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Bolter DR, Cameron N, Hawks J, Churchill SE, Berger L, Bernstein R, Boughner JC, Elton S, Leece AB, Mahoney P, Molopyane K, Monson TA, Pruetz J, Schell L, Stull KE, Wolfe CA. Addressing the growing fossil record of subadult hominins by reaching across disciplines. Evol Anthropol 2023; 32:180-184. [PMID: 37555538 DOI: 10.1002/evan.21995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 07/03/2023] [Indexed: 08/10/2023]
Affiliation(s)
- Debra R Bolter
- Department of Anthropology, Modesto Junior College, Modesto, California, USA
- Faculty of Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Department of Anthropology, California State University Stanislaus, Turlock, California, USA
| | - Noel Cameron
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire, UK
| | - John Hawks
- Faculty of Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Anthropology Department, University of Wisconsin, Madison, Wisconsin, USA
| | - Steven E Churchill
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA
| | - Lee Berger
- Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Department of Explorer in Residence, National Geographic Society, Washington, District of Columbia, USA
| | - Robin Bernstein
- Department of Anthropology, University of Colorado at Boulder, Boulder, Colorado, USA
| | - Julia C Boughner
- Department of Anatomy, Physiology and Pharmacology, University of the Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Sarah Elton
- Faculty of Social Sciences and Health, Durham University, Durham, UK
| | - A B Leece
- Palaeoscience, Department of Archaeology and History, LaTrobe University, Melbourne, Victoria, Australia
- Geoarchaeology and Archaeometry Research Group, Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
| | - Patrick Mahoney
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Keneiloe Molopyane
- Faculty of Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Tesla A Monson
- Department of Anthropology, Western Washington University, Bellingham, Washington, USA
| | - Jill Pruetz
- Department of Anthropology, Texas State University San Marcos, San Marcos, Texas, USA
| | - Lawrence Schell
- Department of Anthropology, State University of New York, Albany, New York, USA
| | - Kyra E Stull
- Department of Anthropology, University of Reno, Reno, Nevada, USA
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Mitteroecker P, Schaefer K. Thirty years of geometric morphometrics: Achievements, challenges, and the ongoing quest for biological meaningfulness. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 178 Suppl 74:181-210. [PMID: 36790612 PMCID: PMC9545184 DOI: 10.1002/ajpa.24531] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 03/28/2022] [Accepted: 04/17/2022] [Indexed: 12/30/2022]
Abstract
The foundations of geometric morphometrics were worked out about 30 years ago and have continually been refined and extended. What has remained as a central thrust and source of debate in the morphometrics community is the shared goal of meaningful biological inference through a tight connection between biological theory, measurement, multivariate biostatistics, and geometry. Here we review the building blocks of modern geometric morphometrics: the representation of organismal geometry by landmarks and semilandmarks, the computation of shape or form variables via superimposition, the visualization of statistical results as actual shapes or forms, the decomposition of shape variation into symmetric and asymmetric components and into different spatial scales, the interpretation of various geometries in shape or form space, and models of the association between shape or form and other variables, such as environmental, genetic, or behavioral data. We focus on recent developments and current methodological challenges, especially those arising from the increasing number of landmarks and semilandmarks, and emphasize the importance of thorough exploratory multivariate analyses rather than single scalar summary statistics. We outline promising directions for further research and for the evaluation of new developments, such as "landmark-free" approaches. To illustrate these methods, we analyze three-dimensional human face shape based on data from the Avon Longitudinal Study of Parents and Children (ALSPAC).
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Affiliation(s)
- Philipp Mitteroecker
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
| | - Katrin Schaefer
- Department of Evolutionary AnthropologyUniversity of ViennaViennaAustria,Human Evolution and Archaeological Sciences (HEAS)University of ViennaViennaAustria
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3
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Hanegraef H, David R, Spoor F. Morphological variation of the maxilla in modern humans and African apes. J Hum Evol 2022; 168:103210. [PMID: 35617847 DOI: 10.1016/j.jhevol.2022.103210] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 11/25/2022]
Abstract
Differences in morphology among modern humans and African apes are frequently used when assessing whether hominin fossils should be attributed to a single species or represent evidence for taxic diversity. A good understanding of the degree and structure of the intergeneric, interspecific, and intraspecific variation, including aspects such as sexual dimorphism and age, are key in this context. Here we explore the variation and differences shown by the maxilla of extant hominines, as maxillary morphology is central in the diagnosis of several hominin taxa. Our sample includes adults of all currently recognized hominine species and subspecies, with a balanced species sex ratio. In addition, we compared the adults with a small sample of late juveniles. The morphology of the maxillae was captured using three-dimensional landmarks, and the size and shape were analyzed using geometric morphometric methods. Key observations are that 1) the maxillae of all extant hominine species and subspecies show statistically significant differences, but complete separation in shape is only seen at the genus level; 2) the degree of variation is not consistent between genera, with subspecies of Gorilla being more different from each other than are species of Pan; 3) the pattern of sexual shape dimorphism is different in Pan, Gorilla, and Homo, often showing opposite trends; and 4) differentiation between maxillary shapes is increased after adjustment for static intraspecific allometry. These results provide a taxonomically up-to-date comparative morphological framework to help interpret the hominin fossil record, and we discuss the practical implications in that context.
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Affiliation(s)
- Hester Hanegraef
- Centre for Human Evolution Research, Natural History Museum, London, United Kingdom; Department of Anthropology, University College London, London, United Kingdom.
| | - Romain David
- Centre for Human Evolution Research, Natural History Museum, London, United Kingdom; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Fred Spoor
- Centre for Human Evolution Research, Natural History Museum, London, United Kingdom; Department of Anthropology, University College London, London, United Kingdom; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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4
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Baab KL, Nesbitt A, Hublin JJ, Neubauer S. Assessing the status of the KNM-ER 42700 fossil using Homo erectus neurocranial development. J Hum Evol 2021; 154:102980. [PMID: 33794419 DOI: 10.1016/j.jhevol.2021.102980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 02/22/2021] [Accepted: 02/22/2021] [Indexed: 10/21/2022]
Abstract
Based on ontogenetic data of endocranial shape, it has been proposed that a younger than previously assumed developmental status of the 1.5-Myr-old KNM-ER 42700 calvaria could explain why the calvaria of this fossil does not conform to the shape of other Homo erectus individuals. Here, we investigate (ecto)neurocranial ontogeny in H. erectus and assess the proposed juvenile status of this fossil using recent Homo sapiens, chimpanzees (Pan troglodytes), and Neanderthals (Homo neanderthalensis) to model and discuss changes in neurocranial shape from the juvenile to adult stages. We show that all four species share common patterns of developmental shape change resulting in a relatively lower cranial vault and expanded supraorbital torus at later developmental stages. This finding suggests that ectoneurocranial data from extant hominids can be used to model the ontogenetic trajectory for H. erectus, for which only one well-preserved very young individual is known. However, our study also reveals differences in the magnitudes and, to a lesser extent, directions of the species-specific trajectories that add to the overall shared pattern of neurocranial shape changes. We demonstrate that the very young H. erectus juvenile from Mojokerto together with subadult and adult H. erectus individuals cannot be accommodated within the pattern of the postnatal neurocranial trajectory for humans. Instead, the chimpanzee pattern might be a better 'fit' for H. erectus despite their more distant phylogenetic relatedness. The data are also compatible with an ontogenetic shape trajectory that is in some regards intermediate between that of recent H. sapiens and chimpanzees, implying a unique trajectory for H. erectus that combines elements of both extant species. Based on this new knowledge, neurocranial shape supports the assessment that KNM-ER 42700 is a young juvenile H. erectus if H. erectus followed an ontogenetic shape trajectory that was more similar to chimpanzees than humans.
