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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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2
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Sandel AA, Negrey JD, Arponen M, Clark IR, Clift JB, Reddy RB, Ivaska KK. The evolution of the adolescent growth spurt: Urinary biomarkers of bone turnover in wild chimpanzees (Pan troglodytes). J Hum Evol 2023; 177:103341. [PMID: 36905703 DOI: 10.1016/j.jhevol.2023.103341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 02/01/2023] [Accepted: 02/01/2023] [Indexed: 03/11/2023]
Abstract
Life history theory addresses how organisms balance development and reproduction. Mammals usually invest considerable energy into growth in infancy, and they do so incrementally less until reaching adult body size, when they shift energy to reproduction. Humans are unusual in having a long adolescence when energy is invested in both reproduction and growth, including rapid skeletal growth around puberty. Although many primates, especially in captivity, experience accelerated growth in mass around puberty, it remains unclear whether this represents skeletal growth. Without data on skeletal growth in nonhuman primates, anthropologists have often assumed the adolescent growth spurt is uniquely human, and hypotheses for its evolution have focused on other uniquely human traits. The lack of data is largely due to methodological difficulties of assessing skeletal growth in wild primates. Here, we use two urinary markers of bone turnover-osteocalcin and collagen-to study skeletal growth in a large, cross-sectional sample of wild chimpanzees (Pan troglodytes) at Ngogo, Kibale National Park, Uganda. For both bone turnover markers, we found a nonlinear effect of age, which was largely driven by males. For male chimpanzees, values for osteocalcin and collagen peaked at age 9.4 years and 10.8 years, respectively, which corresponds to early and middle adolescence. Notably, collagen values increased from 4.5 to 9 years, suggesting faster growth during early adolescence compared to late infancy. Biomarker levels plateaued at 20 years in both sexes, suggesting skeletal growth continues until then. Additional data, notably on females and infants of both sexes, are needed, as are longitudinal samples. However, our cross-sectional analysis suggests an adolescent growth spurt in the skeleton of chimpanzees, especially for males. Biologists should avoid claiming that the adolescent growth spurt is uniquely human, and hypotheses for the patterns of human growth should consider variation in our primate relatives.
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Affiliation(s)
- Aaron A Sandel
- Department of Anthropology, University of Texas at Austin, WCP 4.102, 2201 Speedway Stop C3200, Austin, TX 78712, USA; Primate Ethology and Endocrinology Lab, University of Texas at Austin, 2201 Speedway Stop C3200, Austin, TX 78712, USA.
| | - Jacob D Negrey
- School of Human Evolution and Social Change, Arizona State University, 900 S. Cady Mall, Tempe, AZ 85281, USA; Department of Pathology/Section on Comparative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
| | - Milja Arponen
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland
| | - Isabelle R Clark
- Department of Anthropology, University of Texas at Austin, WCP 4.102, 2201 Speedway Stop C3200, Austin, TX 78712, USA; Primate Ethology and Endocrinology Lab, University of Texas at Austin, 2201 Speedway Stop C3200, Austin, TX 78712, USA
| | - Jeremy B Clift
- Department of Psychological Science, University of Arkansas, 216 Memorial Hall, Fayetteville, AR 72701, USA
| | - Rachna B Reddy
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Ave, Cambridge, MA 02138, USA; Department of Psychology, Harvard University, 33 Kirkland St, Cambridge, MA 02138, USA; Department of Evolutionary Anthropology, Duke University, 104 Biological Sciences, Durham, NC 27708, USA
| | - Kaisa K Ivaska
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland
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3
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Beaudet A. The Australopithecus assemblage from Sterkfontein Member 4 (South Africa) and the concept of variation in palaeontology. Evol Anthropol 2023. [PMID: 36632711 DOI: 10.1002/evan.21972] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/06/2022] [Accepted: 12/17/2022] [Indexed: 01/13/2023]
Abstract
Interpreting morphological variation within the early hominin fossil record is particularly challenging. Apart from the fact that there is no absolute threshold for defining species boundaries in palaeontology, the degree of variation related to sexual dimorphism, temporal depth, geographic variation or ontogeny is difficult to appreciate in a fossil taxon mainly represented by fragmentary specimens, and such variation could easily be conflated with taxonomic diversity. One of the most emblematic examples in paleoanthropology is the Australopithecus assemblage from the Sterkfontein Caves in South Africa. Whereas some studies support the presence of multiple Australopithecus species at Sterkfontein, others explore alternative hypotheses to explain the morphological variation within the hominin assemblage. In this review, I briefly summarize the ongoing debates surrounding the interpretation of morphological variation at Sterkfontein Member 4 before exploring two promising avenues that would deserve specific attention in the future, that is, temporal depth and nonhuman primate diversity.
