What is a migrant death? An operational definition for a more accurate enumeration of migrant mortality along the US-Mexico border.

Over the last forty years an indeterminate number of persons, ranging from thousands to tens of thousands, have died along the US-Mexico border during migration, fleeing poverty, armed conflict, situations of violence, and disasters. An accurate accounting of migrant deaths along the southern US border is the first step toward an understanding of the extent and the contributing factors of these deaths. In this article, we describe a key aspect of our collaborative work aimed at developing a more representative account of migrant mortality along the southwestern US border: the determination of criteria for inclusion of specific forensic cases as "migrant." Our intention is not to propose a definition of "what is a migrant death" applicable to all contexts and situations but rather one specific to the US-Mexico border region. Our main impetus is to build and launch a web portal to track and map migrant deaths at the US-Mexico border. The criteria we have identified are based on an examination of death data collected by various agencies in the four border states (California, Arizona, New Mexico, and Texas) and at the federal level by the National Missing and Unidentified Persons System (NamUs). They include a) context of human remains discovery; b) identification media/documentation; c) geographic setting; and d) personal effects. Taken together, these criteria will facilitate our determination, case by case, of the probability that human remains found along the United States side of the border may be from a person in the context of migration.

Stature estimation equations for modern American Indians in the American Southwest.

Stature estimation is a core component to the biological profile in forensic anthropology casework. Here we provide mathematical equations for estimating stature for contemporary American Indians (AI), which currently are lacking in forensic anthropology. Drawing on postmortem computed tomography data from the New Mexico Decedent Image Database we regressed cadaveric length on four long bone length measures of the tibia, femur, and humerus to produce 11 combinations of models. Separate regression models were calculated for the entire pooled sample, by sex, broad AI language groups, and age + sex subsamples and compared. Sex-specific models were statistically better than general models, which were more accurate than language group and age + sex models. Equations were created for general and sex-specific models. Application to an independent test sample demonstrates the equations are accurate for stature estimation with overestimates of less than 1 cm. The equations provide similar levels of precision to stature estimation programs like the FORDISC 3.0 module and other stature equations in the literature. We provide recommendations for equation use in casework based on our results. These equations are the first for estimating stature in contemporary AI. This paper demonstrates the appropriateness of these newly created stature equations for use in New Mexico and the surrounding region.

No relationship found between dental fluctuating asymmetry, birthweight, and birth term in two modern North American samples.

OBJECTIVE: Deciduous dental crowns primarily develop during gestation and early infancy and embody early life stress exposures. Composite measures of dental fluctuating asymmetry (DFA) generated from the deciduous teeth may therefore indicate cumulative gestational stress in developmental origins of health and disease (DOHaD) studies. This study examines whether higher composite measures of deciduous DFA are associated with low birthweight and prematurity, two aspects of birth phenotype consistently associated with increased morbidity and mortality risks in adulthood. SUBJECTS AND METHODS: We evaluated associations between composite deciduous DFA, birthweight, and birth term in two contemporary North American samples: an autopsy sample from New Mexico (n = 94), and sample from a growth cohort study in Burlington, Ontario (n = 304). Dental metric data for each sample was collected from postmortem CT scans and dental casts, respectively. Composite DFA was estimated using buccolingual (BL) and mesiodistal (MD) crown diameters from paired deciduous teeth. RESULTS: Contrary to expectations, the results of linear regression indicated no significant relationship between birthweight and DFA, or birth term and DFA, in either sample. CONCLUSIONS: Deciduous DFA does not predict aspects of birth phenotype associated with gestational stress. Birthweight and birth term are plastic relative to the more developmentally stable deciduous dentition, which may only subtly embody early life stress. We suggest that deciduous DFA should be utilized with caution in DOHaD studies until its relationship with gestational stress is clarified.

Sex-specific effects of environmental temperature during gestation on fluctuating asymmetry in deciduous teeth.