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Affiliation(s)
- Karen L Baab
- Department of Anatomy, College of Graduate Studies, Midwestern University, Glendale, AZ, 85308, USA; NYCEP Morphometrics Group, New York, NY, 10016, USA.
| | - Allison Nesbitt
- Pathology and Anatomical Sciences, School of Medicine, University of Missouri, Columbia, MO, USA
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; Collège de France, Paris, France
| | - Simon Neubauer
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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5
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Simons EA, Frost SR. Ontogenetic allometry and scaling in catarrhine crania. J Anat 2021; 238:693-710. [PMID: 33084028 PMCID: PMC7855087 DOI: 10.1111/joa.13331] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/13/2020] [Accepted: 09/18/2020] [Indexed: 11/28/2022] Open
Abstract
In studies of ontogenetic allometry, ontogenetic scaling has often been invoked to explain cranial morphological differences between smaller and larger forms of closely related taxa. These scaled variants in shape have been hypothesized to be the result of the extension or truncation of common growth allometries. In this scenario, change in size is the determining factor, perhaps under direct selection, and changes in cranial shapes are byproducts, not under direct selection themselves. However, many of these conclusions are based on studies that used bivariate generalizations of shape. Even among multivariate analyses of growth allometries, there are discrepancies as to the prevalence of ontogenetic scaling among primates, how shared the trajectories need to be, and which taxa evince properties of scaled variants. In this investigation, we use a large, comparative ontogenetic sample, geometric morphometric methods, and multivariate statistical tests to examine ontogenetic allometry and evaluate if differences in cranial shape among closely related catarrhines of varying sizes are primarily driven by size divergence, that is, ontogenetic scaling. We then evaluate the hypothesis of size as a line of least evolutionary resistance in catarrhine cranial evolution. We found that patterns of ontogenetic allometry vary among taxa, indicating that ontogenetic scaling sensu stricto does not often account for most morphological differences and that large and small taxa within clades are generally not scaled variants. The presence of a variety of ontogenetic pathways for the evolution of cranial shapes provides indirect evidence for selection acting directly on the cranial shape, rather than on size alone.
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Affiliation(s)
- Evan A. Simons
- Department of AnthropologyBuffalo Human Evolutionary Morphology LabUniversity at BuffaloBuffaloNYUSA
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6
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Simons EA. Testing the Giles hypothesis using geometric morphometrics. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 174:744-751. [PMID: 33393687 DOI: 10.1002/ajpa.24219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 11/22/2020] [Accepted: 12/20/2020] [Indexed: 11/11/2022]
Abstract
OBJECTIVES The Giles hypothesis posits that differences in the cranial morphology of Pan troglodytes and Gorilla gorilla are largely the result of allometric scaling. However, previous support for the Giles hypothesis was based on bivariate plots of linear measurements. This investigation uses geometric morphometric methods to retest this hypothesis and its prediction that extending the ontogenetic trajectory of a chimpanzee would produce an adult gorilla-like cranial morphology. MATERIALS AND METHODS Forty-three 3D cranial landmarks were collected from an ontogenetic series of 76 Pan troglodytes and 58 Gorilla gorilla specimens. Ontogenetic trajectories of cranial shape change were computed via multivariate regression of Procrustes aligned coordinates against LnCS (size vector) and molar eruption stage (developmental vector). These two vectors were then used in developmental simulations to extend the ontogenetic trajectories of adult chimpanzees. Allometric trajectories of chimpanzees and gorillas were also directly compared using Procrustes ANOVA. RESULTS Pan and Gorilla significantly differ in their allometric trajectories, and none of the Pan developmental simulations resembled actual adult gorillas. Additionally, the more the Pan developmental vector was extended, the more morphologically distinct the simulations became from actual adult gorillas. DISCUSSION Taken together, these results do not support the Giles hypothesis that allometric scaling is primarily responsible for observed morphological differences between chimpanzee and gorilla crania. This investigation demonstrates that neither "growing" a chimpanzee to the size of a gorilla, nor extending a chimpanzee's developmental shape trajectory will result in an adult gorilla-like cranial morphology as they differ in their patterns of allometry.
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Affiliation(s)
- Evan A Simons
- Department of Anthropology, Buffalo Human Evolutionary Morphology Lab, University at Buffalo, Buffalo, New York, USA
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7
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McCarthy R, Zimel E. Revised estimates of Taung’s brain size growth. S AFR J SCI 2020. [DOI: 10.17159/sajs.2020/5963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Cranial capacity, a proxy for the volume of the brain and associated cranial contents, is an important yardstick used to compare early hominin species because increasing brain size is a key characteristic of our lineage. In 1925, Raymond Dart claimed that a natural endocast found at the Buxton Limeworks near Taung, South Africa (which he named Australopithecus africanus), showed signs of neural reorganisation, but its juvenile status complicated comparison to other hominoid species. In an attempt to put its brain size and reorganisation into a comparative context, subsequent researchers have tried to estimate Taung’s adult cranial capacity by comparison to coarse-grained hominoid growth data. In this study, we simulated brain growth in A. africanus using asymptotic growth models in known-age mountain gorillas, chimpanzees and modern humans, and show that, at just under 4 years old, Taung’s brain had already finished or nearly finished growing according to hominoid developmental schedules. Percentage-growth remaining estimates are lower here than in previous studies using cross-sectional ontogenetic samples of unknown chronological age. Our new adult estimates (between 404 cm3 and 430 cm3 overall and 405–406 cm3 for chimpanzee models) are smaller than previous estimates with a ‘starting’ cranial capacity of 404 cm3, supporting the hypothesis that Taung’s adult brain size would have fallen toward the lower end of the A. africanus range of variation and strengthening the case that Taung was female.
