - Sandi R Copeland
- Environmental Stewardship Group, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM, 87545, USA
| | - Sherry V Nelson
- University of New Mexico, Department of Anthropology, MSC01-1040 1, Albuquerque, NM, 87131, USA
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López-Rey JM, Cambra-Moo Ó, González Martín A, Candelas González N, Sánchez-Andrés Á, Tawane M, Cazenave M, Williams SA, Bastir M, García-Martínez D. Covariation between the shape and mineralized tissues of the rib cross section in Homo sapiens, Pan troglodytes and Sts 14. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:157-164. [PMID: 37724468 DOI: 10.1002/ajpa.24844] [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: 12/06/2022] [Revised: 08/10/2023] [Accepted: 08/13/2023] [Indexed: 09/20/2023]
Abstract
OBJECTIVES Studying rib torsion is crucial for understanding the evolution of the hominid ribcage. Interestingly, there are variables of the rib cross section that could be associated with rib torsion and, consequently, with the morphology of the thorax. The aim of this research is to conduct a comparative study of the shape and mineralized tissues of the rib cross section in different hominids to test for significant differences and, if possible, associate them to different thoracic morphotypes. MATERIALS AND METHODS The sample consists of the rib cross sections at the midshaft taken from 10 Homo sapiens and 10 Pan troglodytes adult individuals, as well as from A. africanus Sts 14. The shape of these rib cross sections was quantified using geometric morphometrics, while the mineralized tissues were evaluated using the compartmentalization index. Subsequently, covariation between both parameters was tested by a Spearman's ρ test, a permutation test and a linear regression. RESULTS Generally, P. troglodytes individuals exhibit rib cross sections that are rounder and more mineralized compared to those of H. sapiens. However, the covariation between both parameters was only observed in typical ribs (levels 3-10). Although covariation was not found in the rib cross sections of Sts 14, their parameters are closer to P. troglodytes. DISCUSSION On the one hand, the differences observed in the rib cross sections between H. sapiens and P. troglodytes might be related to different degrees of rib torsion and, consequently, to different thoracic 3D configurations. These findings can be functionally explained by considering their distinct modes of breathing and locomotion. On the other hand, although the rib cross sections belonging to Sts 14 are more similar to those of P. troglodytes, previous publications determined that their overall morphology is closer to modern humans. This discrepancy could reflect a diversity of post-cranial adaptations in Australopithecus.
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Affiliation(s)
- José M López-Rey
- Laboratorio de Poblaciones del Pasado (LAPP), Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
- Paleoanthropology Group, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
| | - Óscar Cambra-Moo
- Laboratorio de Poblaciones del Pasado (LAPP), Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
| | - Armando González Martín
- Laboratorio de Poblaciones del Pasado (LAPP), Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
| | - Nieves Candelas González
- Laboratorio de Poblaciones del Pasado (LAPP), Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
| | | | - Mirriam Tawane
- Department of Paleontology, Ditsong National Museum of Natural History, Pretoria, South Africa
| | - Marine Cazenave
- Division of Anthropology, American Museum of Natural History, New York, 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, Pretoria, South Africa
| | - Scott A Williams
- Center for the Study of Human Origins (CSHO), Department of Anthropology, New York University (NYU), New York, New York, USA
- New York Consortium in Evolutionary Primatology (NYCEP), New York, New York, USA
| | - Markus Bastir
- Paleoanthropology Group, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
| | - Daniel García-Martínez
- Physical Anthropology Unit, Department of Biodiversity, Ecology, and Evolution, Faculty of Biological Sciences, Complutense University of Madrid, Madrid, Spain
- Division of Paleobiology, Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain
- Laboratory of Forensic Anthropology, Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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7
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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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Laudicina NM, Cartmill M. Clavicle length and shoulder breadth in hominoid evolution. Anat Rec (Hoboken) 2023. [PMID: 36594678 DOI: 10.1002/ar.25144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/23/2022] [Accepted: 12/13/2022] [Indexed: 01/04/2023]
Abstract
For a given body mass, hominoids have longer clavicles than typical monkeys, reflecting the lateral reorientation of the hominoid glenoid. Relative length of the clavicle varies among hominoids, with orangutans having longer clavicles than expected for body mass and gorillas and chimpanzees having shorter clavicles than expected. Modern humans conform to the general hominoid distribution, but Neandertals and Upper Paleolithic Homo sapiens have longer clavicles than expected for their size and exhibit marked positive allometry in clavicle length. Relative to clavicle length, adult and newborn humans have broader shoulders (biacromial breadths) than comparable apes, because the reduced elevation of the human shoulder swings the acromion laterally downward away from the head. Since broadened shoulders yield an increased risk of maternal and neonatal injury and/or death from shoulder dystocia during birth, we might expect hominins to manifest trends toward reduction in shoulder breadth and clavicle length. They do not, presumably because of countering selection pressures favoring a long clavicle in the adults. The marked sexual dimorphism seen in patterns of clavicular growth and static adult allometry in humans suggests that those selection pressures have disproportionately affected the males.
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Affiliation(s)
- Natalie M Laudicina
- Biomedical Sciences, Grand Valley State University, Allendale, Michigan, USA.,Department of Anthropology, Boston University, Boston, Massachusetts, USA
| | - Matt Cartmill
- Department of Anthropology, Boston University, Boston, Massachusetts, USA.,Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA
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Grine FE, Mongle CS, Fleagle JG, Hammond AS. The taxonomic attribution of African hominin postcrania from the Miocene through the Pleistocene: Associations and assumptions. J Hum Evol 2022; 173:103255. [PMID: 36375243 DOI: 10.1016/j.jhevol.2022.103255] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 08/21/2022] [Accepted: 08/22/2022] [Indexed: 11/06/2022]
Abstract
Postcranial bones may provide valuable information about fossil taxa relating to their locomotor habits, manipulative abilities and body sizes. Distinctive features of the postcranial skeleton are sometimes noted in species diagnoses. Although numerous isolated postcranial fossils have become accepted by many workers as belonging to a particular species, it is worthwhile revisiting the evidence for each attribution before including them in comparative samples in relation to the descriptions of new fossils, functional analyses in relation to particular taxa, or in evolutionary contexts. Although some workers eschew the taxonomic attribution of postcranial fossils as being less important (or interesting) than interpreting their functional morphology, it is impossible to consider the evolution of functional anatomy in a taxonomic and phylogenetic vacuum. There are 21 widely recognized hominin taxa that have been described from sites in Africa dated from the Late Miocene to the Middle Pleistocene; postcranial elements have been attributed to 17 of these. The bones that have been thus assigned range from many parts of a skeleton to isolated elements. However, the extent to which postcranial material can be reliably attributed to a specific taxon varies considerably from site to site and species to species, and is often the subject of considerable debate. Here, we review the postcranial remains attributed to African hominin taxa from the Late Miocene to the Middle and Late Pleistocene and place these assignations into categories of reliability. The catalog of attributions presented here may serve as a guide for making taxonomic decisions in the future.
