Morphoscopic Traits and the Assessment of Ancestry

Spradley

Anderson³

2014

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A skeletal assessment of ancestry relies on morphoscopic traits and skeletal measurements. Using a sample of American Black (n = 38), American White (n = 39), and Southwest Hispanics (n = 72), the present study investigates whether these data provide similar biological information and combines both data types into a single classification using a random forest model (RFM). Our results indicate that both data types provide similar information concerning the relationships among population groups. Also, by combining both in an RFM, the correct allocation of ancestry for an unknown cranium increases. The distribution of cross-validated grouped cases correctly classified using discriminant analyses and RFMs ranges between 75.4% (discriminant function analysis, morphoscopic data only) and 89.6% (RFM). Unlike the traditional, experience-based approach using morphoscopic traits, the inclusion of both data types in a single analysis is a quantifiable approach accounting for more variation within and between groups, reducing misclassification rates, and capturing aspects of cranial shape, size, and morphology.

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confidence: 99%

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confidence: 99%

Ancestry Assessment Using Random Forest Modeling^,^,

Spradley

Anderson³

2014

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“…Aside from age estimation and for the purpose of identification, teeth have the potential to further aid in the biological profile to include the development of methods for the assessment of ancestry. Metric and morphoscopic methods of ancestry assessment have been explored in great depth, but only for cranial and postcranial remains. Dental morphology is gaining more visibility for the assessment of ancestry as methods for its application are being developed .…”

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confidence: 99%

The Use of Tooth Crown Measurements in the Assessment of Ancestry

Pilloud

Hanihara

et al. 2014

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As the hardest tissue in the body, teeth have the potential to offer a wealth of biological information to the forensic anthropologist, which can include the assessment of ancestry. Using a large data set of dental measurements, the efficacy of mesiodistal and buccolingual tooth dimensions to discriminate between broad, geographically based groups is explored. A general pattern is identified: African populations have the largest teeth, Asians possess teeth of intermediate size, and Europeans have the smallest teeth. In a discriminant function analysis using crown measurements of all teeth (mandibular and maxillary and excluding the third molar), individuals were correctly classified in 71.3% of cases. When the sex of the individual is known, classification is improved up to 88.1% in females and 71.9% of males (cross-validated). Based on these results, we argue that dental metrics can be regularly employed as part of the development of the biological profile.

“…Table presents frequency distribution data for each of the eight morphoscopic traits, by group, among the Hispanic samples. Hefner previously presented frequency data for the American Black and American White samples , which is not repeated here. The Hispanic data fundamentally conform to previous results on morphoscopic trait expression in these populations .…”

Section: Resultsmentioning

confidence: 99%

Morphoscopic Trait Expression in “Hispanic” Populations

Pilloud

Black

et al. 2015

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This study evaluates population variation of eight cranial morphoscopic traits using samples of known southwest Hispanics (n=72), Guatemalans (n=106), American Blacks (n=146), and American Whites (n=218). We applied the support vector machine (SVM) method to build a prediction model based on a subsample (20%) of the data; the remainder of the data was used as a test sample. The SVM approach effectively differentiated between the four groups with correct classification rates between 72% (Guatemalan group) and 94% (American Black group). However, when the Guatemalan and southwest Hispanic samples were pooled, the same model correctly classified all groups with a higher degree of accuracy (American Black=96%; American White=77%; and the pooled Hispanic sample=91%). This study also identified significant differences between the two Hispanic groups in six of the eight traits using univariate statistical tests. These results speak to the unique population histories of these samples and the current use of the term "Hispanic" within forensic anthropology. Finally, we argue that the SVM can be used as a classification model for ancestry estimation in a forensic context and as a diagnostic tool may broaden the application of morphoscopic trait data for the assessment of ancestry.