Patterning of geographic variation in Middle Pleistocene Homo frontal bone morphology

Athreya, Sheela

doi:10.1016/j.jhevol.2005.11.005

Cited by 23 publications

(34 citation statements)

References 111 publications

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“…We believe that the most effective way to quantify chin shape is to use elliptical Fourier functions analysis. This morphometric approach has been applied to a variety of biological traits (Inoue, 1990;Lestrel, 1997;Seiffert and Kappelman, 2001;Lestrel et al, 2004;Athreya, 2006), including primate mandibular symphyses (Chen et al, 2000;Daegling and Jungers, 2000;Schmittbuhl et al, 2001Schmittbuhl et al, , 2002Schmittbuhl et al, , 2007Guy et al, 2008;Brown and Maeda, 2009). EFFA is essentially a technique for computing a trigonometric function that can be used to describe a curve, or in this case the shape of an outline.…”

Section: Quantifying Chin Shapementioning

confidence: 99%

“…EFFA is essentially a technique for computing a trigonometric function that can be used to describe a curve, or in this case the shape of an outline. Curvature is quantified through the use of sine and cosine terms that describe the repeated elements in a sinusoidal waveform, or harmonics (Athreya, 2006). The first harmonic is the most general, and uses an ellipse to approximate the outline of a shape about the long axis.…”

Section: Quantifying Chin Shapementioning

confidence: 99%

“…Amplitudes are a measure of the maximum height of the waveform, and are independent of one another. Each amplitude represents the degree of influence a given harmonic has with regard to transforming the shape away from the original circle and towards the outline of interest (Athreya, 2006).…”

Section: Quantifying Chin Shapementioning

confidence: 99%

“…Also, because elliptical Fourier functions, unlike traditional Fourier functions, do not require an equidistant distribution of points, it is possible to include more points in areas of high curvature and less points in areas with less dramatic curvature, thereby allowing a more accurate fit to the outline of interest (Athreya, 2006). Once computed and appropriately size standardized, Fourier coefficients can be used as general shape descriptors in subsequent multivariate statistical analyses, such as discriminate function analysis (Daegling and Jungers, 2000).…”

Section: Quantifying Chin Shapementioning

confidence: 99%

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Sexual dimorphism in chin shape: Implications for adaptive hypotheses

Thayer

Dobson

2010

American J Phys Anthropol

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The chin, or mentum osseum, is one of the most distinctive anatomical traits of modern humans. A variety of hypotheses for the adaptive value of the chin have been proposed, ranging from mechanical stress resistance to sexual selection via mate choice. While the sexual selection hypothesis predicts dimorphism in chin shape, most biomechanical hypotheses preclude it. Therefore determining the presence or absence of significant sexual dimorphism in chin shape provides a useful method for differentiating between various adaptive hypotheses; however, this has yet to be done due to a lack of quantitative data on chin shape. The goals of this study are therefore: (1) to introduce a new method for quantifying chin shape and (2) to determine the presence or absence of sexual dimorphism in chin shape in a diverse sample of modern humans. Samples were drawn from recent human skeletal collections representing nine geographic regions. Outlines of mentum osseum contours were quantified using elliptical Fourier function analysis (EFFA). Fourier coefficients were analyzed using principal components analysis (PCA). Sexual dimorphism in chin shape was assessed using PC loadings in the pooled geographic sample, and statistically significant differences were found. These findings provide the first quantitative, morphologically based evidence in support of adaptive hypotheses that predict dimorphism in chin shape, including the sexual selection hypothesis.

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Section: Quantifying Chin Shapementioning

confidence: 99%

Section: Quantifying Chin Shapementioning

confidence: 99%

Section: Quantifying Chin Shapementioning

confidence: 99%

Section: Quantifying Chin Shapementioning

confidence: 99%

See 2 more Smart Citations

Sexual dimorphism in chin shape: Implications for adaptive hypotheses

Thayer

Dobson

2010

American J Phys Anthropol

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“…A partial Mantel test was also used to compare two matrices whilst controlling for temporal distance (Athreya, 2006). Minimum geographic distances between the samples are calculated in kilometres from the latitude and longitudinal coordinates of the samples.…”

Section: Stage 1: Quantification Of Polynesian Craniofacial Diversitymentioning

confidence: 99%