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Affiliation(s)
- Frederick E Grine
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794-4364, USA; Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794-4364, USA.
| | - Carrie S Mongle
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794-4364, USA; Division of Anthropology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA; Turkana Basin Institute, Stony Brook University, Stony Brook, NY 11794-4364, USA
| | - John G Fleagle
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794-4364, USA
| | - Ashley S Hammond
- Division of Anthropology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA; New York Consortium of Evolutionary Primatology (NYCEP), New York, NY 10024, USA
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10
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Comparative description and taxonomic affinity of 3.7-million-year-old hominin mandibles from Woranso-Mille (Ethiopia). J Hum Evol 2022; 173:103265. [PMID: 36306541 DOI: 10.1016/j.jhevol.2022.103265] [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: 12/06/2021] [Revised: 09/02/2022] [Accepted: 09/02/2022] [Indexed: 11/06/2022]
Abstract
Fossil discoveries of early Australopithecus species from Woranso-Mille have played a significant role in improving our understanding of mid-Pliocene hominin evolution and diversity. Here, we describe two mandibles with dentitions, recovered from sediments immediately above a tuff radiometrically dated to 3.76 ± 0.02 Ma, and assess their taxonomic affinity. The two mandibles (MSD-VP-5/16 and MSD-VP-5/50) show morphological similarities with both Australopithecus anamensis and Australopithecus afarensis. Some of the unique features that distinguish Au. anamensis from Au. afarensis are present in the mandibles, which also share a few derived features with Au. afarensis. Their retention of more Kanapoi Au. anamensis-like traits, compared to the fewer derived features they share with Au. afarensis, and the presence of Au. anamensis at Woranso-Mille in 3.8-million-year-old deposits, lends support to their assignment to Au. anamensis. However, it is equally arguable that the few derived dentognathic features they share with Au. afarensis could be taxonomically more significant, making it difficult to conclusively assign these specimens to either species. Regardless of which species they are assigned to, the mosaic nature of the dentognathic morphology and geological age of the two mandibles lends further support to the hypothesized ancestor-descendant relationship between Au. anamensis and Au. afarensis. However, there is now limited fossil evidence indicating that these two species may have overlapped in time. Hence, the last appearance of Au. anamensis and first appearance of Au. afarensis are currently unknown. Recovery of Australopithecus fossils from 4.1 to 3.8 Ma is critical to further address the timing of these events.
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11
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The relative limb size of Homonaledi. J Hum Evol 2022; 170:103235. [PMID: 35994845 DOI: 10.1016/j.jhevol.2022.103235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 07/03/2022] [Accepted: 07/03/2022] [Indexed: 11/20/2022]
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12
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Marchi D, Rimoldi A, García‐Martínez D, Bastir M. Morphological correlates of distal fibular morphology with locomotion in great apes, humans, and Australopithecus afarensis. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 178:286-300. [PMID: 36790753 PMCID: PMC9314891 DOI: 10.1002/ajpa.24507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/15/2022] [Accepted: 02/22/2022] [Indexed: 01/27/2023]
Abstract
OBJECTIVES Recent studies highlighted the importance of the fibula to further our understanding of locomotor adaptations in fossil hominins. In this study, we present a three-dimensional geometric morphometric (3D-GM) investigation of the distal fibula in extant hominids and Australopithecus afarensis with the aim of pointing out morphological correlations to arboreal behavior. METHODS Three-dimensional surface meshes of the distal fibula were obtained using computer tomography for 40 extant hominid specimens and laser scanner for five A. afarensis specimens. Distal fibula morphology was quantified positioning 11 fixed landmarks, 40 curve semilandmarks, and 20 surface landmarks on each specimen. A generalized Procrustes analysis (GPA) was carried out on all landmark coordinates followed by Procrustes ANOVA. Principal component analysis (PCA) was performed on the GPA-aligned shape coordinates. Kruskal-Wallis tests and Mann-Whitney test were performed on scores along PCs. RESULTS Great apes are characterized by a shorter subcutaneous triangular surface (STS), more downward facing fibulotalar articular facets, more anteriorly facing lateral malleolus and wider/deeper malleolar fossa than humans. Within great apes, orangutans are characterized by more medially facing fibulotalar articular facets. Australopithecus afarensis shows a unique distal fibular morphology with several traits that are generally associated more to arboreality and less to bipedalism such as a short STS, a more anteriorly facing, laterally pointing malleolus and deeper and larger malleolar fossa. CONCLUSIONS The distal fibula morphology is indicative of locomotor patterns within extant hominids. The 3D-GM method presented here can be successfully used to further our understanding of arboreal adaptations in fossil hominins.
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Affiliation(s)
- Damiano Marchi
- Department of BiologyUniversity of PisaPisa,Centre for the Exploration of the Deep Human JourneyUniversity of the WitwatersrandWits
| | | | - Daniel García‐Martínez
- Centre for the Exploration of the Deep Human JourneyUniversity of the WitwatersrandWits,Centro Nacional de Investigación sobre la Evolución Humana (CENIEH)BurgosSpain,Paleoanthropology GroupMuseo Nacional de Ciencias Naturales (MNCN‐CSIC)MadridSpain
| | - Markus Bastir
- Centre for the Exploration of the Deep Human JourneyUniversity of the WitwatersrandWits,Paleoanthropology GroupMuseo Nacional de Ciencias Naturales (MNCN‐CSIC)MadridSpain
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13
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Frémondière P, Thollon L, Marchal F, Fornai C, Webb NM, Haeusler M. Dynamic finite-element simulations reveal early origin of complex human birth pattern. Commun Biol 2022; 5:377. [PMID: 35440693 PMCID: PMC9018746 DOI: 10.1038/s42003-022-03321-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 03/25/2022] [Indexed: 11/09/2022] Open
Abstract
Human infants are born neurologically immature, potentially owing to conflicting selection pressures between bipedal locomotion and encephalization as suggested by the obstetrical dilemma hypothesis. Australopithecines are ideal for investigating this trade-off, having a bipedally adapted pelvis, yet relatively small brains. Our finite-element birth simulations indicate that rotational birth cannot be inferred from bony morphology alone. Based on a range of pelvic reconstructions and fetal head sizes, our simulations further imply that australopithecines, like humans, gave birth to immature, secondary altricial newborns with head sizes smaller than those predicted for non-human primates of the same body size especially when soft tissue thickness is adequately approximated. We conclude that australopithecines required cooperative breeding to care for their secondary altricial infants. These prerequisites for advanced cognitive development therefore seem to have been corollary to skeletal adaptations for bipedal locomotion that preceded the appearance of the genus Homo and the increase in encephalization.
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Affiliation(s)
- Pierre Frémondière
- UMR 7268 ADES, Aix Marseille University, EFS, CNRS, 51 boulevard Pierre Dramard, 13344, Marseille cedex 15, France. .,Aix Marseille University, School of Midwifery, Faculty of Medical and Paramedical Sciences, 51 boulevard Pierre Dramard, 13344, Marseille cedex 15, France.
| | - Lionel Thollon
- Aix Marseille University, UMR-T24, 51 boulevard Pierre Dramard, 13344, Marseille cedex 15, France
| | - François Marchal
- UMR 7268 ADES, Aix Marseille University, EFS, CNRS, 51 boulevard Pierre Dramard, 13344, Marseille cedex 15, France
| | - Cinzia Fornai
- Institute of Evolutionary Medicine, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,Department of Evolutionary Anthropology, University of Vienna, Djerassiplatz 1, 1030, Wien, Austria.,Vienna School of Interdisciplinary Dentistry-VieSID, Wasserzeile 35, 3400, Klosterneuburg, Austria
| | - Nicole M Webb
- Institute of Evolutionary Medicine, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,Senckenberg Research Institute and Natural History Museum Frankfurt, Senckenberganlage 25, 60325, Frankfurt am Main, Germany.,Senckenberg Centre for Human Evolution and Palaeoenvironment, Institute of Archaeological Sciences, Eberhard Karls University of Tübingen, Rümelinstrasse 23, 72070, Tübingen, Germany
| | - Martin Haeusler
- Institute of Evolutionary Medicine, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.
