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.

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.

Associations between ethnic identity, regional history, and genomic ancestry in New Mexicans of Spanish-speaking descent.

This study examines associations between ethnic identity, regional history, and genomic ancestry in New Mexicans of Spanish-speaking descent (NMS). In structured interviews, we asked 507 NMS to select from a list of eight ethnic identity terms identified in previous research. We estimated genomic ancestry for each individual from 291,917 single nucleotide polymorphisms (SNPs) and compared genomic ancestry, age, and birthplace between groups of individuals who identified using each ethnic identity term. Eighty-eight per cent of NMS who identified as "Hispanic," "Nuevomexicano/a," and "Spanish," on average, were born in New Mexico, as were the vast majority of their parents and grandparents. Thirty-three per cent of NMS who identified as "Mexican" and "Mexican American" were born in Mexico, as were 59 per cent of their parents and 67 per cent of their grandparents. Average Native American and African ancestry proportions in "Hispanic" (0.26, 0.02, respectively), "Spanish" (0.25, 0.01), and "Nuevomexicano/a" (0.24, 0.01) NMS were significantly lower than in "Mexican American" (0.37, 0.04) NMS. Significant age differences between older "Spanish" and younger "Nuevomexicano/a" individuals, combined with widespread use of the term "Hispanic," may reflect ongoing nomenclature changes. Patterns of correspondence between ethnic identity, ethnic nomenclatures, and genomic ancestry reflect historical patterns of migration, colonization, and cultural change.

Social-group identity and population substructure in admixed populations in New Mexico and Latin America.

We examined the relationship between continental-level genetic ancestry and racial and ethnic identity in an admixed population in New Mexico with the goal of increasing our understanding of how racial and ethnic identity influence genetic substructure in admixed populations. Our sample consists of 98 New Mexicans who self-identified as Hispanic or Latino (NM-HL) and who further categorized themselves by race and ethnic subgroup membership. The genetic data consist of 270 newly-published autosomal microsatellites from the NM-HL sample and previously published data from 57 globally distributed populations, including 13 admixed samples from Central and South America. For these data, we 1) summarized the major axes of genetic variation using principal component analyses, 2) performed tests of Hardy Weinberg equilibrium, 3) compared empirical genetic ancestry distributions to those predicted under a model of admixture that lacked substructure, 4) tested the hypotheses that individuals in each sample had 100%, 0%, and the sample-mean percentage of African, European, and Native American ancestry. We found that most NM-HL identify themselves and their parents as belonging to one of two groups, conforming to a region-specific narrative that distinguishes recent immigrants from Mexico from individuals whose families have resided in New Mexico for generations and who emphasize their Spanish heritage. The "Spanish" group had significantly lower Native American ancestry and higher European ancestry than the "Mexican" group. Positive FIS values, PCA plots, and heterogeneous ancestry distributions suggest that most Central and South America admixed samples also contain substructure, and that this substructure may be related to variation in social identity. Genetic substructure appears to be common in admixed populations in the Americas and may confound attempts to identify disease-causing genes and to understand the social causes of variation in health outcomes and social inequality.

Social Identity in New Mexicans of Spanish-Speaking Descent Highlights Limitations of Using Standardized Ethnic Terminology in Research.

In this study, we evaluated the extent to which regional history has shaped the social identity nomenclature in New Mexicans of Spanish-speaking descent (NMSD). We asked 507 NMSD to list the social-identity terms they used to describe themselves and their parents, and we examined the correspondence between these choices and family ties to the region, birthplace, and continental ancestry. NMSD frequently identified using the regional terms "Nuevomexicano/a" (15%) and "Spanish" (12%). These individuals reported family ties to the region that predate New Mexican statehood. They and their parents were frequently born in New Mexico, frequently chose the other of the two terms as a secondary descriptor, and frequently ascribed one of the two terms to their parents. About 10% of NMSD identified as "Mexican American" and "Mexican." About 25% of these individuals, and more than half of their parents, were born in Mexico. They also frequently chose the other of the two terms as a secondary descriptor and frequently ascribed one of the two terms to their parents. Compared to NMSD who identified as "Mexican" and "Mexican American," individuals who identified as "Nuevomexicano/a" and "Spanish" had higher European ancestry and lower Native American and African ancestry. Our results also suggest that the term "Hispanic," frequently chosen as both a primary and secondary social identity term by NMSD, may, as it continues to rise in prominence, mask more deeply rooted and potential socially relevant aspects of social identity in New Mexico. More broadly, these results indicate that regional history influences social identity nomenclatures in ways that are potentially incompatible with US Office of Management and Budget standards. This incompatibility may adversely affect the ability of researchers in the social sciences to assess the causes of social inequality and health disparities in individuals of Spanish-speaking descent in different regions of the United States. We argue that future studies would benefit from more fine-grained, region-specific analyses of social identity.

The effects of socioeconomic status, clinical factors, and genetic ancestry on pulmonary tuberculosis disease in northeastern Mexico.

Diverse socioeconomic and clinical factors influence susceptibility to tuberculosis (TB) disease in Mexico. The role of genetic factors, particularly those that differ between the parental groups that admixed in Mexico, is unclear. The objectives of this study are to identify the socioeconomic and clinical predictors of the transition from latent TB infection (LTBI) to pulmonary TB disease in an urban population in northeastern Mexico, and to examine whether genetic ancestry plays an independent role in this transition. We recruited 97 pulmonary TB disease patients and 97 LTBI individuals from a public hospital in Monterrey, Nuevo León. Socioeconomic and clinical variables were collected from interviews and medical records, and genetic ancestry was estimated for a subset of 142 study participants from 291,917 single nucleotide polymorphisms (SNPs). We examined crude associations between the variables and TB disease status. Significant predictors from crude association tests were analyzed using multivariable logistic regression. We also compared genetic ancestry between LTBI individuals and TB disease patients at 1,314 SNPs in 273 genes from the TB biosystem in the NCBI BioSystems database. In crude association tests, 12 socioeconomic and clinical variables were associated with TB disease. Multivariable logistic regression analyses indicated that marital status, diabetes, and smoking were independently associated with TB status. Genetic ancestry was not associated with TB disease in either crude or multivariable analyses. Separate analyses showed that LTBI individuals recruited from hospital staff had significantly higher European genetic ancestry than LTBI individuals recruited from the clinics and waiting rooms. Genetic ancestry differed between individuals with LTBI and TB disease at SNPs located in two genes in the TB biosystem. These results indicate that Monterrey may be structured with respect to genetic ancestry, and that genetic differences in TB susceptibility in parental populations may contribute to variation in disease susceptibility in the region.