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Mahoney P, McFarlane G, Taurozzi AJ, Madupe PP, O'Hara MC, Molopyane K, Cappellini E, Hawks J, Skinner MM, Berger L. Human-like enamel growth in Homo naledi. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 184:e24893. [PMID: 38180115 DOI: 10.1002/ajpa.24893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/12/2023] [Accepted: 12/14/2023] [Indexed: 01/06/2024]
Abstract
OBJECTIVES A modern pattern (rate and duration) of dental development occurs relatively recently during human evolution. Given the temporal overlap of Homo naledi with the first appearance of fossil Homo sapiens in Africa, this small-bodied and small-brained hominin presents an opportunity to elucidate the evolution of enamel growth in the hominin clade. Here we conduct the first histological study of two permanent mandibular canines and one permanent maxillary first molar, representing three individuals attributed to H. naledi. We reconstruct the rate and duration of enamel growth and compare these findings to those reported for other fossil hominins and recent humans. MATERIALS AND METHODS Thin sections of each tooth were produced using standard histological methods. Daily and longer period incremental markings were measured to reconstruct enamel secretion and extension rates, Retzius periodicity, canine crown and molar cusp formation time. RESULTS Daily enamel secretion rates overlapped with those from recent hominins. Canine crown formation time is similar to that observed in recent Europeans but is longer than canine formation times reported for most other hominins including Australopithecus and H. neanderthalensis. The extended period of canine formation appears to be due to a relatively tall enamel crown and a sustained slow rate of enamel extension in the cervical portion of the crown. A Retzius periodicity of 11 days for the canines, and nine days for the molar, in H. naledi parallel results found in recent humans. An 11-day periodicity has not been reported for Late Pleistocene Homo (H. erectus, H. neanderthalensis) and is rarely found in Australopithecus and Paranthropus species. DISCUSSION Enamel growth of H. naledi is most similar to recent humans though comparative data are limited for most fossil hominin species. The high Retzius periodicity values do not follow expectations for a small-brained hominin.
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Affiliation(s)
- Patrick Mahoney
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Gina McFarlane
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Alberto J Taurozzi
- Section for GeoGenetics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - Palesa P Madupe
- Section for GeoGenetics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
- Human Evolution Research Institute, University of Cape Town, Rondebosch, South Africa
| | - Mackie C O'Hara
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Keneiloe Molopyane
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- The National Geographic Society, Washington, District of Columbia, USA
| | - Enrico Cappellini
- Section for GeoGenetics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - John Hawks
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- Department of Anthropology, University of Wisconsin-Madison, USA
| | - Matthew M Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Lee Berger
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- The National Geographic Society, Washington, District of Columbia, USA
- The Carnegie Institution for Science, Washington, District of Columbia, USA
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Hu R, Du B, Zhao L. Retzius periodicity in the Late Miocene hominoid Lufengpithecus lufengensis from Southwest China: Implications for dental development and life history. J Hum Evol 2023; 181:103400. [PMID: 37307694 DOI: 10.1016/j.jhevol.2023.103400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 05/13/2023] [Accepted: 05/13/2023] [Indexed: 06/14/2023]
Affiliation(s)
- Rong Hu
- Institute of Anthropology, School of Sociology and Anthropology, Xiamen University, Xiamen, 361005, China
| | - Baopu Du
- Department of Anatomy, Histology and Embryology, Capital Medical University, Beijing, 100069, China
| | - Lingxia Zhao
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China.
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3
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McFarlane G, Loch C, Guatelli-Steinberg D, Bayle P, Le Luyer M, Sabel N, Nava A, Floyd B, Skinner M, White S, Pitfield R, Mahoney P. Enamel daily secretion rates of deciduous molars from a global sample of children. Arch Oral Biol 2021; 132:105290. [PMID: 34695672 DOI: 10.1016/j.archoralbio.2021.105290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To investigate and describe the variation in enamel daily secretion rates (DSRs) of naturally exfoliated deciduous molars (n = 345) from five modern-day populations (Aotearoa New Zealand, Britain, Canada, France, and Sweden). DESIGN Each tooth was thin sectioned and examined using a high-powered Olympus BX51 microscope and DP25 digital microscope camera. Mean DSRs were recorded for the inner, mid, and outer regions of cuspal and lateral enamel, excluding enamel nearest the enamel-dentin junction and at the outermost crown surface. RESULTS Mean DSRs did not vary significantly between populations, or by sex. Cuspal enamel grew slightly faster than lateral enamel (mean difference 0.16 µm per day; p < 0.001). The trajectory of DSRs remained relatively constant from inner to outer cuspal enamel and increased slightly in lateral enamel (p = 0.003). CONCLUSIONS The DSRs of deciduous molars from modern-day children are remarkably consistent when compared among populations. While growth rates are faster in cuspal than lateral enamel, the trajectory of enamel formation changes only slightly from inner to outer regions. The trajectory of DSRs for deciduous molars differs to that of permanent molar enamel, which typically display a steep increase in matrix deposition from inner to outer enamel.