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14
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Ruff CB, Junno JA, Burgess ML, Canington SL, Harper C, Mudakikwa A, McFarlin SC. Body proportions and environmental adaptation in gorillas. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 177:501-529. [PMID: 36787793 DOI: 10.1002/ajpa.24443] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/22/2021] [Accepted: 10/19/2021] [Indexed: 11/07/2022]
Abstract
OBJECTIVES Limb length and trunk proportions are determined in a large, taxonomically and environmentally diverse sample of gorillas and related to variation in locomotion, climate, altitude, and diet. MATERIALS AND METHODS The sample includes 299 gorilla skeletons, 115 of which are infants and juveniles, distributed between western lowland (G. gorilla gorilla), low and high elevation grauer (G. beringei graueri), and Virunga mountain gorillas (G. b. beringei). Limb bone and vertebral column lengths scaled to body mass are compared between subgroups by age group. RESULTS All G. beringei have relatively short 3rd metapodials and manual proximal phalanges compared to G. gorilla, and this difference is apparent in infancy. All G. beringei also have shortened total limb lengths relative to either body mass or vertebral column length, although patterns of variation in individual skeletal elements are more complex, and infants do not display the same patterns as adults. Mountain gorillas have relatively long clavicles, present in infancy, and a relatively long thoracic (but not lumbosacral) vertebral column. DISCUSSION A variety of environmental factors likely contributed to observed patterns of morphological variation among extant gorillas. We interpret the short hand and foot bones of all G. beringei as genetic adaptations to greater terrestriality in the last common ancestor of G. beringei; variation in other limb lengths to climatic adaptation, both genetic and developmental; and the larger thorax of G. b. beringei to adaptation to reduced oxygen pressure at high altitudes, again as a product of both genetic differences and environmental influences during development.
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Affiliation(s)
- Christopher B Ruff
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - M Loring Burgess
- Peabody Museum of Archaeology and Ethnology, Harvard University, Cambridge, Massachusetts, USA
| | - Stephanie L Canington
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christine Harper
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey, USA
| | - Antoine Mudakikwa
- Rwanda Development Board, Department of Tourism and Conservation, Kigali, Rwanda
| | - Shannon C McFarlin
- Department of Anthropology, Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, USA.,Human Origins Program, Smithsonian's National Museum of Natural History, Washington, District of Columbia, USA
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15
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Mosaic habitats at Woranso-Mille (Ethiopia) during the Pliocene and implications for Australopithecus paleoecology and taxonomic diversity. J Hum Evol 2022; 163:103076. [PMID: 34998271 DOI: 10.1016/j.jhevol.2021.103076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 08/27/2021] [Accepted: 08/27/2021] [Indexed: 11/21/2022]
Abstract
Many important Pliocene hominin specimens have been recovered from Woranso-Mille, a paleontological research area in the Afar region of Ethiopia, including the complete cranium of Australopithecus anamensis, a partial skeleton of Australopithecus afarensis, mandibular and maxillary elements representing a new species, Australopithecus deyiremeda, and a partial foot of an as-yet-unnamed species. Woranso-Mille is the only site, so far, to have reported the co-existence of more than one early hominin species between 3.8 and 3.3 Ma and the temporal overlap between A. anamensis and A. afarensis. Thus, the site has important implications for our understanding of the paleoecology and taxonomic diversity of early hominins and their ecological niche. This paper explores the paleohabitats of Woranso-Mille through its faunal community ecological structure and taxonomic composition using correspondence analysis and Forbes modified similarity index. The results suggest that Pliocene Woranso-Mille was a mosaic of different habitat types, with riparian woodland and floodplain grassland along rivers draining into a lake, along with less mesic habitats such as woodland, grassland, and shrubland. The apparent high level of vegetation heterogeneity may have promoted dietary specializations and niche differentiation among the different Australopithecus species at Woranso-Mille and allowed for their co-existence at the site.
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16
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Childbirth and Infant Care in Early Human Ancestors: What the Bones Tell Us. EVOLUTIONARY PSYCHOLOGY 2022. [DOI: 10.1007/978-3-030-76000-7_4] [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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17
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Morse PE. Fossil primate research at the 81st Annual Meeting of the Society of Vertebrate Paleontology. Evol Anthropol 2022; 31:9-11. [PMID: 34994493 DOI: 10.1002/evan.21934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 12/22/2021] [Indexed: 11/12/2022]
Affiliation(s)
- Paul E Morse
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA.,Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA
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18
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Haile-Selassie Y. From Trees to the Ground: The Significance of Australopithecus anamensis in Human Evolution. JOURNAL OF ANTHROPOLOGICAL RESEARCH 2021. [DOI: 10.1086/716743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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19
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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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20
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Hunt KD, Dunevant SE, Yohler RM, Carlson KJ. Femoral Bicondylar Angles among Dry-Habitat Chimpanzees ( Pan troglodytes schweinfurthii) Resemble Those of Humans: Implications for Knee Function, Australopith Sexual Dimorphism, and the Evolution of Bipedalism. JOURNAL OF ANTHROPOLOGICAL RESEARCH 2021. [DOI: 10.1086/715398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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21
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Thompson NE, Rubinstein D, Parrella-O'Donnell W, Brett MA, Demes B, Larson SG, O'Neill MC. The loss of the 'pelvic step' in human evolution. J Exp Biol 2021; 224:271233. [PMID: 34412111 DOI: 10.1242/jeb.240440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 07/06/2021] [Indexed: 12/12/2022]
Abstract
Human bipedalism entails relatively short strides compared with facultatively bipedal primates. Unique non-sagittal-plane motions associated with bipedalism may account for part of this discrepancy. Pelvic rotation anteriorly translates the hip, contributing to bipedal stride length (i.e. the 'pelvic step'). Facultative bipedalism in non-human primates entails much larger pelvic rotation than in humans, suggesting that a larger pelvic step may contribute to their relatively longer strides. We collected data on the pelvic step in bipedal chimpanzees and over a wide speed range of human walking. At matched dimensionless speeds, humans have 26.7% shorter dimensionless strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees. Differences in pelvic rotation explain 31.8% of the difference in dimensionless stride length between the two species. We suggest that relative stride lengths and the pelvic step have been significantly reduced throughout the course of hominin evolution.
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Affiliation(s)
- Nathan E Thompson
- Department of Anatomy, NYIT College of Osteopathic Medicine, Old Westbury, NY 11568,USA
| | | | | | - Matthew A Brett
- NYIT College of Osteopathic Medicine, Old Westbury, NY 11568,USA
| | - Brigitte Demes
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794,USA
| | - Susan G Larson
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794,USA
| | - Matthew C O'Neill
- Department of Anatomy, Midwestern University, Glendale, AZ 85308,USA
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22
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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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23
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Carlson KJ, Green DJ, Jashashvili T, Pickering TR, Heaton JL, Beaudet A, Stratford D, Crompton R, Kuman K, Bruxelles L, Clarke RJ. The pectoral girdle of StW 573 ('Little Foot') and its implications for shoulder evolution in the Hominina. J Hum Evol 2021; 158:102983. [PMID: 33888323 DOI: 10.1016/j.jhevol.2021.102983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 02/20/2021] [Accepted: 02/23/2021] [Indexed: 10/21/2022]
Abstract
The ca. 3.67 Ma adult skeleton known as 'Little Foot' (StW 573), recovered from Sterkfontein Member 2 breccia in the Silberberg Grotto, is remarkable for its morphology and completeness. Preservation of clavicles and scapulae, including essentially complete right-side elements, offers opportunities to assess morphological and functional aspects of a nearly complete Australopithecus pectoral girdle. Here we describe the StW 573 pectoral girdle and offer quantitative comparisons to those of extant hominoids and selected homininans. The StW 573 pectoral girdle combines features intermediate between those of humans and other apes: a long and curved clavicle, suggesting a relatively dorsally positioned scapula; an enlarged and uniquely proportioned supraspinous fossa; a relatively cranially oriented glenoid fossa; and ape-like reinforcement of the axillary margin by a stout ventral bar. StW 573 scapulae are as follows: smaller than those of some homininans (i.e., KSD-VP-1/1 and KNM-ER 47000A), larger than others (i.e., A.L. 288-1, Sts 7, and MH2), and most similar in size to another australopith from Sterkfontein, StW 431. Moreover, StW 573 and StW 431 exhibit similar structural features along their axillary margins and inferior angles. As the StW 573 pectoral girdle (e.g., scapular configuration) has a greater affinity to that of apes-Gorilla in particular-rather than modern humans, we suggest that the StW 573 morphological pattern appears to reflect adaptations to arboreal behaviors, especially those with the hand positioned above the head, more than human-like manipulatory capabilities. When compared with less complete pectoral girdles from middle/late Miocene apes and that of the penecontemporaneous KSD-VP-1/1 (Australopithecus afarensis), and mindful of consensus views on the adaptiveness of arboreal positional behaviors soliciting abducted glenohumeral joints in early Pliocene taxa, we propose that the StW 573 pectoral girdle is a reasonable model for hypothesizing pectoral girdle configuration of the crown hominin last common ancestor.
