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McCrary T, Hughes T, Brook AH, Paul KS. Mirror, mirror? An evaluation of identical twin mirroring in tooth crown morphology. Anat Rec (Hoboken) 2024; 307:3102-3119. [PMID: 38372073 DOI: 10.1002/ar.25408] [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: 12/30/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/20/2024]
Abstract
It has been estimated that 25% of monozygotic ("identical") twin pairs exhibit reverse asymmetry (RA) or "mirroring" of minor anatomical features as a result of delayed zygote division. Here, we examine whether identical twin mirroring accounts for patterns of dental asymmetry in a sample of monozygotic and dizygotic ("fraternal") twins. We focus on crown morphology to approach the following question: is there an association between dental RA frequency and twin type suggestive of the presence of mirror image twins in our sample? Data were collected from 208 deciduous and 196 permanent dentitions of participants of the University of Adelaide Twin Study using Arizona State University Dental Anthropology System standards. RA frequencies were compared across morphological complexes (deciduous, permanent), twin types (monozygotic, dizygotic), and traits. Fisher's exact tests were performed to formally evaluate the association between twin type and dental RA. Across the entire dataset, RA rates failed to exceed 8% for any twin type. In monozygotic twins, deciduous mirroring totaled 5.3% of observed cases, while permanent mirroring totaled 7.8% of observed cases. We found no statistically significant association between RA and twin type for any morphological character (p-value range: 0.07-1.00). Our results suggest the timing of monozygotic twin division does not explain the structure of asymmetry for our morphology dataset and that published estimates of identical twin mirroring rates may be inflated or contingent upon phenotype. Instead, rates reported for this sample more closely align with the proposed etiology of this condition.
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Affiliation(s)
- Tess McCrary
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA
- University of Tennessee Health Science Center, College of Dentistry, Memphis, Tennessee, USA
| | - Toby Hughes
- Adelaide Dental School, The University of Adelaide, Adelaide, SA, Australia
| | - Alan H Brook
- Adelaide Dental School, The University of Adelaide, Adelaide, SA, Australia
- Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Kathleen S Paul
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA
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Rathmann H, Vizzari MT, Beier J, Bailey SE, Ghirotto S, Harvati K. Human population dynamics in Upper Paleolithic Europe inferred from fossil dental phenotypes. SCIENCE ADVANCES 2024; 10:eadn8129. [PMID: 39151011 PMCID: PMC11328903 DOI: 10.1126/sciadv.adn8129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 07/11/2024] [Indexed: 08/18/2024]
Abstract
Despite extensive archaeological research, our knowledge of the human population history of Upper Paleolithic Europe remains limited, primarily due to the scarce availability and poor molecular preservation of fossil remains. As teeth dominate the fossil record and preserve genetic signatures in their morphology, we compiled a large dataset of 450 dentitions dating between ~47 and 7 thousand years ago (ka), outnumbering existing skeletal and paleogenetic datasets. We tested a range of competing demographic scenarios using a coalescent-based machine learning Approximate Bayesian Computation (ABC) framework that we modified for use with phenotypic data. Mostly in agreement with but also challenging some of the hitherto available evidence, we identified a population turnover in western Europe at ~28 ka, isolates in western and eastern refugia between ~28 and 14.7 ka, and bottlenecks during the Last Glacial Maximum. Methodologically, this study marks the pioneering application of ABC to skeletal phenotypes, paving the way for exciting future research avenues.
