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Delezene LK, Scott JE, Irish JD, Villaseñor A, Skinner MM, Hawks J, Berger LR. Sex-biased sampling may influence Homo naledi tooth size variation. J Hum Evol 2024; 187:103490. [PMID: 38266614 DOI: 10.1016/j.jhevol.2023.103490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/26/2024]
Abstract
A frequent source of debate in paleoanthropology concerns the taxonomic unity of fossil assemblages, with many hominin samples exhibiting elevated levels of variation that can be interpreted as indicating the presence of multiple species. By contrast, the large assemblage of hominin fossils from the Rising Star cave system, assigned to Homo naledi, exhibits a remarkably low degree of variation for most skeletal elements. Many factors can contribute to low sample variation, including genetic drift, strong natural selection, biased sex ratios, and sampling of closely related individuals. In this study, we tested for potential sex-biased sampling in the Rising Star dental sample. We compared coefficients of variation for the H. naledi teeth to those for eight extant hominoid samples. We used a resampling procedure that generated samples from the extant taxa that matched the sample size of the fossil sample for each possible Rising Star dental sex ratio. We found that variation at four H. naledi tooth positions-I2, M1, P4, M1-is so low that the possibility that one sex is represented by few or no individuals in the sample cannot be excluded. Additional evidence is needed to corroborate this inference, such as ancient DNA or enamel proteome data, and our study design does not address other potential factors that would account for low sample variation. Nevertheless, our results highlight the importance of considering the taphonomic history of a hominin assemblage and suggest that sex-biased sampling is a plausible explanation for the low level of phenotypic variation found in some aspects of the current H. naledi assemblage.
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Affiliation(s)
- Lucas K Delezene
- Department of Anthropology, University of Arkansas, Fayetteville, AR, 72701, USA; Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa.
| | - Jeremiah E Scott
- Department of Medical Anatomical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, 91766, USA
| | - Joel D Irish
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa; School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Amelia Villaseñor
- Department of Anthropology, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Matthew M Skinner
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa; Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany
| | - John Hawks
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa; Department of Anthropology, University of Wisconsin-Madison. Madison, WI, 53706, USA
| | - Lee R Berger
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa; National Geographic Society, 1145 17th Street NW, Washington DC, 20036, USA
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Ward CV, Hammond AS, Grine FE, Mongle CS, Lawrence J, Kimbel WH. Taxonomic attribution of the KNM-ER 1500 partial skeleton from the Burgi Member of the Koobi Fora Formation, Kenya. J Hum Evol 2023; 184:103426. [PMID: 37769373 DOI: 10.1016/j.jhevol.2023.103426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/16/2023] [Accepted: 08/18/2023] [Indexed: 09/30/2023]
Abstract
Paranthropus boisei is well represented in the eastern African fossil record by craniodental remains, but very few postcranial fossils can be securely attributed to this taxon. For this reason, KNM-ER 1500 from East Turkana, Kenya, is especially important. KNM-ER 1500 is a badly weathered and fragmented postcranial skeleton associated with a small piece of mandibular corpus. It derives from the Burgi Member, which has yielded diagnostic craniodental fossils attributable to P. boisei, Homo habilis, Homo rudolfensis and Homo erectus. Although it has been proposed that KNM-ER 1500 may be attributable to P. boisei based on the small mandibular fragment, this hypothesis remained challenging to test. Here we re-examine the preserved portions of KNM-ER 1500 and reassess support for its taxonomic attribution. There are compelling features of the mandible, proximal femur, and especially the proximal radius that support attribution of KNM-ER 1500 to P. boisei. These features include the absolute width of the mandible and its lack of a lateral intertoral sulcus, an anteroposteriorly compressed femoral neck with a distinctive posteroinferior marginal ridge, the rim of the radial head that is proximodistally uniform in thickness around its circumference, and a long radial neck that is elliptical in cross section. No feature serves to align KNM-ER 1500 with Homo to the exclusion of Paranthropus. KNM-ER 1500 was a small-bodied individual and attributing this specimen to P. boisei confirms that significant postcranial-size dimorphism was present in this species.