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Affiliation(s)
- Kristian J Carlson
- Department of Integrative Anatomical Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa.
| | - David J Green
- Department of Anatomy, Campbell University School of Osteopathic Medicine, Buies Creek, NC 27506, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa
| | - Tea Jashashvili
- Department of Integrative Anatomical Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; Department of Geology and Paleontology, Georgian National Museum, Tbilisi 0105, Georgia
| | - Travis R Pickering
- Department of Anthropology, University of Wisconsin, Madison, WI 53706, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa; Plio-Pleistocene Palaeontology Section, Department of Vertebrates, Ditsong National Museum, Pretoria 0001, South Africa
| | - Jason L Heaton
- Department of Biology, Birmingham-Southern College, Birmingham, AL 35254, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa; Plio-Pleistocene Palaeontology Section, Department of Vertebrates, Ditsong National Museum, Pretoria 0001, South Africa
| | - Amélie Beaudet
- School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050 South Africa; Department of Anatomy, University of Pretoria, PO Box 2034, Pretoria 0001, South Africa
| | - Dominic Stratford
- School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050 South Africa
| | - Robin Crompton
- Department of Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L7 8TX, UK
| | - Kathleen Kuman
- School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050 South Africa
| | - Laurent Bruxelles
- TRACES, UMR 5608 of the French National Centre for Scientific Research, Jean Jaurès University, 31058 Toulouse, France; French National Institute for Preventive Archaeological Researches (INRAP), 30900 Nîmes, France; School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050 South Africa
| | - Ronald J Clarke
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa
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24
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Yegian AK, Tucker Y, Gillinov S, Lieberman DE. Shorter distal forelimbs benefit bipedal walking and running mechanics: Implications for hominin forelimb evolution. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 175:589-598. [PMID: 33818760 DOI: 10.1002/ajpa.24274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 02/10/2021] [Accepted: 03/07/2021] [Indexed: 11/07/2022]
Abstract
OBJECTIVES Brachial index is a skeletal ratio that describes the relative length of the distal forelimb. Over the course of hominin evolution, a shift toward smaller brachial indices occurred. First, Pleistocene australopiths yield values between extant chimpanzees and humans, with further evolution in Pliocene Homo to the modern human range. We hypothesized that shorter distal forelimbs benefit walking and running performance, notably elbow and shoulder joint torques, and predicted that the benefit would be greater in running compared to walking. MATERIALS AND METHODS We tested our hypothesis in a modern human sample walking and running while carrying hand weights, which increase the inertia (mass and effective length) of the distal forelimb, simulating a larger brachial index. RESULTS We found longer distal forelimbs and the added mass increased elbow muscle torque by 98% while walking and 70% in running, confirming our hypothesis that shorter distal forelimbs benefit walking and running performance. Shoulder muscle torque similarly increased in both gaits with the addition of hand weights due to elongation of the effective forelimb length. Normalized elbow torque, which accounted for the effect on shoulder torque caused by the experimental manipulation, increased by 16% while walking but 52% while running, indicating that shorter distal forelimbs provide a greater benefit for running by approximately three-fold. DISCUSSION Selection for economical bipedal walking in Australopithecus and endurance running in Homo likely contributed to the shift toward relatively smaller distal forelimbs across hominin evolution, with modern human proportions attained in Pleistocene Homo erectus and retained in later species.
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Affiliation(s)
- Andrew K Yegian
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Yanish Tucker
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA.,School of Clinical Medicine, University of Cambridge, Cambridge, England
| | - Stephen Gillinov
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Daniel E Lieberman
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
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25
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Melillo SM, Gibert L, Saylor BZ, Deino A, Alene M, Ryan TM, Haile-Selassie Y. New Pliocene hominin remains from the Leado Dido'a area of Woranso-Mille, Ethiopia. J Hum Evol 2021; 153:102956. [PMID: 33711722 DOI: 10.1016/j.jhevol.2021.102956] [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: 09/03/2020] [Revised: 01/25/2021] [Accepted: 01/25/2021] [Indexed: 10/22/2022]
Abstract
Fossiliferous deposits at Woranso-Mille span the period when Australopithecus anamensis gave rise to Australopithecus afarensis (3.8-3.6 Ma) and encompass the core of the A. afarensis range (ca. 3.5-3.2 Ma). Within the latter period, fossils described to date include the intriguing but taxonomically unattributed Burtele foot, dentognathic fossils attributed to Australopithecus deyiremeda, and one specimen securely attributed to A. afarensis (the Nefuraytu mandible). These fossils suggest that at least one additional hominin lineage lived alongside A. afarensis in the Afar Depression. Here we describe a collection of hominin fossils from a new locality in the Leado Dido'a area of Woranso-Mille (LDD-VP-1). The strata in this area are correlated to the same chron as those in the Burtele area (C2An.3n; 3.59-3.33 Ma), and similar in age to the Maka Sands and the Basal through lower Sidi Hakoma Members of the Hadar Formation. We attribute all but one of the LDD hominin specimens to A. afarensis, based on diagnostic morphology of the mandible, maxilla, canines, and premolars. The LDD specimens generally fall within the range of variation previously documented for A. afarensis but increase the frequency of some rare morphological variants. However, one isolated M3 is extremely small, and its taxonomic affinity is currently unknown. The new observations support previous work on temporal trends in A. afarensis and demonstrate that the large range of variation accepted for this species is present even within a limited spatiotemporal range. The value added with this sample lies in its contribution to controlling for spatiotemporal differences among site samples in the A. afarensis hypodigm and its contemporaneity with non-A. afarensis specimens at Woranso-Mille.