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Affiliation(s)
- Hannes Rathmann
- Senckenberg Centre for Human Evolution and Palaeoenvironment, University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
- Paleoanthropology Section, Institute for Archaeological Sciences, Department of Geosciences, University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
| | - Maria T Vizzari
- Department of Life Sciences and Biotechnology, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy
| | - Judith Beier
- Paleoanthropology Section, Institute for Archaeological Sciences, Department of Geosciences, University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
- DFG Center for Advanced Studies "Words, Bones, Genes, Tools," University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
| | - Shara E Bailey
- Department of Anthropology, New York University, 25 Waverly Place, New York, NY 10003, USA
| | - Silvia Ghirotto
- Department of Life Sciences and Biotechnology, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy
| | - Katerina Harvati
- Senckenberg Centre for Human Evolution and Palaeoenvironment, University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
- Paleoanthropology Section, Institute for Archaeological Sciences, Department of Geosciences, University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
- DFG Center for Advanced Studies "Words, Bones, Genes, Tools," University of Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany
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Kenessey DE, Stojanowski CM, Paul KS. Evaluating predictions of the patterning cascade model of crown morphogenesis in the human lower mixed and permanent dentition. PLoS One 2024; 19:e0304455. [PMID: 38935640 PMCID: PMC11210800 DOI: 10.1371/journal.pone.0304455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 05/13/2024] [Indexed: 06/29/2024] Open
Abstract
OBJECTIVE The patterning cascade model of crown morphogenesis has been studied extensively in a variety of organisms to elucidate the evolutionary history surrounding postcanine tooth form. The current research is the first to use a large modern human sample to examine whether the crown configuration of lower deciduous and permanent molars aligns with expectations derived from the model. This study has two main goals: 1) to determine if metameric and antimeric pairs significantly differ in size, accessory trait expression, and relative intercusp spacing, and 2) assess whether the relative distance among early-forming cusps accounts for observed variation in accessory cusp expression. METHODS Tooth size, intercusp distance, and morphological trait expression data were collected from 3D scans of mandibular dental casts representing participants of the Harvard Solomon Islands Project. Paired tests were utilized to compare tooth size, accessory trait expression, and relative intercusp distance between diphyodont metameres and permanent antimeres. Proportional odds logistic regression was implemented to investigate how the odds of greater accessory cusp expression vary as a function of the distance between early-developing cusps. RESULTS/SIGNIFICANCE Comparing paired molars, significant differences were identified for tooth size and cusp 5 expression. Several relative intercusp distances emerged as important predictors of cusp 6 expression, however, results for cusp 5 and cusp 7 did not match expected patterns. These findings support previous quantitative genetic results and suggest the development of neighboring crown structures represents a zero-sum partitioning of cellular territory and resources. As such, this study contributes to a better understanding of the foundations of deciduous and permanent molar crown variation in humans.
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Affiliation(s)
- Dori E. Kenessey
- Department of Anthropology, U niversity of Nevada, Reno, Nevada, United States of America
| | - Christopher M. Stojanowski
- Center for Bioarchaeological Research, School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona, United States of America
| | - Kathleen S. Paul
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, United States of America
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Sgheiza V. Sex and ancestry patterning of residual correlations in human dental development: Cooperative genetic interaction and phenotypic plasticity. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 184:e24908. [PMID: 38329212 DOI: 10.1002/ajpa.24908] [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: 03/02/2022] [Revised: 10/31/2022] [Accepted: 01/22/2024] [Indexed: 02/09/2024]
Abstract
OBJECTIVES Most research in human dental age estimation has focused on point estimates of age, and most research on dental development theories has focused on morphology or eruption. Correlations between developing teeth using ordinal staging have received less attention. The effect of demographic variables on these correlations is unknown. I tested the effect of reference sample demographic variables on the residual correlation matrix using the lens of cooperative genetic interaction (CGI). MATERIALS AND METHODS The sample consisted of Moorrees et al., Journal of Dental Research, 1963, 42, 1490-1502, scores of left mandibular permanent teeth from panoramic radiographs of 880 London children 3-22.99 years of age stratified by year of age, sex, and Bangladeshi or European ancestry. A multivariate cumulative probit model was fit to each sex/ancestry group (n = 220), each sex or ancestry (n = 440), and all individuals (n = 880). Residual correlation matrices from nine reference sample configurations were compared using Bartlett's tests of between-sample difference matrices against the identity matrix, hierarchical cluster analysis, and dendrogram cophenetic correlations. RESULTS Bartlett's test results were inconclusive. Cluster analysis showed clustering by tooth class, position within class, and developmental timing. Clustering patterns and dendrogram correlations showed similarity by sex but not ancestry. DISCUSSION Expectations of CGI were supported for developmental staging. This supports using CGI as a model for explaining patterns of variation within the dentition. Sex was found to produce consistent patterns of dental correlations, whereas ancestry did not. Clustering by timing of development supports phenotypic plasticity in the dentition and suggests shared environment over genetic ancestry to explain population differences.