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Affiliation(s)
- Carol V Ward
- Department of Pathology and Anatomical Sciences, M263 Medical Sciences Building, University of Missouri, Columbia, MO 65212, USA; Department of Anthropology, 107 Swallow Hall, University of Missouri, Columbia, MO 65211, USA.
| | - Ashley S Hammond
- Division of Anthropology, American Museum of Natural History, 79th St. at Central Park West, New York, NY 10024, USA; New York Consortium of Evolutionary Primatology (NYCEP), American Museum of Natural History, 79th St. at Central Park West, New York, NY 10024, USA
| | - Frederick E Grine
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA; Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - Carrie S Mongle
- Division of Anthropology, American Museum of Natural History, 79th St. at Central Park West, New York, NY 10024, USA; Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA; Turkana Basin Institute, Stony Brook University, Stony Brook, NY 11794, USA
| | - Julie Lawrence
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Institute of Human Origins and School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85281, USA
| | - William H Kimbel
- Institute of Human Origins and School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85281, USA
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Bermúdez de Castro JM, Modesto‐Mata M, Martín‐Francés L, García‐Campos C, Martínez de Pinillos M, Martinón‐Torres M. Testing the inhibitory cascade model in the Middle Pleistocene Sima de los Huesos (Sierra de Atapuerca, Spain) hominin sample. J Anat 2021; 238:173-184. [PMID: 32839991 PMCID: PMC7755082 DOI: 10.1111/joa.13292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 07/04/2020] [Accepted: 07/13/2020] [Indexed: 01/03/2023] Open
Abstract
The Middle Pleistocene Sima de los Huesos (SH) site has yielded more than 7.500 human fossil remains belonging to a minimum of 29 individuals. Most of these individuals preserve either the complete mandibular molar series or at least the first (M1 ) and second (M2 ) molars. The inhibitory cascade mathematical model was proposed by Kavanagh et al. (Nature, 449, 427-433 [2007]) after their experimental studies on the dental development of murine rodent species. The activator-inhibitor mechanism of this model has shown its ability for predicting evolutionary size patterns of mammalian teeth, including hominins. The main aim of this study is to test whether the size molar patterns observed in the SH hominins fit the inhibitory cascade model. With this purpose, we have measured the crown area of all SH molars in photographs, using a planimeter and following techniques used and well contrasted in previous works. Following one of the premises of the inhibitory cascade model, we expect that the central tooth (M2 in our case) of a triplet would have the average size of the two outer teeth. The absolute difference between the observed and the expected values for the M2 s ranges from 0.23 to 8.46 mm2 in the SH sample. In terms of percentage, the difference ranges between 0.25% and 10.34%, although in most cases, it is below 5%. The plot of the estimated M3 /M1 and M2 /M1 size ratios obtained in the SH hominins occupies a small area of the theoretical developmental morphospace obtained for rodent species. In addition, the majority of the values are placed near the theoretical line which defines the relationship predicted by the inhibitory cascade model in these mammals. The values of the slope and intercept of the reduced major regression obtained for the SH individuals do not differ significantly from those obtained for rodent species, thus confirming that the size of the molars of the SH hominins fits the inhibitory cascade model. We discuss these results in terms of dental development. Despite the promising results in the SH sample, we draw the attention to the fact that most Early Pleistocene Homo specimens exhibit a pattern (M1 < M2 > M3 ), which is outside the expected theoretical morphospace predicted by the inhibitory cascade model. The shift from the M1 < M2 < M3 size relationship observed in early hominins (including H. habilis) to the M1 > M2 > M3 size relationship, which is predominant in modern humans, includes sequences that depart from predictions of the inhibitory cascade model. Additional studies are required to understand these deviations.
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Affiliation(s)
- José María Bermúdez de Castro
- CENIEH (National Research Center on Human EvolutionBurgosSpain,Anthropology DepartmentUniversity College LondonLondonUK
| | - Mario Modesto‐Mata
- Equipo Primeros Pobladores de ExtremaduraCasa de la Cultura Rodríguez MoñinoCáceresSpain,Fundación AtapuercaBurgosSpain
| | - Laura Martín‐Francés
- CENIEH (National Research Center on Human EvolutionBurgosSpain,Anthropology DepartmentUniversity College LondonLondonUK,Fundación AtapuercaBurgosSpain
| | - Cecilia García‐Campos
- CENIEH (National Research Center on Human EvolutionBurgosSpain,Fundación AtapuercaBurgosSpain
| | | | - María Martinón‐Torres
- CENIEH (National Research Center on Human EvolutionBurgosSpain,Anthropology DepartmentUniversity College LondonLondonUK
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4
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García-Campos C, Modesto-Mata M, Martinón-Torres M, Martínez de Pinillos M, Martín-Francés L, Arsuaga JL, Bermúdez de Castro JM. Sexual dimorphism of the enamel and dentine dimensions of the permanent canines of the Middle Pleistocene hominins from Sima de los Huesos (Burgos, Spain). J Hum Evol 2020; 144:102793. [PMID: 32442650 DOI: 10.1016/j.jhevol.2020.102793] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 03/26/2020] [Accepted: 03/26/2020] [Indexed: 01/26/2023]