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Affiliation(s)
- Stephanie M Melillo
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology Leipzig, Germany.
| | - Luis Gibert
- Departament de Mineralogia, Petrologia i Geologia Aplicada Facultat de Ciències de la Terra, Universitat de Barcelona, Barcelona, Spain
| | - Beverly Z Saylor
- Department of Earth, Environmental and Planetary Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Alan Deino
- Berkeley Geochronology Center, Berkeley, CA, USA
| | - Mulugeta Alene
- School of Earth Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Timothy M Ryan
- Department of Anthropology, Pennsylvania State University, University Park, PA, USA
| | - Yohannes Haile-Selassie
- Department of Physical Anthropology, Cleveland Museum of Natural History, Cleveland, OH, USA; Departments of Anthropology and Biology, Case Western Reserve University, Cleveland, OH, USA
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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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García-Martínez D, Green DJ, Bermúdez de Castro JM. Evolutionary development of the Homo antecessor scapulae (Gran Dolina site, Atapuerca) suggests a modern-like development for Lower Pleistocene Homo. Sci Rep 2021; 11:4102. [PMID: 33602966 PMCID: PMC7892855 DOI: 10.1038/s41598-021-83039-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/25/2021] [Indexed: 01/31/2023] Open
Abstract
Two well-preserved, subadult 800 ky scapulae from Gran Dolina belonging to Homo antecessor, provide a unique opportunity to investigate the ontogeny of shoulder morphology in Lower Pleistocene humans. We compared the H. antecessor scapulae with a sample of 98 P. troglodytes and 108 H. sapiens representatives covering seven growth stages, as well as with the DIK-1-1 (Dikika; Australopithecus afarensis), KNM-WT 15000 (Nariokotome; H. ergaster), and MH2 (Malapa; A. sediba) specimens. We quantified 15 landmarks on each scapula and performed geometric morphometric analyses. H. sapiens scapulae are mediolaterally broader with laterally oriented glenoid fossae relative to Pan and Dikika shoulder blades. Accordingly, H. antecessor scapulae shared more morphological affinities with modern humans, KNM-WT 15000, and even MH2. Both H. antecessor and modern Homo showed significantly more positive scapular growth trajectories than Pan (slopes: P. troglodytes = 0.0012; H. sapiens = 0.0018; H. antecessor = 0.0020). Similarities in ontogenetic trajectories between the H. antecessor and modern human data suggest that Lower Pleistocene hominin scapular development was already modern human-like. At the same time, several morphological features distinguish H. antecessor scapulae from modern humans along the entire trajectory. Future studies should include additional Australopithecus specimens for further comparative assessment of scapular growth trends.
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Affiliation(s)
- Daniel García-Martínez
- Centro Nacional para el Estudio de la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca 3, 09002, Burgos, Spain.
- Departamento de Paleobiología, Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal 2, 28006, Madrid, Spain.
| | - David J Green
- Department of Anatomy, Campbell University School of Osteopathic Medicine, Buies Creek, NC, 27506, USA
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg, WITS, 2050, South Africa
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MacLean KFE, Dickerson CR. Development of a comparative chimpanzee musculoskeletal glenohumeral model: implications for human function. J Exp Biol 2020; 223:jeb225987. [PMID: 33071220 DOI: 10.1242/jeb.225987] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 10/01/2020] [Indexed: 11/20/2022]
Abstract
Modern human shoulder function is affected by the evolutionary adaptations that have occurred to ensure survival and prosperity of the species. Robust examination of behavioral shoulder performance and injury risk can be holistically improved through an interdisciplinary approach that integrates anthropology and biomechanics. Coordination of these fields can allow different perspectives to contribute to a more complete interpretation of biomechanics of the modern human shoulder. The purpose of this study was to develop a novel biomechanical and comparative chimpanzee glenohumeral model, designed to parallel an existing human glenohumeral model, and compare predicted musculoskeletal outputs between the two models. The chimpanzee glenohumeral model consists of three modules - an external torque module, a musculoskeletal geometric module and an internal muscle force prediction module. Together, these modules use postural kinematics, subject-specific anthropometrics, a novel shoulder rhythm, glenohumeral stability ratios, hand forces, musculoskeletal geometry and an optimization routine to estimate joint reaction forces and moments, subacromial space dimensions, and muscle and tissue forces. Using static postural data of a horizontal bimanual suspension task, predicted muscle forces and subacromial space were compared between chimpanzees and humans. Compared with chimpanzees, the human model predicted a 2 mm narrower subacromial space, deltoid muscle forces that were often double those of chimpanzees and a strong reliance on infraspinatus and teres minor (60-100% maximal force) over other rotator cuff muscles. These results agree with previous work on inter-species differences that inform basic human rotator cuff function and pathology.
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Affiliation(s)
- Kathleen F E MacLean
- Division of Kinesiology, School of Health and Human Performance, Dalhousie University, 6260 South Street, Halifax, NS, Canada B3H 4R2
| | - Clark R Dickerson
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada N2L 3G1
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Comparative anatomy and 3D geometric morphometrics of the El Sidrón atlases (C1). J Hum Evol 2020; 149:102897. [PMID: 33137550 DOI: 10.1016/j.jhevol.2020.102897] [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] [Received: 01/29/2020] [Revised: 09/22/2020] [Accepted: 09/24/2020] [Indexed: 12/28/2022]
Abstract
The first cervical vertebra (atlas, C1) is an important element of the vertebral column because it connects the cranial base with the cervical column, thus helping to maintain head posture and contributing to neck mobility. However, few atlases are preserved in the fossil record because of the fragility of this vertebra. Consequently, only eight well-preserved atlases from adult Neandertals have been recovered and described. Here, we present nine new atlas remains from the El Sidrón Neandertal site (Asturias, Spain), two of which (SD-1643 and SD-1605/1595) are sufficiently well preserved to allow for a detailed comparative and three-dimensional geometric morphometric analysis. We compared standard linear measurements of SD-1643 and SD-1605/1595 with those of other Neandertal atlases and carried out three-dimensional geometric morphometric analyses to compare size and shape of SD-1643 and SD-1605/1595 with those of 28 Pan (Pan troglodytes and Pan paniscus), a broad comparative sample of 55 anatomically modern humans from African and European populations, and other fossil hominins (Neandertals, Homo antecessor, Paranthropus boisei). The El Sidrón atlas fossils show typical features of the Neandertal atlas morphology, such as caudal projection of the anterior tubercle, gracility of both the posterior tubercle and the tuberosity for the insertion of the transverse ligament, and an anteroposteriorly elongated neural canal. Furthermore, when compared with atlases from the other taxa, Neandertals exhibit species-specific features of atlas morphology including a relatively lower lateral mass height, relatively narrower transverse foramina, and flatter and more horizontally oriented articular facets. Some of these features fit with previous suggestions of shorter overall length of the cervical spine and potential differences in craniocervical posture and mobility. Our results may support a different spinopelvic alignment in this species, as the atlas morphology suggests reduced cervical lordosis.
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Villaseñor A, Bobe R, Behrensmeyer AK. Middle Pliocene hominin distribution patterns in Eastern Africa. J Hum Evol 2020; 147:102856. [DOI: 10.1016/j.jhevol.2020.102856] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 06/30/2020] [Accepted: 06/30/2020] [Indexed: 11/28/2022]
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Ruff CB, Squyres N, Junno J. Body mass estimation in hominins from humeral articular dimensions. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 173:480-499. [DOI: 10.1002/ajpa.24090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 04/02/2020] [Accepted: 05/17/2020] [Indexed: 12/31/2022]
Affiliation(s)
- Christopher B. Ruff
- Center for Functional Anatomy and Evolution Johns Hopkins University School of Medicine Baltimore Maryland USA
| | - Nicole Squyres
- Center for Functional Anatomy and Evolution Johns Hopkins University School of Medicine Baltimore Maryland USA
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32
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Is step width decoupled from pelvic motion in human evolution? Sci Rep 2020; 10:7806. [PMID: 32385415 PMCID: PMC7210942 DOI: 10.1038/s41598-020-64799-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/17/2020] [Indexed: 11/09/2022] Open
Abstract
Humans are the only primate that walk bipedally with adducted hips, valgus knees, and swing-side pelvic drop. These characteristic frontal-plane aspects of bipedalism likely play a role in balance and energy minimization during walking. Understanding when and why these aspects of bipedalism evolved also requires an understanding of how each of these features are interrelated during walking. Here we investigated the relationship between step width, hip adduction, and pelvic list during bipedalism by altering step widths and pelvic motions in humans in ways that both mimic chimpanzee gait as well as an exaggerated human gait. Our results show that altering either step width or pelvic list to mimic those of chimpanzees affects hip adduction, but neither of these gait parameters dramatically affects the other in ways that lead to a chimpanzee-like gait. These results suggest that the evolution of valgus knees and narrow steps in humans may be decoupled from the evolution of the human-like pattern of pelvic list. While the origin of narrow steps in hominins may be linked to minimizing energetic cost of locomotion, the origin of the human-like pattern of pelvic list remains unresolved.
