Secular change has been documented in a number of studies focused on cranial and postcranial morphometrics and nonmetric traits. However, to date, few studies have addressed the potential of temporal change occurring in the expression of cranial nonmetric traits utilized in ancestry estimation. This study examines the effect of secular change on the expression of 23 cranial and mandibular nonmetric traits frequently employed in ancestry estimation; with age-at-death, sex, and year-of-birth of each individual documented for data analysis. Data were collected from European American individuals from the Hamann-Todd Skeletal Collection (n=518) and from the William M. Bass Donated Skeletal Collection (n=602). Individuals were divided into birth-year cohorts as follows: Hamann-Todd Skeletal Collection: 1824-1849 (Cohort 1), 1850-1874 (Cohort 2), 1875-1899 (Cohort 3), and 1900-1924 (Cohort 4); William M. Bass Donated Skeletal Collection: 1900-1924 (Cohort 4), 1925-1949 (Cohort 5), and 1950-1987 (Cohort 6). Pearson’s chi-square analyses produced significant p-values (≤ 0.01) in 19 of the 23 traits between the six birth-year cohorts. Factor maps generated through correspondence analyses were used as visual representations of relative trait expression between the cohorts. Ordinal regression analyses assessed the degree of variation between each cohort in relation to Cohort 1 along with the influence of age-at-death and sex on trait expression. Overall, analyses of the data revealed that secular change has occurred in 11 of the 23 traits, including: anterior nasal spine (ANS), malar tubercle (MT), nasal bone contour (NBC), postbregmatic depression (PBD), supranasal suture (SPS), transverse palatine suture (TPS), zygomaticomaxillary suture (ZS), gonial angle flare (GAF), mandibular tori (MDT), and posterior ramus edge inversion (PREI). Change in trait expression occurred in both males and females in seven traits, including: ANS, MT, TPS, ZS, GAF, MDT, and PREI. Significant change in trait expression occurred predominately between Cohorts 3 and 4 (birth years ranging from 1875 to 1924) and Cohorts 4 and 5 (birth years ranging from 1900 to 1949). This study demonstrates that secular change in nonmetric cranial and mandibular traits has occurred over the last two centuries with the greatest change appearing at the turn of the twentieth century.

Ancestry estimation for Hispanic Americans is increasing in importance as this minority population increases in the United States. Hispanics are historically an admixture of various geographic populations including European, Native American, and African. This combination of genes has caused many intermediate skeletal features that make identification of Hispanics a complicated process, especially when compared to Native Americans. "Hispanic" cannot efficiently encompass, as a term, the genotypic composition of multiple populations, as Hispanics from the Southwestern United States are historically a combination of Native American and European genes, whereas those from the Caribbean are historically an admixture of Native American, European, and African genes. While each of these regions can exhibit a certain combination of all three of these ancestral populations, each region has experienced a characteristic frequency of admixture. Southwest Hispanic populations are genotypically and phenotypically primarily comprised of Native American and European genes, resulting in an intermediate skeletal composition that prevents the distinct ancestry discrimination attainable by broad geographic groups. Previous dental morphological studies (Edgar 2013) have also presented results of intermediacy and particular difficulty separating these individuals from Native American and Asian groups; however, metric studies of the dentition of this population have yet to be investigated. Data were collected from n=569 dental casts from the James K. Economides collection which is housed at the Maxwell Museum in Albuquerque, New Mexico. Measurements included were the mesiodistal and buccolingual dimensions of the polar teeth of the morphogenetic field theory and the width and depth of the mandibular and maxillary arches. The morphogenetic field theory, as developed by Butler (1939) and adapted by Dahlberg (1945), represent the most stable teeth of the four fields of the dentition - incisors, canines, premolars, and molars. These "polar" teeth exhibit the least variation in crown size and shape. Significant differences were identified between ancestry groups and these were subsequently used to identify allocation rates between all groups and between particular sets, or groups, of ancestries. Discriminant function equations were developed as a tool for ancestry estimation. Success was greatest when both dental crown and arcade variables were pooled together in an analysis. Results of this study indicate odontometric analyses are useful in differentiating between Native Americans and European Americans, with classification rates ranging between 75.2% and 86.3%; however, much work must be conducted before application on Hispanic populations is possible. The Southwest Hispanic population exhibited greater phenotypic similarity to the European American population and had significantly lower success in allocation than between Southwest Hispanics and Native Americans. In cases where sex was known, successful allocation decreased, although females generally exhibited greater success than males. Potential utility is observed in this study when sex is unknown, and the development of a statistical methodology utilizing the dentition is proposed.