OBJECTIVES: External environmental heat exposure during gestation impacts the physiology of human development in utero, but evidence for these impacts has not yet been explored in dentition. We examined deciduous teeth for fluctuating asymmetry (FA), a measure of developmental instability, together with gestational environmental temperature data drawn from historical weather statistics. MATERIALS AND METHODS: We measured dental casts from the longitudinal Burlington Growth Study, representing 172 participants (ages 3-6 years) with health records. FA was calculated from crown dimensions and intercuspal distances that develop during gestation. Multiple regression separated by sex (nfemale = 81) examined the effects of mean temperatures in each trimester, controlling for birth year. RESULTS: In females, increased temperatures during the first trimester are significantly associated with an increase in FA (p = 0.03), specifically during the second and third prenatal months (p = 0.03). There is no relationship between temperature and FA for either sex in the second or third trimesters, when enamel is formed. DISCUSSION: Dental instability may be sensitive to temperature in the first trimester in females during the scaffolding of crown shape and size in the earliest stages of tooth formation. Sexual dimorphism in growth investment strategies may explain the differences in results between males and females. Using enduring dental characteristics, these results advance our understanding of the effects of temperature on fetal physiology within a discrete period.

Error and bias in race and ethnicity descriptions in medical examiner records in New Mexico: Consequences for understanding mortality among Hispanic/Latinos.

Researchers use public records from deceased individuals to identify trends in manners and causes of death. Errors in the description of race and ethnicity can affect the inferences researchers draw, adversely impacting public health policies designed to eliminate health inequity. Using the New Mexico Decedent Image Database, we examine: 1) the accuracy of death investigator descriptions of race and ethnicity by comparing their reports to those from next of kin (NOK), 2) the impact of decedent age and sex on disagreement between death investigators and NOK, and 3) the relationship between investigators' descriptions of decedent race and ethnicity and cause and manner of death from forensic pathologists (n = 1813). Results demonstrate that investigators frequently describe race and ethnicity incorrectly for Hispanic/Latino decedents, especially regarding homicide manner of death and injury and substance abuse causes of death. Inaccuracies may cause biased misperceptions of violence within specific communities and affect investigative processes.

South-to-north migration preceded the advent of intensive farming in the Maya region.

The genetic prehistory of human populations in Central America is largely unexplored leaving an important gap in our knowledge of the global expansion of humans. We report genome-wide ancient DNA data for a transect of twenty individuals from two Belize rock-shelters dating between 9,600-3,700 calibrated radiocarbon years before present (cal. BP). The oldest individuals (9,600-7,300 cal. BP) descend from an Early Holocene Native American lineage with only distant relatedness to present-day Mesoamericans, including Mayan-speaking populations. After ~5,600 cal. BP a previously unknown human dispersal from the south made a major demographic impact on the region, contributing more than 50% of the ancestry of all later individuals. This new ancestry derived from a source related to present-day Chibchan speakers living from Costa Rica to Colombia. Its arrival corresponds to the first clear evidence for forest clearing and maize horticulture in what later became the Maya region.

A biological approach to adult sex differences in skeletal indicators of childhood stress.

OBJECTIVES: In previous work examining the etiology of cribra orbitalia (CO) and porotic hyperostosis (PH) in a contemporary juvenile mortality sample, we noted that males had higher odds of having CO lesions than females. Here, we examine potential reasons for this pattern in greater detail. Four non-mutually exclusive mechanisms could explain the observed sex differences: (1) sex-biased mortality; (2) sexual dimorphism in immune responses; (3) sexual dimorphism in bone turnover; or (4) sexual dimorphism in marrow conversion. SUBJECTS AND METHODS: The sample consists of postmortem computed tomography scans and autopsy reports, field reports, and limited medical records of 488 individuals from New Mexico (203 females; 285 males) aged between 0.5 and 15 years. We used Kaplan-Meier survival analysis, predicted probabilities, and odds ratios to test each mechanism. RESULTS: Males do not have lower survival probabilities than females, and we find no indications of sex differences in immune response. Overall, males have a higher probability of having CO or PH lesions than females. CONCLUSIONS: All results indicate that lesion formation in juveniles is influenced by some combination of sex differences in the pace of red-yellow conversion of the bone marrow and bone turnover. The preponderance of males with CO and PH likely speaks to the potential for heightened osteoblastic activity in males. We find no support for the hypotheses that sex biases in mortality or immune responses impacted lesion frequency in this sample. Sex differences in biological processes experienced by children may affect lesion formation and lesion expression in later life.