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Affiliation(s)
- Robert McCarthy
- Department of Biological Sciences, Benedictine University, Lisle, Illinois, USA
| | - Emily Zimel
- Department of Physical Sciences, Benedictine University, Lisle, Illinois, USA
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8
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Comparing Rates of Linage Diversification with Rates of Size and Shape Evolution in Catarrhine Crania. Evol Biol 2020. [DOI: 10.1007/s11692-020-09500-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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9
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Balolia KL, Jakeman EC, Massey JS, Groves C, Wood B. Mandibular corpus shape is a taxonomic indicator in extant hominids. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 172:25-40. [DOI: 10.1002/ajpa.24030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 01/22/2020] [Accepted: 02/05/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Katharine L. Balolia
- School of Archaeology and AnthropologyThe Australian National University Canberra ACT Australia
| | - Elise C. Jakeman
- School of Archaeology and AnthropologyThe Australian National University Canberra ACT Australia
| | - Jason S. Massey
- Department of Integrative Biology and PhysiologyUniversity of Minnesota Medical School Minneapolis Minnesota
| | - Colin Groves
- School of Archaeology and AnthropologyThe Australian National University Canberra ACT Australia
| | - Bernard Wood
- Department of Anthropology, Center for the Advanced Study of Human PaleobiologyGeorge Washington University Washington District of Columbia
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10
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Ontogeny and phylogeny of the cercopithecine cranium: A geometric morphometric approach to comparing shape change trajectories. J Hum Evol 2018; 124:40-51. [DOI: 10.1016/j.jhevol.2018.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 08/03/2018] [Accepted: 08/07/2018] [Indexed: 01/19/2023]
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Abstract
In humans, patterns of cranial variation mirror genetic diversity globally, implicating population history as a key driver of cranial disparity. Here, we demonstrate that the magnitude of genetic diversity within 12 extant ape taxa explains a large proportion of cranial shape variation. Taxa that are more genetically diverse tend to be more cranially diverse also. Our results suggest that neutral evolutionary processes such as mutation, genetic drift, and gene flow are reflected in both genetic and cranial diversity in apes. This work provides a perspective on intraspecific cranial variation in apes which has important implications for interpreting selective and developmental pressures on the cranium and for understanding shape variation in fossil hominin crania. Natural selection, developmental constraint, and plasticity have all been invoked as explanations for intraspecific cranial variation in humans and apes. However, global patterns of human cranial variation are congruent with patterns of genetic variation, demonstrating that population history has influenced cranial variation in humans. Here we show that this finding is not unique to Homo sapiens but is also broadly evident across extant ape species. Specifically, taxa that exhibit greater intraspecific cranial shape variation also exhibit greater genetic diversity at neutral autosomal loci. Thus, cranial shape variation within hominoid taxa reflects the population history of each species. Our results suggest that neutral evolutionary processes such as mutation, gene flow, and genetic drift have played an important role in generating cranial variation within species. These findings are consistent with previous work on human cranial morphology and improve our understanding of the evolutionary processes that generate intraspecific cranial shape diversity within hominoids. This work has implications for the analysis of selective and developmental pressures on the cranium and for interpreting shape variation in fossil hominin crania.
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12
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Mandibular ramus shape variation and ontogeny in Homo sapiens and Homo neanderthalensis. J Hum Evol 2018; 121:55-71. [DOI: 10.1016/j.jhevol.2018.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 03/26/2018] [Accepted: 03/27/2018] [Indexed: 01/29/2023]
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13
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Turley K, Simons EA, Frost SR. Trajectory analysis among African hominoids can provide insights into genetic and epigenetic influences during ontogeny. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 167:173-177. [DOI: 10.1002/ajpa.23625] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 05/18/2018] [Accepted: 05/19/2018] [Indexed: 01/18/2023]
Affiliation(s)
- Kevin Turley
- Department of Anthropology; University of Oregon; Eugene Oregon 97403
| | - Evan A. Simons
- Department of Anthropology; University of Oregon; Eugene Oregon 97403
| | - Stephen R. Frost
- Department of Anthropology; University of Oregon; Eugene Oregon 97403
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14
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Stratford DJ. The Sterkfontein Caves after Eighty Years of Paleoanthropological Research: The Journey Continues. AMERICAN ANTHROPOLOGIST 2018. [DOI: 10.1111/aman.12982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dominic Justin Stratford
- Department of Archaeology, School of Geography, Archaeology and Environmental Studies; University of the Witwatersrand; Johanneburg South Africa
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15
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Three-Dimensional Geometric Morphometrics in Paleoecology. VERTEBRATE PALEOBIOLOGY AND PALEOANTHROPOLOGY 2018. [DOI: 10.1007/978-3-319-94265-0_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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16
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Antón SC, Kuzawa CW. Early Homo, plasticity and the extended evolutionary synthesis. Interface Focus 2017; 7:20170004. [PMID: 28839926 PMCID: PMC5566814 DOI: 10.1098/rsfs.2017.0004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Modern Synthesis led to fundamental advances in understandings of human evolution. For human palaeontology, a science that works from ancestral phenotypes (i.e. the fossil record), particularly important have been perspectives used to help understand the heritable aspects of phenotypes and how fossil individuals might then be aggregated into species, and relationships among these groups understood. This focus, coupled with the fragmentary nature of the fossil record, however, means that individual phenotypic variation is often treated as unimportant 'noise', rather than as a source of insight into population adaptation and evolutionary process. The emphasis of the extended evolutionary synthesis on plasticity as a source of phenotypic novelty, and the related question of the role of such variation in long-term evolutionary trends, focuses welcome attention on non-genetic means by which novel phenotypes are generated and in so doing provides alternative approaches to interpreting the fossil record. We review evidence from contemporary human populations regarding some of the aspects of adult phenotypes preserved in the fossil record that might be most responsive to non-genetic drivers, and we consider how these perspectives lead to alternate hypotheses for interpreting the fossil record of early genus Homo. We conclude by arguing that paying closer attention to the causes and consequences of intraspecific phenotypic variation in its own right, as opposed to as noise around a species mean, may inspire a new generation of hypotheses regarding species diversity in the Early Pleistocene and the foundations for dispersal and regional diversification in Homo erectus and its descendants.
