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Williams MP, Flegontov P, Maier R, Huber CD. Testing times: disentangling admixture histories in recent and complex demographies using ancient DNA. Genetics 2024; 228:iyae110. [PMID: 39013011 PMCID: PMC11373510 DOI: 10.1093/genetics/iyae110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 04/08/2024] [Accepted: 06/11/2024] [Indexed: 07/18/2024] Open
Abstract
Our knowledge of human evolutionary history has been greatly advanced by paleogenomics. Since the 2020s, the study of ancient DNA has increasingly focused on reconstructing the recent past. However, the accuracy of paleogenomic methods in resolving questions of historical and archaeological importance amidst the increased demographic complexity and decreased genetic differentiation remains an open question. We evaluated the performance and behavior of two commonly used methods, qpAdm and the f3-statistic, on admixture inference under a diversity of demographic models and data conditions. We performed two complementary simulation approaches-firstly exploring a wide demographic parameter space under four simple demographic models of varying complexities and configurations using branch-length data from two chromosomes-and secondly, we analyzed a model of Eurasian history composed of 59 populations using whole-genome data modified with ancient DNA conditions such as SNP ascertainment, data missingness, and pseudohaploidization. We observe that population differentiation is the primary factor driving qpAdm performance. Notably, while complex gene flow histories influence which models are classified as plausible, they do not reduce overall performance. Under conditions reflective of the historical period, qpAdm most frequently identifies the true model as plausible among a small candidate set of closely related populations. To increase the utility for resolving fine-scaled hypotheses, we provide a heuristic for further distinguishing between candidate models that incorporates qpAdm model P-values and f3-statistics. Finally, we demonstrate a significant performance increase for qpAdm using whole-genome branch-length f2-statistics, highlighting the potential for improved demographic inference that could be achieved with future advancements in f-statistic estimations.
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Affiliation(s)
- Matthew P Williams
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Pavel Flegontov
- Department of Biology and Ecology, University of Ostrava, Ostrava 701 03, Czechia
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Robert Maier
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Christian D Huber
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
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2
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Carvalho VHV, Rodrigues JCG, Vinagre LWMS, Pereira EEB, Monte N, Fernandes MR, Ribeiro-Dos-Santos AM, Guerreiro JF, Ribeiro-Dos-Santos Â, Dos Santos SEB, Dos Santos NPC. Genomic investigation on genes related to mercury metabolism in Amazonian indigenous populations. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 923:171232. [PMID: 38402986 DOI: 10.1016/j.scitotenv.2024.171232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 02/27/2024]
Abstract
Studies have identified elevated levels of mercury in Amazonian Indigenous individuals, highlighting them as one of the most exposed to risks. In the unique context of the Brazilian Indigenous population, it is crucial to identify genetic variants with clinical significance to better understand vulnerability to mercury and its adverse effects. Currently, there is a lack of research on the broader genomic profile of Indigenous people, particularly those from the Amazon region, concerning mercury contamination. Therefore, the aim of this study was to assess the genomic profile related to the processes of mercury absorption, distribution, metabolism, and excretion in 64 Indigenous individuals from the Brazilian Amazon. We aimed to determine whether these individuals exhibit a higher susceptibility to mercury exposure. Our study identified three high-impact variants (GSTA1 rs1051775, GSTM1 rs1183423000, and rs1241704212), with the latter two showing a higher frequency in the study population compared to global populations. Additionally, we discovered seven new variants with modifier impact and a genomic profile different from the worldwide populations. These genetic variants may predispose the study population to more harmful mercury exposure compared to global populations. As the first study to analyze broader genomics of mercury metabolism pathways in Brazilian Amazonian Amerindians, we emphasize that our research aims to contribute to public policies by utilizing genomic investigation as a method to identify populations with a heightened susceptibility to mercury exposure.
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Affiliation(s)
- Victor Hugo Valente Carvalho
- Núecleo de Pesquisas em Oncologia, Unidade de Alta Complexidade em Oncologia, Hospital Universitário João de Barros Barreto, 66073-005 Belém, Pará, Brazil.
