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Biometric evidence that sexual selection has shaped the hominin face.

Weston EM, Friday AE, Liò P - PLoS ONE (2007)

Bottom Line: We consider sex differences in human facial morphology in the context of developmental change.A link between this developmental model and sexual dimorphism is made for the first time, and provides a new set of morphological criteria to sex human crania.This finding has important implications for the role of sexual selection in the evolution of anthropoid faces and for theories of human facial attractiveness.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University College London, London, United Kingdom. e.weston@nhm.ac.uk

ABSTRACT
We consider sex differences in human facial morphology in the context of developmental change. We show that at puberty, the height of the upper face, between the lip and the brow, develops differently in males and females, and that these differences are not explicable in terms of sex differences in body size. We find the same dimorphism in the faces of human ancestors. We propose that the relative shortening in men and lengthening in women of the anterior upper face at puberty is the mechanistic consequence of extreme maxillary rotation during ontogeny. A link between this developmental model and sexual dimorphism is made for the first time, and provides a new set of morphological criteria to sex human crania. This finding has important implications for the role of sexual selection in the evolution of anthropoid faces and for theories of human facial attractiveness.

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Male and female H. sapiens ontogenetic trajectories plotted with fossil hominin crania.The relationship between bizygomatic width (BZW) and upper facial height (FHT) shows a departure from ontogenetic scaling. Major axis slopes and 95% confidence intervals: male 0.7847 (0.74–0.83), female 0.6988 (0.65–0. 75). The FHT value for specimen KNM-ER 406 is a conservative estimate as the subnasal region is slightly damaged [28]. However, a small increase in FHT would align this cranium even more closely to the male ontogenetic trajectory.
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pone-0000710-g001: Male and female H. sapiens ontogenetic trajectories plotted with fossil hominin crania.The relationship between bizygomatic width (BZW) and upper facial height (FHT) shows a departure from ontogenetic scaling. Major axis slopes and 95% confidence intervals: male 0.7847 (0.74–0.83), female 0.6988 (0.65–0. 75). The FHT value for specimen KNM-ER 406 is a conservative estimate as the subnasal region is slightly damaged [28]. However, a small increase in FHT would align this cranium even more closely to the male ontogenetic trajectory.

Mentions: The negative allometric relationship between bizygomatic width (BZW) and FHT exemplifies this sexual dimorphism (Figure 1). Young children possess shorter, broader faces relative to those of adults. However, a distinction between the sexes can also be observed that is linked to distinct male and female growth trajectories (Figure 1). Analysis of individual traits against age indicates that male and female growth trajectories diverge at puberty for BZW but not for FHT (Figures S2 and S3). This relationship of width-to-height of the upper face deviates from predictions based on ontogenetic scaling, as males (which are, on average, larger than females) have similar facial heights to females, whereas facial breadth is larger in the male: adult men have relatively shorter upper faces and adult women have relatively longer upper faces (Figure 2 and Figures S2, A and B). Hominin fossil crania with preserved facial skeletons reveal a similar type of sexual dimorphism (Figure 1).


Biometric evidence that sexual selection has shaped the hominin face.

Weston EM, Friday AE, Liò P - PLoS ONE (2007)

Male and female H. sapiens ontogenetic trajectories plotted with fossil hominin crania.The relationship between bizygomatic width (BZW) and upper facial height (FHT) shows a departure from ontogenetic scaling. Major axis slopes and 95% confidence intervals: male 0.7847 (0.74–0.83), female 0.6988 (0.65–0. 75). The FHT value for specimen KNM-ER 406 is a conservative estimate as the subnasal region is slightly damaged [28]. However, a small increase in FHT would align this cranium even more closely to the male ontogenetic trajectory.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1937021&req=5

pone-0000710-g001: Male and female H. sapiens ontogenetic trajectories plotted with fossil hominin crania.The relationship between bizygomatic width (BZW) and upper facial height (FHT) shows a departure from ontogenetic scaling. Major axis slopes and 95% confidence intervals: male 0.7847 (0.74–0.83), female 0.6988 (0.65–0. 75). The FHT value for specimen KNM-ER 406 is a conservative estimate as the subnasal region is slightly damaged [28]. However, a small increase in FHT would align this cranium even more closely to the male ontogenetic trajectory.
Mentions: The negative allometric relationship between bizygomatic width (BZW) and FHT exemplifies this sexual dimorphism (Figure 1). Young children possess shorter, broader faces relative to those of adults. However, a distinction between the sexes can also be observed that is linked to distinct male and female growth trajectories (Figure 1). Analysis of individual traits against age indicates that male and female growth trajectories diverge at puberty for BZW but not for FHT (Figures S2 and S3). This relationship of width-to-height of the upper face deviates from predictions based on ontogenetic scaling, as males (which are, on average, larger than females) have similar facial heights to females, whereas facial breadth is larger in the male: adult men have relatively shorter upper faces and adult women have relatively longer upper faces (Figure 2 and Figures S2, A and B). Hominin fossil crania with preserved facial skeletons reveal a similar type of sexual dimorphism (Figure 1).

Bottom Line: We consider sex differences in human facial morphology in the context of developmental change.A link between this developmental model and sexual dimorphism is made for the first time, and provides a new set of morphological criteria to sex human crania.This finding has important implications for the role of sexual selection in the evolution of anthropoid faces and for theories of human facial attractiveness.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University College London, London, United Kingdom. e.weston@nhm.ac.uk

ABSTRACT
We consider sex differences in human facial morphology in the context of developmental change. We show that at puberty, the height of the upper face, between the lip and the brow, develops differently in males and females, and that these differences are not explicable in terms of sex differences in body size. We find the same dimorphism in the faces of human ancestors. We propose that the relative shortening in men and lengthening in women of the anterior upper face at puberty is the mechanistic consequence of extreme maxillary rotation during ontogeny. A link between this developmental model and sexual dimorphism is made for the first time, and provides a new set of morphological criteria to sex human crania. This finding has important implications for the role of sexual selection in the evolution of anthropoid faces and for theories of human facial attractiveness.

Show MeSH
Related in: MedlinePlus