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Affiliation(s)
- Susan C. Antón
- Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA
| | - Christopher W. Kuzawa
- Department of Anthropology, Northwestern University, 1810 Hinman Avenue, Evanston, IL 60201, USA
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17
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Singleton M, Seitelman BC, Krecioch JR, Frost SR. Cranial sexual dimorphism in the Kinda baboon (Papio hamadryas kindae). AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2017; 164:665-678. [PMID: 28877335 DOI: 10.1002/ajpa.23304] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 07/20/2017] [Accepted: 08/18/2017] [Indexed: 02/01/2023]
Abstract
OBJECTIVES The smallest extant member of genus Papio, the Kinda baboon exhibits low sexual dimorphism and a distinctive cranial shape. Ontogenetic scaling accounts for most cranial-shape differences within Papio, but studies have shown that the Kinda follows a separate ontogenetic trajectory. If so, its cranial-dimorphism pattern should differ from other subspecies. To evaluate this hypothesis, morphometric analysis was used to investigate cranial dimorphism in Papio. MATERIALS AND METHODS Three-dimensional landmarks were digitized on 434 adult crania representing six Papio subspecies. Size- and shape-dimorphism magnitudes were quantified using centroid size and Procrustes distances. Patterns of sex- and size-related variation were explored using MAN(C)OVA, multivariate regression, and form-space PCA. Canine dimorphism was investigated using dental metrics. RESULTS Kinda size and shape dimorphism are significantly lower than in other Papio subspecies. The relative magnitude of Kinda shape dimorphism is similar to other southern baboons; Kinda canine dimorphism is unremarkable. MAN(C)OVA results support subspecies differences in cranial dimorphism and scaling. Allometric and dimorphism vectors differ significantly in some subspecies, and their vector-angle matrices are strongly correlated. The Kinda's allometric vector angles are divergent. Form-space PC3, summarizing size-independent dimorphism, separates the Kinda from other subspecies. DISCUSSION The Kinda baboon exhibits significantly lower size and shape dimorphism than other baboons, but its relative dimorphism levels are unexceptional. The Kinda differs from other subspecies in patterns of allometry, size-related shape dimorphism, and residual shape dimorphism. Kinda facial shape is "masculinized" relative to size, especially in females, suggesting female sexual selection contributed to the evolution of Kinda dimorphism.
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Affiliation(s)
- Michelle Singleton
- Department of Anatomy, Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, Illinois
| | | | - Joseph R Krecioch
- Department of Anatomy, Midwestern University, Downers Grove, Illinois
| | - Stephen R Frost
- Department of Anthropology, University of Oregon, Eugene, Oregon
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18
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Piras P, Teresi L, Traversetti L, Varano V, Gabriele S, Kotsakis T, Raia P, Puddu PE, Scalici M. The conceptual framework of ontogenetic trajectories: parallel transport allows the recognition and visualization of pure deformation patterns. Evol Dev 2017; 18:182-200. [PMID: 27161949 DOI: 10.1111/ede.12186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Ontogeny is usually studied by analyzing a deformation series spanning over juvenile to adult shapes. In geometric morphometrics, this approach implies applying generalized Procrustes analysis coupled with principal component analysis on multiple individuals or multiple species datasets. The trouble with such a procedure is that it mixes intra- and inter-group variation. While MANCOVA models are relevant statistical/mathematical tools to draw inferences about the similarities of trajectories, if one wants to observe and interpret the morphological deformation alone by filtering inter-group variability, a particular tool, namely parallel transport, is necessary. In the context of ontogenetic trajectories, one should firstly perform separate multivariate regressions between shape and size, using regression predictions to estimate within-group deformations relative to the smallest individuals. These deformations are then applied to a common reference (the mean of per-group smallest individuals). The estimation of deformations can be performed on the Riemannian manifold by using sophisticated connection metrics. Nevertheless, parallel transport can be effectively achieved by estimating deformations in the Euclidean space via ordinary Procrustes analysis. This approach proved very useful in comparing ontogenetic trajectories of species presenting large morphological differences at early developmental stages.
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Affiliation(s)
- P Piras
- Dipartimento di Scienze, Università Roma Tre, Rome, Italy.,Center for Evolutionary Ecology, Università Roma Tre, Rome, Italy.,Dipartimento di Ingegneria Strutturale e Geotecnica "Sapienza", Università di Roma, Rome, Italy.,Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Sapienza, Università di Roma, Rome, Italy
| | - L Teresi
- Dipartimento di Matematica e Fisica, Università Roma Tre, Rome, Italy
| | - L Traversetti
- Dipartimento di Scienze, Università Roma Tre, Rome, Italy
| | - V Varano
- Dipartimento di Architettura, Università Roma Tre, Rome, Italy
| | - S Gabriele
- Dipartimento di Architettura, Università Roma Tre, Rome, Italy
| | - T Kotsakis
- Dipartimento di Scienze, Università Roma Tre, Rome, Italy.,Center for Evolutionary Ecology, Università Roma Tre, Rome, Italy
| | - P Raia
- Dipartimento di Scienze della Terra, dell'Ambiente e delle Risorse (DiSTAR), Università degli Studi di Napoli Federico II, Naples, Italy
| | - P E Puddu
- Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Sapienza, Università di Roma, Rome, Italy
| | - M Scalici
- Dipartimento di Scienze, Università Roma Tre, Rome, Italy
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Carlson KB, de Ruiter DJ, DeWitt TJ, Carlson KB, Carlson KJ, Tafforeau P, Berger LR. Developmental simulation of the adult cranial morphology of Australopithecus sediba. S AFR J SCI 2016. [DOI: 10.17159/sajs.2016/20160012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Abstract The type specimen of Australopithecus sediba (MH1) is a late juvenile, prompting some commentators to suggest that had it lived to adulthood its morphology would have changed sufficiently so as to render hypotheses regarding its phylogenetic relations suspect. Considering the potentially critical position of this species with regard to the origins of the genus Homo, a deeper understanding of this change is especially vital. As an empirical response to this critique, a developmental simulation of the MH1 cranium was carried out using geometric morphometric techniques to extrapolate adult morphology using extant male and female chimpanzees, gorillas and humans by modelling remaining development. Multivariate comparisons of the simulated adult A. sediba crania with other early hominin taxa indicate that subsequent cranial development primarily reflects development of secondary sexual characteristics and would not likely be substantial enough to alter suggested morphological affinities of A. sediba. This study also illustrates the importance of separating developmental vectors by sex when estimating ontogenetic change. Results of the ontogenetic projections concur with those from mandible morphology, and jointly affirm the taxonomic validity of A. sediba.
