Bruce E. Anderson

Identifying Southwest Hispanics Using Nonmetric Traits and the Cultural Profile

Abstract:  Due to the increasing number of Southwest Hispanics in the United States, as well as the overwhelming number of foreign nationals that die every year trying to enter the United States along the southern United States border with Mexico, new methods for classifying individuals have been established at the Pima County Office of the Medical Examiner in Tucson, Arizona (PCOME). For each of the past 5 years, the PCOME has investigated a record number of deaths associated with these border crossings. The overwhelming majority of the identified decedents are Mexican Nationals. However, approximately 25% of these undocumented border crossers have yet to be identified, making it clear that improved methods for human identification are greatly needed. The first goal of this paper is to delineate the suite of skeletal nonmetric traits utilized in assessing Southwest Hispanic ancestry at the PCOME. This suite of nonmetric traits has proven to be an effective component in establishing the “biological profile” of unknown individuals in these cases. The second goal of this paper is to introduce methods used at the PCOME to establish the “cultural profile” of individuals in these cases. The “cultural profile” is a set of identification criteria that include: the geographic context of recovery, personal effects, dental health, and cultural accoutrements. Establishing the “cultural profile” in these cases is essential in identifying individuals as foreign nationals who have died trying to cross the border.

Identifying the Dead: Methods Utilized by the Pima County (Arizona) Office of the Medical Examiner for Undocumented Border Crossers: 2001–2006*

Abstract:  The Pima County (Arizona) Office of the Medical Examiner has seen a dramatic rise over the past 6 years in the number of deaths related to the illegal crossing of our international border with Mexico. This rise in deaths is undoubtedly related to an increase in the number of foreign nationals who cross into the various Arizona jurisdictions that utilize the Pima County Medical Examiner to investigate their unnatural deaths. Because of the utterly dangerous nature of trekking across the Sonoran Desert, especially in the summer months, many of these unfortunate migrants succumb to the effects of heat‐related illness and perish along the journey. The combined effects of a dry, hot environment and the remoteness of some of the trekking corridors can quickly render a deceased person unidentifiable by visual means. Thus, our office is faced with not only an increase in the number of deaths requiring medico‐legal investigation but also an increase in the number of decedents needing additional specialized examinations in an effort to effect identification. This paper attempts to outline the problems and the methods utilized by our office over the past 6 years in the identification process of undocumented border crossers. It is hoped that this paper, as well as the others presented at this symposium, will allow for the sharing of information amongst all medical investigators who assist in the identification of these migrants. The identification of these individuals takes on added importance when one considers the possible nationalities, and perhaps motivation for entering into the US, of those that remain unidentified.

Ancestry Assessment Using Random Forest Modeling

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.

Morphoscopic Trait Expression in “Hispanic” Populations

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.

The Role of the Anthropologist in the Identification of Migrant Remains in the American Southwest

This article focuses on the role of the forensic anthropologist in the identification of migrant remains in the American Southwest. These migrant cases present a unique set of circumstances that necessitate a regional approach to identification. The Pima County Office of the Medical Examiner (PCOME), located in Tucson, Arizona has developed best practices that facilitate high identification rates of migrant deaths. These best practices have provided a foundation for other agencies that are faced with similar issues; namely, developing specific protocols for migrant deaths, working with nongovernmental humanitarian organizations, and sharing information have maximized identification efforts. In 2012, Texas surpassed Arizona in the number of migrant deaths. The Forensic Anthropology Center at Texas State (FACTS) began identification efforts for migrant remains found in Brooks County, Texas in 2013. Informed by best practices from the PCOME, FACTS has made successful identifications. Descriptions of the processes at both the PCOME and FACTS are described in detail.

Enigmatic Cranial Superstructures Among Chamorro Ancestors From The Mariana Islands: Gross Anatomy and Microanatomy

This study focuses on the gross anatomy, anatomic relations, microanatomy, and the meaning of three enigmatic, geographically patterned, and quasi‐continuous superstructures of the posterior cranium. Collectively known as occipital superstructures (OSSs), these traits are the occipital torus tubercle (TOT), retromastoid process (PR), and posterior supramastoid tubercle (TSP). When present, TOT, PR, and TSP develop at posterior cranial attachment sites of the upper trapezius, superior oblique, and sternocleidomastoid muscles, respectively. Marked expression and co‐occurrence of these OSSs are virtually circumscribed within Oceania and reach highest recorded frequencies in protohistoric Chamorros (CHamoru) of the Mariana Islands. Prior to undertaking scanning electron microscopy (SEM) work, our working multifactorial model for OSS development was that early‐onset, long‐term, and chronic activity‐related microtrauma at enthesis sites led to exuberant reactive or reparative responses in a substantial minority of genetically predisposed (and mostly male) individuals. SEM imaging, however, reveals topographic patterning that questions, but does not negate, activity induction of these superstructures. Although OSSs appear macroscopically as relatively large and discrete phenomena, SEM findings reveal a unique, widespread, and seemingly systemic distribution of structures over the occipital surface that have the appearance of OSS microforms. Nevertheless, apparent genetic underpinnings, anatomic relationships with muscle entheses, and positive correlation of OSS development with humeral robusticity continue to suggest that these superstructures have potential to at once bear witness to Chamorro population history and inform osteobiographical constructions of chronic activity patterns in individuals bearing them. Further work is outlined that would illuminate the proximate and ultimate meanings of OSS. Anat Rec, 297:1009–1021, 2014.

Immature Human Skeletal Remains from Homol'ovi III

ABSTRACTThe well-preserved immature skeletons of three individuals, aged at about five and one-half fetal months, nine and one-half fetal months, and one year, are examined. The youngest was delivered to the Human Identification Laboratory in its surrounding matrix, thus enabling precise identification of individual bones. This fact takes on added importance because vertebral anomalies are present. These anomalies, fusions of adjacent neural hemi-arches, are also exhibited by the individual aged at nine and one-half fetal months. Additional abnormalities in two ribs of this infant indicate the possibility of Klippel-Feil Syndrome, an inherited cervical spine disorder. The one-year-old infant has a marked facial asymmetry, another manifestation of this syndrome, thus suggesting a genetic link among all three individuals. Finally, cribra orbitalia, which could have been caused by an iron-deficiency anemia, may be evident in the one-year-old child.

Understanding (Mis)classification Trends of Latin Americans in Fordisc 3.1: Incorporating Cranial Morphology, Microgeographic Origin, and Admixture Proportions for Interpretation

Assigning correct population affinity to a skeleton can contribute important information to an investigation—yet recent work highlights high error rates when classifying Latinos with a traditional tool, Fordisc 3.1 (FD3). Our study examines whether misclassification trends exist, and whether these can be used to infer population affinity. We examine the relationships among ancestry, geography, and FD3 misclassifications of Latinos using canonical variate analysis and unsupervised model‐based clustering of craniometrics. Northern Mexicans appear more strongly associated with FD3 references samples with elevated amounts of European ancestry (e.g., American Blacks and Whites), while Southern Mexicans are more strongly associated with FD3 reference samples with reduced amounts of European ancestry (e.g., Guatemalans and Native Americans). FD3 classifications revealed that Latinos exhibited lower posterior probabilities when compared to other common case demographics (Whites and African Americas), even when the classification was “correct.” We make recommendations for practitioner interpretation of FD3 reports for casework.