Abstract
Sexual dimorphism is an important component of the total variation seen in populations and plays a key role in taxonomic debates. In this study, microtomographic (microcomputed tomography) techniques were applied to a sample of hominin teeth from the Sima de los Huesos site (Spain). Dental tissue proportions of the permanent canines were assessed to characterize the pattern and degree of sexual dimorphism within this population. In addition, the possible similarities and differences with the Homo neanderthalensis remains from Krapina (Croatia) and with a recent modern human sample were evaluated. A combination of classical statistical approaches with more novel techniques allowed us not only to ratify the sex allocation of the individuals previously assigned in the literature but also to estimate the sex of the youngest individuals, which were not assessed in previous studies. Likewise, the sexes of certain extensively worn canines and isolated pieces were estimated. As a result, the sex ratio observed in our dental sample from the Sima de los Huesos population is 5:9 (Nm:Nf). In general terms, both Sima de los Huesos and Krapina dental samples have a degree of sexual dimorphism in their permanent canine tissue proportions that does not surpass that of modern humans. The marked dimorphic root volume of Sima de los Huesos mandibular canines is the exception, which surpasses the modern human mean, although it falls within the 95% confidence interval. Therefore, our results do not support that dental tissue proportions of the European Middle Pleistocene populations were more dimorphic than in modern humans. However, the differences in canine tissue proportions are great enough to allow sex estimation with a high degree of confidence.
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Affiliation(s)
- Cecilia García-Campos
- Centro Nacional de Investigación Sobre La Evolución Humana, Paseo de La Sierra de Atapuerca 3, 09002, Burgos, Spain; Anthropology Department, University College London, 14 Taviton Street, London, WC1H 0BW, UK.
| | - Mario Modesto-Mata
- Centro Nacional de Investigación Sobre La Evolución Humana, Paseo de La Sierra de Atapuerca 3, 09002, Burgos, Spain; Anthropology Department, University College London, 14 Taviton Street, London, WC1H 0BW, UK
| | - María Martinón-Torres
- Centro Nacional de Investigación Sobre La Evolución Humana, Paseo de La Sierra de Atapuerca 3, 09002, Burgos, Spain; Anthropology Department, University College London, 14 Taviton Street, London, WC1H 0BW, UK
| | - Marina Martínez de Pinillos
- Centro Nacional de Investigación Sobre La Evolución Humana, Paseo de La Sierra de Atapuerca 3, 09002, Burgos, Spain; Anthropology Department, University College London, 14 Taviton Street, London, WC1H 0BW, UK
| | - Laura Martín-Francés
- Centro Nacional de Investigación Sobre La Evolución Humana, Paseo de La Sierra de Atapuerca 3, 09002, Burgos, Spain; Anthropology Department, University College London, 14 Taviton Street, London, WC1H 0BW, UK; Université de Bordeaux, CNRS, MCC, PACEA, UMR 5199, F-33615, Pessac Cedex, France
| | - Juan Luis Arsuaga
- Centro Mixto UCM-ISCIII de Evolución y Comportamiento Humanos, Madrid, Spain
| | - José María Bermúdez de Castro
- Centro Nacional de Investigación Sobre La Evolución Humana, Paseo de La Sierra de Atapuerca 3, 09002, Burgos, Spain; Anthropology Department, University College London, 14 Taviton Street, London, WC1H 0BW, UK
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Pitirri MK, Begun D. Ontogenetic insights into the significance of mandibular corpus shape variation in hominoids: Developmental covariation between M 2 crypt formation and corpus shape. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 171:76-88. [PMID: 31710703 DOI: 10.1002/ajpa.23969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/18/2019] [Accepted: 10/27/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVES Here, we quantify and compare the cross-sectional shape of the mandibular corpus between M1 and M2 during growth in Pan paniscus, Pan troglodytes, and Pongo pygmaeus. The goal is to assess the hypothesis that the shape of the corpus is influenced by the development of permanent molars in their crypts, by examining ontogenetic changes in corpus shape and investigating covariation between corpus shape and M2 and M3 molar crypt forms. MATERIALS AND METHODS Ontogenetic changes in mandibular corpus shape were assessed using landmarks and semilandmarks, and measurements of length, width, and height were used to quantify molar crypts (M2 and M3 ). Ontogenetic changes in corpus growth from the eruption of M1 to the eruption of M3 were evaluated for each species through generalized Procrustes analysis and principal components analysis in shape-space and form-space. The relationship between corpus shape and molar crypt form was investigated at three different developmental stages using two-block partial least squares (2B-PLS) analysis. RESULTS The results show clear differences in growth patterns among all three species and provide evidence that species-level differences in mandibular corpus growth occur prior to the emergence of M1 . The results of the 2B-PLS analysis reveal that significant covariance between corpus shape and molar crypt form is limited to the developmental stage marked by the emergence of M1 , with covariance between corpus shape and M2 crypt width. Corpora that are relatively narrower in the inferior portion of the cross section covary with relatively narrower M2 crypts. CONCLUSIONS These results have important implications for understanding the taxonomic and phylogenetic significance of mandibular corpus shape variation in the hominoid fossil record.