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Affiliation(s)
- Amélie Beaudet
- Department of Archaeology, University of Cambridge, Cambridge, UK.,School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa.,Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Sabadell, Cerdanyola del Vallès, Barcelona, Spain
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4
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Hawks J, Berger LR. Mandibular ramus morphology and species identification in Australopithecus sediba. S AFR J SCI 2022. [DOI: 10.17159/sajs.2022/12544] [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
The site of Malapa, South Africa, has produced fossil evidence from multiple individuals of Australopithecus sediba including the partial skeletons designated as MH1 (holotype) and MH2 (paratype). A recent article in this Journal presented the hypothesis that MH1 and MH2 are not one species but instead represent two different genera: Australopithecus and Homo, respectively. Here we briefly evaluate this claim. We review the evidence from across the skeleton that demonstrates that MH1 and MH2 represent a single species, and we highlight other fossil samples that show the same pattern of mandibular ramus variation as observed in MH1 and MH2. The evidence shows that there is no reason to separate MH1 and MH2 into different species or genera based upon mandibular ramus morphology. This case illustrates how misleading small fragments of anatomy can be, why researchers should not use such fragments particularly for species and genus-level diagnoses, and why it is essential to use all available evidence.
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Affiliation(s)
- John Hawks
- Department of Anthropology, University of Wisconsin–Madison, Madison, Wisconsin, USA
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
| | - Lee R. Berger
- 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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Wolfe CA, Herrmann NP. Interpreting error in the estimation of skeletal growth profiles from past populations: An example demonstrating skeletal growth in historic African American communities. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 177:83-99. [PMID: 36787783 DOI: 10.1002/ajpa.24415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/27/2021] [Accepted: 09/13/2021] [Indexed: 12/19/2022]
Abstract
OBJECTIVES The study of growth in the past is a critical component of bioarcheological analyses. However, our understanding of growth in the past is subject to a number of methodological challenges. This study aims to model the skeletal growth of past populations by considering the challenges associated with the data collection process and the challenges associated with the age estimation procedures. MATERIALS AND METHODS We use skeletal remains from two historic African American cemeteries in the American South to model femoral diaphyseal length-for-age. We estimate the age of each individual using dental development techniques and present growth curves as both a product of the maximum likelihood (MLE) age estimate and the estimated posterior age distribution. Growth was compared against a reference sample from the University of Colorado Child Research Council Study. RESULTS The results of our analyses showed that femoral diaphyseal length in two historic African American communities is small-for-estimated age as compared to a modern reference sample. However, the magnitude and characterization of this difference is variable when taking into account the broader posterior age distribution. DISCUSSION Both samples may be small-for-age due to physiological stress associated with racism, inequality, and the compounding effects of early urbanization. However, the interpretation of growth in the past is muddled when considering the relationship between the study sample and the reference sample, when accounting for uncertainty in the age estimation procedure, and the error-inducing steps taken during the data collection process. Future interpretation of skeletal growth in the past must include a full account of the possible sources of error in order to present an accurate representation of growth.