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Affiliation(s)
- Valerie Sgheiza
- Department of Anthropology, University of Illinois at Urbana-Champaign, Urbana, USA
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Rathmann H, Perretti S, Porcu V, Hanihara T, Scott GR, Irish JD, Reyes-Centeno H, Ghirotto S, Harvati K. Inferring human neutral genetic variation from craniodental phenotypes. PNAS NEXUS 2023; 2:pgad217. [PMID: 37457893 PMCID: PMC10338903 DOI: 10.1093/pnasnexus/pgad217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/14/2023] [Accepted: 06/20/2023] [Indexed: 07/18/2023]
Abstract
There is a growing consensus that global patterns of modern human cranial and dental variation are shaped largely by neutral evolutionary processes, suggesting that craniodental features can be used as reliable proxies for inferring population structure and history in bioarchaeological, forensic, and paleoanthropological contexts. However, there is disagreement on whether certain types of data preserve a neutral signature to a greater degree than others. Here, we address this unresolved question and systematically test the relative neutrality of four standard metric and nonmetric craniodental data types employing an extensive computational genotype-phenotype comparison across modern populations from around the world. Our computation draws on the largest existing data sets currently available, while accounting for geographically structured environmental variation, population sampling uncertainty, disparate numbers of phenotypic variables, and stochastic variation inherent to a neutral model of evolution. Our results reveal that the four data types differentially capture neutral genomic variation, with highest signals preserved in dental nonmetric and cranial metric data, followed by cranial nonmetric and dental metric data. Importantly, we demonstrate that combining all four data types together maximizes the neutral genetic signal compared with using them separately, even with a limited number of phenotypic variables. We hypothesize that this reflects a lower level of genetic integration through pleiotropy between, compared to within, the four data types, effectively forming four different modules associated with relatively independent sets of loci. Therefore, we recommend that future craniodental investigations adopt holistic combined data approaches, allowing for more robust inferences about underlying neutral genetic variation.
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Affiliation(s)
| | - Silvia Perretti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara 44121, Italy
| | - Valentina Porcu
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara 44121, Italy
| | - Tsunehiko Hanihara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara 252-0374, Japan
| | - G Richard Scott
- Department of Anthropology, University of Nevada, Reno, NV 89557, USA
| | - Joel D Irish
- Research Centre in Evolutionary Anthropology and Palaeoecology, School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
- The Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg WITS 2050, South Africa
| | - Hugo Reyes-Centeno
- Department of Anthropology, University of Kentucky, Lexington, KY 40506, USA
- William S. Webb Museum of Anthropology, University of Kentucky, Lexington, KY 40504, USA
- DFG Center for Advanced Studies ‘Words, Bones, Genes, Tools’, University of Tübingen, Tübingen 72070, Germany
| | - Silvia Ghirotto
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara 44121, Italy
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Cvrček J, Kuběna AA, Jor T, Naňka O, Drtikolová Kaupová S, Velemínský P. Does sternal body shape reflect family relationships? A study on a genealogically documented Central European osteological sample (19th-20th centuries). Anat Rec (Hoboken) 2023; 306:366-377. [PMID: 36168706 DOI: 10.1002/ar.25091] [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: 05/26/2022] [Revised: 09/21/2022] [Accepted: 09/23/2022] [Indexed: 01/25/2023]
Abstract
In forensic contexts, sternal anatomical varieties represent useful tools for the identification of an individual, either by comparison of ante-mortem and post-mortem data, or by potential comparison of data from biologically related individuals. Sternal body variation is also used to detect the biological affinity of individuals in bioarchaeology. However, no study has been made available to date on the degree to which the overall shape of the sternal body reflects the degree of biological relatedness. We, therefore, analyzed the sternal body shape of 10 individuals with known genealogical data, members of one family over three generations including inbred individuals (19th-20th centuries, Bohemia, Czech Republic), and a control sample of 12 biologically unrelated individuals. First, closely biologically related individuals were compared with unrelated individuals based on 10 variables expressing the morphological characteristics of the sternum, and then all individuals were compared based on Fourier analysis depending on their degree of relationship. The results showed that there is a greater degree of shape similarity in biologically related individuals than in unrelated individuals, and variability decreases with an increasing degree of relatedness. Inbred individuals showed the lowest sternum-shape distances and degree of variability, while unrelated individuals, showed the highest distances and variability. Moreover, in some cases, the documented relationships were also supported by a similar morphology of the ossified and fused xiphoid process. Thus, sternal shape analysis expands the possibilities for individual identification and the detection of the biological affinity of individuals for both the forensic sciences and bioarchaeology.