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Affiliation(s)
- M K Pitirri
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania.,Department of Anthropology, University of Toronto, Toronto, Ontario
| | - David Begun
- Department of Anthropology, University of Toronto, Toronto, Ontario
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6
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Complete permanent mandibular dentition of early Homo from the upper Burgi Member of the Koobi Fora Formation, Ileret, Kenya. J Hum Evol 2019; 131:152-175. [PMID: 31182200 DOI: 10.1016/j.jhevol.2019.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 03/15/2019] [Accepted: 03/18/2019] [Indexed: 01/24/2023]
Abstract
The KNM-ER 64060 dentition derives from a horizon that most likely dates to between 2.02 and 2.03 Ma. A proximate series of postcranial bones (designated KNM-ER 64061) derives from the same siltstone unit and may be associated with the dentition, but their separation on the surface of the site leaves some room for doubt. KNM-ER 64060 is one of fewer than ten hominin specimens from the Early Pleistocene of East Africa that comprises a full or nearly complete mandibular dentition. Its taxonomic attribution is potentially significant, especially if the postcranial elements are related. At least three, and probably four hominin species, including Paranthropus boisei and Homo erectus (= H. ergaster), are known at about this time in East Africa. Other penecontemporaneous fossils have been referred to a single, highly variable species, H. habilis, or two taxa, namely H. habilis and H. rudolfensis. Although the weight of evidence supports the attribution of these specimens to two species, there is notable lack of agreement over the assignation of individual fossils. We take a conservative approach and group all such specimens under the designation "early Homo sp." for comparative purposes. KNM-ER 64060 is clearly attributable to Homo rather than Paranthropus. The preponderance of the evidence suggests that the affinities of KNM-ER 64060 are with fossils assigned to the early Homo sp. category rather than with H. erectus. This is indicated by the overall sizes of the KNM-ER 64060 canine, premolar and molar crowns, the size relationships of the P3 to P4, the relative narrowness of its premolar crowns, the cusp proportions of the M1 and especially those of the M2 and M3, and seemingly the possession of a two-rooted P4. Some of these comparisons suggest further that among the fossils comprising the early Homo sp. sample, the KNM-ER 64060 dentition exhibits greater overall similarity to specimens such as OH 7 and OH 16 that represent Homo habilis sensu stricto.
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Rightmire GP, Margvelashvili A, Lordkipanidze D. Variation among the Dmanisi hominins: Multiple taxa or one species? AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 168:481-495. [PMID: 30578552 DOI: 10.1002/ajpa.23759] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 11/05/2018] [Accepted: 11/06/2018] [Indexed: 11/08/2022]
Abstract
OBJECTIVES There is continuing controversy over the number of taxa documented by the Dmanisi hominins. Variation may reflect age and sex differences within a single population. Alternatively, two (or more) distinct species may be present. Our null hypothesis states that just one population is represented at the site. MATERIALS AND METHODS We assess the likely sources of variation in endocranial capacity, craniofacial and mandibular morphology, and the expression of characters related to aging and sex dimorphism. We use the coefficient of variation and a modified version of Levene's test for equal variances to compare trait variation at Dmanisi with that in fossil hominins and modern Homo sapiens from Africa. RESULTS Skull 5 presents a low, massive vault, and a muzzle-like lower face. Other individuals have larger brains and more globular vaults. Despite such variation, the five crania share numerous features. All of the mandibles possess marginal tubercles, mandibular tori, and a distinctive patterning of mental foramina. Relative variation at Dmanisi is comparable to that in selected reference groups. Further growth anticipated in Skull 3, age-related remodeling affecting the D2600 mandible, pathology, and sex dimorphism can account for much of the interindividual variation observed. The preponderance of evidence supports our null hypothesis. DISCUSSION Sources of the variation within ancient Homo assemblages remain poorly understood. Skull 5 is a very robust male, with a brain smaller than that of both a juvenile (Skull 3) and a probable female (Skull 2). Skull 1 has the largest brain, but cranial superstructures do not clearly mark this individual as male or female. It is likely that the Dmanisi hominins represent a single paleospecies of Homo displaying a pattern of sex dimorphism not seen in living hominids.