| | - Juliana Carla Gomes Rodrigues
- Núecleo de Pesquisas em Oncologia, Unidade de Alta Complexidade em Oncologia, Hospital Universitário João de Barros Barreto, 66073-005 Belém, Pará, Brazil
| | - Lui Wallacy Morikawa Souza Vinagre
- Núecleo de Pesquisas em Oncologia, Unidade de Alta Complexidade em Oncologia, Hospital Universitário João de Barros Barreto, 66073-005 Belém, Pará, Brazil
| | - Esdras Edgar Batista Pereira
- Núecleo de Pesquisas em Oncologia, Unidade de Alta Complexidade em Oncologia, Hospital Universitário João de Barros Barreto, 66073-005 Belém, Pará, Brazil
| | - Natasha Monte
- Núecleo de Pesquisas em Oncologia, Unidade de Alta Complexidade em Oncologia, Hospital Universitário João de Barros Barreto, 66073-005 Belém, Pará, Brazil
| | - Marianne Rodrigues Fernandes
- Núecleo de Pesquisas em Oncologia, Unidade de Alta Complexidade em Oncologia, Hospital Universitário João de Barros Barreto, 66073-005 Belém, Pará, Brazil
| | - André Maurício Ribeiro-Dos-Santos
- Laboratório de Genética Humana e Médica, Instituto de Ciências Biológicas, Universidade Federal do Pará, 66075-110, Belém, Pará, Brazil
| | - João Farias Guerreiro
- Laboratório de Genética Humana e Médica, Instituto de Ciências Biológicas, Universidade Federal do Pará, 66075-110, Belém, Pará, Brazil
| | - Ândrea Ribeiro-Dos-Santos
- Laboratório de Genética Humana e Médica, Instituto de Ciências Biológicas, Universidade Federal do Pará, 66075-110, Belém, Pará, Brazil
| | - Sidney Emanuel Batista Dos Santos
- Núecleo de Pesquisas em Oncologia, Unidade de Alta Complexidade em Oncologia, Hospital Universitário João de Barros Barreto, 66073-005 Belém, Pará, Brazil
| | - Ney Pereira Carneiro Dos Santos
- Núecleo de Pesquisas em Oncologia, Unidade de Alta Complexidade em Oncologia, Hospital Universitário João de Barros Barreto, 66073-005 Belém, Pará, Brazil
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3
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Padilla-Iglesias C, Derkx I. Hunter-gatherer genetics research: Importance and avenues. EVOLUTIONARY HUMAN SCIENCES 2024; 6:e15. [PMID: 38516374 PMCID: PMC10955370 DOI: 10.1017/ehs.2024.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 01/17/2024] [Accepted: 02/02/2024] [Indexed: 03/23/2024] Open
Abstract
Major developments in the field of genetics in the past few decades have revolutionised notions of what it means to be human. Although currently only a few populations around the world practise a hunting and gathering lifestyle, this mode of subsistence has characterised members of our species since its very origins and allowed us to migrate across the planet. Therefore, the geographical distribution of hunter-gatherer populations, dependence on local ecosystems and connections to past populations and neighbouring groups have provided unique insights into our evolutionary origins. However, given the vulnerable status of hunter-gatherers worldwide, the development of the field of anthropological genetics requires that we reevaluate how we conduct research with these communities. Here, we review how the inclusion of hunter-gatherer populations in genetics studies has advanced our understanding of human origins, ancient population migrations and interactions as well as phenotypic adaptations and adaptability to different environments, and the important scientific and medical applications of these advancements. At the same time, we highlight the necessity to address yet unresolved questions and identify areas in which the field may benefit from improvements.
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Affiliation(s)
| | - Inez Derkx
- Department of Evolutionary Anthropology, University of Zurich, Zurich, Switzerland
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4
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Balboa RF, Bertola LD, Brüniche-Olsen A, Rasmussen MS, Liu X, Besnard G, Salmona J, Santander CG, He S, Zinner D, Pedrono M, Muwanika V, Masembe C, Schubert M, Kuja J, Quinn L, Garcia-Erill G, Stæger FF, Rakotoarivony R, Henrique M, Lin L, Wang X, Heaton MP, Smith TPL, Hanghøj K, Sinding MHS, Atickem A, Chikhi L, Roos C, Gaubert P, Siegismund HR, Moltke I, Albrechtsen A, Heller R. African bushpigs exhibit porous species boundaries and appeared in Madagascar concurrently with human arrival. Nat Commun 2024; 15:172. [PMID: 38172616 PMCID: PMC10764920 DOI: 10.1038/s41467-023-44105-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/30/2023] [Indexed: 01/05/2024] Open
Abstract
Several African mammals exhibit a phylogeographic pattern where closely related taxa are split between West/Central and East/Southern Africa, but their evolutionary relationships and histories remain controversial. Bushpigs (Potamochoerus larvatus) and red river hogs (P. porcus) are recognised as separate species due to morphological distinctions, a perceived lack of interbreeding at contact, and putatively old divergence times, but historically, they were considered conspecific. Moreover, the presence of Malagasy bushpigs as the sole large terrestrial mammal shared with the African mainland raises intriguing questions about its origin and arrival in Madagascar. Analyses of 67 whole genomes revealed a genetic continuum between the two species, with putative signatures of historical gene flow, variable FST values, and a recent divergence time (<500,000 years). Thus, our study challenges key arguments for splitting Potamochoerus into two species and suggests their speciation might be incomplete. Our findings also indicate that Malagasy bushpigs diverged from southern African populations and underwent a limited bottleneck 1000-5000 years ago, concurrent with human arrival in Madagascar. These results shed light on the evolutionary history of an iconic and widespread African mammal and provide insight into the longstanding biogeographic puzzle surrounding the bushpig's presence in Madagascar.