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Affiliation(s)
- Jan Cvrček
- Department of Anthropology, National Museum, Prague, Czech Republic
| | - Aleš Antonín Kuběna
- Department of Social and Clinical Pharmacy, Faculty of Pharmacy, Charles University, Hradec Králové, Czech Republic
| | - Tomáš Jor
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Ondřej Naňka
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | | | - Petr Velemínský
- Department of Anthropology, National Museum, Prague, Czech Republic
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Hardin AM, Knigge RP, Duren DL, Williams-Blangero S, Subedi J, Mahaney MC, Sherwood RJ. Genetic influences on dentognathic morphology in the Jirel population of Nepal. Anat Rec (Hoboken) 2022; 305:2137-2157. [PMID: 34981668 PMCID: PMC9250551 DOI: 10.1002/ar.24857] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022]
Abstract
Patterns of genetic variation and covariation impact the evolution of the craniofacial complex and contribute to clinically significant malocclusions in modern human populations. Previous quantitative genetic studies have estimated the heritabilities and genetic correlations of skeletal and dental traits in humans and nonhuman primates, but none have estimated these quantitative genetic parameters across the dentognathic complex. A large and powerful pedigree from the Jirel population of Nepal was leveraged to estimate heritabilities and genetic correlations in 62 maxillary and mandibular arch dimensions, incisor and canine lengths, and post-canine tooth crown areas (N ≥ 739). Quantitative genetic parameter estimation was performed using maximum likelihood-based variance decomposition. Residual heritability estimates were significant for all traits, ranging from 0.269 to 0.898. Genetic correlations were positive for all trait pairs. Principal components analyses of the phenotypic and genetic correlation matrices indicate an overall size effect across all measurements on the first principal component. Additional principal components demonstrate positive relationships between post-canine tooth crown areas and arch lengths and negative relationships between post-canine tooth crown areas and arch widths, and between arch lengths and arch widths. Based on these findings, morphological variation in the human dentognathic complex may be constrained by genetic relationships between dental dimensions and arch lengths, with weaker genetic correlations between these traits and arch widths allowing for variation in arch shape. The patterns identified are expected to have impacted the evolution of the dentognathic complex and its genetic architecture as well as the prevalence of dental crowding in modern human populations.