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Affiliation(s)
- G Philip Rightmire
- Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts
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Pitirri MK, Begun D. A new method to quantify mandibular corpus shape in extant great apes and its potential application to the hominoid fossil record. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 168:318-328. [PMID: 30537105 DOI: 10.1002/ajpa.23749] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 10/08/2018] [Accepted: 10/20/2018] [Indexed: 11/10/2022]
Abstract
OBJECTIVES Mandibular corpus robusticity (corpus breadth/corpus height) is the most commonly utilized descriptor of the mandibular corpus in the great ape and hominin fossil records. As a consequence of its contoured shape, linear metrics used to characterize mandibular robusticity are inadequate to quantify the shape of the mandibular corpus. Here, we present an alternative to the traditional assessment of mandibular shape by analyzing the outline of the mandibular corpus in cross-section using landmarks and semilandmarks. MATERIALS AND METHODS Outlines of the mandibular corpus in cross-section between M1 and M2 were quantified in a sample of hominoids and analyzed using generalized Procrustes analysis, Procrustes ANOVA, CVA, and cluster analysis. Corpus breadth and width were also collected from the same sample and analyzed using regression, ANOVA, and cluster analysis. RESULTS Analysis of corpus outline shape revealed significant differences in mandibular corpus shape that are independent of size and sex at the genus level across hominoids. Cluster analysis based on the analysis of corpus outline shape results in almost all specimens grouping based on taxonomic affinity (99.28% correct classification). Comparison of these results to results using traditional measures of mandibular robusticity shows that analysis of the outline of the corpus in cross-section discriminate extant great apes more reliably. CONCLUSION The strong taxonomic signal revealed by this analysis indicates that quantification of the outline of the mandibular corpus more fully captures mandibular corpus shape and offers the potential for greater power in discriminating among taxa in the hominoid fossil record.
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Affiliation(s)
- M Kathleen Pitirri
- Department of Anthropology, Pennsylvania State University, Pennsylvania.,Department of Anthropology, University of Toronto, St. Toronto, Ontario, Canada
| | - David Begun
- Department of Anthropology, University of Toronto, St. Toronto, Ontario, Canada
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Pampush JD, Scott JE, Robinson CA, Delezene LK. Oblique human symphyseal angle is associated with an evolutionary rate-shift early in the hominin clade. J Hum Evol 2018; 123:84-95. [DOI: 10.1016/j.jhevol.2018.06.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/19/2018] [Accepted: 06/21/2018] [Indexed: 01/06/2023]
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10
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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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11
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EarlyHomoand the role of the genus in paleoanthropology. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 165 Suppl 65:72-89. [DOI: 10.1002/ajpa.23387] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 12/12/2017] [Indexed: 11/07/2022]
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12
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Skull 5 from Dmanisi: Descriptive anatomy, comparative studies, and evolutionary significance. J Hum Evol 2017; 104:50-79. [PMID: 28317556 DOI: 10.1016/j.jhevol.2017.01.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 11/21/2022]
Abstract
A fifth hominin skull (cranium D4500 and mandible D2600) from Dmanisi is massively constructed, with a large face and a very small brain. Traits documented for the first time in a basal member of the Homo clade include the uniquely low ratio of endocranial volume to basicranial width, reduced vertex height, angular vault profile, smooth nasal sill coupled with a long and sloping maxillary clivus, elongated palate, and tall mandibular corpus. The convex clivus and receding symphysis of skull 5 produce a muzzle-like form similar to that of Australopithecus afarensis. While the Dmanisi cranium is very robust, differing from OH 13, OH 24, and KNM-ER 1813, it resembles Homo habilis specimens in the "squared off" outline of its maxilla in facial view, maxillary sulcus, rounded and receding zygomatic arch, and flexed zygomaticoalveolar pillar. These characters distinguish early Homo from species of Australopithecus and Paranthropus. Skull 5 is unlike Homo rudolfensis cranium KNM-ER 1470. Although it appears generally primitive, skull 5 possesses a bar-like supraorbital torus, elongated temporal squama, occipital transverse torus, and petrotympanic traits considered to be derived for Homo erectus. As a group, the Dmanisi crania and mandibles display substantial anatomical and metric variation. A key question is whether the fossils document age-related growth and sex dimorphism within a single population, or whether two (or more) distinct taxa may be present at the site. We use the coefficient of variation to compare Dmanisi with Paranthropus boisei, H. erectus, and recent Homo sapiens, finding few signals that the Dmanisi sample is excessively variable in comparison to these reference taxa. Using cranial measurements and principal components analysis, we explore the proposal that the Dmanisi skulls can be grouped within a regionally diverse hypodigm for H. erectus. Our results provide only weak support for this hypothesis. Finally, we consider all available morphological and paleobiological evidence in an attempt to clarify the phyletic relationship of Dmanisi to Homo species evolving >2.0 to 1.0 Ma.