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Affiliation(s)
- Renzo F Balboa
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Laura D Bertola
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Xiaodong Liu
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Guillaume Besnard
- Laboratoire Evolution et Diversité Biologique (EDB), UMR 5174, CNRS, IRD, Université Toulouse Paul Sabatier, 31062, Toulouse, France
| | - Jordi Salmona
- Laboratoire Evolution et Diversité Biologique (EDB), UMR 5174, CNRS, IRD, Université Toulouse Paul Sabatier, 31062, Toulouse, France
| | - Cindy G Santander
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Shixu He
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Dietmar Zinner
- Cognitive Ecology Laboratory, German Primate Center, Leibniz Institute for Primate Research, 37077, Göttingen, Germany
- Department of Primate Cognition, Georg-August-Universität Göttingen, 37077, Göttingen, Germany
- Leibniz Science Campus Primate Cognition, 37077, Göttingen, Germany
| | - Miguel Pedrono
- UMR ASTRE, CIRAD, Campus International de Baillarguet, Montpellier, France
| | - Vincent Muwanika
- College of Agricultural and Environmental Sciences, Makerere University, Kampala, Uganda
| | - Charles Masembe
- College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Mikkel Schubert
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Josiah Kuja
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Liam Quinn
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | | | | | | | - Long Lin
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Xi Wang
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Kristian Hanghøj
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Anagaw Atickem
- Department of Zoological Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
| | - Lounès Chikhi
- Laboratoire Evolution et Diversité Biologique (EDB), UMR 5174, CNRS, IRD, Université Toulouse Paul Sabatier, 31062, Toulouse, France
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Christian Roos
- Gene Bank of Primates and Primate Genetics Laboratory, German Primate Center, Leibniz Institute for Primate Research, 37077, Göttingen, Germany
| | - Philippe Gaubert
- Laboratoire Evolution et Diversité Biologique (EDB), UMR 5174, CNRS, IRD, Université Toulouse Paul Sabatier, 31062, Toulouse, France
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Universidade do Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208, Porto, Portugal
| | - Hans R Siegismund
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Ida Moltke
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
| | | | - Rasmus Heller
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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Williams MP, Flegontov P, Maier R, Huber CD. Testing Times: Challenges in Disentangling Admixture Histories in Recent and Complex Demographies. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.13.566841. [PMID: 38014190 PMCID: PMC10680674 DOI: 10.1101/2023.11.13.566841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Paleogenomics has expanded our knowledge of human evolutionary history. Since the 2020s, the study of ancient DNA has increased its focus on reconstructing the recent past. However, the accuracy of paleogenomic methods in answering questions of historical and archaeological importance amidst the increased demographic complexity and decreased genetic differentiation within the historical period remains an open question. We used two simulation approaches to evaluate the limitations and behavior of commonly used methods, qpAdm and the f3-statistic, on admixture inference. The first is based on branch-length data simulated from four simple demographic models of varying complexities and configurations. The second, an analysis of Eurasian history composed of 59 populations using whole-genome data modified with ancient DNA conditions such as SNP ascertainment, data missingness, and pseudo-haploidization. We show that under conditions resembling historical populations, qpAdm can identify a small candidate set of true sources and populations closely related to them. However, in typical ancient DNA conditions, qpAdm is unable to further distinguish between them, limiting its utility for resolving fine-scaled hypotheses. Notably, we find that complex gene-flow histories generally lead to improvements in the performance of qpAdm and observe no bias in the estimation of admixture weights. We offer a heuristic for admixture inference that incorporates admixture weight estimate and P-values of qpAdm models, and f3-statistics to enhance the power to distinguish between multiple plausible candidates. Finally, we highlight the future potential of qpAdm through whole-genome branch-length f2-statistics, demonstrating the improved demographic inference that could be achieved with advancements in f-statistic estimations.
