TY - JOUR
T1 - Faster growth corresponds with shallower linear hypoplastic defects in great ape canines
AU - McGrath, Kate
AU - Reid, Donald J.
AU - Guatelli-Steinberg, Debbie
AU - Arbenz-Smith, Keely
AU - El Zaatari, Sireen
AU - Fatica, Lawrence M.
AU - Kralick, Alexandra E.
AU - Cranfield, Michael R.
AU - Stoinski, Tara S.
AU - Bromage, Timothy G.
AU - Mudakikwa, Antoine
AU - McFarlin, Shannon C.
N1 - Funding Information:
This work was supported by the National Science Foundation (grant numbers: IGERT 0801634, BCS 0852866, BCS 0964944, BCS 1520221, BCS-DDRIG 1613626); The Leakey Foundation; National Geographic CRE (grant number: 8486-08); The Smithsonian Institution Graduate Student Fellowship; and the GW Anthropology Department Cotlow Award. We gratefully acknowledge the Rwandan government and national parks authorities for permission to work in their country, and for access to mountain gorilla skeletal data for research. The sample utilized in this study is curated by the Mountain Gorilla Skeletal Project in Rwanda, which is indebted to the many field assistants, researchers, and other staff of the Rwanda Development Board?Department of Tourism and Conservation, Mountain Gorilla Veterinary Project, and Dian Fossey Gorilla Fund International's Karisoke Research Center, and The George Washington University, and the many participants from academic institutions in Rwanda and the USA who have contributed to the MGSP since 2008. We are indebted to the Paleoanthropology, Senckenberg Center for Human Evolution and Paleoenvironment, Universit?t T?bingen, Germany, for allowing data collection using their imaging equipment. We thank Kristofer Helgen and Darrin Lunde of the Smithsonian's National Museum of Natural History for access to the Division of Mammals specimens. We thank Wendy Dirks and Christopher Dean for access to specimens of the Newcastle Collection, as well as the Royal College of Surgeons and Marcia Ponce de Le?n of Universit?t Z?rich for access to their collections and helpful discussions about this project. We acknowledge those who helped with the creation of dental impressions and/or replicas: Jordi Galbany, Andr?s Bonilla, Sonora Lanham, and Umang Gurung. Finally, we thank Andrew Barr, Carson Murray, and Bernard Wood for their thoughtful feedback on this research.
Funding Information:
This work was supported by the National Science Foundation (grant numbers: IGERT 0801634 , BCS 0852866 , BCS 0964944 , BCS 1520221 , BCS-DDRIG 1613626 ); The Leakey Foundation ; National Geographic CRE (grant number: 8486-08 ); The Smithsonian Institution Graduate Student Fellowship; and the GW Anthropology Department Cotlow Award . We gratefully acknowledge the Rwandan government and national parks authorities for permission to work in their country, and for access to mountain gorilla skeletal data for research. The sample utilized in this study is curated by the Mountain Gorilla Skeletal Project in Rwanda, which is indebted to the many field assistants, researchers, and other staff of the Rwanda Development Board—Department of Tourism and Conservation, Mountain Gorilla Veterinary Project, and Dian Fossey Gorilla Fund International's Karisoke Research Center, and The George Washington University, and the many participants from academic institutions in Rwanda and the USA who have contributed to the MGSP since 2008. We are indebted to the Paleoanthropology, Senckenberg Center for Human Evolution and Paleoenvironment, Universität Tübingen, Germany, for allowing data collection using their imaging equipment. We thank Kristofer Helgen and Darrin Lunde of the Smithsonian's National Museum of Natural History for access to the Division of Mammals specimens. We thank Wendy Dirks and Christopher Dean for access to specimens of the Newcastle Collection, as well as the Royal College of Surgeons and Marcia Ponce de León of Universität Zürich for access to their collections and helpful discussions about this project. We acknowledge those who helped with the creation of dental impressions and/or replicas: Jordi Galbany, Andrés Bonilla, Sonora Lanham, and Umang Gurung. Finally, we thank Andrew Barr, Carson Murray, and Bernard Wood for their thoughtful feedback on this research.
Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/12
Y1 - 2019/12
N2 - Deeper or more ‘severe’ linear enamel hypoplasia (LEH) defects are hypothesized to reflect more severe stress during development, but it is not yet clear how depth is influenced by intrinsic enamel growth patterns. Recent work documented inter- and intraspecific differences in LEH defect depth in extant great apes, with mountain gorillas having shallower defects than other taxa, and females having deeper defects than males. Here, we assess the correspondence of inter- and intraspecific defect depth and intrinsic aspects of enamel growth: enamel extension rates, outer enamel striae of Retzius angles, and linear enamel thickness. Thin sections of great ape canines (n = 40) from Gorilla beringei beringei, Gorilla gorilla gorilla, Pan troglodytes, and Pongo spp. were analyzed. Enamel extension rates were calculated within deciles of enamel-dentine junction length. Linear enamel thickness and the angle of intersection between striae of Retzius and the outer enamel surface were measured in the imbricational enamel. Mountain gorillas have faster enamel extension rates and shallower striae angles than the other taxa examined. Mountain gorillas have thinner imbricational enamel than western lowland gorillas and orangutans, but not chimpanzees. In the combined-taxon sample, females exhibit larger striae angles and thicker imbricational enamel than males. Enamel extension rates are highly negatively correlated with striae angles and LEH defect depth. Enamel growth variation corresponds with documented inter- and intraspecific differences in LEH defect depth in great ape canines. Mountain gorillas have shallower striae angles and faster extension rates than other taxa, which might explain their shallow LEH defect morphology and the underestimation of their LEH prevalence in previous studies. These results suggest that stressors of similar magnitude and timing might produce defects of different depths in one species or sex vs. another, which has implications for interpretations of stress histories in hominins with variable enamel growth patterns.
AB - Deeper or more ‘severe’ linear enamel hypoplasia (LEH) defects are hypothesized to reflect more severe stress during development, but it is not yet clear how depth is influenced by intrinsic enamel growth patterns. Recent work documented inter- and intraspecific differences in LEH defect depth in extant great apes, with mountain gorillas having shallower defects than other taxa, and females having deeper defects than males. Here, we assess the correspondence of inter- and intraspecific defect depth and intrinsic aspects of enamel growth: enamel extension rates, outer enamel striae of Retzius angles, and linear enamel thickness. Thin sections of great ape canines (n = 40) from Gorilla beringei beringei, Gorilla gorilla gorilla, Pan troglodytes, and Pongo spp. were analyzed. Enamel extension rates were calculated within deciles of enamel-dentine junction length. Linear enamel thickness and the angle of intersection between striae of Retzius and the outer enamel surface were measured in the imbricational enamel. Mountain gorillas have faster enamel extension rates and shallower striae angles than the other taxa examined. Mountain gorillas have thinner imbricational enamel than western lowland gorillas and orangutans, but not chimpanzees. In the combined-taxon sample, females exhibit larger striae angles and thicker imbricational enamel than males. Enamel extension rates are highly negatively correlated with striae angles and LEH defect depth. Enamel growth variation corresponds with documented inter- and intraspecific differences in LEH defect depth in great ape canines. Mountain gorillas have shallower striae angles and faster extension rates than other taxa, which might explain their shallow LEH defect morphology and the underestimation of their LEH prevalence in previous studies. These results suggest that stressors of similar magnitude and timing might produce defects of different depths in one species or sex vs. another, which has implications for interpretations of stress histories in hominins with variable enamel growth patterns.
KW - Dental development
KW - Hominoids
KW - Linear enamel hypoplasia
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U2 - 10.1016/j.jhevol.2019.102691
DO - 10.1016/j.jhevol.2019.102691
M3 - Article
C2 - 31704354
AN - SCOPUS:85074259562
VL - 137
JO - Journal of Human Evolution
JF - Journal of Human Evolution
SN - 0047-2484
M1 - 102691
ER -