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13
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Dembo M, Matzke NJ, Mooers AØ, Collard M. Bayesian analysis of a morphological supermatrix sheds light on controversial fossil hominin relationships. Proc Biol Sci 2016. [PMID: 26202999 DOI: 10.1098/rspb.2015.0943] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The phylogenetic relationships of several hominin species remain controversial. Two methodological issues contribute to the uncertainty-use of partial, inconsistent datasets and reliance on phylogenetic methods that are ill-suited to testing competing hypotheses. Here, we report a study designed to overcome these issues. We first compiled a supermatrix of craniodental characters for all widely accepted hominin species. We then took advantage of recently developed Bayesian methods for building trees of serially sampled tips to test among hypotheses that have been put forward in three of the most important current debates in hominin phylogenetics--the relationship between Australopithecus sediba and Homo, the taxonomic status of the Dmanisi hominins, and the place of the so-called hobbit fossils from Flores, Indonesia, in the hominin tree. Based on our results, several published hypotheses can be statistically rejected. For example, the data do not support the claim that Dmanisi hominins and all other early Homo specimens represent a single species, nor that the hobbit fossils are the remains of small-bodied modern humans, one of whom had Down syndrome. More broadly, our study provides a new baseline dataset for future work on hominin phylogeny and illustrates the promise of Bayesian approaches for understanding hominin phylogenetic relationships.
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Affiliation(s)
- Mana Dembo
- Human Evolutionary Studies Program, Simon Fraser University, Burnaby, British Columbia, Canada Department of Archaeology,, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Nicholas J Matzke
- National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN, USA
| | - Arne Ø Mooers
- Human Evolutionary Studies Program, Simon Fraser University, Burnaby, British Columbia, Canada Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Mark Collard
- Human Evolutionary Studies Program, Simon Fraser University, Burnaby, British Columbia, Canada Department of Archaeology,, Simon Fraser University, Burnaby, British Columbia, Canada Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada Department of Archaeology, University of Aberdeen, Aberdeen, UK
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Margvelashvili A, Zollikofer CPE, Lordkipanidze D, Tafforeau P, Ponce de León MS. Comparative analysis of dentognathic pathologies in the Dmanisi mandibles. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2016; 160:229-53. [PMID: 26919277 DOI: 10.1002/ajpa.22966] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 01/20/2016] [Accepted: 02/02/2016] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Due to the scarcity of the fossil record, in vivo changes in the dentognathic system of early Homo are typically documented at the level of individual fossil specimens, and it remains difficult to draw population-level inferences about dietary habits, diet-related activities and lifestyle from individual patterns of dentognathic alterations. The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, offers a unique opportunity to study in vivo changes in the dentognathic system of individuals belonging to a single paleodeme of early Homo. MATERIALS AND METHODS We analyze dentognathic pathologies in the Dmanisi sample, and in comparative samples of modern Australian and Greenlander hunter-gatherer populations, applying clinical protocols of dentognathic diagnostics. RESULTS The Dmanisi hominins exhibit a similarly wide diversity and similar incidence of dentognathic pathologies as the modern human hunter-gatherer population samples investigated here. Dmanisi differs from the modern population samples in several respects: At young age tooth wear is already advanced, and pathologies are more prevalent. At old age, hypercementosis is substantial. CONCLUSIONS Results indicate that dentognathic pathologies and disease trajectories are largely similar in early Homo and modern humans, but that the disease load was higher in early Homo, probably as an effect of higher overall stress on the dentognathic system. Am J Phys Anthropol 160:229-253, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ann Margvelashvili
- Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland.,Georgian National Museum, Purtseladze 3, Tbilisi, 0105, Georgia
| | - Christoph P E Zollikofer
- Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland
| | | | - Paul Tafforeau
- European Synchrotron Radiation Facility, 71 avenue des martyrs, 38043, Grenoble, France
| | - Marcia S Ponce de León
- Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland
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Bermúdez de Castro JM, Martinón-Torres M, Sier MJ, Martín-Francés L. On the variability of the Dmanisi mandibles. PLoS One 2014; 9:e88212. [PMID: 24586309 PMCID: PMC3930530 DOI: 10.1371/journal.pone.0088212] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/03/2014] [Indexed: 11/18/2022] Open
Abstract
The description of a new skull (D4500) from the Dmanisi site (Republic of Georgia) has reopened the debate about the morphological variability within the genus Homo. The new skull fits with a mandible (D2600) often referred as 'big' or 'enigmatic' because of its differences with the other Dmanisi mandibles (D211 and D2735). In this report we present a comparative study of the variability of the Dmanisi mandibles under a different perspective, as we focus in morphological aspects related to growth and development. We have followed the notion of modularity and phenotypic integration in order to understand the architectural differences observed within the sample. Our study reveals remarkable shape differences between D2600 and the other two mandibles, that are established early in the ontogeny (during childhood or even before) and that do not depend on size or sexual dimorphism. In addition, D2600 exhibits a mosaic of primitive and derived features regarding the Homo clade, which is absent in D211 and D2735. This mosaic expression is related to the location of the features and can be explained under the concept of modularity. Our study would support the possibility of two different paleodemes represented at the Dmanisi site. This hypothesis has been previously rejected on the basis that all the individuals were constrained in the same stratigraphic and taphonomic settings. However, our revision of the complex Dmanisi stratigraphy suggests that the accumulation could cover an undetermined period of time. Even if "short" in geological terms, the hominin accumulation was not necessarily synchronic. In the same line we discard that the differences between D2600 and the small mandibles are consequence of wear-related dentoalveolar remodeling. In addition, dental wear pattern of D2600 could suggest an adaptation to a different ecological niche than the other Dmanisi individuals.