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Affiliation(s)
- Anna M. Hardin
- Biology Department, Western Oregon University
- Craniofacial Research Center, Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine
- Department of Orthopaedic Surgery, University of Missouri School of Medicine
| | - Ryan P. Knigge
- Craniofacial Research Center, Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine
- Department of Orthopaedic Surgery, University of Missouri School of Medicine
- Department of Integrative Biology and Physiology, University of Minnesota Medical School
| | - Dana L. Duren
- Craniofacial Research Center, Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine
- Department of Orthopaedic Surgery, University of Missouri School of Medicine
| | - Sarah Williams-Blangero
- South Texas Diabetes and Obesity Institute, School of Medicine, University of Texas Rio Grande Valley
| | | | - Michael C. Mahaney
- South Texas Diabetes and Obesity Institute, School of Medicine, University of Texas Rio Grande Valley
- Department of Human Genetics, School of Medicine, University of Texas Rio Grande Valley
| | - Richard J. Sherwood
- Craniofacial Research Center, Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine
- Department of Orthopaedic Surgery, University of Missouri School of Medicine
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Monson TA, Brasil MF, Mahaney MC, Schmitt CA, Taylor CE, Hlusko LJ. Keeping 21st Century Paleontology Grounded: Quantitative Genetic Analyses and Ancestral State Reconstruction Re-Emphasize the Essentiality of Fossils. BIOLOGY 2022; 11:biology11081218. [PMID: 36009845 PMCID: PMC9404954 DOI: 10.3390/biology11081218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/10/2022] [Accepted: 08/10/2022] [Indexed: 02/06/2023]
Abstract
Simple Summary Over the last two decades of biological research, our understanding of how genes determine dental development and variation has expanded greatly. Here, we explore how this new knowledge can be applied to the fossil record of cercopithecid monkeys. We compare a traditional paleontological method for assessing dental size variation with measurement approaches derived from quantitative genetics and developmental biology. We find that these new methods for assessing dental variation provide novel insight to the evolution of the cercopithecid monkey dentition, different from the insight provided by traditional size measurements. When we explore the variation of these traits in the cercopithecid fossil record, we find that the variation is outside the range predicted based on extant variation alone. Our 21st century biological approach to paleontology reveals that we have even more to learn from fossils than previously recognized. Abstract Advances in genetics and developmental biology are revealing the relationship between genotype and dental phenotype (G:P), providing new approaches for how paleontologists assess dental variation in the fossil record. Our aim was to understand how the method of trait definition influences the ability to reconstruct phylogenetic relationships and evolutionary history in the Cercopithecidae, the Linnaean Family of monkeys currently living in Africa and Asia. We compared the two-dimensional assessment of molar size (calculated as the mesiodistal length of the crown multiplied by the buccolingual breadth) to a trait that reflects developmental influences on molar development (the inhibitory cascade, IC) and two traits that reflect the genetic architecture of postcanine tooth size variation (defined through quantitative genetic analyses: MMC and PMM). All traits were significantly influenced by the additive effects of genes and had similarly high heritability estimates. The proportion of covariate effects was greater for two-dimensional size compared to the G:P-defined traits. IC and MMC both showed evidence of selection, suggesting that they result from the same genetic architecture. When compared to the fossil record, Ancestral State Reconstruction using extant taxa consistently underestimated MMC and PMM values, highlighting the necessity of fossil data for understanding evolutionary patterns in these traits. Given that G:P-defined dental traits may provide insight to biological mechanisms that reach far beyond the dentition, this new approach to fossil morphology has the potential to open an entirely new window onto extinct paleobiologies. Without the fossil record, we would not be able to grasp the full range of variation in those biological mechanisms that have existed throughout evolution.