Refined, regionally-specific data standards reveal heterogeneity in Hispanic death records.

Hispanic ethnicity can be captured with differing levels of granularity using various data standards, including those from the Office of Management and Budget, Health and Human Services and National Academy of Medicine. Previous research identified seven subgroups of Hispanics in New Mexico using open-ended interviews and information about the culture/history of the state. We examined age and manner of death to determine whether differences among subgroups are hidden by less-refined categorization. Significant differences in the mean age at death were found between some groups, including Spanish and Mexican Americans. We found an association between specific manners of death codes and subgroups. However, significance disappeared when manners of death were grouped (e.g. accident, homicide, etc.). This indicates that while certain manners of death are associated with group membership, overall types of death are not. Data descriptors for Hispanics should reflect more refined, regionally relevant groups, in order to unmask heterogeneity.

Colonialism, ethnogenesis, and biogeographic ancestry in the US Southwest.

OBJECTIVE: Differences between self-perceived biogeographic ancestry and estimates derived from DNA are potentially informative about the formation of ethnic identities in different sociohistorical contexts. Here, we compared self-estimates and DNA-estimates in New Mexico, where notions of shared ancestry and ethnic identity have been shaped by centuries of migration and admixture. MATERIALS AND METHODS: We asked 507 New Mexicans of Spanish-speaking descent (NMS) to list their ethnic identity and to estimate their percentages of European and Native American ancestry. We then compared self-estimates to estimates derived from 291,917 single nucleotide polymorphisms (SNPs), and we examined how differences between the estimates varied by ethnic identity. RESULTS: Most NMS (94%) predicted that they had non-zero percentages of European and Native American ancestry. Self-estimates and SNP-estimates were positively correlated (rEuropean  = 0.38, rNative-American  = 0.36, p < 0.001). The correlations belie systematic patterns of underestimation and overestimation based on ethnic identity. NMS with ancestral ties to 20th century immigrants, who identified as Mexican or Mexican American, often underestimated their European ancestry (self-estimate < SNP-estimate) and overestimated their Native American ancestry. The pattern was reversed for NMS who emphasized deep connections to colonial New Mexico and identified as Spanish or Spanish American. DISCUSSION: While NMS accurately predicted that they had European and Native American ancestry, they predicted ancestry percentages with only moderate accuracy. Differences between self-estimated and SNP-estimated ancestry were associated with ethnic identities that were shaped by migration to the region over the past 400 years. We connect ethnic identities and patterns of ancestry estimation to resistance to colonial hegemony and discuss the implications of our results for the construction of ethnic identities, now and in the past.

Conventional microscopy makes perikymata count and spacing data feasible for large samples.

OBJECTIVES: Current methods of quantifying defects of dental enamel (DDE) include either gross or low-level examination for linear enamel hypoplasia, histological analysis of striae of Retzius, or scanning electron microscopy (SEM) of a tooth or a tooth cast. Gross examination has been shown to miss many defects. Other methods can be destructive, require transporting samples, and are expensive. Here, we show that digital light microscopy (DLM) can be used for the analysis of DDE as indicated by widened perikymata spacing (WPS). This method takes advantage of high-power (100×) microscopy, but is non-destructive, can be implemented almost anywhere, and is inexpensive. MATERIALS AND METHODS: As proof of concept, we created photomontages of labial surfaces of five human canines from images made using DLM and SEM. We counted and measured the widths of all visible perikymata for each imaging modality and fit measurements to a negative curve representing the expected values for each tooth. We calculated residuals for each measurement. WPS were defined when R2 was in the 90th percentile, and were considered matched in DLM and SEM images when observed within the same decile of the tooth surface. RESULTS: There were more WPS detected in the images derived from DLM than from SEM. Overall, the data derived from the two imaging modalities provided similar information about the frequency and timing of stress during dental development. CONCLUSIONS: The method described here allows for DDE data acquisition as WPS from large samples, making feasible population-level studies that reflect sophisticated understanding of dental development.