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Affiliation(s)
- Gina McFarlane
- Human Osteology Lab, School of Anthropology and Conservation, University of Kent, Canterbury, UK.
| | - Carolina Loch
- Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand
| | | | | | - Mona Le Luyer
- Univ. Bordeaux, CNRS, MC, UMR 5199 PACEA, Pessac, France
| | - Nina Sabel
- Department of Pedodontics, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Alessia Nava
- Human Osteology Lab, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Bruce Floyd
- School of Social Sciences, University of Auckland, New Zealand
| | - Mark Skinner
- Department of Archaeology, Simon Fraser University, Burnaby, Canada
| | - Sophie White
- Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand
| | - Rosie Pitfield
- Human Osteology Lab, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Patrick Mahoney
- Human Osteology Lab, School of Anthropology and Conservation, University of Kent, Canterbury, UK
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4
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Hu R, Zhao L. Molar crown formation times of fossil orangutan molars from Guangxi, China. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 174:315-326. [PMID: 33253429 DOI: 10.1002/ajpa.24183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 09/14/2020] [Accepted: 11/09/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVES We aimed to investigate molar enamel development in fossil orangutans from Guangxi and shed light on the evolution of Asian great apes. MATERIALS AND METHODS We collected 32 fossil orangutan molars, most of which were from Guangxi apothecaries and the Guangxi Daxin Heidong cave, and prepared histological sections of each molar. We then characterized aspects of dental development, including long period line periodicity, number of Retzius lines and lateral enamel formation time, cuspal enamel thickness, and enamel formation time. RESULTS The long period line periodicity in fossil orangutans ranged from 9 to 10 days (mean, 9.09 days). The molar lateral enamel formation time ranged from 1.48 to 3.17 years (540-1,152 days). Cuspal enamel thickness in fossil orangutan molars ranged from 949 to 2,535 μm, and cuspal enamel formation time ranged from 0.64 to 1.87 years. Molar enamel formation time of fossil orangutans ranged from 2.47 to 4.67 years. DISCUSSION Long-period line periodicity of fossil orangutans from Guangxi was within the variation range of extant orangutans, and the average long period line periodicity (9.09 days) of fossil orangutans from Guangxi in this study was lower than the values for extant orangutans (9.5 days) and fossil orangutans (10.9 days) from Sumatra and Vietnam. Orangutan enamel thickness may have gradually decreased from the Middle Pleistocene to Holocene. Crown formation time of fossil orangutans was slightly longer than that of extant orangutans, and the M1 emergence age of fossil orangutans from Guangxi was about 4-6 years. These findings might indicate the regional difference or evolutionary changes in orangutans since Pleistocene. Dental development of the Guangxi fossil orangutans were more similar to that of Asian Miocene apes, suggesting the closer evolutionary relationship of orangutans to Miocene Asian fossil apes.
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Affiliation(s)
- Rong Hu
- Institute of Anthropology, Department of Anthropology and Ethology, Xiamen University, Xiamen, China
| | - Lingxia Zhao
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Science, Beijing, China
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Mahoney P, McFarlane G, Pitfield R, O'Hara MC, Miszkiewicz JJ, Deter C, Seal H, Guatelli-Steinberg D. A structural biorhythm related to human sexual dimorphism. J Struct Biol 2020; 211:107550. [DOI: 10.1016/j.jsb.2020.107550] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 01/26/2023]
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Enamel thickness and dental development in Rudapithecus hungaricus. J Hum Evol 2019; 136:102649. [DOI: 10.1016/j.jhevol.2019.102649] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 08/05/2019] [Accepted: 08/05/2019] [Indexed: 11/19/2022]
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7
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Evidence for increased hominid diversity in the Early to Middle Pleistocene of Indonesia. Nat Ecol Evol 2019; 3:755-764. [PMID: 30962558 DOI: 10.1038/s41559-019-0860-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 02/28/2019] [Indexed: 11/08/2022]
Abstract
Since the first discovery of Pithecanthropus (Homo) erectus by E. Dubois at Trinil in 1891, over 200 hominid dentognathic remains have been collected from the Early to Middle Pleistocene deposits of Java, Indonesia, forming the largest palaeoanthropological collection in South East Asia. Most of these fossils are currently attributed to H. erectus. However, because of the substantial morphological and metric variation in the Indonesian assemblage, some robust specimens, such as the partial mandibles Sangiran 5 and Sangiran 6a, were formerly variably allocated to other taxa (Meganthropus palaeojavanicus, Pithecanthropus dubius, Pongo sp.). To resolve the taxonomic uncertainty surrounding these and other contentious Indonesian hominid specimens, we used occlusal fingerprint analysis (OFA) to reconstruct their chewing kinematics; we also used various morphometric approaches based on microtomography to examine the internal dental structures. Our results confirm the presence of Meganthropus as a Pleistocene Indonesian hominid distinct from Pongo, Gigantopithecus and Homo, and further reveal that Dubois's H. erectus paratype molars from 1891 are not hominin (human lineage), but instead are more likely to belong to Meganthropus.
