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Prang TC. The relative size of the calcaneal tuber reflects heel strike plantigrady in African apes and humans. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24865. [PMID: 38058279 DOI: 10.1002/ajpa.24865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 08/30/2023] [Accepted: 10/10/2023] [Indexed: 12/08/2023]
Abstract
OBJECTIVES The positional repertoire of the human-chimpanzee last common ancestor is critical for reconstructing the evolution of bipedalism. African apes and humans share a heel strike plantigrade foot posture associated with terrestriality. Previous research has established that modern humans have a relatively large and intrinsically robust calcaneal tuber equipped to withstand heel strike forces associated with bipedal walking and running. However, it is unclear whether African apes have a relatively larger calcaneal tuber than non-heel-striking primates, and how this trait might have evolved among anthropoids. Here, I test the hypothesis that heel-striking primates have a relatively larger calcaneal tuber than non-heel-striking primates. METHODS The comparative sample includes 331 individuals and 53 taxa representing hominoids, cercopithecoids, and platyrrhines. Evolutionary modeling was used to test for the effect of foot posture on the relative size of the calcaneal tuber in a phylogenetic framework that accounts for adaptation and inertia. Bayesian evolutionary modeling was used to identify selective regime shifts in the relative size of the calcaneal tuber among anthropoids. RESULTS The best fitting evolutionary model was a Brownian motion model with regime-dependent trends characterized by relatively large calcaneal tubers among African apes and humans. Evolutionary modeling provided support for an evolutionary shift toward a larger calcaneal tuber at the base of the African ape and human clade. CONCLUSIONS The results of this study support the view that African apes and humans share derived traits related to heel strike plantigrady, which implies that humans evolved from a semi-terrestrial quadrupedal ancestor.
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Affiliation(s)
- Thomas C Prang
- Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, USA
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2
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Harper CM, Roach CS, Goldstein DM, Sylvester AD. Morphological variation of the Pan talus relative to that of Gorilla. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023. [PMID: 37300336 DOI: 10.1002/ajpa.24796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 03/27/2023] [Accepted: 05/27/2023] [Indexed: 06/12/2023]
Abstract
OBJECTIVES Differences in talar articular morphology relative to locomotion have recently been found within Pan and Gorilla. Whole-bone talar morphology within, and shared variation among, Pan and Gorilla (sub)species, however, has yet to be investigated. Here we separately analyze talar external shape within Pan (P. t. troglodytes, P. t. schweinfurthii, P. t. verus, P. paniscus) and Gorilla (G. g. gorilla, G. b. beringei, G. b. graueri) relative to degree of arboreality and body size. Pan and Gorilla are additionally analyzed together to determine if consistent shape differences exist within the genera. MATERIALS AND METHODS Talar external shape was quantified using a weighted spherical harmonic analysis. Shape variation both within and among Pan and Gorilla was described using principal component analyses. Root mean square distances were calculated between taxon averages, and resampling statistics conducted to test for pairwise differences. RESULTS P. t. verus (most arboreal Pan) talar shape significantly differs from other Pan taxa (p < 0.05 for pairwise comparisons) driven by more asymmetrical trochlear rims and a medially-set talar head. P. t. troglodytes, P. t. schweinfurthii, and P. paniscus do not significantly differ (p > 0.05 for pairwise comparisons). All gorilla taxa exhibit significantly different talar morphologies (p < 0.007 for pairwise comparisons). The more terrestrial subspecies of G. beringei and P. troglodytes exhibit a superoinferiorly taller talar head/neck complex. DISCUSSION P. t. verus exhibits talar morphologies that have been previously related to more frequent arboreality. The adaptations in the more terrestrial G. beringei and P. troglodytes subspecies may serve to facilitate load transmission.