Childhood dietary quality predicts adult facial fluctuating asymmetry in contemporary New Mexicans.

Fluctuating asymmetry (FA) in adults is thought to reflect specific types of developmental stress. If true, adult FA may be a proxy for developmental stress in past as well as current populations. To date, studies of the link between development and adult FA have produced ambiguous results due to insufficient measurement data for childhood environments. This study seeks to overcome this limitation using a structural equation modeling approach to evaluate the relationship between 29 measures of developmental environments and precise measures of adult FA. Sociodemographic information and 3D facial photographs were collected from 80 adult New Mexicans. Facial FA was measured from the photographs using geometric morphometric analysis of 12 facial landmarks. Each participant responded to a questionnaire addressing the developmental environment, including childhood home environment, family SES, health, and dietary quality. We used structural equation models to examine predictive relationships between latent variables constructed from questionnaire responses and adult facial FA. Childhood dietary quality was negatively associated with adult FA scores, meaning that poorer diets predict higher FA (standardized path coefficient -0.174, p = 0.039). Factors that loaded positively on the dietary quality construct were a diet quality index, the frequency of homemade meals, and the frequency of homemade breakfast, while the frequency of fast-food meals loaded negatively. No other latent variable predicted adult facial FA. We posit that the negative relationship between dietary quality and FA reflects a negative energy balance experienced during development. Insufficient nutrition results in a reduced capacity to buffer against environmental perturbations, with increased FA as evidence. Given previously established links between FA and adult health outcomes in humans, this finding also underscores the importance of dietary quality during development for ensuring health and wellbeing later in life. These results indicate that FA in facial shape may signal the relative quality of dietary conditions during development.

Developing the Minimum Dataset for the New Mexico Decedent Image Database.

BACKGROUND: A minimum dataset (MDS) can be determined ad hoc by an investigator or small team; by a metadata expert; or by using a consensus method to take advantage of the global knowledge and expertise of a large group of experts. The first method is the most commonly applied. OBJECTIVE: Here, we describe a use of the third approach using a modified Delphi method to determine the optimal MDS for a dataset of full body computed tomography scans. The scans are of decedents whose deaths were investigated at the New Mexico Office of the Medical Investigator and constitute the New Mexico Decedent Image Database (NMDID). METHODS: The authors initiated the consensus process by suggesting 50 original variables to elicit expert reactions. Experts were recruited from a variety of scientific disciplines and from around the world. Three rounds of variable selection showed high rates of consensus. RESULTS: In total, 59 variables were selected, only 52% of which the original resource authors selected. Using a snowball method, a second set of experts was recruited to validate the variables chosen in the design phase. During the validation phase, no variables were selected for deletion. CONCLUSION: NMDID is likely to remain more "future proof" than if a single metadata expert or only the original team of investigators designed the metadata.

Geographic and temporal diversity in dental morphology reflects a history of admixture, isolation, and drift in African Americans.

OBJECTIVES: While genetic studies have documented variation in admixture proportions in contemporary African Americans across the US, relatively little is known about the socio-historical roots of this variation. Our goal in this study is to use dental morphology to explore the socio-historical correlates of admixture, localized gene flow, and drift in African Americans. METHODS: Our data are ordinally-graded dental morphological traits scored in 196 Africans, 335 Europeans and European Americans, 291 pre-Spanish-contact Native Americans, and 722 African Americans. The African American data derived from contemporary and historic samples. We eliminated from analysis individuals and traits with greater than 20% missing data. We summarized the major axes of trait variation using principal component analysis (PCA), estimated biological distance, constructed multidimensional scaling (MDS) plots of the distances, and measured the correlation between geographic and biological distance. RESULTS: In the PCA, African American groups clustered between Africans and Europeans on PC 1, reflecting admixture between the groups. PC 2 separated African American samples, possibly reflecting movement, isolation, and drift. MDS analyses confirmed the existence of sizable biological distances between African American samples, especially between contemporary and past African American samples. We found no relationship between biological and geographic distances. DISCUSSION: We demonstrate that admixture and drift can be inferred from multi-variable analyses of patterns of dental morphology in admixed populations. Localized gene flow has not affected patterns of trait variation in African Americans, but long-range movement, isolation, and drift have. We connect patterns of dental trait variation to efforts to flee oppression during the Great Migration, and the repeal of anti-miscegenation laws.