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Mahoney P, Miszkiewicz JJ, Chapple S, Le Luyer M, Schlecht SH, Stewart TJ, Griffiths RA, Deter C, Guatelli‐Steinberg D. The biorhythm of human skeletal growth. J Anat 2018; 232:26-38. [PMID: 29023695 PMCID: PMC5735060 DOI: 10.1111/joa.12709] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2017] [Indexed: 12/15/2022] Open
Abstract
Evidence of a periodic biorhythm is retained in tooth enamel in the form of Retzius lines. The periodicity of Retzius lines (RP) correlates with body mass and the scheduling of life history events when compared between some mammalian species. The correlation has led to the development of the inter-specific Havers-Halberg oscillation (HHO) hypothesis, which holds great potential for studying aspects of a fossil species biology from teeth. Yet, our understanding of if, or how, the HHO relates to human skeletal growth is limited. The goal here is to explore associations between the biorhythm and two hard tissues that form at different times during human ontogeny, within the context of the HHO. First, we investigate the relationship of RP to permanent molar enamel thickness and the underlying daily rate that ameloblasts secrete enamel during childhood. Following this, we develop preliminary research conducted on small samples of adult human bone by testing associations between RP, adult femoral length (as a proxy for attained adult stature) and cortical osteocyte lacunae density (as a proxy for the rate of osteocyte proliferation). Results reveal RP is positively correlated with enamel thickness, negatively correlated with femoral length, but weakly associated with the rate of enamel secretion and osteocyte proliferation. These new data imply that a slower biorhythm predicts thicker enamel for children but shorter stature for adults. Our results develop the intra-specific HHO hypothesis suggesting that there is a common underlying systemic biorhythm that has a role in the final products of human enamel and bone growth.
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Affiliation(s)
- Patrick Mahoney
- Human Osteology LabSkeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Justyna J. Miszkiewicz
- Skeletal Biology and Forensic Anthropology Research GroupSchool of Archaeology and AnthropologyAustralian National UniversityCanberraACTAustralia
| | - Simon Chapple
- Human Osteology LabSkeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Mona Le Luyer
- Human Osteology LabSkeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
- De la Prehistoire à l'Actuel: CultureEnvironment et Anthropologie (UMR 5199 PACEA)Université de BordeauxPessacFrance
| | | | - Tahlia J. Stewart
- Skeletal Biology and Forensic Anthropology Research GroupSchool of Archaeology and AnthropologyAustralian National UniversityCanberraACTAustralia
| | - Richard A. Griffiths
- Durrell Institute of Conservation and EcologySchool of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Chris Deter
- Human Osteology LabSkeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
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9
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Le Cabec A, Dean MC, Begun DR. Dental development and age at death of the holotype of Anapithecus hernyaki (RUD 9) using synchrotron virtual histology. J Hum Evol 2017. [PMID: 28622928 DOI: 10.1016/j.jhevol.2017.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The chronology of dental development and life history of primitive catarrhines provides a crucial comparative framework for understanding the evolution of hominoids and Old World monkeys. Among the extinct groups of catarrhines are the pliopithecoids, with no known descendants. Anapithecus hernyaki is a medium-size stem catarrhine known from Austria, Hungary and Germany around 10 Ma, and represents a terminal lineage of a clade predating the divergence of hominoids and cercopithecoids, probably more than 30 Ma. In a previous study, Anapithecus was characterized as having fast dental development. Here, we used non-destructive propagation phase contrast synchrotron micro-tomography to image several dental microstructural features in the mixed mandibular dentition of RUD 9, the holotype of A. hernyaki. We estimate its age at death to be 1.9 years and describe the pattern, sequence and timing of tooth mineralization. Our results do not support any simplistic correlation between body mass and striae periodicity, since RUD 9 has a 3-day periodicity, which was previously thought unlikely based on body mass estimates in Anapithecus. We demonstrate that the teeth in RUD 9 grew even faster and initiated even earlier in development than suggested previously. Permanent first molars and the canine initiated 49 and 38 days prenatally, respectively. These results contribute to a better understanding of dental development in Anapithecus and may provide a window into the dental development of the last common ancestor of hominoids and cercopithecoids.