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Affiliation(s)
- Christine M Harper
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey, USA
| | - Caleigh S Roach
- Krieger School of Arts and Sciences, The Johns Hopkins University, Baltimore, Maryland, USA
| | - Deanna M Goldstein
- Department of Anatomical Sciences, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, USA
| | - Adam D Sylvester
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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3
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Antón SC, Middleton ER. Making meaning from fragmentary fossils: Early Homo in the Early to early Middle Pleistocene. J Hum Evol 2023; 179:103307. [PMID: 37030994 DOI: 10.1016/j.jhevol.2022.103307] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 11/16/2022] [Accepted: 11/27/2022] [Indexed: 04/10/2023]
Abstract
In celebration of the 50th anniversary of the Journal of Human Evolution, we re-evaluate the fossil record for early Homo (principally Homo erectus, Homo habilis, and Homo rudolfensis) from early diversification and dispersal in the Early Pleistocene to the ultimate demise of H. erectus in the early Middle Pleistocene. The mid-1990s marked an important historical turning point in our understanding of early Homo with the redating of key H. erectus localities, the discovery of small H. erectus in Asia, and the recovery of an even earlier presence of early Homo in Africa. As such, we compare our understanding of early Homo before and after this time and discuss how the order of fossil discovery and a focus on anchor specimens has shaped, and in many ways biased, our interpretations of early Homo species and the fossils allocated to them. Fragmentary specimens may counter conventional wisdom but are often overlooked in broad narratives. We recognize at least three different cranial and two or three pelvic morphotypes of early Homo. Just one postcranial morph aligns with any certainty to a cranial species, highlighting the importance of explicitly identifying how we link specimens together and to species; we offer two ways of visualizing these connections. Chronologically and morphologically H. erectus is a member of early Homo, not a temporally more recent species necessarily evolved from either H. habilis or H. rudolfensis. Nonetheless, an ancestral-descendant notion of their evolution influences expectations around the anatomy of missing elements, especially the foot. Weak support for long-held notions of postcranial modernity in H. erectus raises the possibility of alternative drivers of dispersal. New observations suggest that the dearth of faces in later H. erectus may mask taxonomic diversity in Asia and suggest various later mid-Pleistocene populations could derive from either Asia or Africa. Future advances will rest on the development of nuanced ways to affiliate fossils, greater transparency of implicit assumptions, and attention to detailed life history information for comparative collections; all critical pursuits for future research given the great potential they have to enrich our evolutionary reconstructions for the next fifty years and beyond.
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Affiliation(s)
- Susan C Antón
- Center for the Study of Human Origins, Department of Anthropology, New York University, NY, NY 10003, USA.
| | - Emily R Middleton
- Department of Anthropology, University of Wisconsin-Milwaukee, WI 53211, USA
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4
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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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5
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Harper CM, Zipfel B, DeSilva JM, McNutt EJ, Thackeray F, Braga J. A new early hominin calcaneus from Kromdraai (South Africa). J Anat 2022; 241:500-517. [PMID: 35373345 PMCID: PMC9296044 DOI: 10.1111/joa.13660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 12/22/2022] Open
Abstract
The Kromdraai site in South Africa has yielded numerous early hominin fossils since 1938. As a part of recent excavations within Unit P, a largely complete early hominin calcaneus (KW 6302) was discovered. Due to its role in locomotion, the calcaneus has the potential to reveal important form/function relationships. Here, we describe KW 6302 and analyze its preserved morphology relative to human and nonhuman ape calcanei, as well as calcanei attributed to Australopithecus afarensis, Australopithecus africanus, Australopithecus sediba, Homo naledi, and the Omo calcaneus (either Paranthropus or early Homo). KW 6302 calcaneal morphology is assessed using numerous quantitative metrics including linear measures, calcaneal robusticity index, relative lateral plantar process position, Achilles tendon length reconstruction, and a three-dimensional geometric morphometric sliding semilandmark analysis. KW 6302 exhibits an overall calcaneal morphology that is intermediate between humans and nonhuman apes, although closer to modern humans. KW 6302 possesses many traits that indicate it was likely well-adapted for terrestrial bipedal locomotion, including a relatively flat posterior talar facet and a large lateral plantar process that is similarly positioned to modern humans. It also retains traits that indicate that climbing may have remained a part of its locomotor repertoire, such as a relatively gracile tuber and a large peroneal trochlea. Specimens from Kromdraai have been attributed to either Paranthropus robustus or early Homo; however, there are no definitively attributed calcanei for either genus, making it difficult to taxonomically assign this specimen. KW 6302 and the Omo calcaneus, however, fall outside the range of expected variation for an extant genus, indicating that if the Omo calcaneus was Paranthropus, then KW 6302 would likely be attributed to early Homo (or vice versa).
