Metameric variation of upper molars in hominoids and its implications for the diversification of molar morphogenesis

Wataru Morita, Naoki Morimoto, Reiko T. Kono, Gen Suwa

Research output: Contribution to journalArticle

Abstract

Metameric variation of molar size is in part associated with the dietary adaptations of mammals and results from slight alterations of developmental processes. Humans and great apes exhibit conspicuous variation in tooth morphology both between taxa and across tooth types. However, the manner in which metameric variation in molars emerged among apes and humans via evolutionary alterations in developmental processes remains largely unknown. In this study, we compare the enamel-dentine junction of the upper molars of humans—which closely correlates with morphology of the outer enamel surface and is less affected by wear—with that of the other extant hominoids: chimpanzees, bonobos, gorillas, orangutans, and gibbons. We used the morphometric mapping method to quantify and visualize three-dimensional morphological variation, and applied multivariate statistical analyses. Results revealed the following: 1) extant hominoids other than humans share a common pattern of metameric variation characterized by a largely linear change in morphospace; this indicates a relatively simple graded change in metameric molar shape; 2) intertaxon morphological differences become less distinct from the mesial to distal molars; and 3) humans diverge from the extant ape pattern in exhibiting a distinct metameric shape change trajectory in the morphospace. The graded shape change and lower intertaxon resolution from the mesial to distal molars are consistent with the concept of a ‘key’ tooth. The common metameric pattern observed among the extant nonhuman hominoids indicates that developmental patterns underlying metameric variation were largely conserved during ape evolution. Furthermore, the human-specific metameric pattern suggests considerable developmental modifications in the human lineage.

Original languageEnglish
Article number102706
JournalJournal of Human Evolution
Volume138
DOIs
Publication statusPublished - 2020 Jan

Fingerprint

morphogenesis
Hominidae
diversification
tooth
enamel
Pongidae
teeth
tooth enamel
mapping method
mammal
trajectory
Pan paniscus
Hylobatidae
Pongo pygmaeus
Gorilla
Pan troglodytes
trajectories
mammals

Keywords

  • Enamel-dentine junction
  • Hominoid evolution
  • Metameric variation
  • Molar morphology
  • Morphometric mapping

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Anthropology

Cite this

Metameric variation of upper molars in hominoids and its implications for the diversification of molar morphogenesis. / Morita, Wataru; Morimoto, Naoki; Kono, Reiko T.; Suwa, Gen.

In: Journal of Human Evolution, Vol. 138, 102706, 01.2020.

Research output: Contribution to journalArticle

@article{529e410452c549cc888fd304ab7559f8,
title = "Metameric variation of upper molars in hominoids and its implications for the diversification of molar morphogenesis",
abstract = "Metameric variation of molar size is in part associated with the dietary adaptations of mammals and results from slight alterations of developmental processes. Humans and great apes exhibit conspicuous variation in tooth morphology both between taxa and across tooth types. However, the manner in which metameric variation in molars emerged among apes and humans via evolutionary alterations in developmental processes remains largely unknown. In this study, we compare the enamel-dentine junction of the upper molars of humans—which closely correlates with morphology of the outer enamel surface and is less affected by wear—with that of the other extant hominoids: chimpanzees, bonobos, gorillas, orangutans, and gibbons. We used the morphometric mapping method to quantify and visualize three-dimensional morphological variation, and applied multivariate statistical analyses. Results revealed the following: 1) extant hominoids other than humans share a common pattern of metameric variation characterized by a largely linear change in morphospace; this indicates a relatively simple graded change in metameric molar shape; 2) intertaxon morphological differences become less distinct from the mesial to distal molars; and 3) humans diverge from the extant ape pattern in exhibiting a distinct metameric shape change trajectory in the morphospace. The graded shape change and lower intertaxon resolution from the mesial to distal molars are consistent with the concept of a ‘key’ tooth. The common metameric pattern observed among the extant nonhuman hominoids indicates that developmental patterns underlying metameric variation were largely conserved during ape evolution. Furthermore, the human-specific metameric pattern suggests considerable developmental modifications in the human lineage.",
keywords = "Enamel-dentine junction, Hominoid evolution, Metameric variation, Molar morphology, Morphometric mapping",
author = "Wataru Morita and Naoki Morimoto and Kono, {Reiko T.} and Gen Suwa",
year = "2020",
month = "1",
doi = "10.1016/j.jhevol.2019.102706",
language = "English",
volume = "138",
journal = "Journal of Human Evolution",
issn = "0047-2484",
publisher = "Academic Press Inc.",