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Affiliation(s)
- Tesla A. Monson
- Department of Anthropology, Western Washington University, 516 High Street, Bellingham, WA 98225, USA
| | - Marianne F. Brasil
- Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA
- Human Evolution Research Center, Valley Life Sciences Building, University of California Berkeley, MC-3140, Berkeley, CA 94720, USA
| | - Michael C. Mahaney
- Department of Human Genetics, South Texas Diabetes and Obesity Institute, University of Texas Rio Grande Valley School of Medicine, Brownsville, TX 78520, USA
| | - Christopher A. Schmitt
- Department of Anthropology, Boston University, 232 Bay State Road, Boston, MA 02115, USA
| | - Catherine E. Taylor
- Human Evolution Research Center, Valley Life Sciences Building, University of California Berkeley, MC-3140, Berkeley, CA 94720, USA
| | - Leslea J. Hlusko
- Human Evolution Research Center, Valley Life Sciences Building, University of California Berkeley, MC-3140, Berkeley, CA 94720, USA
- National Center for Research on Human Evolution (CENIEH), Paseo Sierra de Atapuerca 3, 09002 Burgos, Spain
- Correspondence:
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Paul KS, Stojanowski CM, Hughes T, Brook AH, Townsend GC. Genetic Correlation, Pleiotropy, and Molar Morphology in a Longitudinal Sample of Australian Twins and Families. Genes (Basel) 2022; 13:genes13060996. [PMID: 35741762 PMCID: PMC9222655 DOI: 10.3390/genes13060996] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 01/01/2023] Open
Abstract
This study aims to expand our understanding of the genetic architecture of crown morphology in the human diphyodont dentition. Here, we present bivariate genetic correlation estimates for deciduous and permanent molar traits and evaluate the patterns of pleiotropy within (e.g., m1–m2) and between (e.g., m2–M1) dentitions. Morphology was observed and scored from dental models representing participants of an Australian twin and family study (deciduous n = 290, permanent n = 339). Data collection followed Arizona State University Dental Anthropology System standards. Genetic correlation estimates were generated using maximum likelihood variance components analysis in SOLAR v.8.1.1. Approximately 23% of deciduous variance components models and 30% of permanent variance components models yielded significant genetic correlation estimates. By comparison, over half (56%) of deciduous–permanent homologues (e.g., m2 hypocone–M1 hypocone) were significantly genetically correlated. It is generally assumed that the deciduous and permanent molars represent members of a meristic molar field emerging from the primary dental lamina. However, stronger genetic integration among m2–M1/M2 homologues than among paired deciduous traits suggests the m2 represents the anterior-most member of a “true” molar field. The results indicate genetic factors act at distinct points throughout development to generate homologous molar form, starting with the m2, which is later replaced by a permanent premolariform crown.
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Affiliation(s)
- Kathleen S. Paul
- Department of Anthropology, University of Arkansas, Fayetteville, AR 72701, USA
- Correspondence: ; Tel.: +1-479-718-1352
| | - Christopher M. Stojanowski
- Center for Bioarchaeological Research, School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287, USA;
| | - Toby Hughes
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia; (T.H.); (A.H.B.)
| | - Alan H. Brook
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia; (T.H.); (A.H.B.)
- Barts and the London Dental Institute, Queen Mary University of London, London EC1M 6AX, UK
| | - Grant C. Townsend
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia; (T.H.); (A.H.B.)
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Takenaka R, Clay SM, Yoo S, Hlusko LJ. Conserved and Taxon-Specific Patterns of Phenotypic Modularity in the Mammalian Dentition. Integr Org Biol 2022; 4:obac017. [PMID: 35709132 PMCID: PMC9191923 DOI: 10.1093/iob/obac017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 12/21/2021] [Accepted: 04/25/2022] [Indexed: 11/23/2022] Open
Abstract
Previous genotype:phenotype mapping of the mouse and primate dentition revealed the presence of pre- and post-canine modules in mice and anthropoid primates, as well as molar and premolar submodules in anthropoid primates. We estimated phenotypic correlation matrices for species that sample broadly across Mammalia to test the hypothesis that these modules exist across a broader range of taxa and thereby represent a conserved mammalian trait. We calculated phenotypic correlation matrices from linear dental measurements of 419 individual specimens representing 5 species from 4 mammalian orders: Artiodactyla (Odocoileus hemionus), Carnivora (Canis latrans and Ursus americanus), Didelphimorphia (Didelphis virginiana), and Primates (Colobus guereza). Our results based on hierarchical clustering indicate a generally higher correlation within incisors and among post-canine teeth. However, the post-canine phenotypic correlation matrices do not consistently exhibit the premolar and molar submodularity observed in anthropoid primates. Additionally, we find evidence of sex differences in the Odocoileus phenotypic correlation matrices: Males of this species exhibit overall higher inter-trait correlations compared to females. Our overall findings support the interpretation that incisors and post-canine dentition represent different phenotypic modules, and that this architecture may be a conserved trait for mammals.