Cribra orbitalia and porotic hyperostosis are associated with respiratory infections in a contemporary mortality sample from New Mexico.

OBJECTIVES: Cribra orbitalia (CO) and porotic hyperostosis (PH) are porous cranial lesions (PCLs) classically associated with iron-deficiency anemia in bioarchaeological contexts. However, recent studies indicate a need to reassess the interpretation of PCLs. This study addresses the potential health correlates of PCLs in a contemporary sample by examining relationships between the known cause of death (COD) and PCL presence/absence. METHODS: This study includes a sample of 461 juvenile individuals (6 months to 15 years of age) who underwent examination at the University of New Mexico's Office of the Medical Investigator between 2011 and 2019. The information available for each individual includes their sex, age at death, and their COD and manner of death. RESULTS: Odds ratio of having CO (OR = 3.92, p < .01) or PH (OR = 2.86, p = .02) lesions are increased in individuals with respiratory infections. Individuals with heart conditions have increased odds of having CO (OR = 3.52, p = .03) lesions, but not PH. CONCLUSION: Individuals with respiratory infection are more likely to have CO and/or PH. CO appears to have a greater range of health correlates than PH does, as indicated by the heart condition results. However, individuals with congenital heart defects are at higher risk for respiratory infections, so bony alterations in cases of heart conditions may be due to respiratory illness. Since respiratory infection remains a leading cause of mortality today, CO and PH in bioarchaeological contexts should be considered as potential indicators of respiratory infections in the past.

Early isotopic evidence for maize as a staple grain in the Americas.

Maize is a cultigen of global economic importance, but when it first became a staple grain in the Americas, was unknown and contested. Here, we report direct isotopic dietary evidence from 52 radiocarbon-dated human skeletons from two remarkably well-preserved rock-shelter contexts in the Maya Mountains of Belize spanning the past 10,000 years. Individuals dating before ~4700 calendar years before present (cal B.P.) show no clear evidence for the consumption of maize. Evidence for substantial maize consumption (~30% of total diet) appears in some individuals between 4700 and 4000 cal B.P. Isotopic evidence after 4000 cal B.P. indicates that maize became a persistently used staple grain comparable in dietary significance to later maize agriculturalists in the region (>70% of total diet). These data provide the earliest definitive evidence for maize as a staple grain in the Americas.

Extracting and Standardizing Medical Examiner Data to Improve Health.

Data from medical examiner offices are not commonly used in informatics but may contain information not in medical records. However, the vast majority of data is not standardized and is available only in large free text fields. We sought to extract information from the medical examiner database using Canary, a natural language processing tool. The text was then standardized to fit the selected normative answer list for each field. Multiple terminology and vocabulary standards from a variety of settings were utilized as data came from the medical examiner and interviews with next of kin. Thirty-seven percent of the metadata fields could be mapped directly to existing standards, twenty-five percent required a modification, and thirty-eight required creation of a standardized normative answer list. The newly formed database (New Mexico Decedent Image Database (NMDID)), will be available to researchers and educators at the beginning of 2020.

Colonialism and the co-evolution of ethnic and genetic structure in New Mexico.