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Affiliation(s)
| | - María Martinón-Torres
- Dental Anthropology Group, National Research Center on Human Evolution (CENIEH), Burgos, Spain
| | - Mark Jan Sier
- Dental Anthropology Group, National Research Center on Human Evolution (CENIEH), Burgos, Spain
- Paleomagnetic Laboratory ‘Fort Hoofddijk’, Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
- Human Origins Group, Faculty of Archaeology, Leiden University, Leiden, The Netherlands
| | - Laura Martín-Francés
- Dental Anthropology Group, National Research Center on Human Evolution (CENIEH), Burgos, Spain
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Affiliation(s)
- Fred Spoor
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig 04103, Germany, and University College London, UK
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17
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Tooth wear and dentoalveolar remodeling are key factors of morphological variation in the Dmanisi mandibles. Proc Natl Acad Sci U S A 2013; 110:17278-83. [PMID: 24101504 DOI: 10.1073/pnas.1316052110] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, is unique in offering detailed insights into patterns of morphological variation within a paleodeme of early Homo. Cranial and dentoalveolar morphologies exhibit a high degree of diversity, but the causes of variation are still relatively unexplored. Here we show that wear-related dentoalveolar remodeling is one of the principal mechanisms causing mandibular shape variation in fossil Homo and in modern human hunter-gatherer populations. We identify a consistent pattern of mandibular morphological alteration, suggesting that dental wear and compensatory remodeling mechanisms remained fairly constant throughout the evolution of the genus Homo. With increasing occlusal and interproximal tooth wear, the teeth continue to erupt, the posterior dentition tends to drift in a mesial direction, and the front teeth become more upright. The resulting changes in dentognathic size and shape are substantial and need to be taken into account in comparative taxonomic analyses of isolated hominin mandibles. Our data further show that excessive tooth wear eventually leads to a breakdown of the normal remodeling mechanisms, resulting in dentognathic pathologies, tooth loss, and loss of masticatory function. Complete breakdown of dentognathic homeostasis, however, is unlikely to have limited the life span of early Homo because this effect was likely mediated by the preparation of soft foods.
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Plavcan JM. Body Size, Size Variation, and Sexual Size Dimorphism in Early Homo. CURRENT ANTHROPOLOGY 2012. [DOI: 10.1086/667605] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Robinson C. Geometric morphometric analysis of mandibular shape diversity in Pan. J Hum Evol 2012; 63:191-204. [PMID: 22682959 DOI: 10.1016/j.jhevol.2012.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 04/27/2012] [Accepted: 05/01/2012] [Indexed: 11/17/2022]
Affiliation(s)
- Chris Robinson
- Department of Biology, Bronx Community College, City University of New York, 2155 University Avenue, Bronx, NY 10453, USA.