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33
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Selby MS, Lovejoy CO, Byron CD. Odd-nosed monkey scapular morphology converges on that of arm-swinging apes. J Hum Evol 2020; 143:102784. [PMID: 32315868 DOI: 10.1016/j.jhevol.2020.102784] [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] [Received: 03/07/2019] [Revised: 03/13/2020] [Accepted: 03/13/2020] [Indexed: 10/24/2022]
Abstract
Odd-nosed monkeys 'arm-swing' more frequently than other colobines. They are therefore somewhat behaviorally analogous to atelines and apes. Scapular morphology regularly reflects locomotor mode, with both arm-swinging and climbing anthropoids showing similar characteristics, especially a mediolaterally narrow blade and cranially angled spine and glenoid. However, these traits are not expressed uniformly among anthropoids. Therefore, behavioral convergences in the odd-nosed taxa of Nasalis, Pygathrix, and Rhinopithecus with hominoids may not have resulted in similar structural convergences. We therefore used a broad sample of anthropoids to test how closely odd-nosed monkey scapulae resemble those of other arm-swinging primates. We used principal component analyses on size-corrected linear metrics and angles that reflect scapular size and shape in a broad sample of anthropoids. As in previous studies, our first component separated terrestrial and above-branch quadrupeds from clambering and arm-swinging taxa. On this axis, odd-nosed monkeys were closer than other colobines to modern apes and Ateles. All three odd-nosed genera retain glenoid orientations that are more typical of other colobines, but Pygathrix and Rhinopithecus are closer to hominoids than to other Asian colobines in mediolateral blade breadth, spine angle, and glenoid position. This suggests that scapular morphology of Pygathrix may reflect a significant reliance on arm-swinging and that the morphology of Rhinopithecus may reflect more reliance on general climbing. As 'arm-swinging' features are also found in taxa that only rarely arm-swing, we hypothesize that these features are also adaptive for scrambling and bridging in larger bodied anthropoids that use the fine-branch component of their arboreal niches.
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Affiliation(s)
- Michael S Selby
- Department of Biomedical Sciences, PCOM Georgia, Suwanee, GA, 30024-2937, USA.
| | - C Owen Lovejoy
- Department of Anthropology, School of Biomedical Sciences, Kent State University, Kent, OH, 44242-0001, USA
| | - Craig D Byron
- Department of Biology, Mercer University, Macon, GA, 31207, USA
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34
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Bermúdez de Castro JM, Martínez de Pinillos M, López-Polín L, Martín-Francés L, García-Campos C, Modesto-Mata M, Rosell J, Martinón-Torres M. A descriptive and comparative study of two Early Pleistocene immature scapulae from the TD6.2 level of the Gran Dolina cave site (Sierra de Atapuerca, Spain). J Hum Evol 2020; 139:102689. [PMID: 31902740 DOI: 10.1016/j.jhevol.2019.102689] [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] [Received: 03/21/2019] [Revised: 10/03/2019] [Accepted: 10/09/2019] [Indexed: 11/26/2022]
Abstract
Here we present the descriptive and comparative study of two immature scapulae recovered from the TD6.2 level of the Gran Dolina cave site (Sierra de Atapuerca, Spain) and assigned to Homo antecessor. This is the first time that data on the morphology and dimensions of the scapulae of a European late Early Pleistocene hominin population are provided. Considering the state of development and the linear dimensions, the scapula ATD6-116 could belong to a child of about 2-4 years. The morphology of ATD6-116 clearly departs from that of the Australopithecus afarensis juvenile specimen DIK-1-1, pointing to functional differences in locomotor behavior between Australopithecus and the late Early Pleistocene hominins. The immature scapula ATD6-118 belonged to an immature individual with a development of the scapula equivalent to that of adolescents of recent human populations. The scapulae ATD6-118 and KNM-WT 15000 present a similar state of development. Although the scapula KNM-WT 15000 is clearly larger than ATD6-118, these two specimens share some characteristics such as their relative narrowness and the value of the axilloglenoid and spinoglenoid angles. The glenoid fossa of ATD6-116 show a lateral orientation, whereas in ATD6-118 the glenoid fossa is slightly cranially oriented, but still within the range of variation of modern humans. The glenoid index of both ATD6-116 and ATD6-118 is low in accordance to the values usually observed in other early hominins, thus showing the primitive condition for this feature. Both scapulae show a ventrally placed axillary sulcus. The presence of this primitive feature in ATD-116 confirms that the shape of the axillary border has a genetic basis and it is not related to physical activity.
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Affiliation(s)
- José María Bermúdez de Castro
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo de la Sierra de Atapuerca 3, 09002 Burgos, Spain; Anthropology Department, University College London, 14 Taviton Street, London WC1 H 0BW, UK.
| | - Marina Martínez de Pinillos
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo de la Sierra de Atapuerca 3, 09002 Burgos, Spain.
| | - Lucía López-Polín
- IPHES, Institut Català de Paleoecologia Humana i Evolució Social, Unit Associated to CSIC, C/Marcel.lí Domingo s/n-Campus Sescelades URV (Edifici W3), 43007 Tarragona, Spain.
| | - Laura Martín-Francés
- Univ. Bordeaux, CNRS, MCC, PACEA, UMR 5199, F-33615 Pessac Cedex, France; Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo de la Sierra de Atapuerca 3, 09002 Burgos, Spain.
| | - Cecilia García-Campos
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo de la Sierra de Atapuerca 3, 09002 Burgos, Spain.
| | - Mario Modesto-Mata
- Equipo Primeros Pobladores de Extremadura, Casa de la Cultura Rodríguez Moñino, Avda. Cervantes s/n., 10003 Cáceres, Spain.
| | - Jordi Rosell
- Área de Prehistoria, Universitat Rovira i Virgili (URV), Avinguda de Catalunya 35, 43002 Tarragona, Spain; IPHES, Institut Català de Paleoecologia Humana i Evolució Social, Unit Associated to CSIC, C/Marcel.lí Domingo s/n-Campus Sescelades URV (Edifici W3), 43007 Tarragona, Spain.
| | - María Martinón-Torres
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo de la Sierra de Atapuerca 3, 09002 Burgos, Spain; Anthropology Department, University College London, 14 Taviton Street, London WC1 H 0BW, UK.
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35
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Du A, Rowan J, Wang SC, Wood BA, Alemseged Z. Statistical estimates of hominin origination and extinction dates: A case study examining the Australopithecus anamensis–afarensis lineage. J Hum Evol 2020; 138:102688. [DOI: 10.1016/j.jhevol.2019.102688] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 10/03/2019] [Accepted: 10/09/2019] [Indexed: 11/28/2022]
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Trumble BC, Finch CE. THE EXPOSOME IN HUMAN EVOLUTION: FROM DUST TO DIESEL. THE QUARTERLY REVIEW OF BIOLOGY 2019; 94:333-394. [PMID: 32269391 PMCID: PMC7141577 DOI: 10.1086/706768] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Global exposures to air pollution and cigarette smoke are novel in human evolutionary history and are associated with about 16 million premature deaths per year. We investigate the history of the human exposome for relationships between novel environmental toxins and genetic changes during human evolution in six phases. Phase I: With increased walking on savannas, early human ancestors inhaled crustal dust, fecal aerosols, and spores; carrion scavenging introduced new infectious pathogens. Phase II: Domestic fire exposed early Homo to novel toxins from smoke and cooking. Phases III and IV: Neolithic to preindustrial Homo sapiens incurred infectious pathogens from domestic animals and dense communities with limited sanitation. Phase V: Industrialization introduced novel toxins from fossil fuels, industrial chemicals, and tobacco at the same time infectious pathogens were diminishing. Thereby, pathogen-driven causes of mortality were replaced by chronic diseases driven by sterile inflammogens, exogenous and endogenous. Phase VI: Considers future health during global warming with increased air pollution and infections. We hypothesize that adaptation to some ancient toxins persists in genetic variations associated with inflammation and longevity.