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Affiliation(s)
- Matthew P. Williams
- Pennsylvania State University, Department of Biology, University Park, PA 16802, USA
| | - Pavel Flegontov
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czechia
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Robert Maier
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Christian D. Huber
- Pennsylvania State University, Department of Biology, University Park, PA 16802, USA
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6
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Abstract
Nearly 20 y ago, Jared Diamond and Peter Bellwood reviewed the evidence for the associated spread of farming and large language families by the demographic expansions of farmers. Since then, advances in obtaining and analyzing genomic data from modern and ancient populations have transformed our knowledge of human dispersals during the Holocene. Here, we provide an overview of Holocene dispersals in the light of genomic evidence and conclude that they have a complex history. Even when there is a demonstrated connection between a demographic expansion of people, the spread of agriculture, and the spread of a particular language family, the outcome in the results of contact between expanding and resident groups is highly variable. Further research is needed to identify the factors and social circumstances that have influenced this variation and complex history.
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Churchill SE, Keys K, Ross AH. Midfacial Morphology and Neandertal-Modern Human Interbreeding. BIOLOGY 2022; 11:1163. [PMID: 36009790 PMCID: PMC9404802 DOI: 10.3390/biology11081163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 06/15/2023]
Abstract
Ancient DNA from, Neandertal and modern human fossils, and comparative morphological analyses of them, reveal a complex history of interbreeding between these lineages and the introgression of Neandertal genes into modern human genomes. Despite substantial increases in our knowledge of these events, the timing and geographic location of hybridization events remain unclear. Six measures of facial size and shape, from regional samples of Neandertals and early modern humans, were used in a multivariate exploratory analysis to try to identify regions in which early modern human facial morphology was more similar to that of Neandertals, which might thus represent regions of greater introgression of Neandertal genes. The results of canonical variates analysis and hierarchical cluster analysis suggest important affinities in facial morphology between both Middle and Upper Paleolithic early modern humans of the Near East with Neandertals, highlighting the importance of this region for interbreeding between the two lineages.
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Affiliation(s)
- Steven E. Churchill
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA;
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Kamryn Keys
- Human Identification & Forensic Analysis Laboratory, Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA;
| | - Ann H. Ross
- Human Identification & Forensic Analysis Laboratory, Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA;
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8
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Ancient DNA and deep population structure in sub-Saharan African foragers. Nature 2022; 603:290-296. [PMID: 35197631 PMCID: PMC8907066 DOI: 10.1038/s41586-022-04430-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 01/14/2022] [Indexed: 12/16/2022]
Abstract
Multiple lines of genetic and archaeological evidence suggest that there were major demographic changes in the terminal Late Pleistocene epoch and early Holocene epoch of sub-Saharan Africa1–4. Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations3,5. Here we present genome-wide ancient DNA data for six individuals from eastern and south-central Africa spanning the past approximately 18,000 years (doubling the time depth of sub-Saharan African ancient DNA), increase the data quality for 15 previously published ancient individuals and analyse these alongside data from 13 other published ancient individuals. The ancestry of the individuals in our study area can be modelled as a geographically structured mixture of three highly divergent source populations, probably reflecting Pleistocene interactions around 80–20 thousand years ago, including deeply diverged eastern and southern African lineages, plus a previously unappreciated ubiquitous distribution of ancestry that occurs in highest proportion today in central African rainforest hunter-gatherers. Once established, this structure remained highly stable, with limited long-range gene flow. These results provide a new line of genetic evidence in support of hypotheses that have emerged from archaeological analyses but remain contested, suggesting increasing regionalization at the end of the Pleistocene epoch. DNA analysis of 6 individuals from eastern and south-central Africa spanning the past approximately 18,000 years, and of 28 previously published ancient individuals, provides genetic evidence supporting hypotheses of increasing regionalization at the end of the Pleistocene.