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Affiliation(s)
- Adeline Le Cabec
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103, Leipzig, Germany; Beamline ID19, Structure of Materials, ESRF - The European Synchrotron, 71, avenue des Martyrs, CS 40220, F-38043, Grenoble, Cédex 9, France.
| | - M Christopher Dean
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK.
| | - David R Begun
- Department of Anthropology, University of Toronto, Toronto, ONT M5S 3G3, Canada.
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10
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Mahoney P, Miszkiewicz JJ, Pitfield R, Deter C, Guatelli‐Steinberg D. Enamel biorhythms of humans and great apes: the Havers-Halberg Oscillation hypothesis reconsidered. J Anat 2017; 230:272-281. [PMID: 27726135 PMCID: PMC5244461 DOI: 10.1111/joa.12551] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2016] [Indexed: 11/27/2022] Open
Abstract
The Havers-Halberg Oscillation (HHO) hypothesis links evidence for the timing of a biorhythm retained in permanent tooth enamel (Retzius periodicity) to adult body mass and life history traits across mammals. Potentially, these links provide a way to access life history of fossil species from teeth. Recently we assessed intra-specific predictions of the HHO on human children. We reported Retzius periodicity (RP) corresponded with enamel thickness, and cusp formation time, when calculated from isolated deciduous teeth. We proposed the biorhythm might not remain constant within an individual. Here, we test our findings. RP is compared between deciduous second and permanent first molars within the maxillae of four human children. Following this, we report the first RPs for deciduous teeth from modern great apes (n = 4), and compare these with new data for permanent teeth (n = 18) from these species, as well as with previously published values. We also explore RP in teeth that retain hypoplastic defects. Results show RP changed within the maxilla of each child, from thinner to thicker enameled molars, and from one side of a hypoplastic defect to the other. When considered alongside correlations between RP and cusp formation time, these observations provide further evidence that RP is associated with enamel growth processes and does not always remain constant within an individual. RP of 5 days for great ape deciduous teeth lay below the lowermost range of those from permanent teeth of modern orangutan and gorilla, and within the lowermost range of RPs from chimpanzee permanent teeth. Our data suggest associations between RP and enamel growth processes of humans might extend to great apes. These findings provide a new framework from which to develop the HHO hypothesis, which can incorporate enamel growth along with other physiological systems. Applications of the HHO to fossil teeth should avoid transferring RP between deciduous and permanent enamel, or including hypoplastic teeth.
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Affiliation(s)
- Patrick Mahoney
- Human Osteology LabSkeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Justyna J. Miszkiewicz
- School of Archaeology and AnthropologyThe Australian National University2601 CanberraACTAustralia
| | - Rosie Pitfield
- Human Osteology LabSkeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Chris Deter
- Human Osteology LabSkeletal Biology Research CentreSchool of Anthropology and ConservationUniversity of KentCanterburyUK
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11
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Smith TM. Dental development in living and fossil orangutans. J Hum Evol 2016; 94:92-105. [DOI: 10.1016/j.jhevol.2016.02.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 12/29/2015] [Accepted: 02/25/2016] [Indexed: 10/22/2022]
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12
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Patnaik R, Cerling TE, Uno KT, Fleagle JG. Diet and Habitat of Siwalik PrimatesIndopithecus, SivaladapisandTheropithecus. ANN ZOOL FENN 2014. [DOI: 10.5735/086.051.0214] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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13
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Smith TM, Kupczik K, Machanda Z, Skinner MM, Zermeno JP. Enamel thickness in Bornean and Sumatran orangutan dentitions. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 147:417-26. [DOI: 10.1002/ajpa.22009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 12/06/2011] [Indexed: 11/10/2022]
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14
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15
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Dean MC, Kelley J. Comparative dental development in Hispanopithecus laietanus and Pan troglodytes. J Hum Evol 2011; 62:174-8. [PMID: 22082569 DOI: 10.1016/j.jhevol.2011.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 09/17/2011] [Accepted: 10/12/2011] [Indexed: 10/15/2022]
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16
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Mahoney P. Human deciduous mandibular molar incremental enamel development. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2010; 144:204-14. [DOI: 10.1002/ajpa.21386] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 07/02/2010] [Indexed: 11/08/2022]
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17