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6
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Dean C, Zanolli C, Le Cabec A, Tawane M, Garrevoet J, Mazurier A, Macchiarelli R. Growth and development of the third permanent molar in Paranthropus robustus from Swartkrans, South Africa. Sci Rep 2020; 10:19053. [PMID: 33149180 PMCID: PMC7642444 DOI: 10.1038/s41598-020-76032-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/15/2020] [Indexed: 11/24/2022] Open
Abstract
Third permanent molars (M3s) are the last tooth to form but have not been used to estimate age at dental maturation in early fossil hominins because direct histological evidence for the timing of their growth has been lacking. We investigated an isolated maxillary M3 (SK 835) from the 1.5 to 1.8-million-year-old (Mya) site of Swartkrans, South Africa, attributed to Paranthropus robustus. Tissue proportions of this specimen were assessed using 3D X-ray micro-tomography. Thin ground sections were used to image daily growth increments in enamel and dentine. Transmitted light microscopy and synchrotron X-ray fluorescence imaging revealed fluctuations in Ca concentration that coincide with daily growth increments. We used regional daily secretion rates and Sr marker-lines to reconstruct tooth growth along the enamel/dentine and then cementum/dentine boundaries. Cumulative growth curves for increasing enamel thickness and tooth height and age-of-attainment estimates for fractional stages of tooth formation differed from those in modern humans. These now provide additional means for assessing late maturation in early hominins. M3 formation took ≥ 7 years in SK 835 and completion of the roots would have occurred between 11 and 14 years of age. Estimated age at dental maturation in this fossil hominin compares well with what is known for living great apes.
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Affiliation(s)
- Christopher Dean
- Department of Earth Sciences, Natural History Museum, London, UK. .,Department of Cell and Developmental Biology, University College London, London, UK.
| | - Clément Zanolli
- Univ. Bordeaux, CNRS, MCC, PACEA, UMR 5199, 33600 Pessac, France.,Department of Maxillofacial and Oral Surgery, Sefako Makgatho Health Sciences University, Ga-Rankuwa, Pretoria, South Africa
| | - Adeline Le Cabec
- Univ. Bordeaux, CNRS, MCC, PACEA, UMR 5199, 33600 Pessac, France.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Mirriam Tawane
- Ditsong National Museum of Natural History, Pretoria, South Africa
| | - Jan Garrevoet
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - Arnaud Mazurier
- IC2MP, UMR 7285 CNRS, Université de Poitiers, Poitiers, France
| | - Roberto Macchiarelli
- UMR 7194 CNRS, Muséum National D'Histoire Naturelle, Musée de L'Homme, Paris, France.,Unité de Formation Géosciences, Université de Poitiers, Poitiers, France
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7
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Bolter DR, Cameron N. Utilizing auxology to understand ontogeny of extinct hominins: A case study on Homo naledi. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 173:368-380. [PMID: 32537780 DOI: 10.1002/ajpa.24088] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 02/03/2020] [Accepted: 05/10/2020] [Indexed: 02/05/2023]
Abstract
The methods used to study human growth and development (auxology) have not previously been applied within the setting of hominin maturation (ontogeny). Ontogeny is defined here as the pattern of biological change into an adult form, both at the individual and species level. The hominin fossil record has a lack of recovered immature materials, due to such factors as taphonomic processes that destroy pre-adults; the fragility of immature compared to adult bone; and the lower mortality rates of juveniles compared to adults. The recent discovery of pre-adult hominin skeletal material from a single, homogeneous Homo naledi species from the Rising Star cave system in South Africa provides the opportunity for a broader application of auxology methods and thus the need to understand their use in a modern context. Human auxology studies benefit from a robust database, across multiple populations, and with longitudinal studies in order to assess the patterns and variations in typical growth, development and life history stages. Here, we review the approach, vocabulary, and methods of these human studies, investigate commonalities in data with the fossil record, and then advance the reconstruction of ontogeny for the extinct hominin species H. naledi. To this end, we apply an auxology model into the paleontological context to broadly predict H. naledi birthweight of the offspring at 2.06 kg with a range (±1 SD) of 1.89 to 2.24 kg, with a length at birth 45.5 cm. We estimate a H. naledi juvenile partial skeleton DH7 to be a height of 111-125 cm at death.