}

TY - JOUR

T1 - Metameric variation of upper molars in hominoids and its implications for the diversification of molar morphogenesis

AU - Morita, Wataru

AU - Morimoto, Naoki

AU - Kono, Reiko T.

AU - Suwa, Gen

PY - 2020/1

Y1 - 2020/1

N2 - Metameric variation of molar size is in part associated with the dietary adaptations of mammals and results from slight alterations of developmental processes. Humans and great apes exhibit conspicuous variation in tooth morphology both between taxa and across tooth types. However, the manner in which metameric variation in molars emerged among apes and humans via evolutionary alterations in developmental processes remains largely unknown. In this study, we compare the enamel-dentine junction of the upper molars of humans—which closely correlates with morphology of the outer enamel surface and is less affected by wear—with that of the other extant hominoids: chimpanzees, bonobos, gorillas, orangutans, and gibbons. We used the morphometric mapping method to quantify and visualize three-dimensional morphological variation, and applied multivariate statistical analyses. Results revealed the following: 1) extant hominoids other than humans share a common pattern of metameric variation characterized by a largely linear change in morphospace; this indicates a relatively simple graded change in metameric molar shape; 2) intertaxon morphological differences become less distinct from the mesial to distal molars; and 3) humans diverge from the extant ape pattern in exhibiting a distinct metameric shape change trajectory in the morphospace. The graded shape change and lower intertaxon resolution from the mesial to distal molars are consistent with the concept of a ‘key’ tooth. The common metameric pattern observed among the extant nonhuman hominoids indicates that developmental patterns underlying metameric variation were largely conserved during ape evolution. Furthermore, the human-specific metameric pattern suggests considerable developmental modifications in the human lineage.

AB - Metameric variation of molar size is in part associated with the dietary adaptations of mammals and results from slight alterations of developmental processes. Humans and great apes exhibit conspicuous variation in tooth morphology both between taxa and across tooth types. However, the manner in which metameric variation in molars emerged among apes and humans via evolutionary alterations in developmental processes remains largely unknown. In this study, we compare the enamel-dentine junction of the upper molars of humans—which closely correlates with morphology of the outer enamel surface and is less affected by wear—with that of the other extant hominoids: chimpanzees, bonobos, gorillas, orangutans, and gibbons. We used the morphometric mapping method to quantify and visualize three-dimensional morphological variation, and applied multivariate statistical analyses. Results revealed the following: 1) extant hominoids other than humans share a common pattern of metameric variation characterized by a largely linear change in morphospace; this indicates a relatively simple graded change in metameric molar shape; 2) intertaxon morphological differences become less distinct from the mesial to distal molars; and 3) humans diverge from the extant ape pattern in exhibiting a distinct metameric shape change trajectory in the morphospace. The graded shape change and lower intertaxon resolution from the mesial to distal molars are consistent with the concept of a ‘key’ tooth. The common metameric pattern observed among the extant nonhuman hominoids indicates that developmental patterns underlying metameric variation were largely conserved during ape evolution. Furthermore, the human-specific metameric pattern suggests considerable developmental modifications in the human lineage.

KW - Enamel-dentine junction

KW - Hominoid evolution

KW - Metameric variation

KW - Molar morphology

KW - Morphometric mapping

UR - http://www.scopus.com/inward/record.url?scp=85075512018&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85075512018&partnerID=8YFLogxK

U2 - 10.1016/j.jhevol.2019.102706

DO - 10.1016/j.jhevol.2019.102706

M3 - Article

AN - SCOPUS:85075512018

VL - 138

JO - Journal of Human Evolution

JF - Journal of Human Evolution

SN - 0047-2484

M1 - 102706

ER -