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Affiliation(s)
- Christine M. Harper
- Department of Biomedical SciencesCooper Medical School of Rowan UniversityCamdenNew JerseyUSA
| | - Bernhard Zipfel
- Evolutionary Studies InstituteUniversity of the WitwatersrandJohannesburgSouth Africa
| | | | - Ellison J. McNutt
- Department of Biomedical SciencesOhio University Heritage College of Osteopathic MedicineAthensOhioUSA
| | - Francis Thackeray
- Evolutionary Studies InstituteUniversity of the WitwatersrandJohannesburgSouth Africa
| | - José Braga
- Evolutionary Studies InstituteUniversity of the WitwatersrandJohannesburgSouth Africa
- Centre d'Anthropobiologie et de Génomique de ToulouseUniversité Paul Sabatier Toulouse IIIToulouseFrance
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6
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Unique foot posture in Neanderthals reflects their body mass and high mechanical stress. J Hum Evol 2021; 161:103093. [PMID: 34749003 DOI: 10.1016/j.jhevol.2021.103093] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 10/02/2021] [Accepted: 10/03/2021] [Indexed: 11/20/2022]
Abstract
Neanderthal foot bone proportions and morphology are mostly indistinguishable from those of Homo sapiens, with the exception of several distinct Neanderthal features in the talus. The biomechanical implications of these distinct talar features remain contentious, fueling debate around the adaptive meaning of this distinctiveness. With the aim of clarifying this controversy, we test phylogenetic and behavioral factors as possible contributors, comparing tali of 10 Neanderthals and 81 H. sapiens (Upper Paleolithic and Holocene hunter-gatherers, agriculturalists, and postindustrial group) along with the Clark Howell talus (Omo, Ethiopia). Variation in external talar structures was assessed through geometric morphometric methods, while bone volume fraction and degree of anisotropy were quantified in a subsample (n = 45). Finally, covariation between point clouds of site-specific trabecular variables and surface landmark coordinates was assessed. Our results show that although Neanderthal talar external and internal morphologies were distinct from those of H. sapiens groups, shape did not significantly covary with either bone volume fraction or degree of anisotropy, suggesting limited covariation between external and internal talar structures. Neanderthal external talar morphology reflects ancestral retentions, along with various adaptations to high levels of mobility correlated to their presumably unshod hunter-gatherer lifestyle. This pairs with their high site-specific trabecular bone volume fraction and anisotropy, suggesting intense and consistently oriented locomotor loading, respectively. Relative to H.sapiens, Neanderthals exhibit differences in the talocrural joint that are potentially attributable to cultural and locomotor behavior dissimilarity, a talonavicular joint that mixes ancestral and functional traits, and a derived subtalar joint that suggests a predisposition for a pronated foot during stance phase. Overall, Neanderthal talar variation is attributable to mobility strategy and phylogenesis, while H. sapiens talar variation results from the same factors plus footwear. Our results suggest that greater Neanderthal body mass and/or higher mechanical stress uniquely led to their habitually pronated foot posture.
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7
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Harper CM, Ruff CB, Sylvester AD. Calcaneal shape variation in humans, nonhuman primates, and early hominins. J Hum Evol 2021; 159:103050. [PMID: 34438297 DOI: 10.1016/j.jhevol.2021.103050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 06/29/2021] [Accepted: 06/29/2021] [Indexed: 01/08/2023]
Abstract
The foot has played a prominent role in evaluating early hominin locomotion. The calcaneus, in particular, plays an important role in weight-bearing. Although the calcanei of early hominins have been previously scrutinized, a three-dimensional analysis of the entire calcaneal shape has not been conducted. Here, we investigate the relationship between external calcaneal shape and locomotion in modern Homo sapiens (n = 130), Gorilla (n = 86), Pan (n = 112), Pongo (n = 31), Papio (n = 28), and hylobatids (Hylobates, Symphalangus; n = 32). We use these results to place the calcanei attributed to Australopithecus sediba, A. africanus, A. afarensis, H. naledi, and Homo habilis/Paranthropus boisei into a locomotor context. Calcanei were scanned using either surface scanning or micro-CT and their external shape analyzed using a three-dimensional geometric morphometric sliding semilandmark analysis. Blomberg's K statistic was used to estimate phylogenetic signal in the shape data. Shape variation was summarized using a principal components analysis. Procrustes distances between all taxa as well as distances between each fossil and the average of each taxon were calculated. Blomberg's K statistic was small (K = 0.1651), indicating weak phylogenetic effects, suggesting variation is driven by factors other than phylogeny (e.g., locomotion or body size). Modern humans have a large calcaneus relative to body size and display a uniquely convex cuboid facet, facilitating a rigid midfoot for bipedalism. More arboreal great apes display relatively deeper cuboid facet pivot regions for increased midfoot mobility. Australopithecus afarensis demonstrates the most human-like calcaneus, consistent with obligate bipedalism. Homo naledi is primarily modern human-like, but with some intermediate traits, suggesting a different form of bipedalism than modern humans. Australopithecus africanus, A. sediba, and H. habilis/P. boisei calcanei all possess unique combinations of human and nonhuman ape-like morphologies, suggesting a combination of bipedal and arboreal behaviors.
