TY - JOUR
T1 - Cranial vault thickness in primates
T2 - Homo erectus does not have uniquely thick vault bones
AU - Copes, Lynn E.
AU - Kimbel, William
N1 - Funding Information:
Financial support for this research came from an NSF DDIG # 0925793 and a Wenner-Gren dissertation grant to LC. A National Geographic Society fieldwork grant ( 8827-10 ) to WHK funded travel to photograph fossils at the National Museums of Kenya and Ethiopia. We thank Emma Mubua and her staff at the National Museums of Kenya, as well as staff at the National Museums of Ethiopia for access to specimens in their care. μCT scanning of the non-human primate sample at Harvard University was made possible with assistance from Lynn Lucas, Fettah Kosar, Judy Chapasko, and Mark Omura. CT scans of humans were obtained during a Smithsonian 10-week summer fellowship to LC with the assistance of Bruno Frohlich, Ian Tattersall, Gisselle Garcia, David Hunt, and Mary Sangrey. Additional measurements of the Point Hope collection were obtained with the help of Jill Shapiro, Dru Munsell, and Nathan Ashe. Richard Feinn provided excellent statistical advice. Gary Schwartz, Mark Spencer, Matt Ravosa, Larry Copes, and Steven Tommasini read and provided invaluable comments on early drafts of this paper. We also thank three anonymous reviewers for their comments, which immensely improved the manuscript.
Publisher Copyright:
© 2015 Elsevier Ltd.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - Extremely thick cranial vaults have been noted as a diagnostic characteristic of Homo erectus since the first fossil of the species was identified, but relatively little work has been done on elucidating its etiology or variation across fossils, living humans, or extant non-human primates. Cranial vault thickness (CVT) is not a monolithic trait, and the responsiveness of its layers to environmental stimuli is unknown. We obtained measurements of cranial vault thickness in fossil hominins from the literature and supplemented those data with additional measurements taken on African fossil specimens. Total CVT and the thickness of the cortical and diploë layers individually were compared to measures of CVT in extant species measured from more than 500 CT scans of human and non-human primates. Frontal and parietal CVT in fossil primates was compared to a regression of CVT on cranial capacity calculated for extant species. Even after controlling for cranial capacity, African and Asian H. erectus do not have uniquely high frontal or parietal thickness residuals, either among hominins or extant primates. Extant primates with residual CVT thickness similar to or exceeding H. erectus (depending on the sex and bone analyzed) include Nycticebus coucang, Perodicticus potto, Alouatta caraya, Lophocebus albigena, Galago alleni, Mandrillus sphinx, and Propithecus diadema. However, the especially thick vaults of extant non-human primates that overlap with H. erectus values are composed primarily of cortical bone, while H. erectus and other hominins have diploë-dominated vault bones. Thus, the combination of thick vaults comprised of a thickened diploë layer may be a reliable autapomorphy for members of the genus Homo.
AB - Extremely thick cranial vaults have been noted as a diagnostic characteristic of Homo erectus since the first fossil of the species was identified, but relatively little work has been done on elucidating its etiology or variation across fossils, living humans, or extant non-human primates. Cranial vault thickness (CVT) is not a monolithic trait, and the responsiveness of its layers to environmental stimuli is unknown. We obtained measurements of cranial vault thickness in fossil hominins from the literature and supplemented those data with additional measurements taken on African fossil specimens. Total CVT and the thickness of the cortical and diploë layers individually were compared to measures of CVT in extant species measured from more than 500 CT scans of human and non-human primates. Frontal and parietal CVT in fossil primates was compared to a regression of CVT on cranial capacity calculated for extant species. Even after controlling for cranial capacity, African and Asian H. erectus do not have uniquely high frontal or parietal thickness residuals, either among hominins or extant primates. Extant primates with residual CVT thickness similar to or exceeding H. erectus (depending on the sex and bone analyzed) include Nycticebus coucang, Perodicticus potto, Alouatta caraya, Lophocebus albigena, Galago alleni, Mandrillus sphinx, and Propithecus diadema. However, the especially thick vaults of extant non-human primates that overlap with H. erectus values are composed primarily of cortical bone, while H. erectus and other hominins have diploë-dominated vault bones. Thus, the combination of thick vaults comprised of a thickened diploë layer may be a reliable autapomorphy for members of the genus Homo.
KW - Allometry
KW - Autapomorphy
KW - CVT
KW - Diploë
KW - Homo erectus
KW - Residuals
KW - Skull
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U2 - 10.1016/j.jhevol.2015.08.008
DO - 10.1016/j.jhevol.2015.08.008
M3 - Article
C2 - 26767964
AN - SCOPUS:84952927906
VL - 90
SP - 120
EP - 134
JO - Journal of Human Evolution
JF - Journal of Human Evolution
SN - 0047-2484
ER -