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Affiliation(s)
- Debra R Bolter
- Department of Anthropology, Modesto Junior College, Modesto, California, USA
- Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Noel Cameron
- Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Johannesburg, South Africa
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
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8
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Cazenave M, Dean C, Zanolli C, Oettlé AC, Hoffman J, Tawane M, Thackeray F, Macchiarelli R. Reassessment of the TM 1517 odonto-postcranial assemblage from Kromdraai B, South Africa, and the maturational pattern of Paranthropus robustus. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 172:714-722. [PMID: 32449177 DOI: 10.1002/ajpa.24082] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 04/03/2020] [Accepted: 05/10/2020] [Indexed: 11/11/2022]
Abstract
OBJECTIVES The Pleistocene taxon Paranthropus robustus was established in 1938 following the discovery at Kromdraai B, South Africa, of the partial cranium TM 1517a and associated mandible TM 1517b. Shortly thereafter, a distal humerus (TM 1517g), a proximal ulna (TM 1517e), and a distal hallucial phalanx (TM 1517k) were collected nearby at the site, and were considered to be associated with the holotype. TM 1517a-b represents an immature individual; however, no analysis of the potentially associated postcranial elements has investigated the presence of any endostructural remnant of recent epiphyseal closure. This study aims at tentatively detecting such traces in the three postcranial specimens from Kromdraai B. MATERIALS AND METHODS By using μXCT techniques, we assessed the developmental stage of the TM 1517b's C-M3 roots and investigated the inner structure of TM 1517g, TM 1517e, and TM 1517k. RESULTS The M2 shows incompletely closed root apices and the M3 a half-completed root formation stage. The distal humerus was likely completely fused, while the proximal ulna and the distal hallucial phalanx preserve endosteal traces of the diaphyseo-epiphyseal fusion process. DISCUSSION In the hominin fossil record, there are few unambiguously associated craniodental and postcranial remains sampling immature individuals, an essential condition for assessing the taxon-specific maturational patterns. Our findings corroborate the original association of the craniodental and postcranial remains representing the P. robustus type specimen. As with other Plio-Pleistocene hominins, the odonto-postcranial maturational pattern of TM 1517 more closely fits an African great ape rather than the extant human pattern.
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Affiliation(s)
- Marine Cazenave
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Department of Anatomy and Histology, Sefako Makgatho Health Sciences University, Ga-Rankuwa, Pretoria, South Africa
| | - Christopher Dean
- Department of Earth Sciences, Natural History Museum, London, UK.,Department of Cell and Developmental Biology, University College London, London, UK
| | | | - Anna C Oettlé
- Department of Anatomy and Histology, Sefako Makgatho Health Sciences University, Ga-Rankuwa, Pretoria, South Africa.,Department of Anatomy, University of Pretoria, Pretoria, South Africa
| | - Jakobus Hoffman
- South African Nuclear Energy Corporation SOC, Ltd., Pelindaba, South Africa
| | - Mirriam Tawane
- Ditsong National Museum of Natural History, Pretoria, South Africa
| | - Francis Thackeray
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Roberto Macchiarelli
- UMR 7194 CNRS, Muséum national d'Histoire naturelle, Musée de l'Homme, Paris, France.,Unité de Formation Géosciences, Université de Poitiers, Poitiers, France
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9
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Bolter DR, Elliott MC, Hawks J, Berger LR. Immature remains and the first partial skeleton of a juvenile Homo naledi, a late Middle Pleistocene hominin from South Africa. PLoS One 2020; 15:e0230440. [PMID: 32236122 PMCID: PMC7112188 DOI: 10.1371/journal.pone.0230440] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 02/29/2020] [Indexed: 11/18/2022] Open
Abstract
Immature remains are critical for understanding maturational processes in hominin species as well as for interpreting changes in ontogenetic development in hominin evolution. The study of these subjects is hindered by the fact that associated juvenile remains are extremely rare in the hominin fossil record. Here we describe an assemblage of immature remains of Homo naledi recovered from the 2013–2014 excavation season. From this assemblage, we attribute 16 postcranial elements and a partial mandible with some dentition to a single juvenile Homo naledi individual. The find includes postcranial elements never before discovered as immature elements in the sub-equatorial early hominin fossil record, and contributes new data to the field of hominin ontogeny.