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Affiliation(s)
- Christine M Harper
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States; Cooper Medical School of Rowan University, Department of Biomedical Sciences, 401 S Broadway, Room 453, Camden, NJ 08103, United States.
| | - Christopher B Ruff
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States
| | - Adam D Sylvester
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 East Monument Street, Room 302, Baltimore, MD 21205, United States
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8
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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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9
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Yapuncich GS, Granatosky MC. Footloose: Articular surface morphology and joint movement potential in the ankles of lorisids and cheirogaleids. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 175:876-894. [PMID: 33931869 DOI: 10.1002/ajpa.24298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 02/24/2021] [Accepted: 04/09/2021] [Indexed: 11/06/2022]
Abstract
OBJECTIVES The competing functional demands of diarthrodial joints, permitting mobility while retaining enough stability to transmit forces across the joint, have been linked with the shape and size of the joint's articular surfaces. A clear understanding of the relationship between joint morphology and joint movement potential is important for reconstructing locomotor behaviors in fossil taxa. METHODS In a sample of matched tali and calcanei of lorisids (n = 28) and cheirogaleids (n = 38), we quantify the surface areas of the talar and calcaneal ectal (=posterior talocalcaneal) articular surfaces and model the principal curvatures of these surfaces with quadric formulas. These two taxonomic groups have similar body masses, but differ substantially in positional behavior, so that differences in joint surface morphology should reflect adaptive demands of their locomotor behavior. RESULTS Compared with cheirogaleids, lorisids exhibit: (a) a significantly greater area difference between their paired joint surfaces; and (b) a more pronounced saddle shape for the talar ectal facet. CONCLUSION The increased subtalar joint mobility observed in lorisids may be achieved by increasing the amount of sliding and rolling that can occur at the subtalar joint. The subtalar joint morphology observed in two fossil euarchontans, the plesiadapiforms Purgatorius sp. and Plesiadapis cookei, compares favorably with the morphology observed among lorisids, potentially suggesting antipronograde postures within these extinct taxa.
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Affiliation(s)
- Gabriel S Yapuncich
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA
| | - Michael C Granatosky
- Department of Anatomy, New York Institute of Technology, Old Westbury, New York, USA
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10
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Harper CM, Ruff CB, Sylvester AD. Scaling and relative size of the human, nonhuman ape, and baboon calcaneus. Anat Rec (Hoboken) 2021; 305:100-122. [PMID: 33843151 DOI: 10.1002/ar.24642] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/28/2021] [Accepted: 03/06/2021] [Indexed: 01/04/2023]
Abstract
Among human and nonhuman apes, calcaneal morphology exhibits significant variation that has been related to locomotor behavior. Due to its role in weight-bearing, however, both body size and locomotion may impact calcaneal morphology. Determining how calcaneal morphologies vary as a function of body size is thus vital to understanding calcaneal functional adaptation. Here, we study calcaneus allometry and relative size in humans (n = 120) and nonhuman primates (n = 278), analyzing these relationships in light of known locomotor behaviors. Twelve linear measures and three articular facet surface areas were collected on calcaneus surface models. Body mass was estimated using femoral head superoinferior breadth. Relationships between calcaneal dimensions and estimated body mass were analyzed across the sample using phylogenetic least squares regression analyses (PGLS). Differences between humans and pooled nonhuman primates were tested using RMA ANCOVAs. Among (and within) genera residual differences from both PGLS regressions and isometry were analyzed using ANOVAs with post hoc multiple comparison tests. The relationships between all but two calcaneus dimensions and estimated body mass exhibit phylogenetic signal at the smallest taxonomic scale. This signal disappears when reanalyzed at the genus level. Calcaneal morphology varies relative to both body size and locomotor behavior. Humans have larger calcanei for estimated body mass relative to nonhuman primates as a potential adaptation for bipedalism. More terrestrial taxa exhibit longer calcaneal tubers for body mass, increasing the triceps surae lever arm. Among nonhuman great apes, more arboreal taxa have larger cuboid facet surface areas for body mass, increasing calcaneocuboid mobility.
