Evaluating sexual dimorphism in the human mastoid process: A viewpoint on the methodology

Petaros, Anja; Sholts, Sabrina B.; Šlaus, Mario; Bosnar, Alan; Wärmländer, Sebastian K.T.S.

doi:10.1002/ca.22545

Cited by 35 publications

(48 citation statements)

References 48 publications

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“…Selecting the particular landmarks to use is one of the most important tasks in the design of morphometric research projects and case studies. Even though landmark‐free approaches to shape analysis are gaining ground (Koehl and Hass, ; Bulut et al, ; Ghoneima et al, ), and even though non‐shape features such as volume and surface area remain relevant (Sholts et al, ; Shearer et al, ; Petaros et al, ), we believe that landmark‐based shape analysis will continue to be a very important research method. One clear advantage of landmarks, compared to landmark‐free approaches, is that it is relatively easy to establish anatomical equivalence or correspondence.…”

Section: Discussionmentioning

confidence: 99%

Landmark Typology in Applied Morphometrics Studies: What's the Point?

Wärmländer

Garvin

Guyomarc’h

et al. 2018

The Anatomical Record

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Landmarks are the hallmark of biological shape analysis as discrete anatomical points of correspondence. Various systems have been developed for their classification. In the most widely used system, developed by Bookstein in the 1990s, landmarks are divided into three distinct types based on their anatomical locations and biological significance. As Bookstein and others have argued that different landmark types possess different qualities, e.g., that Type 3 landmarks contain deficient information about shape variation and are less reliably measured, researchers began using landmark types as justification for selecting or avoiding particular landmarks for measurement or analysis. Here, we demonstrate considerable variation in landmark classifications among 17 studies using geometric morphometrics (GM), due to disagreement in the application of both Bookstein's landmark typology and individual landmark definitions. A review of the literature furthermore shows little correlation between landmark type and measurement reproducibility, especially when factors such as differences in measurement tools (calipers, digitizer, or computer software) and data sources (dry crania, 3D models, or 2D images) are considered. Although landmark typology is valuable when teaching biological shape analysis, we find that employing it in research design introduces confusion without providing useful information. Instead, researchers should choose landmark configurations based on their ability to test specific research hypotheses, and research papers should include justifications of landmark choices along with landmark definitions, details on landmark collection methods, and appropriate interobserver and intraobserver analyses. Hence, while the landmarks themselves are crucial for GM, we argue that their typology is of little use in applied studies. Anat Rec, 302:1144–1153, 2019. © 2018 Wiley Periodicals, Inc.

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Section: Discussionmentioning

confidence: 99%

Landmark Typology in Applied Morphometrics Studies: What's the Point?

Wärmländer

Garvin

Guyomarc’h

et al. 2018

The Anatomical Record

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“…The asymmetry of the biface surfaces was computed by analyzing the digital 3D models with spherical harmonics, a mathematical extension of elliptic Fourier analysis into 3D space developed during the last decade [20]. Thus, we here continue our efforts to develop new ways to investigate archaeological material using 3D technology [51–58]. With new mathematical tools available for analyzing 3D surfaces, it becomes natural to ask what kind of information can be obtained from respectively 2D contours and 3D surfaces [59].…”

Section: Discussionmentioning

confidence: 99%

Tracing social interactions in Pleistocene North America via 3D model analysis of stone tool asymmetry

et al. 2017

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Stone tools, often the sole remnant of prehistoric hunter-gatherer behavior, are frequently used as evidence of ancient human mobility, resource use, and environmental adaptation. In North America, studies of morphological variation in projectile points have provided important insights into migration and interactions of human groups as early as 12–13 kya. Using new approaches to 3D imaging and morphometric analysis, we here quantify bifacial asymmetry among early North American projectile point styles to better understand changes in knapping technique and cultural transmission. Using a sample of 100 fluted bifaces of Clovis and post-Clovis styles in the eastern United States ca. 13,100–9,000 cal BP (i.e., Clovis, Debert-Vail, Bull Brook, Michaud-Neponset/Barnes, and Crowfield), we employed two different approaches for statistical shape analysis: our previously presented method for analysis of 2D flake scar contours, and a new approach for 3D surface analysis using spherical harmonics (SPHARM). Whereas bifacial asymmetry in point shape does not vary significantly across this stylistic sequence, our measure of asymmetric flake scar patterning shows temporal variation that may signify the beginning of regionalization among early New World colonists.

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“…Additionally, visual inspection employs an ordinal scale, which represents the most minimal to maximal expression of the mastoid (i.e., female, probable female, indeterminate, probable male, and male). In previous studies, the accuracy of sex classification using the two conventional methods was shown to be relatively high . For example, the correct classification rate of mastoid height was 85.7% in South Indian samples and 74.7% in Japanese samples .…”

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confidence: 96%

Evaluation of Mastoid Process as Sex Indicator in Modern White Americans using Geometric Morphometrics

Jung

Woo

2016

Journal of Forensic Sciences

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Conventional methods for evaluating the mastoid as a sex indicator cannot determine whether mastoid shape is an independent and reliable sex indicator. Here, shape differences between the mastoids of 100 male and 100 female modern white Americans were statistically analyzed and visualized using the geometric morphometric method. Discriminant analysis was performed on mastoid size and shape. The relation between size and shape was analyzed to examine the effect of size on shape. In the results, mastoid size and shape were statistically significant sex indicators, while size factor explained 87.3% of the total variance of the shape variables. Nevertheless, females had relatively broader and shorter mastoid shape than males regardless of size, reflecting 12.7% of the total variance of the shape variables. In conclusion, mastoid size and shape were statistically significant sex indicators, while size may matter more in the mastoid than in other cranial parts in terms of sexual dimorphism.

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Evaluating sexual dimorphism in the human mastoid process: A viewpoint on the methodology

Cited by 35 publications

References 48 publications

Landmark Typology in Applied Morphometrics Studies: What's the Point?

Landmark Typology in Applied Morphometrics Studies: What's the Point?

Tracing social interactions in Pleistocene North America via 3D model analysis of stone tool asymmetry

Evaluation of Mastoid Process as Sex Indicator in Modern White Americans using Geometric Morphometrics

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