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Affiliation(s)
- Benjamin C Trumble
- School of Human Evolution & Social Change and Center for Evolution and Medicine, Arizona State University Tempe, Arizona 85287 USA
| | - Caleb E Finch
- Leonard Davis School of Gerontology and Dornsife College, University of Southern California Los Angeles, California 90089-0191 USA
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37
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Böhme M, Spassov N, Fuss J, Tröscher A, Deane AS, Prieto J, Kirscher U, Lechner T, Begun DR. A new Miocene ape and locomotion in the ancestor of great apes and humans. Nature 2019; 575:489-493. [DOI: 10.1038/s41586-019-1731-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 09/27/2019] [Indexed: 01/26/2023]
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38
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Age and context of mid-Pliocene hominin cranium from Woranso-Mille, Ethiopia. Nature 2019; 573:220-224. [DOI: 10.1038/s41586-019-1514-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 07/26/2019] [Indexed: 11/08/2022]
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39
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Heaton JL, Pickering TR, Carlson KJ, Crompton RH, Jashashvili T, Beaudet A, Bruxelles L, Kuman K, Heile AJ, Stratford D, Clarke RJ. The long limb bones of the StW 573 Australopithecus skeleton from Sterkfontein Member 2: Descriptions and proportions. J Hum Evol 2019; 133:167-197. [DOI: 10.1016/j.jhevol.2019.05.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 05/30/2019] [Accepted: 05/31/2019] [Indexed: 02/07/2023]
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40
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Haile-Selassie Y, Ryan TM. Comparative description and taxonomy of new hominin juvenile mandibles from the Pliocene of Woranso-Mille (Central Afar, Ethiopia). J Hum Evol 2019; 132:15-31. [DOI: 10.1016/j.jhevol.2019.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 04/13/2019] [Accepted: 04/15/2019] [Indexed: 12/01/2022]
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41
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Walker CS, Cofran ZD, Grabowski M, Marchi D, Cook RW, Churchill SE, Tommy KA, Throckmorton Z, Ross AH, Hawks J, Yapuncich GS, Van Arsdale AP, Rentzeperis FI, Berger LR, DeSilva JM. Morphology of the Homo naledi femora from Lesedi. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 170:5-23. [PMID: 31228254 DOI: 10.1002/ajpa.23877] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 05/26/2019] [Accepted: 05/27/2019] [Indexed: 11/07/2022]
Abstract
OBJECTIVES The femoral remains recovered from the Lesedi Chamber are among the most complete South African fossil hominin femora discovered to date and offer new and valuable insights into the anatomy and variation of the bone in Homo naledi. While the femur is one of the best represented postcranial elements in the H. naledi assemblage from the Dinaledi Chamber, the fragmentary and commingled nature of the Dinaledi femoral remains has impeded the assessment of this element in its complete state. MATERIALS AND METHODS Here we analyze and provide descriptions of three new relatively well-preserved femoral specimens of H. naledi from the Lesedi Chamber: U.W. 102a-001, U.W. 102a-003, and U.W. 102a-004. These femora are quantitatively and qualitatively compared to multiple extinct hominin femoral specimens, extant hominid taxa, and, where possible, each other. RESULTS The Lesedi femora are morphologically similar to the Dinaledi femora for all overlapping regions, with differences limited to few traits of presently unknown significance. The Lesedi distal femur and mid-diaphysis preserve anatomy previously unidentified or unconfirmed in the species, including an anteroposteriorly expanded midshaft and anteriorly expanded patellar surface. The hypothesis that the Lesedi femoral sample may represent two individuals is supported. DISCUSSION The Lesedi femora increase the range of variation of femoral morphology in H. naledi. Newly described features of the diaphysis and distal femur are either taxonomically uninformative or Homo-like. Overall, these three new femora are consistent with previous functional interpretations of the H. naledi lower limb as belonging to a species adapted for long distance walking and, possibly, running.
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Affiliation(s)
- Christopher S Walker
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina.,Department of Evolutionary Anthropology, Duke University, Durham, North Carolina.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Zachary D Cofran
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Anthropology Department, Vassar College, Poughkeepsie, New York
| | - Mark Grabowski
- Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK
| | - Damiano Marchi
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Biology, University of Pisa, Pisa, Italy
| | - Rebecca W Cook
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina.,Department of Evolutionary Anthropology, Duke University, Durham, North Carolina
| | - Steven E Churchill
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Kimberleigh A Tommy
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Human Variation and Identification Research Unit, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Zachary Throckmorton
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Anatomy, Arkansas College of Osteopathic Medicine, Fort Smith, Arkansas
| | - Ann H Ross
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina
| | - John Hawks
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Anthropology, University of Wisconsin, Madison, Wisconsin
| | - Gabriel S Yapuncich
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina.,Department of Evolutionary Anthropology, Duke University, Durham, North Carolina
| | | | | | - Lee R Berger
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Jeremy M DeSilva
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Anthropology, Dartmouth College, Hanover, New Hampshire
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42
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Joordens JC, Feibel CS, Vonhof HB, Schulp AS, Kroon D. Relevance of the eastern African coastal forest for early hominin biogeography. J Hum Evol 2019; 131:176-202. [DOI: 10.1016/j.jhevol.2019.03.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 03/10/2019] [Accepted: 03/13/2019] [Indexed: 12/25/2022]
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43
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Callison WÉ, Holowka NB, Lieberman DE. Thoracic adaptations for ventilation during locomotion in humans and other mammals. J Exp Biol 2019; 222:jeb.189357. [DOI: 10.1242/jeb.189357] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/01/2019] [Indexed: 11/20/2022]
Abstract
Bipedal humans, like canids and some other cursorial mammals, are thought to have been selected for endurance running, which requires the ability to sustain aerobic metabolism over long distances by inspiring large volumes of air for prolonged periods of time. Here we test the general hypothesis that humans and other mammals selected for vigorous endurance activities evolved derived thoracic features to increase ventilatory capacity. To do so, we investigate whether humans and dogs rely on thoracic motion to increase tidal volume during running to a greater extent than goats, a species that was not selected for endurance locomotion. We found that while all three species use diaphragmatic breathing to increase tidal volume with increasing oxygen demand, humans also use both dorsoventral and mediolateral expansions of the thorax. Dogs use increased dorsoventral expansion of the thorax, representing an intermediate between humans and goats. 3D analyses of joint morphology of 10 species across four mammalian orders also show that endurance-adapted cursorial species independently evolved more concavo-convex costovertebral joint morphologies that allow for increased rib mobility for thoracic expansion. Evidence for similarly derived concavo-convex costovertebral joints in Homo erectus corresponds with other evidence for the evolution of endurance running in the genus Homo.