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Affiliation(s)
- Christine M Harper
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, Baltimore, Maryland, USA.,Cooper Medical School of Rowan University, Department of Biomedical Sciences, Camden, New Jersey, USA
| | - Christopher B Ruff
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, Baltimore, Maryland, USA
| | - Adam D Sylvester
- The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, Baltimore, Maryland, USA
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11
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Harper CM, Ruff CB, Sylvester AD. Gorilla calcaneal morphological variation and ecological divergence. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 174:49-65. [PMID: 32871028 DOI: 10.1002/ajpa.24135] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/11/2020] [Accepted: 08/02/2020] [Indexed: 01/19/2023]
Abstract
OBJECTIVES The primate foot has been extensively investigated because of its role in weight-bearing; however, the calcaneus has been relatively understudied. Here we examine entire gorilla calcaneal external shape to understand its relationship with locomotor behavior. MATERIALS AND METHODS Calcanei of Gorilla gorilla gorilla (n = 43), Gorilla beringei graueri (n = 20), and Gorilla beringei beringei (n = 15) were surface or micro-CT scanned. External shape was analyzed through a three-dimensional geometric morphometric sliding semilandmark analysis. Semilandmarks were slid relative to an updated Procrustes average in order to minimize the bending energy of the thin plate spline interpolation function. Shape variation was summarized using principal components analysis of shape coordinates. Procrustes distances between taxa averages were calculated and resampling statistics run to test pairwise differences. Linear measures were collected and regressed against estimated body mass. RESULTS All three taxa exhibit statistically different morphologies (p < .001 for pairwise comparisons). G. g. gorilla demonstrates an anteroposteriorly elongated calcaneus with a deeper cuboid pivot region and mediolaterally flatter posterior talar facet. G. b. beringei possesses the flattest cuboid and most medially-angled posterior talar facets. G. b. graueri demonstrates intermediate articular facet morphology, a medially-angled tuberosity, and an elongated peroneal trochlea. DISCUSSION Articular facet differences separate gorillas along a locomotor gradient. G. g. gorilla is adapted for arboreality with greater joint mobility, while G. b. beringei is adapted for more stereotypical loads associated with terrestriality. G. b. graueri's unique posterolateral morphology may be due to a secondary transition to greater arboreality from a more terrestrial ancestor.
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Affiliation(s)
- Christine M Harper
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher B Ruff
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Adam D Sylvester
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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12
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Morphometric analysis of the hominin talus: Evolutionary and functional implications. J Hum Evol 2020; 142:102747. [PMID: 32240884 DOI: 10.1016/j.jhevol.2020.102747] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 01/07/2020] [Accepted: 01/21/2020] [Indexed: 11/21/2022]
Abstract
The adoption of bipedalism is a key benchmark in human evolution that has impacted talar morphology. Here, we investigate talar morphological variability in extinct and extant hominins using a 3D geometric morphometric approach. The evolutionary timing and appearance of modern human-like features and their contributions to bipedal locomotion were evaluated on the talus as a whole, each articular facet separately, and multiple combinations of facets. Distinctive suites of features are consistently present in all fossil hominins, despite the presence of substantial interspecific variation, suggesting a potential connection of these suites to bipedal gait. A modern human-like condition evolved in navicular and lateral malleolar facets early in the hominin lineage compared with other facets, which demonstrate more complex morphological variation within Homininae. Interestingly, navicular facet morphology of Australopithecus afarensis is derived in the direction of Homo, whereas more recent hominin species such as Australopithecus africanus and Australopithecus sediba retain more primitive states in this facet. Combining the navicular facet with the trochlea and the posterior calcaneal facet as a functional suite, however, distinguishes Australopithecus from Homo in that the medial longitudinal arch had not fully developed in the former. Our results suggest that a more everted foot and stiffer medial midtarsal region are adaptations that coincide with the emergence of bipedalism, whereas a high medial longitudinal arch emerges later in time, within Homo. This study provides novel insights into the emergence of talar morphological traits linked to bipedalism and its transition from a facultative to an obligate condition.
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DeSilva J, McNutt E, Benoit J, Zipfel B. One small step: A review of Plio‐Pleistocene hominin foot evolution. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 168 Suppl 67:63-140. [DOI: 10.1002/ajpa.23750] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/01/2018] [Accepted: 10/05/2018] [Indexed: 01/03/2023]
Affiliation(s)
- Jeremy DeSilva
- Department of AnthropologyDartmouth College Hanover New Hampshire
- Evolutionary Studies Institute and School of GeosciencesUniversity of the Witwatersrand Johannesburg South Africa
| | - Ellison McNutt
- Department of AnthropologyDartmouth College Hanover New Hampshire
| | - Julien Benoit
- Evolutionary Studies Institute and School of GeosciencesUniversity of the Witwatersrand Johannesburg South Africa
| | - Bernhard Zipfel
- Evolutionary Studies Institute and School of GeosciencesUniversity of the Witwatersrand Johannesburg South Africa
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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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15
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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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