The Combination of Cranial Morphoscopic and Dental Morphological Methods to Improve the Forensic Estimation of Ancestry
AuthorMaier, Christopher Allan
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The estimation of ancestry is central to the construction of a biological profile, andhas traditionally been done through the analysis of cranial morphoscopic traits.Morphological traits of the dentition have also been used to assess population affinity,though largely outside of the forensic sphere. The Daubert standard of evidence requiresthat methods used in the forensic sciences be testable and have known rates of error. Withfew exceptions, the methods employed by anthropologists in the analysis of cranialmorphoscopic and dental morphological traits do not comply with that standard.Furthermore, no method exists for reliably producing an ancestry estimate from multipledata sources.This research examines 79 cranial and dental traits in a sample of 693 individualsfrom various ancestry groups, including several newly or recently standardized traits thathave not been fully explored. The Asian/Native American sample was excluded due tosample size. For the remaining sample, the pool of 79 variables was reduced to 34,removing those that did not differ significantly among ancestry groups or were highlycorrelated with other variables. These 34 variables were used to build classificatorymodels using random forest modeling and naïve Bayes classification.Overall these models correctly estimated ancestry in 67%-84% of cases. In general,the naïve Bayes classifier performed better than the random forest models. Also, modelsthat combined cranial and dental data outperformed models based on a single data source.Although the improvement of the combined data models over the cranial data models wasnot statistically significant. Interestingly, the combined data model showed the mostmarked improvement in estimating the ancestry of Hispanic individuals. This suggests thatthe cranium and dentition provide different information with regard to ancestry, and moreaccurate ancestry estimates can be produced by combining them.The methods used to produce ancestry estimates in this research comply with theDaubert standard of evidence, making them applicable to modern forensic casework.Additionally, the results highlight the potential improvement to ancestry estimation bycombining data from different regions of the skeleton, and the utility of the dentition inforensic estimates of ancestry.