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Curran SC, Haile-Selassie Y. Paleoecological reconstruction of hominin-bearing middle Pliocene localities at Woranso-Mille, Ethiopia. J Hum Evol 2016; 96:97-112. [DOI: 10.1016/j.jhevol.2016.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 04/14/2016] [Accepted: 04/16/2016] [Indexed: 10/21/2022]
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Simons EA, Frost SR. Constructing cranial ontogenetic trajectories: A comparison of growth, development, and chronological age proxies using a known-age sample ofMacaca mulatta. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2016; 161:296-308. [DOI: 10.1002/ajpa.23031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 05/28/2016] [Accepted: 05/30/2016] [Indexed: 12/19/2022]
Affiliation(s)
- Evan A. Simons
- Department of Anthropology; University of Oregon; Eugene OR 97402
| | - Stephen R. Frost
- Department of Anthropology; University of Oregon; Eugene OR 97402
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Mechanical evidence that Australopithecus sediba was limited in its ability to eat hard foods. Nat Commun 2016; 7:10596. [PMID: 26853550 PMCID: PMC4748115 DOI: 10.1038/ncomms10596] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 01/04/2016] [Indexed: 11/09/2022] Open
Abstract
Australopithecus sediba has been hypothesized to be a close relative of the genus Homo. Here we show that MH1, the type specimen of A. sediba, was not optimized to produce high molar bite force and appears to have been limited in its ability to consume foods that were mechanically challenging to eat. Dental microwear data have previously been interpreted as indicating that A. sediba consumed hard foods, so our findings illustrate that mechanical data are essential if one aims to reconstruct a relatively complete picture of feeding adaptations in extinct hominins. An implication of our study is that the key to understanding the origin of Homo lies in understanding how environmental changes disrupted gracile australopith niches. Resulting selection pressures led to changes in diet and dietary adaption that set the stage for the emergence of our genus. Dietary adaptations of extinct early humans are often inferred from dental microwear data. Here, the authors employ mechanical analyses to show that Australopithecus sediba had limited ability to consume hard foods.
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Williams FL, Cofran Z. Postnatal craniofacial ontogeny in neandertals and modern humans. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2016; 159:394-409. [DOI: 10.1002/ajpa.22895] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 09/21/2015] [Accepted: 10/31/2015] [Indexed: 11/10/2022]
Affiliation(s)
| | - Zachary Cofran
- School of Humanities and Social Sciences; Nazarbayev University; Kabanbay Batyr 53 Astana 010000 Kazakhstan
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García-Martínez D, Recheis W, Bastir M. Ontogeny of 3D rib curvature and its importance for the understanding of human thorax development. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 159:423-31. [PMID: 26890054 DOI: 10.1002/ajpa.22893] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/26/2015] [Accepted: 10/29/2015] [Indexed: 11/11/2022]
Abstract
OBJECTIVES Sagittal and axial rib orientation relative to the spine are two factors that modify rib cage morphology during ontogeny. Some studies suggest that these factors do not operate in the same way at the upper (ribs 1-5) and lower thorax (ribs 6-10) during postnatal growth, but it is unknown if the ontogenetic thoracic changes are produced by morphological changes of the ribs (intrinsic rib factors) or by external factors related to costal joints (extrinsic rib factors). MATERIAL AND METHODS To clarify these questions, we applied 3D geometric morphometrics of landmarks and sliding semilandmarks (N = 20/rib) to 280 individual ribs (1-10) of Homo sapiens comprising the entire human ontogeny and growth simulations were carried out. RESULTS PCA shows that intrinsic rib factors (rib torsion and axial rib curvature) are ontogenetic factors of variability that contribute to configuring the adult thorax shape. Moreover, growth simulations and regression slopes suggest that the upper thorax unit is comprised by ribs 1-7 and the lower unit at least by ribs 8-10. DISCUSSION These results suggest anatomical constraints for ontogenetic rib variation, since ribs 1-7 (true ribs) are directly linked to the sternum. Moreover, these results are supported by functional anatomy because pulmonary kinematics would influence the upper unit and diaphragmatic kinematics would influence the lower one. Our findings are relevant not only to understanding how changes at individual ribs contribute to the adult thorax morphology, but also to the development and evolution of the modern human rib cage.
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Affiliation(s)
- Daniel García-Martínez
- Paleoanthropology Group, Paleobiology Department, Museo Nacional de Ciencias Naturales (MNCN-CSIC), JG. Abascal 2, Madrid, 28006, Spain.,Biology Department, Faculty of Sciences, Universidad Autónoma De Madrid. Darwin 2, Madrid, 28049, Spain
| | - Wolfgang Recheis
- Department of Radiology, Medizinische Universität Innsbruck, 6020, Austria
| | - Markus Bastir
- Paleoanthropology Group, Paleobiology Department, Museo Nacional de Ciencias Naturales (MNCN-CSIC), JG. Abascal 2, Madrid, 28006, Spain
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Freidline SE, Gunz P, Hublin JJ. Ontogenetic and static allometry in the human face: contrasting Khoisan and Inuit. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 158:116-31. [PMID: 26146938 DOI: 10.1002/ajpa.22759] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 04/14/2015] [Accepted: 04/14/2015] [Indexed: 12/17/2022]
Abstract
OBJECTIVES Regional differences in modern human facial features are present at birth, and ontogenetic allometry contributes to variation in adults. However, details regarding differential rates of growth and timing among regional groups are lacking. We explore ontogenetic and static allometry in a cross-sectional sample spanning Africa, Europe and North America, and evaluate tempo and mode in two regional groups with very different adult facial morphology, the Khoisan and Inuit. MATERIALS AND METHODS Semilandmark geometric morphometric methods, multivariate statistics and growth simulations were used to quantify and compare patterns of facial growth and development. RESULTS Regional-specific facial morphology develops early in ontogeny. The Inuit has the most distinct morphology and exhibits heterochronic differences in development compared to other regional groups. Allometric patterns differ during early postnatal development, when significant increases in size are coupled with large amounts of shape changes. All regional groups share a common adult static allometric trajectory, which can be attributed to sexual dimorphism, and the corresponding allometric shape changes resemble developmental patterns during later ontogeny. DISCUSSION The amount and pattern of growth and development may not be shared between regional groups, indicating that a certain degree of flexibility is allowed for in order to achieve adult size. In early postnatal development the face is less constrained compared to other parts of the cranium allowing for greater evolvability. The early development of region-specific facial features combined with heterochronic differences in timing or rate of growth, reflected in differences in facial size, suggest different patterns of postnatal growth.
