What We Learned From Our Study

Articles appearing in refereed journals:

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

Authors: Meghan E. Healy, Deirdre Hill, Marianne Berwick, Heather Edgar, Jessica Gross, Keith Hunley

Citation: Healy, Meghan E., Deirdre Hill, Marianne Berwick, Heather Edgar, Jessica Gross, and Keith Hunley. “Social-Group Identity and Population Substructure in Admixed Populations in New Mexico and Latin America.” PLOS ONE 12, no. 10 (October 4, 2017): e0185503. https://doi.org/10.1371/journal.pone.0185503

Abstract

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 NMHL 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 ªSpanishº group had significantly lower Native American ancestry and higher European ancestry than the ªMexicanº 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.

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

Authors: Meghan Healy, Heather Edgar, Carmen Mosley, Keith Hunley

Abstract

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

Authors: Keith Hunley, Heather Edgar, Carmen Mosley, Graciela Cabana, Frankie West

Abstract

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.

Refereed abstracts

  • Rusk K, Mosley C, Hunley K, Healy M, Edgar H. Facial fluctuating asymmetry as a marker of cumulative health burden in women. Am J Phys Anthropol: Suppl. 2018
  • West F, Hunley K, Healy M, Mosley C, Cabana GS, Edgar H. Return of Genetic Ancestry Testing Results: An Academic-Setting Case Study. Am J Phys Anthropol TBA. 2017
  • Mosley C, Healy M, Hunley K, and Edgar HJH. 2015. Exploring Hispanic Identity: Relationships among Socioeconomic Status, Genetic Ancestry, Skin Color, and Ethnicity in the Land of Enchantment. Society for Applied Anthropology, Pittsburgh, PA. 2014
  • Mosley C, Healy M, Hunley K, Edgar HJH. Skin deep: is skin color linked to blood pressure in New Mexicans of Spanish-speaking descent? Am J Hum Biol 25:268. 2013
  • Mosley C, Healy M, Hunley K, Edgar HJH. Self--‐reported ethnicity predicts allostatic load in New Mexicans of Spanish--‐speaking descent. Human Biology Association, Knoxville, Tennessee. 2013