TY - JOUR
T1 - Allometric scaling of infraorbital surface topography in Homo
AU - Maddux, Scott D.
AU - Franciscus, Robert G.
N1 - Funding Information:
We are indebted to the following individuals for providing access to skeletal and cast material under their care: M. Teschler-Nicola, K. Wiltschke-Schrotta, M. Berner, D. Hunt, and J. Clark. We thank S. Miller, D. Proctor, C. Terhune, and especially N. Holton for helpful comments regarding analytical aspects of this study. We also wish to thank B. Maureille, F. Smith, K. Harvati, J. Polanski, and H. Marsh for insightful discussions. S. Antón and four anonymous reviewers also provided constructive comments which improved this manuscript. We additionally thank J. Rodgers for aid with the arrangement of several figures and C. Franciscus for aid in SAS modeling. This work was supported by grants from UISG and the UI Department of Anthropology.
PY - 2009/2
Y1 - 2009/2
N2 - Infraorbital morphology is often included in phylogenetic and functional analyses of Homo. The inclusion of distinct infraorbital configurations, such as the "canine fossa" in Homo sapiens or the "inflated" maxilla in Neandertals, is generally based on either descriptive or qualitative assessments of this morphology, or simple linear chord and subtense measurements. However, the complex curvilinear surface of the infraorbital region has proven difficult to quantify through these traditional methods. In this study, we assess infraorbital shape and its potential allometric scaling in fossil Homo (n = 18) and recent humans (n = 110) with a geometric morphometric method well-suited for quantifying complex surface topographies. Our results indicate that important aspects of infraorbital shape are correlated with overall infraorbital size across Homo. Specifically, individuals with larger infraorbital areas tend to exhibit relatively flatter infraorbital surface topographies, taller and narrower infraorbital areas, sloped inferior orbital rims, anteroinferiorly oriented maxillary body facies, posteroinferiorly oriented maxillary processes of the zygomatic, and non-everted lateral nasal margins. In contrast, individuals with smaller infraorbital regions generally exhibit relatively depressed surface topographies, shorter and wider infraorbital areas, projecting inferior orbital rims, posteroinferiorly oriented maxillary body facies, anteroinferiorly oriented maxillary processes, and everted lateral nasal margins. These contrasts form a continuum and only appear dichotomized at the ends of the infraorbital size spectrum. In light of these results, we question the utility of incorporating traditionally polarized infraorbital morphologies in phylogenetic and functional analyses without due consideration of continuous infraorbital and facial size variation in Homo. We conclude that the essentially flat infraorbital surface topography of Neandertals is not unique and can be explained, in part, as a function of possessing large infraorbital regions, the ancestral condition for Homo. Furthermore, it appears likely that the diminutive infraorbital region of anatomically modern Homo sapiens is a primary derived trait, with related features such as depressed infraorbital surface topography expressed as correlated secondary characters.
AB - Infraorbital morphology is often included in phylogenetic and functional analyses of Homo. The inclusion of distinct infraorbital configurations, such as the "canine fossa" in Homo sapiens or the "inflated" maxilla in Neandertals, is generally based on either descriptive or qualitative assessments of this morphology, or simple linear chord and subtense measurements. However, the complex curvilinear surface of the infraorbital region has proven difficult to quantify through these traditional methods. In this study, we assess infraorbital shape and its potential allometric scaling in fossil Homo (n = 18) and recent humans (n = 110) with a geometric morphometric method well-suited for quantifying complex surface topographies. Our results indicate that important aspects of infraorbital shape are correlated with overall infraorbital size across Homo. Specifically, individuals with larger infraorbital areas tend to exhibit relatively flatter infraorbital surface topographies, taller and narrower infraorbital areas, sloped inferior orbital rims, anteroinferiorly oriented maxillary body facies, posteroinferiorly oriented maxillary processes of the zygomatic, and non-everted lateral nasal margins. In contrast, individuals with smaller infraorbital regions generally exhibit relatively depressed surface topographies, shorter and wider infraorbital areas, projecting inferior orbital rims, posteroinferiorly oriented maxillary body facies, anteroinferiorly oriented maxillary processes, and everted lateral nasal margins. These contrasts form a continuum and only appear dichotomized at the ends of the infraorbital size spectrum. In light of these results, we question the utility of incorporating traditionally polarized infraorbital morphologies in phylogenetic and functional analyses without due consideration of continuous infraorbital and facial size variation in Homo. We conclude that the essentially flat infraorbital surface topography of Neandertals is not unique and can be explained, in part, as a function of possessing large infraorbital regions, the ancestral condition for Homo. Furthermore, it appears likely that the diminutive infraorbital region of anatomically modern Homo sapiens is a primary derived trait, with related features such as depressed infraorbital surface topography expressed as correlated secondary characters.
KW - Canine fossa
KW - Infraorbital size shape scaling
KW - Maxillary inflation
KW - Midface
KW - Modern humans
KW - Neandertals
UR - http://www.scopus.com/inward/record.url?scp=58549104887&partnerID=8YFLogxK
U2 - 10.1016/j.jhevol.2008.10.003
DO - 10.1016/j.jhevol.2008.10.003
M3 - Article
C2 - 19118866
AN - SCOPUS:58549104887
SN - 0047-2484
VL - 56
SP - 161
EP - 174
JO - Journal of Human Evolution
JF - Journal of Human Evolution
IS - 2
ER -