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Affiliation(s)
- Sarah E Freidline
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig, 04103, Germany
| | - Philipp Gunz
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig, 04103, Germany
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig, 04103, Germany
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Dental ontogeny in pliocene and early pleistocene hominins. PLoS One 2015; 10:e0118118. [PMID: 25692765 PMCID: PMC4334485 DOI: 10.1371/journal.pone.0118118] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 01/06/2015] [Indexed: 11/19/2022] Open
Abstract
Until recently, our understanding of the evolution of human growth and development derived from studies of fossil juveniles that employed extant populations for both age determination and comparison. This circular approach has led to considerable debate about the human-like and ape-like affinities of fossil hominins. Teeth are invaluable for understanding maturation as age at death can be directly assessed from dental microstructure, and dental development has been shown to correlate with life history across primates broadly. We employ non-destructive synchrotron imaging to characterize incremental development, molar emergence, and age at death in more than 20 Australopithecus anamensis, Australopithecus africanus, Paranthropus robustus and South African early Homo juveniles. Long-period line periodicities range from at least 6–12 days (possibly 5–13 days), and do not support the hypothesis that australopiths have lower mean values than extant or fossil Homo. Crown formation times of australopith and early Homo postcanine teeth fall below or at the low end of extant human values; Paranthropus robustus dentitions have the shortest formation times. Pliocene and early Pleistocene hominins show remarkable variation, and previous reports of age at death that employ a narrow range of estimated long-period line periodicities, cuspal enamel thicknesses, or initiation ages are likely to be in error. New chronological ages for SK 62 and StW 151 are several months younger than previous histological estimates, while Sts 24 is more than one year older. Extant human standards overestimate age at death in hominins predating Homo sapiens, and should not be applied to other fossil taxa. We urge caution when inferring life history as aspects of dental development in Pliocene and early Pleistocene fossils are distinct from modern humans and African apes, and recent work has challenged the predictive power of primate-wide associations between hominoid first molar emergence and certain life history variables.
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Curran SC. ExploringEucladocerosEcomorphology Using Geometric Morphometrics. Anat Rec (Hoboken) 2014; 298:291-313. [DOI: 10.1002/ar.23066] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 10/11/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Sabrina C. Curran
- Ohio University; Department of Sociology and Anthropology; Athens OH 45701
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Cooke SB, Terhune CE. Form, Function, and Geometric Morphometrics. Anat Rec (Hoboken) 2014; 298:5-28. [DOI: 10.1002/ar.23065] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 10/11/2014] [Indexed: 01/08/2023]
Affiliation(s)
- Siobhán B. Cooke
- Department of Anthropology; Northeastern Illinois University; Chicago Illinois
- New York Consortium in Evolutionary Primatology Morphometrics Group; New York New York
| | - Claire E. Terhune
- Department of Anthropology; University of Arkansas; Fayetteville Arkansas
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Turley K, Frost SR. The ontogeny of talo-crural appositional articular morphology among catarrhine taxa: Adult shape reflects substrate use. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 154:447-58. [DOI: 10.1002/ajpa.22528] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 04/29/2014] [Indexed: 12/16/2022]
Affiliation(s)
- Kevin Turley
- Department of Anthropology; University of Oregon; Eugene OR 97403-1218
| | - Stephen R. Frost
- Department of Anthropology; University of Oregon; Eugene OR 97403-1218
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31
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Cofran Z. Mandibular development inAustralopithecus robustus. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 154:436-46. [DOI: 10.1002/ajpa.22527] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 04/22/2014] [Accepted: 04/23/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Zachary Cofran
- School of Humanities and Social Sciences; Nazarbayev University; 53 Kabanbay Batyr Avenue 010000 Astana Kazakhstan
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Singh N. Ontogenetic study of allometric variation in Homo and Pan mandibles. Anat Rec (Hoboken) 2014; 297:261-72. [PMID: 24347386 DOI: 10.1002/ar.22843] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 11/04/2013] [Indexed: 11/10/2022]
Abstract
Investigating ontogenetic variation and allometry in the mandible can provide valuable insight and aid in addressing questions related to the ontogeny of the skull. Here, patterns of ontogenetic shape change and allometric trajectories were examined in the mandible of 187 sub-adult and adult humans, bonobos, and chimpanzees. Procrustes-based geometric morphometrics was employed to quantify and analyze mandibular form. Thirty three-dimensional landmarks were used to capture the overall morphology of the mandible, and the landmarks were analyzed as a whole and subdivided into separate anterior and posterior units. Principal component analyses in Procrustes shape-space and form-space, and multivariate regressions were used to examine patterns of ontogenetic and allometric shape change. Results suggest that humans are distinct from Pan both in their mandibular morphology, particularly in the anterior-alveolar region, and direction of allometric trajectory. Chimpanzees and bonobos have parallel ontogenetic trajectories, but also show differences in mandibular shape. Species-specific features and adult mandibular shape are established before or by the eruption of the deciduous dentition. This suggests that developmental processes prior to deciduous teeth eruption have a stronger effect establishing taxa-specific phenotypes than later postnatal effects. This additionally implies that divergent trajectories between Pan and Homo do not contribute much to the adult mandibular shape after deciduous teeth eruption. Separate analyses of the anterior-alveolar region and ascending ramus show that these regions are semi-independent in their developmental pattern of shape change and allometry. This implies that allometric variation and ontogenetic shape change in the hominoid mandible is decoupled.
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Affiliation(s)
- Nandini Singh
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; Paleoanthropology, Senckenberg Center for Human Evolution and Paleoecology, University of Tübingen, Tübingen, Germany
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Terhune CE, Robinson CA, Ritzman TB. Ontogenetic variation in the mandibular ramus of great apes and humans. J Morphol 2014; 275:661-77. [DOI: 10.1002/jmor.20246] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 12/07/2013] [Accepted: 12/15/2013] [Indexed: 11/12/2022]
Affiliation(s)
- Claire E. Terhune
- Department of Anthropology; University of Arkansas; Fayetteville Arkansas
| | - Chris A. Robinson
- Department of Biology; Bronx Community College, City University of New York; Bronx New York
| | - Terrence B. Ritzman
- Institute of Human Origins and School of Human Evolution and Social Change; Arizona State University; Tempe Arizona
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A 3-D geometric morphometric study of intraspecific variation in the ontogeny of the temporal bone in modern Homo sapiens. J Hum Evol 2013; 65:479-89. [DOI: 10.1016/j.jhevol.2013.01.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 11/05/2012] [Accepted: 01/18/2013] [Indexed: 12/30/2022]
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Freidline SE, Gunz P, Harvati K, Hublin JJ. Evaluating developmental shape changes in Homo antecessor subadult facial morphology. J Hum Evol 2013; 65:404-23. [PMID: 23998458 DOI: 10.1016/j.jhevol.2013.07.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 07/25/2013] [Accepted: 07/25/2013] [Indexed: 11/26/2022]
Abstract
The fossil ATD6-69 from Atapuerca, Spain, dated to ca. 900 ka (thousands of years ago) has been suggested to mark the earliest appearance of modern human facial features. However, this specimen is a subadult and the interpretation of its morphology remains controversial, because it is unclear how developmental shape changes would affect the features that link ATD6-69 to modern humans. Here we analyze ATD6-69 in an evolutionary and developmental context. Our modern human sample comprises cross-sectional growth series from four populations. The fossil sample covers human specimens from the Pleistocene to the Upper Paleolithic, and includes several subadult Early Pleistocene humans and Neanderthals. We digitized landmarks and semilandmarks on surface and CT scans and analyzed the Procrustes shape coordinates using multivariate statistics. Ontogenetic allometric trajectories and developmental simulations were employed in order to identify growth patterns and to visualize potential adult shapes of ATD6-69. We show that facial differences between modern and archaic humans are not exclusively allometric. We find that while postnatal growth further accentuates the differences in facial features between Neanderthals and modern humans, those features that have been suggested to link ATD6-69's morphology to modern humans would not have been significantly altered in the course of subsequent development. In particular, the infraorbital depression on this specimen would have persisted into adulthood. However, many of the facial features that ATD6-69 shares with modern humans can be considered to be part of a generalized pattern of facial architecture. Our results present a complex picture regarding the polarity of facial features and demonstrate that some modern human-like facial morphology is intermittently present in Middle Pleistocene humans. We suggest that some of the facial features that characterize recent modern humans may have developed multiple times in human evolution.