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Affiliation(s)
- W. Éamon Callison
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA, USA
| | - Nicholas B. Holowka
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA, USA
| | - Daniel E. Lieberman
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA, USA
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Pickering TR, Heaton JL, Clarke RJ, Stratford D. Hominin vertebrae and upper limb bone fossils from Sterkfontein Caves, South Africa (1998-2003 excavations). AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 168:459-480. [DOI: 10.1002/ajpa.23758] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/08/2018] [Accepted: 11/05/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Travis Rayne Pickering
- Department of Anthropology; University of Wisconsin-Madison; Madison Wisconsin
- Evolutionary Studies Institute; University of the Witwatersand; Johannesburg South Africa
- Plio-Pleistocene Palaeontology Section, Department of Vertebrates; Ditsong National Museum of Natural History (Transvaal Museum); Pretoria South Africa
| | - Jason L. Heaton
- Evolutionary Studies Institute; University of the Witwatersand; Johannesburg South Africa
- Plio-Pleistocene Palaeontology Section, Department of Vertebrates; Ditsong National Museum of Natural History (Transvaal Museum); Pretoria South Africa
- Department of Biology; Birmingham-Southern College; Birmingham Alabama
| | - R. J. Clarke
- Evolutionary Studies Institute; University of the Witwatersand; Johannesburg South Africa
| | - Dominic Stratford
- School of Geography, Archaeology and Environmental Studies; University of the Witwatersrand; Johannesburg South Africa
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VanSickle C, Cofran Z, García-Martínez D, Williams SA, Churchill SE, Berger LR, Hawks J. Homo naledi pelvic remains from the Dinaledi Chamber, South Africa. J Hum Evol 2018; 125:122-136. [DOI: 10.1016/j.jhevol.2017.10.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 09/27/2017] [Accepted: 10/03/2017] [Indexed: 11/30/2022]
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Thompson NE, O’Neill MC, Holowka NB, Demes B. Step width and frontal plane trunk motion in bipedal chimpanzee and human walking. J Hum Evol 2018; 125:27-37. [DOI: 10.1016/j.jhevol.2018.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 09/22/2018] [Accepted: 09/24/2018] [Indexed: 10/28/2022]
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Thompson NE, Rubinstein D, Larson SG. Great ape thorax and shoulder configuration-An adaptation for arboreality or knuckle-walking? J Hum Evol 2018; 125:15-26. [PMID: 30502892 DOI: 10.1016/j.jhevol.2018.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 09/19/2018] [Accepted: 09/24/2018] [Indexed: 10/28/2022]
Abstract
Great apes exhibit a suite of morphological traits of the shoulder and upper thorax that have traditionally been linked to orthograde arborealism. Recently it has been proposed that these traits are instead adaptations for knuckle-walking, and more broadly, that knuckle-walking itself is an adaptation for shock absorption during terrestriality. Here we test several tenets of these hypotheses using kinematic and kinetic data from chimpanzees and macaques, and electromyographic data of shoulder muscle activity in chimpanzees. We collected 3D kinematic data to quantify motion of the acromion and trunk during quadrupedalism and vertical climbing in chimpanzees as well as ground reaction forces to investigate the presence and magnitude of impact transient forces during terrestrial locomotion in chimpanzees and macaques. We also investigated patterns of recruitment of select forelimb musculature (triceps brachii and serratus anterior) using previously collected data in chimpanzees to determine whether these muscles may function to absorb impact transient forces. We found that the acromion is significantly more elevated in vertical climbing than during knuckle-walking, while dorsoventral ranges and magnitudes of motion were similar between gaits. Ground reaction forces indicate that only a minority of strides in either chimpanzees or macaques have transient forces and, when present, these transient forces as well as loading rates are small. Electromyographic results show that activity of the triceps brachii may facilitate energy absorption while serratus anterior likely functions to support the trunk, as in other primates. Our data suggest there is little to no evidence supporting recent hypotheses that the African ape upper thorax and shoulder configuration is an adaptation for knuckle-walking, or more broadly, that knuckle-walking exists as an adaptation to absorb impact shock during terrestriality. We do however find some evidence that shoulder configuration allows greater scapular elevation in chimpanzees during arboreal behaviors (e.g., vertical climbing).
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Affiliation(s)
- Nathan E Thompson
- Department of Anatomy, NYIT College of Osteopathic Medicine, Old Westbury, NY 11568, USA.
| | - Danielle Rubinstein
- New York Institute of Technology, College of Osteopathic Medicine, NY 11568 USA
| | - Susan G Larson
- Department of Anatomical Sciences, Stony Brook University School of Medicine, Stony Brook, NY 11794-8081, USA
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Boyle EK, McNutt EJ, Sasaki T, Suwa G, Zipfel B, DeSilva JM. A quantification of calcaneal lateral plantar process position with implications for bipedal locomotion in Australopithecus. J Hum Evol 2018; 123:24-34. [PMID: 30075872 DOI: 10.1016/j.jhevol.2018.05.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 05/23/2018] [Accepted: 05/24/2018] [Indexed: 11/25/2022]
Abstract
The evolution of bipedalism in the hominin lineage has shaped the posterior human calcaneus into a large, robust structure considered to be adaptive for dissipating peak compressive forces and energy during heel-strike. A unique anatomy thought to contribute to the human calcaneus and its function is the lateral plantar process (LPP). While it has long been known that humans possess a plantarly positioned LPP and apes possess a more dorsally positioned homologous structure, the relative position of the LPP and intraspecific variation of this structure have never been quantified. Here, we present a method for quantifying relative LPP position and find that, while variable, humans have a significantly more plantar position of the LPP than that found in the apes. Among extinct hominins, while the position of the LPP in Australopithecus afarensis falls within the human distribution, the LPP is more dorsally positioned in Australopithecus sediba and barely within the modern human range of variation. Results from a resampling procedure suggest that these differences can reflect either individual variation of a foot structure/function largely shared among Australopithecus species, or functionally distinct morphologies that reflect locomotor diversity in Plio-Pleistocene hominins. An implication of the latter possibility is that calcaneal changes adaptive for heel-striking bipedalism may have evolved independently in two different hominin lineages.
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Affiliation(s)
- Eve K Boyle
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, 800 22nd St. NW, Suite 6000, Washington, DC 20052, USA.
| | - Ellison J McNutt
- Department of Anthropology, Dartmouth College, Hanover, NH 03755, USA; Ecology, Evolution, Ecosystems, and Society, Dartmouth College, Hanover, NH 03755, USA
| | - Tomohiko Sasaki
- The University Museum, The University of Tokyo, Tokyo, Japan
| | - Gen Suwa
- The University Museum, The University of Tokyo, Tokyo, Japan
| | - Bernhard Zipfel
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa; School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Jeremy M DeSilva
- Department of Anthropology, Dartmouth College, Hanover, NH 03755, USA; Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
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Ruff CB. Functional morphology in the pages of the AJPA. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 165:688-704. [PMID: 29574828 DOI: 10.1002/ajpa.23402] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 12/20/2017] [Accepted: 12/20/2017] [Indexed: 12/16/2022]
Affiliation(s)
- Christopher B Ruff
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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Ruff CB, Burgess ML, Junno J, Mudakikwa A, Zollikofer CPE, Ponce de León MS, McFarlin SC. Phylogenetic and environmental effects on limb bone structure in gorillas. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 166:353-372. [DOI: 10.1002/ajpa.23437] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/29/2018] [Accepted: 01/30/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Christopher B. Ruff
- Johns Hopkins University School of MedicineCenter for Functional Anatomy and Evolution, 1830 E. Monument StBaltimore Maryland 21205
| | - M. Loring Burgess
- Johns Hopkins University School of MedicineCenter for Functional Anatomy and Evolution, 1830 E. Monument StBaltimore Maryland 21205
| | | | - Antoine Mudakikwa
- Department of Tourism and ConservationRwanda Development BoardKigali Rwanda
| | | | | | - Shannon C. McFarlin
- Department of Anthropology, Center for the Advanced Study of Human PaleobiologyThe George Washington UniversityWashington DC
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