OBJECTIVE: Socially constructed ethnic identities are frequently rooted in beliefs about common descent that form when people with disparate cultures, languages, and biology come into contact. This study explores connections between beliefs about common descent, as represented by ethnic nomenclatures, and histories of migration and isolation ascertained from genomic data in New Mexicans of Spanish-speaking descent (NMS). MATERIALS AND METHODS: We interviewed 507 NMS who further identified using one of seven ethnic terms that they associated with beliefs about connections to past ancestors. For groups of individuals who identified using each term, we estimated biogeographic ancestry, fit admixture models to ancestry distributions, and partitioned genetic distance into admixture and drift components. RESULTS: Regardless of which ethnic term they used, all NMS had appreciable Native American (avg. 27%) and European ancestry (avg.71%). However, individuals who identified using terms associated with beliefs connecting them to colonial-period Spanish ancestors had significantly higher European ancestry than individuals who identified using terms associated with ancestral connections to post-colonial-period migrants from Mexico. Model-fitting analyses show that this ancestry difference reflects post-colonial gene flow with non-NMS European Americans, not colonial-period gene flow with Spaniards. Drift, not admixture, accounted for most of the genetic distance between NMS who expressed connections to Mexican versus Spanish ancestors, reflecting relative isolation of New Mexico and Mexico through the 19th century. DISCUSSION: Patterns of genomic diversity in NMS are consistent with beliefs about common descent in showing that New Mexico was isolated for generations following initial colonization. They are inconsistent with these beliefs in showing that all NMS have substantial European and Native American ancestry, and in showing that a proportion of European ancestry derives from post-colonial-period admixture with non-NMS European Americans. Our findings provide insights into the construction of ethnic identity in contexts of migration and isolation in New Mexico and, potentially, throughout human prehistory.

Sociocultural determinants of health and wealth in historic African Americans.

In this study, we examine the impacts of individual ancestry and socioeconomic status (SES) on health in historic African Americans through bioarchaeological means. We estimate ancestry from dental morphology and SES from the costs of coffin hardware. We include 188 adult individuals from Freedman's Cemetery in Dallas, Texas, and 2,301 individuals of African and European descent for comparison. Freedman's Cemetery functioned as the only cemetery available to freed people and their descendants between 1869 and 1907. Linear discriminant analysis (LDA) of dental morphological traits was used to estimate individual ancestry. LDA results were then used in Cox proportional hazards analysis to examine whether ancestry impacted mortality risk or SES. Ancestry was not found to impact SES. However, paralleling results from analysis of census mortality data, individuals with greater African ancestry on average have shorter lifespans and higher mortality hazards than individuals who have more European ancestry. This finding provides evidence for structural violence in this historic African American skeletal sample. The negative effects of social constructs are embodied and can be detected in skeletal samples through use of statistical methods combined with information about the cultural context in which people lived.

Standardizing Data from the Dead.

A database of full-body CT scans and associated lifestyle and health data from decedents who underwent an autopsy at the Office of the Medical Investigator (OMI) is under construction. The dataset has 68 metadata fields containing data from the OMI's database and interviews with next of kin. Some metadata fields could be mapped to existing standards, but the majority of fields required some modifications to current standards or the creation of new standards.

Informativeness of dental morphology in ancestry estimation in African Americans.

OBJECTIVES: Our objective is to assess the informativeness of dental morphology in estimating biogeographic ancestry in African Americans. MATERIALS AND METHODS: The data are 62 dental morphological traits scored as nondichotomized and dichotomized in 797 individuals, 992,601 SNPs from 271 individuals, and 645 STRs from 177 individuals. Each dataset consists of Africans, Europeans, and African Americans. For each dataset, we summed Fisher Information (FI), then used STRUCTURE to estimate ancestry. RESULTS: Total FI was highest for SNPs, followed by STRs, nondichotomized dental traits, and dichotomized dental traits. For both genetic datasets, Africans and Europeans fell into two distinctive clusters with low 90% credible regions for individual ancestry estimates. In African Americans, membership in the African cluster was 76.4% and 80.4% for SNPs and STRs, respectively. For the dental data, all Africans and Europeans had appreciable membership in both clusters and comparatively high 90% credible regions for individual ancestry estimates. Nonetheless, African Americans had consistently higher membership in the same cluster in which Africans had high membership. African American membership in this cluster was significantly higher for the nondichotomized form than for the dichotomized. DISCUSSION AND CONCLUSIONS: FI potentially provides a useful gauge of the effectiveness of dental and genetic data for ancestry estimation. The comparatively high FI of nondichotomized dental traits suggests data in this form may be better suited for studies of admixture than dichotomized data. Because of high error in individual ancestry estimates, dental morphological data may be unable to distinguish differences in ancestry among individuals within admixed populations.