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Affiliation(s)
- Debra R. Bolter
- Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Johannesburg, South Africa
- Department of Anthropology, Modesto Junior College, Modesto, California, United States of America
- * E-mail:
| | - Marina C. Elliott
- Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Johannesburg, South Africa
| | - John Hawks
- Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Johannesburg, South Africa
- Department of Anthropology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Lee R. Berger
- Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Johannesburg, South Africa
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10
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Abstract
Hominin birth mechanics have been examined and debated from limited and often fragmentary fossil pelvic material. Some have proposed that birth in the early hominin genus Australopithecus was relatively easy and ape-like, while others have argued for a more complex, human-like birth mechanism in australopiths. Still others have hypothesized a unique birth mechanism, with no known modern equivalent. Preliminary work on the pelvis of the recently discovered 1.98 million-year-old hominin Australopithecus sediba found it to possess a unique combination of Homo and Australopithecus-like features. Here, we create a composite pelvis of Australopithecus sediba to reconstruct the birth process in this early hominin. Consistent with other hominin species, including modern humans, the fetus would enter the pelvic inlet in a transverse direction. However, unlike in modern humans, the fetus would not need additional rotations to traverse the birth canal. Further fetal rotation is unnecessary even with a Homo-like pelvic midplane expansion, not seen in earlier hominin species. With a birth canal shape more closely associated with specimens from the genus Homo and a lack of cephalopelvic or shoulder constraints, we therefore find evidence to support the hypothesis that the pelvic morphology of Australopithecus sediba is a result of locomotor, rather than strictly obstetric constraints.
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11
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Brimacombe CS, Kuykendall KL, Nystrom P. Epiphyseal fusion and dental development in Pan paniscus with comparisons with Pan troglodytes. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 167:903-913. [PMID: 30318603 DOI: 10.1002/ajpa.23710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 08/20/2018] [Accepted: 08/23/2018] [Indexed: 11/06/2022]
Abstract
OBJECTIVES Compared with frequent studies of skeletal development in chimpanzees, relatively little is known about bonobo skeletal development. This study seeks to explore the relationship between skeletal and dental development in both species of Pan. New data are presented for fusion sites not previously observed in bonobos. MATERIALS AND METHODS In a sample of 34 Pan paniscus and 168 Pan troglodytes subadults, state of fusion was recorded for 30 epiphyseal fusion sites using a three-stage system of unfused, midfusion, and complete fusion based on Wintheiser, Clauser, and Tappen. Stage of dental development for permanent mandibular dentition was assessed using the Demrijian, Goldstein, and Tanner method. These data allowed for comparisons of both species of Pan and the two subspecies of P. troglodytes. RESULTS The sequence of fusion events was generally consistent between the two species, but some exceptions may exist for the knee and ankle. The number of fusion events that occurred after complete dental mineralization was similar in both species. No statistically significant differences were found in the fusion timing for the subspecies of P. troglodytes. DISCUSSION Bolter and Zihlman suggested that fusion at the acetabulum occurs earlier in Pan paniscus, while fusion of epiphyses at the knee are delayed, compared with P. troglodytes. Our data do not indicate earlier fusion of the acetabulum, but fusion events at the knee may complete later relative to dental mineralization in Pan pansicus. Compared with Homo sapiens, both P. troglodytes and Pan paniscus demonstrate later completion of epiphyseal fusion relative to dental mineralization.