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Mahoney P. Two-dimensional patterns of human enamel thickness on deciduous (dm1, dm2) and permanent first (M1) mandibular molars. Arch Oral Biol 2010; 55:115-26. [DOI: 10.1016/j.archoralbio.2009.11.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 11/25/2009] [Accepted: 11/26/2009] [Indexed: 10/20/2022]
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18
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Canine tooth size and fitness in male mandrills (Mandrillus sphinx). J Hum Evol 2008; 55:75-85. [DOI: 10.1016/j.jhevol.2008.01.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 11/07/2007] [Accepted: 01/16/2008] [Indexed: 11/17/2022]
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19
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Mahoney P. Intraspecific variation in M1 enamel development in modern humans: implications for human evolution. J Hum Evol 2008; 55:131-47. [DOI: 10.1016/j.jhevol.2008.02.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 12/03/2007] [Accepted: 02/04/2008] [Indexed: 10/22/2022]
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20
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Smith TM. Incremental dental development: methods and applications in hominoid evolutionary studies. J Hum Evol 2007; 54:205-24. [PMID: 18045649 DOI: 10.1016/j.jhevol.2007.09.020] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Accepted: 09/30/2007] [Indexed: 10/22/2022]
Abstract
This survey of dental microstructure studies reviews recent methods used to quantify developmental variables (daily secretion rate, periodicity of long-period lines, extension rate, formation time) and applications to the study of hominoid evolution. While requisite preparative and analytical methods are time consuming, benefits include more precise identification of tooth crown initiation and completion than conventional radiographic approaches. Furthermore, incremental features facilitate highly accurate estimates of the speed and duration of crown and root formation, stress experienced during development (including birth), and age at death. These approaches have provided insight into fossil hominin and Miocene hominoid life histories, and have also been applied to ontogenetic and taxonomic studies of fossil apes and humans. It is shown here that, due to the rapidly evolving nature of dental microstructure studies, numerous methods have been applied over the past few decades to characterize the rate and duration of dental development. Yet, it is often unclear whether data derived from different methods are comparable or which methods are the most accurate. Areas for future research are identified, including the need for validation and standardization of certain methods, and new methods for integrating nondestructive structural and developmental studies are highlighted.
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Affiliation(s)
- Tanya M Smith
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany.
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21
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Preliminary observations on increasing root length during the eruptive phase of tooth development in modern humans and great apes. J Hum Evol 2007; 54:258-71. [PMID: 18045653 DOI: 10.1016/j.jhevol.2007.09.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Accepted: 09/30/2007] [Indexed: 11/22/2022]
Abstract
Ground sections of incisors, canines, and molars were selected that showed clear incremental markings in root dentine. The sample comprised 98 Homo sapiens, 53 Pan troglodytes, and a more limited combined sample of 51 Gorilla and Pongo sections. Daily rates of root dentine formation, together with the orientation of incremental markings in roots close to the cement-dentine junction (CDJ), were used to calculate root extension rates for the first 10mm of root formed beyond the buccal enamel cervix. Modern human anterior tooth roots showed a more regular pattern of increase in root length than those in great apes. In Pan, root growth rose quickly to higher rates but then flattened off. The fastest extension rates in modern humans were in incisor roots (10-12 microm per day), followed by canines (8-9 microm per day). Extension rates in Pan rose to slightly greater values in canines ( approximately 12-14 microm per day) than in incisors ( approximately 10-11 microm per day). Molar tooth roots in both modern humans and great apes grew in a nonlinear manner. Peak rates in molars reduced from M1 to M3 (8, 7, and 6 microm per day, respectively). Like humans, root growth in Pan peaked earlier in M1s at rates of between 8 and 9 microm per day, and later in M3s at rates of 7 to 8 microm per day. The more limited data set for Gorilla and Pongo molars suggests that extension rates were generally higher than in Pan by approximately 1.0-1.5 microm per day. There were greater differences in peak extension rates, with Gorilla and Pongo extension rates being between 2.5 and 4.5 microm per day higher than those in Pan. These findings highlight for the first time that root growth rates differ between tooth types in both pattern and rate and between taxa. They provide the basis with which to explore further the potential comparative relationships between root growth, jaw growth, and the eruption process.
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