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Affiliation(s)
- Sarah E Freidline
- Max Planck Institute for Evolutionary Anthropology, Department of Human Evolution, Deutscher Platz 6, Leipzig 04103, Germany; City University of New York Graduate School, 365 Fifth Avenue, New York, NY 10016, USA; New York Consortium in Evolutionary Primatology, USA; Paleoanthropology, Department of Early Prehistory and Quaternary Ecology, Eberhard Karls Universität Tübingen and Senckenberg Center for Human Evolution and Paleoecology, Rümelinstrasse 23, 72070 Tübingen, Germany.
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Terhune CE, Kimbel WH, Lockwood CA. Postnatal temporal bone ontogeny inPan,Gorilla, andHomo, and the implications for temporal bone ontogeny inAustralopithecus afarensis. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 151:630-42. [DOI: 10.1002/ajpa.22318] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Accepted: 05/16/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Claire E. Terhune
- Department of Community and Family Medicine; Duke University Medical Center; Durham; NC; 27710
| | - William H. Kimbel
- Institute of Human Origins, School of Human Evolution and Social Change; Arizona State University; Tempe; AZ; 85287-4101
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Terhune CE. How Effective Are Geometric Morphometric Techniques for Assessing Functional Shape Variation? An Example From the Great Ape Temporomandibular Joint. Anat Rec (Hoboken) 2013; 296:1264-82. [DOI: 10.1002/ar.22724] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 04/28/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Claire E. Terhune
- Department of Community and Family Medicine; Duke University Medical Center; Durham North Carolina
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Gunz P, Bulygina E. The Mousterian child from Teshik-Tash is a Neanderthal: A geometric morphometric study of the frontal bone. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 149:365-79. [DOI: 10.1002/ajpa.22133] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 07/23/2012] [Indexed: 01/10/2023]
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Freidline SE, Gunz P, Harvati K, Hublin JJ. Middle Pleistocene human facial morphology in an evolutionary and developmental context. J Hum Evol 2012; 63:723-40. [PMID: 22981042 DOI: 10.1016/j.jhevol.2012.08.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Revised: 08/03/2012] [Accepted: 08/08/2012] [Indexed: 12/23/2022]
Abstract
Neanderthals and modern humans exhibit distinct facial architectures. The patterning of facial morphology of their predecessors, the Middle Pleistocene humans, is more mosaic showing a mix of archaic and modern morphologies. Significant changes in facial size and robusticity occurred throughout Pleistocene human evolution, resulting in temporal trends in both facial reduction and enlargement. However, the allometric patterning in facial morphology in archaic humans is not well understood. This study explores temporal trends in facial morphology in order to gain a clearer understanding of the polarity of features, and describes the allometric patterning of facial shape. The modern human sample comprises cross-sectional growth series of four morphologically distinct human populations. The fossil sample covers specimens from the Middle Pleistocene to the Upper Paleolithic. We digitized landmarks and semilandmarks on surface and computed tomography scans and analyzed the Procrustes shape coordinates. Principal component analyses were performed, and Procrustes distances were used to identify phenetic similarities between fossil hominins. In order to explore the influence of size on facial features, allometric trajectories were calculated for fossil and modern human groups, and developmental simulations were performed. We show that facial features can be used to separate Pleistocene humans into temporal clusters. The distinctly modern human pattern of facial morphology is already present around 170 ka. Species- and population-specific facial features develop before two years of age, and several of the large-scale facial differences between Neanderthals and Middle Pleistocene humans are due to scaling along a shared allometric trajectory. These features include aspects of the frontal bone, browridge morphology, nasal aperture size and facial prognathism. Infraorbital surface topography and orientation of the midface in the European Middle Pleistocene hominins is intermediate between the African Middle Pleistocene and Neanderthal condition. This could suggest that the European Middle Pleistocene hominins display incipient Neanderthal features.
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Affiliation(s)
- Sarah E Freidline
- Max Planck Institute for Evolutionary Anthropology, Department of Human Evolution, Deutscher Platz 6, Leipzig 04103, Germany.
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41
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Baab KL, McNulty KP, Rohlf FJ. The shape of human evolution: A geometric morphometrics perspective. Evol Anthropol 2012; 21:151-65. [DOI: 10.1002/evan.21320] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Neubauer S, Gunz P, Weber GW, Hublin JJ. Endocranial volume of Australopithecus africanus: new CT-based estimates and the effects of missing data and small sample size. J Hum Evol 2012; 62:498-510. [PMID: 22365336 DOI: 10.1016/j.jhevol.2012.01.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 01/12/2012] [Accepted: 01/19/2012] [Indexed: 11/29/2022]
Abstract
Estimation of endocranial volume in Australopithecus africanus is important in interpreting early hominin brain evolution. However, the number of individuals available for investigation is limited and most of these fossils are, to some degree, incomplete and/or distorted. Uncertainties of the required reconstruction ('missing data uncertainty') and the small sample size ('small sample uncertainty') both potentially bias estimates of the average and within-group variation of endocranial volume in A. africanus. We used CT scans, electronic preparation (segmentation), mirror-imaging and semilandmark-based geometric morphometrics to generate and reconstruct complete endocasts for Sts 5, Sts 60, Sts 71, StW 505, MLD 37/38, and Taung, and measured their endocranial volumes (EV). To get a sense of the reliability of these new EV estimates, we then used simulations based on samples of chimpanzees and humans to: (a) test the accuracy of our approach, (b) assess missing data uncertainty, and (c) appraise small sample uncertainty. Incorporating missing data uncertainty of the five adult individuals, A. africanus was found to have an average adult endocranial volume of 454-461 ml with a standard deviation of 66-75 ml. EV estimates for the juvenile Taung individual range from 402 to 407 ml. Our simulations show that missing data uncertainty is small given the missing portions of the investigated fossils, but that small sample sizes are problematic for estimating species average EV. It is important to take these uncertainties into account when different fossil groups are being compared.