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Affiliation(s)
- Conrad S Brimacombe
- University of Sheffield, Department of Archaeology, Minalloy House, Sheffield, United Kingdom.,University of Sheffield Bioinformatics Hub, Department of Molecular Biology and Biotechnology, Sheffield, United Kingdom
| | - Kevin L Kuykendall
- University of Sheffield, Department of Archaeology, Minalloy House, Sheffield, United Kingdom
| | - Pia Nystrom
- University of Sheffield, Department of Archaeology, Minalloy House, Sheffield, United Kingdom
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12
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Cunningham DL, Graves RR, Wescott DJ, McCarthy RC. The effect of ontogeny on estimates of KNM-WT 15000's adult body size. J Hum Evol 2018; 121:119-127. [PMID: 29754743 DOI: 10.1016/j.jhevol.2018.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 03/30/2018] [Accepted: 04/02/2018] [Indexed: 02/04/2023]
Abstract
The Homo erectus specimen KNM-WT 15000 has played a critical role in our understanding of body size evolution. New interpretations suggest that KNM-WT 15000 had a younger age-at-death and a more rapid ontogenetic trajectory than previously suggested. Recent fossil discoveries and new interpretations suggest a wide range of body size and shape variation in H. erectus. Based on these new insights, we argue that KNM-WT 15000's adult stature and body mass could have been much smaller than has been traditionally presented in the literature. Using chimpanzee and modern human growth trajectories, we bracketed the range of possibilities for KNM-WT 15000's adult body size between 160.0 and 177.7 cm (5'3″-5'10″) for stature and 60.0 and 82.7 kg (132-182 lbs.) for body mass. These estimates put KNM-WT 15000 near the mean rather than among the largest known H. erectus specimens.
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Affiliation(s)
| | - Ronda R Graves
- Grunley Construction Company, Inc., Rockville, MD 20850, USA
| | - Daniel J Wescott
- Texas State University, Department of Anthropology, San Marcos, TX 78666, USA
| | - Robert C McCarthy
- Benedictine University, Department of Biological Sciences, Lisle, IL 60532, USA
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13
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Meyer MR, Woodward C, Tims A, Bastir M. Neck function in early hominins and suspensory primates: Insights from the uncinate process. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 166:613-637. [PMID: 29492962 DOI: 10.1002/ajpa.23448] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 02/02/2018] [Accepted: 02/06/2018] [Indexed: 11/11/2022]
Abstract
OBJECTIVES Uncinate processes are protuberances on the cranial surface of subaxial cervical vertebrae that assist in stabilizing and guiding spinal motion. Shallow uncinate processes reduce cervical stability but confer an increased range of motion in clinical studies. Here we assess uncinate processes among extant primates and model cervical kinematics in early fossil hominins. MATERIALS AND METHODS We compare six fossil hominin vertebrae with 48 Homo sapiens and 99 nonhuman primates across 20 genera. We quantify uncinate morphology via geometric morphometric methods to understand how uncinate process shape relates to allometry, taxonomy, and mode of locomotion. RESULTS Across primates, allometry explains roughly 50% of shape variation, as small, narrow vertebrae feature the relatively tallest, most pronounced uncinate processes, whereas larger, wider vertebrae typically feature reduced uncinates. Taxonomy only weakly explains the residual variation, however, the association between Uncinate Shape and mode of locomotion is robust, as bipeds and suspensory primates occupy opposite extremes of the morphological continuum and are distinguished from arboreal generalists. Like humans, Australopithecus afarensis and Homo erectus exhibit shallow uncinate processes, whereas A. sediba resembles more arboreal taxa, but not fully suspensory primates. DISCUSSION Suspensory primates exhibit the most pronounced uncinates, likely to maintain visual field stabilization. East African hominins exhibit reduced uncinate processes compared with African apes and A. sediba, likely signaling different degrees of neck motility and modes of locomotion. Although soft tissues constrain neck flexibility beyond limits suggested by osteology alone, this study may assist in modeling cervical kinematics and positional behaviors in extinct taxa.
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Affiliation(s)
- Marc R Meyer
- Department of Anthropology, Chaffey College, Rancho Cucamonga, California 91737
| | - Charles Woodward
- Department of Anthropology, University of California, Berkeley, California 94720
| | - Amy Tims
- Department of Wildlife, Fish, & Conservation Biology, University of California, Davis, California 95616
| | - Markus Bastir
- Paleoanthropology Group, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid 28006, Spain
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