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22
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23
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Scott JE, Schrein CM, Kelley J. BeyondGorillaandPongo: Alternative models for evaluating variation and sexual dimorphism in fossil hominoid samples. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2009; 140:253-64. [DOI: 10.1002/ajpa.21059] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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24
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Liang X, Jacobs R, Corpas L, Semal P, Lambrichts I. Chronologic and geographic variability of neurovascular structures in the human mandible. Forensic Sci Int 2009; 190:24-32. [DOI: 10.1016/j.forsciint.2009.05.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Revised: 04/09/2009] [Accepted: 05/08/2009] [Indexed: 11/16/2022]
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Comparisons of Early Pleistocene Skulls from East Africa and the Georgian Caucasus: Evidence Bearing on the Origin and Systematics of Genus Homo. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/978-1-4020-9980-9_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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26
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Lague MR, Collard NJ, Richmond BG, Wood BA. Hominid mandibular corpus shape variation and its utility for recognizing species diversity within fossil Homo. J Anat 2008; 213:670-85. [PMID: 19094183 PMCID: PMC2666136 DOI: 10.1111/j.1469-7580.2008.00989.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2008] [Indexed: 11/28/2022] Open
Abstract
Mandibular corpora are well represented in the hominin fossil record, yet few studies have rigorously assessed the utility of mandibular corpus morphology for species recognition, particularly with respect to the linear dimensions that are most commonly available. In this study, we explored the extent to which commonly preserved mandibular corpus morphology can be used to: (i) discriminate among extant hominid taxa and (ii) support species designations among fossil specimens assigned to the genus Homo. In the first part of the study, discriminant analysis was used to test for significant differences in mandibular corpus shape at different taxonomic levels (genus, species and subspecies) among extant hominid taxa (i.e. Homo, Pan, Gorilla, Pongo). In the second part of the study, we examined shape variation among fossil mandibles assigned to Homo (including H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster, late African H. erectus, Asian H. erectus, H. heidelbergensis, H. neanderthalensis and H. sapiens). A novel randomization procedure designed for small samples (and using group 'distinctness values') was used to determine whether shape variation among the fossils is consistent with conventional taxonomy (or alternatively, whether a priori taxonomic groupings are completely random with respect to mandibular morphology). The randomization of 'distinctness values' was also used on the extant samples to assess the ability of the test to recognize known taxa. The discriminant analysis results demonstrated that, even for a relatively modest set of traditional mandibular corpus measurements, we can detect significant differences among extant hominids at the genus and species levels, and, in some cases, also at the subspecies level. Although the randomization of 'distinctness values' test is more conservative than discriminant analysis (based on comparisons with extant specimens), we were able to detect at least four distinct groups among the fossil specimens (i.e. H. sapiens, H. heidelbergensis, Asian H. erectus and a combined 'African Homo' group consisting of H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster and late African H. erectus). These four groups appear to be distinct at a level similar to, or greater than, that of modern hominid species. In addition, the mandibular corpora of H. neanderthalensis could be distinguished from those of 'African Homo', although not from those of H. sapiens, H. heidelbergensis, or the Asian H. erectus group. The results suggest that the features most commonly preserved on the hominin mandibular corpus have some taxonomic utility, although they are unlikely to be useful in generating a reliable alpha taxonomy for early African members of the genus Homo.
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Affiliation(s)
- Michael R Lague
- Natural Sciences & Mathematics, The Richard Stockton College of New Jersey, Pomona, NJ 08240-0195, USA.
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Dental remains from Dmanisi (Republic of Georgia): Morphological analysis and comparative study. J Hum Evol 2008; 55:249-73. [DOI: 10.1016/j.jhevol.2007.12.008] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 12/15/2007] [Accepted: 12/26/2007] [Indexed: 11/22/2022]
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Symphyseal shape variation in extant and fossil hominoids, and the symphysis of Australopithecus bahrelghazali. J Hum Evol 2008; 55:37-47. [DOI: 10.1016/j.jhevol.2007.12.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 11/09/2007] [Accepted: 12/03/2007] [Indexed: 11/17/2022]
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The taxonomic implications of cranial shape variation in Homo erectus. J Hum Evol 2008; 54:827-47. [DOI: 10.1016/j.jhevol.2007.11.003] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 10/27/2007] [Accepted: 11/18/2007] [Indexed: 11/23/2022]
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30
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Green DJ, Gordon AD. Metacarpal proportions in Australopithecus africanus. J Hum Evol 2008; 54:705-19. [DOI: 10.1016/j.jhevol.2007.10.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 08/30/2007] [Accepted: 10/09/2007] [Indexed: 11/29/2022]
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31
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Variation in the mandibles from Dmanisi, Georgia. J Hum Evol 2008; 54:904-8. [PMID: 18394678 DOI: 10.1016/j.jhevol.2008.02.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 12/18/2007] [Accepted: 02/04/2008] [Indexed: 11/21/2022]
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Gordon AD, Green DJ, Richmond BG. Strong postcranial size dimorphism inAustralopithecus afarensis: Results from two new resampling methods for multivariate data sets with missing data. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2008; 135:311-28. [DOI: 10.1002/ajpa.20745] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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