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Miller JM, Wang YV. Ostrich eggshell beads reveal 50,000-year-old social network in Africa. Nature 2022; 601:234-239. [PMID: 34931044 PMCID: PMC8755535 DOI: 10.1038/s41586-021-04227-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022]
Abstract
Humans evolved in a patchwork of semi-connected populations across Africa1,2; understanding when and how these groups connected is critical to interpreting our present-day biological and cultural diversity. Genetic analyses reveal that eastern and southern African lineages diverged sometime in the Pleistocene epoch, approximately 350-70 thousand years ago (ka)3,4; however, little is known about the exact timing of these interactions, the cultural context of these exchanges or the mechanisms that drove their separation. Here we compare ostrich eggshell bead variations between eastern and southern Africa to explore population dynamics over the past 50,000 years. We found that ostrich eggshell bead technology probably originated in eastern Africa and spread southward approximately 50-33 ka via a regional network. This connection breaks down approximately 33 ka, with populations remaining isolated until herders entered southern Africa after 2 ka. The timing of this disconnection broadly corresponds with the southward shift of the Intertropical Convergence Zone, which caused periodic flooding of the Zambezi River catchment (an area that connects eastern and southern Africa). This suggests that climate exerted some influence in shaping human social contact. Our study implies a later regional divergence than predicted by genetic analyses, identifies an approximately 3,000-kilometre stylistic connection and offers important new insights into the social dimension of ancient interactions.
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Affiliation(s)
- Jennifer M Miller
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany.
- Department of Anthropology, University of Alberta, Edmonton, Alberta, Canada.
| | - Yiming V Wang
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany.
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Grine FE, Gonzalvo E, Rossouw L, Holt S, Black W, Braga J. Variation in Middle Stone Age mandibular molar enamel-dentine junction topography at Klasies River Main Site assessed by diffeomorphic surface matching. J Hum Evol 2021; 161:103079. [PMID: 34739985 DOI: 10.1016/j.jhevol.2021.103079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 09/07/2021] [Accepted: 09/12/2021] [Indexed: 11/19/2022]
Abstract
The morphology and variability of the Middle Stone Age (MSA) hominin fossils from Klasies River Main Site have been the focus of investigation for more than four decades. The mandibular remains have figured prominently in discussions relating to robusticity, size dimorphism, and symphyseal morphology. Variation in corpus size between the robust SAM-AP 6223 and the diminutive SAM-AP 6225 mandibles is particularly impressive, and the difference between the buccolingual diameters of their M2s significantly exceeds recent human sample variation. SAM-AP 6223 and SAM-AP 6225 are the only Klasies specimens with homologous teeth (M2 and M3) that permit comparisons of crown morphology. While the differences in dental trait expression at the outer enamel surfaces of these molars are slight, diffeomorphic surface analyses of their underlying enamel-dentine junction (EDJ) topographies reveal differences that are well beyond the means of pairwise differences among comparative samples of Later Stone Age (LSA) Khoesan and recent African homologues. The EDJs of both SAM-AP 6225 molars and the SAM-AP 6223 M3 fall outside the envelopes that define the morphospace of these two samples. Although the radiocarbon dated LSA individuals examined here differ by a maximum of some 7000 years, and the two Klasies jaws may differ by perhaps as much as 18,000 years, it is difficult to ascribe their differences to time alone. With reference to the morphoscopic traits by which the SAM-AP 6223 and SAM-AP 6225 EDJs differ, the most striking is the expression of the protoconid cingulum. This is very weakly developed on the SAM-AP 6223 molars and distinct in SAM-AP 6225. As such, this diminutive fossil exhibits a more pronounced manifestation of what is likely a plesiomorphic feature, thus adding to the morphological mosaicism that is evident in the Klasies hominin assemblage. Several possible explanations for the variation and mosaicism in this MSA sample are discussed.
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Affiliation(s)
- Frederick E Grine
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794-4364, USA; Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794-4364, USA.
| | - Elsa Gonzalvo
- Centre d'Anthropobiologie et de Génomique de Toulouse, Université Paul Sabatier Toulouse III, Faculté de Médecine Purpan, 37 Allées Jules Guesde, Toulouse, France
| | - Lloyd Rossouw
- Florisbad Quaternary Research Department, The National Museum, 36 Aliwal Street, Bloemfontein 9300, South Africa
| | - Sharon Holt
- Florisbad Quaternary Research Department, The National Museum, 36 Aliwal Street, Bloemfontein 9300, South Africa
| | - Wendy Black
- Archaeology Unit, Research and Exhibitions Department, Iziko Museums of South Africa, Cape Town, South Africa
| | - José Braga
- Centre d'Anthropobiologie et de Génomique de Toulouse, Université Paul Sabatier Toulouse III, Faculté de Médecine Purpan, 37 Allées Jules Guesde, Toulouse, France; Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, 2050, South Africa
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