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Affiliation(s)
| | | | - Sunwoo Yoo
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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López-Onaindia D, Schmitt A, Gibaja JF, Subirà ME. Non-metric dental analysis of human interactions around the Pyrenees during the Neolithic and their biological impact. Ann Anat 2022; 242:151895. [DOI: 10.1016/j.aanat.2022.151895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 09/10/2021] [Accepted: 01/17/2022] [Indexed: 12/26/2022]
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12
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Paul KS, Stojanowski CM, Hughes T, Brook A, Townsend GC. The genetic architecture of anterior tooth morphology in a longitudinal sample of Australian twins and families. Arch Oral Biol 2021; 129:105168. [PMID: 34174590 DOI: 10.1016/j.archoralbio.2021.105168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 12/21/2022]
Abstract
OBJECTIVE This study presents a quantitative genetic analysis of human anterior dental morphology in a longitudinal sample of known genealogy. The primary aim of this work is to generate a suite of genetic correlations within and between deciduous and permanent characters to access patterns of integration across the diphyodont dental complex. DESIGN Data were recorded from casted tooth crowns representing participants of a long-term Australian twin and family study (deciduous n = 290, permanent n = 339). Morphological trait expression was observed and scored following Arizona State University Dental Anthropology System standards. Bivariate genetic correlations were estimated using maximum likelihood variance decomposition models in SOLAR v.8.1.1. RESULTS Genetic correlation estimates indicate high levels of integration between antimeres but low to moderate levels among traits within a tooth row. Only 9% of deciduous model comparisons were significant, while pleiotropy was indicated for one third of permanent trait pairs. Canine characters stood out as strongly integrated, especially in the deciduous dentition. For homologous characters across dentitions (e.g., deciduous i1 shoveling and permanent I1 shoveling), ∼70% of model comparisons yielded significant genetic correlations. CONCLUSIONS Patterns of genetic correlation suggest a morphological canine module that spans the primary and secondary dentition. Results also point to the existence of a genetic mechanism conserving morphology across the diphyodont dental complex, such that paired deciduous and permanent traits are more strongly integrated than characters within individual tooth rows/teeth.
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Affiliation(s)
- Kathleen S Paul
- Department of Anthropology, University of Arkansas, Fayetteville, AR 72701, United States.
| | - Christopher M Stojanowski
- Center for Bioarchaeological Research, School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287, United States
| | - Toby Hughes
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Alan Brook
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia; Barts and the London Dental Institute, Queen Mary University of London, London, E1, UK
| | - Grant C Townsend
- Adelaide Dental School, The University of Adelaide, Adelaide, SA 5005, Australia
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Remembering John C. Loehlin: 'Our Field Has Lost a Lion'/Twin Research Reviews: Cognitive Skills and Social Mobility, Risk of Arachnoid Hemorrhage, Heritability of Dental Traits, and Twin-to-Twin Transfusion Syndrome/Media Reports: Identical Twins With Different Health Histories, Twins Born 97 Days Apart, Retiring Twin Tennis Players, TikTok Twins and Twin Reality Stars. Twin Res Hum Genet 2020; 23:359-362. [PMID: 33267937 DOI: 10.1017/thg.2020.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
John C. Loehlin, professor of psychology at the University of Texas, at Austin, passed away on August 9, 2020. John was 94 years of age. He will be remembered for his seminal contributions that have furthered the field of twin research in so many ways. An overview of his career is presented, with fond memories from his son and several colleagues. This tribute is followed by reviews of twin research on cognitive skills and social mobility, risk of subarachnoid hemorrhage, heritability of selected dental traits and twin-to-twin transfusion syndrome. Finally, twin-related topics of human interest include identical twins with different health histories, twins born 97 days apart, retiring twin tennis players, TikTok twins and twin reality stars.
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