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Affiliation(s)
- Simon Neubauer
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
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Postnatal Cranial Development in Papionin Primates: An Alternative Model for Hominin Evolutionary Development. Evol Biol 2012. [DOI: 10.1007/s11692-011-9153-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Gunz P, Neubauer S, Golovanova L, Doronichev V, Maureille B, Hublin JJ. A uniquely modern human pattern of endocranial development. Insights from a new cranial reconstruction of the Neandertal newborn from Mezmaiskaya. J Hum Evol 2012; 62:300-13. [PMID: 22221766 DOI: 10.1016/j.jhevol.2011.11.013] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 10/20/2011] [Accepted: 11/24/2011] [Indexed: 11/16/2022]
Abstract
The globular braincase of modern humans is distinct from all fossil human species, including our closest extinct relatives, the Neandertals. Such adult shape differences must ultimately be rooted in different developmental patterns, but it is unclear at which point during ontogeny these group characteristics emerge. Here we compared internal shape changes of the braincase from birth to adulthood in Neandertals (N = 10), modern humans (N = 62), and chimpanzees (N = 62). Incomplete fossil specimens, including the two Neandertal newborns from Le Moustier 2 and Mezmaiskaya, were reconstructed using reference-based estimation methods. We used 3D geometric morphometrics to statistically compare shapes of virtual endocasts extracted from computed-tomographic scans. Throughout the analysis, we kept track of possible uncertainties due to the missing data values and small fossil sample sizes. We find that some aspects of endocranial development are shared by the three species. However, in the first year of life, modern humans depart from this presumably ancestral pattern of development. Newborn Neandertals and newborn modern humans have elongated braincases, and similar endocranial volumes. During a 'globularization-phase' modern human endocasts change to the globular shape that is characteristic for Homo sapiens. This phase of early development is unique to modern humans, and absent from chimpanzees and Neandertals. Our results support the notion that Neandertals and modern humans reach comparable adult brain sizes via different developmental pathways. The differences between these two human groups are most prominent directly after birth, a critical phase for cognitive development.
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Affiliation(s)
- Philipp Gunz
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Deutscher Platz 6, D-04103 Leipzig, Germany.
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Abstract
Hominin evolution is characterized by two main trends, transition to bipedality and increase in brain size. Fossil evidence shows that both trends had a major impact on the structure and function of the hominin skull. This chapter asks how evolutionary modification of the cranial ontogenetic program led to morphological reorganization of the hominin skull and ultimately to hominin cranial diversity. Three major mechanisms of evolutionary developmental reorganization are proposed: modified prenatal development of the cranial base and face reflects adaptation to bipedality; high rates of neurocranial growth during early postnatal ontogeny are essential to attain large brain sizes; taxon-specific modification of facial development reflects dietary adaptation and-in the genus Homo-a general trend toward neoteny.
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Holloway RL, Broadfield DC. Technical note: the midline and endocranial volume of the Taung endocast. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2011; 146:319-22. [PMID: 21826639 DOI: 10.1002/ajpa.21570] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 05/11/2011] [Indexed: 11/09/2022]
Abstract
The Taung endocast is one of the best-preserved and most important known in paleoanthropology. Although the endocast is undistorted and preserves distinctive landmarks, Taung has proved a difficult endocast, because it is only about 60% complete. To reconstruct Taung it is necessary to first use the available anatomical landmarks to define the midline of the endocast. It is only with a proper description of the midline that it is possible to reconstruct the endocast and obtain an accurate measurement of Taung's endocranial volume. Holloway (Science 168 (1970) 966-968) determined a conservative estimate for Taung of 404 ml. More recently this estimate has been revised downward by Falk and Clarke (Am J Phys Anthropol 134 (2007) 529-534) to 382 ml, giving Taung the smallest endocast for A. africanus. Certain challenges exist with the reconstruction of any endocast, particularly a hemi-endocast such as Taung. A virtual reconstruction of Taung must assume perfect symmetry, a feature called into question here in Taung's most recent reconstruction by Falk and Clarke (2007). Holloway's (1970) reconstruction of Taung provides a guidepost for a conservative approach to endocast reconstructions, and the most reliable measurement of Taung's true endocranial volume.
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Affiliation(s)
- Ralph L Holloway
- Department of Anthropology, Columbia University, New York, NY 10027, USA.
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Neubauer S, Gunz P, Hublin JJ. Endocranial shape changes during growth in chimpanzees and humans: a morphometric analysis of unique and shared aspects. J Hum Evol 2010; 59:555-66. [PMID: 20727571 DOI: 10.1016/j.jhevol.2010.06.011] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 06/26/2010] [Accepted: 06/27/2010] [Indexed: 12/26/2022]
Abstract
Compared to our closest living and extinct relatives, humans have a large, specialized, and complex brain embedded in a uniquely shaped braincase. Here, we quantitatively compare endocranial shape changes during ontogeny in humans and chimpanzees. Identifying shared and unique aspects in developmental patterns of these two species can help us to understand brain evolution in the hominin lineage. Using CT scans of 58 humans and 60 chimpanzees varying in age from birth to adulthood, we generated virtual endocasts to measure and analyze 29 three-dimensional endocranial landmarks and several hundred semilandmarks on curves and the endocranial surface; these data were then analyzed using geometric morphometric methods. The ontogenetic shape trajectories are nonlinear for both species, which indicates several developmental phases. Endocranial shape is already distinct at birth and there is no overlap between the two species throughout ontogeny. While some aspects of the pattern of endocranial shape change are shared between humans and chimpanzees, the shape trajectories differ substantially directly after birth until the eruption of the deciduous dentition: in humans but not in chimpanzees, the parietal and cerebellar regions expand relatively (contributing to neurocranial globularity) and the cranial base flexes within the first postnatal year when brain growth rates are high. We show that the shape changes associated with this early "globularization phase" are unique to humans and do not occur in chimpanzees before or after birth.
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Affiliation(s)
- Simon Neubauer
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany.
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