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Traditionally, pre-contact Native Americans have served as a biological reference for identifying modern Asian individuals in aspects of the biological profile due to their distantly shared genetic history, although this assumption remains largely untested. This study explores the craniomorphic variability between Asian and Asian-derived groups to ascertain whether they can be differentiated using population-specific models. Cranial and mandibular nonmetric trait data were recorded on pre-contact Native Americans (n=150) and compared within a statistical framework to cranial trait data for modern Thai (n=150) and Japanese (n=150) individuals. Chi-square analyses indicate that the groups exhibit statistically significant differences in their trait expressions. Of the 35 traits analyzed, 31 differ significantly between the groups. Binary logistic regression equations for differentiating the Japanese, Thai, and Native Americans are presented, and cross-validated correct classification rates range 60.0-90.0%. Further, the inclusion of sex into the logistic regression equations failed to improve their accuracies. The results indicate that the Native American and Asian groups are not skeletally homogenous due to divergent population histories, and that numerous cranial and mandibular nonmetric traits are resolute enough to detect differences within and between Asian and Asian-derived groups. Thus, this study highlights the utility of nonmetric traits in identifying individuals beyond the traditional African (“Black”), (“White”), and Asian groupings.

Ancestry estimation of skeletonized remains by forensic anthropologists is conducted through comparative means, and a lack of population-specific data results in possible misclassifications. This is especially germane to individuals of Latin American ancestry. Generally, each country in Latin America can trace their ancestry to three parental groups: Indigenous, European, and African. However, grouping all Latin American individuals together under the broad “Hispanic” category ignores the specific genetic contributions from each parental group, which is variable and dependent on the population histories and sociocultural dynamics of each country. This study analyzes the craniometric ancestry of Hispaniola (the Dominican Republic and Haiti) using the island’s history, along with 190 cranial Computed Tomography (CT) scans (f = 103; m = 87), to determine similarities and differences between the two groups. A total of 12 linear discriminant function analyses produced cross-validated classification accuracies of 75.0 – 83.3% for females, 71.8 – 87.5% for males, and 72.0 – 82.2% for pooled sexes. This study demonstrates that, despite sharing a small island, Dominican and Haitian individuals can be differentiated with a fair amount of statistical certainty, which is possible due to complex socio-cultural, -political, and –demographic factors that have maintained genetic heterogeneity. Moreover, the discriminant functions provided here can be used by the international forensic science community to identify individuals living on Hispaniola.

In ancestry estimation of South African individuals, non-metric morphological trait assessment has not proven useful and previous results in FORDISC 3.0 leave room for improvement. The accuracy rates of software programs FORDISC 3.1 and 3D-ID were compared for ancestry estimation based on cranial data of black and white South Africans using discriminant function analysis. Cranial landmarks were digitized using a Microscribe G2 for geometric morphometric analysis in 3D-ID, and traditional craniometric measurements for use in FORDISC were calculated using the data collection software 3Skull. Data was collected from a total of 385 individuals (186 black and 199 white crania) from the Pretoria Bone Collection. Overall accuracy rates of 75.6% using FORDISC 3.1 and 63.1% using 3D-ID were obtained for black and white South Africans. Incorrect estimates were more often due to misclassifications of sex rather than ancestry, reflecting the decreased amount of sexual dimorphism in South African populations when compared against American populations, discussed previously. Black South Africans were more often classified correctly in FORDISC 3.1, and white South Africans were more often classified correctly in 3D-ID. Low sample size in comparative databases and broad ancestral differences between South Africans and the proxy populations used (American, European, and African) likely explain the low accuracy rates. The use of FORDISC and 3D-ID in conjunction can help South African anthropologists in estimating ancestry and ensuring correct classifications.