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This article provides an estimation of how frequently, and from whom, children aged 0-11 years (Ns between 9 and 24) receive one-on-one verbal input among Tsimane forager-horticulturalists of lowland Bolivia. Analyses of systematic daytime behavioral observations reveal < 1 min per daylight hour is spent talking to children younger than 4 years of age, which is 4 times less than estimates for others present at the same time and place. Adults provide a majority of the input at 0-3 years of age but not afterward. When integrated with previous work, these results reveal large cross-cultural variation in the linguistic experiences provided to young children. Consideration of more diverse human populations is necessary to build generalizable theories of language acquisition.

This research tests how perceived school and peer norms predict interethnic experiences among ethnic minority and majority youth. With studies in Chile (654 nonindigenous and 244 Mapuche students, M = 11.20 and 11.31 years) and the United States (468 non-Hispanic White and 126 Latino students, M = 11.66 and 11.68 years), cross-sectional results showed that peer norms predicted greater comfort in intergroup contact, interest in cross-ethnic friendships, and higher contact quality, whereas longitudinal results showed that school norms predicted greater interest in cross-ethnic friendships over time. Distinct effects of school and peer norms were also observed for ethnic minority and majority youth in relation to perceived discrimination, suggesting differences in how they experience cross-ethnic relations within school environments.

The genetic background of Brazilians encompasses Amerindian, African, and European components as a result of the colonization of an already Amerindian inhabited region by Europeans, associated to a massive influx of Africans. Other migratory flows introduced into the Brazilian population genetic components from Asia and the Middle East. Currently, Brazil has a highly admixed population and, therefore, the study of genetic factors in the context of health or disease in Brazil is a challenging and remarkably interesting subject. This phenomenon is exemplified by the genetic variant CCR5Δ32, a 32 base-pair deletion in the CCR5 gene. CCR5Δ32 originated in Europe, but the time of origin as well as the selective pressures that allowed the maintenance of this variant and the establishment of its current frequencies in the different human populations is still a field of debates. Due to its origin, the CCR5Δ32 allele frequency is high in European-derived populations (~10%) and low in Asian and African native human populations. In Brazil, the CCR5Δ32 allele frequency is intermediate (4-6%) and varies on the Brazilian States, depending on the migratory history of each region. CCR5 is a protein that regulates the activity of several immune cells, also acting as the main HIV-1 co-receptor. The CCR5 expression is influenced by CCR5Δ32 genotypes. No CCR5 expression is observed in CCR5Δ32 homozygous individuals. Thus, the CCR5Δ32 has particular effects on different diseases. At the population level, the effect that CCR5Δ32 has on European populations may be different than that observed in highly admixed populations. Besides less evident due to its low frequency in admixed groups, the effect of the CCR5Δ32 variant may be affected by other genetic traits. Understanding the effects of CCR5Δ32 on Brazilians is essential to predict the potential use of pharmacological CCR5 modulators in Brazil. Therefore, this study reviews the impacts of the CCR5Δ32 on the Brazilian population, considering infectious diseases, inflammatory conditions, and cancer. Finally, this article provides a general discussion concerning the impacts of a European-derived variant, the CCR5Δ32, on a highly admixed population.

This article tests a longitudinal model of the antecedents and consequences of changes in identification with indigenous (Mapuche) among indigenous and nonindigenous youth in Chilean school contexts over a 6-month period (633 nonindigenous and 270 Mapuche students, Mages = 12.47 and 12.80 years, respectively). Results revealed that in-group norms supporting contact and quality of intergroup contact at Time 1 predicted student's changes in Mapuche identification at Time 2, which in turn predicted changes in support for adoption of Chilean culture and maintenance of Mapuche culture at Time 2; some of the relationships between these variables were found to be moderated by age and ethnicity. Conceptual and policy implications are addressed in the Discussion.

Human populations often exhibit contrasting patterns of genetic diversity in the mtDNA and the nonrecombining portion of the Y-chromosome (NRY), which reflect sex-specific cultural behaviors and population histories. Here, we sequenced 2.3 Mb of the NRY from 284 individuals representing more than 30 Native American groups from Northwestern Amazonia (NWA) and compared these data to previously generated mtDNA genomes from the same groups, to investigate the impact of cultural practices on genetic diversity and gain new insights about NWA population history. Relevant cultural practices in NWA include postmarital residential rules and linguistic exogamy, a marital practice in which men are required to marry women speaking a different language. We identified 2,969 SNPs in the NRY sequences, only 925 of which were previously described. The NRY and mtDNA data showed different sex-specific demographic histories: female effective population size has been larger than that of males through time, which might reflect larger variance in male reproductive success. Both markers show an increase in lineage diversification beginning ∼5,000 years ago, which may reflect the intensification of agriculture, technological innovations, and the expansion of regional trade networks documented in the archaeological evidence. Furthermore, we find similar excesses of NRY versus mtDNA between-population divergence at both the local and continental scale, suggesting long-term stability of female versus male migration. We also find evidence of the impact of sociocultural practices on diversity patterns. Finally, our study highlights the importance of analyzing high-resolution mtDNA and NRY sequences to reconstruct demographic history, since this can differ considerably between sexes.

This phenomenologically oriented ethnography focuses on experiential aspects of Yanomami shamanism, including shamanistic activities in the context of cultural change. The author interweaves ethnographic material with theoretical components of a holographic principle, or the idea that the \"part is equal to the whole,\" which is embedded in the nature of the Yanomami macrocosm, human dwelling, multiple-soul components, and shamans' relationships with embodied spirit-helpers. This book fills an important gap in the regional study of Yanomami people, and, on a broader scale, enriches understanding of this ancient phenomenon by focusing on the consciousness involved in shamanism through firsthand experiential involvement.

Ethnic groups are universal and unique to human societies. Such groups sometimes have norms of behavior that are adaptively linked to their social and ecological circumstances, and ethnic boundaries may function to protect that variation from erosion by interethnic interaction. However, such interaction is often frequent and voluntary, suggesting that individuals may be able to strategically reduce its costs, allowing adaptive cultural variation to persist in spite of interaction with out-groups with different norms. We examine five mechanisms influencing the dynamics of ethnically distinct cultural norms, each focused on strategic individual-level choices in interethnic interaction: bargaining, interaction-frequency-biased norm adoption, assortment on norms, success-biased interethnic social learning, and childhood socialization. We use Bayesian item response models to analyze patterns of norm variation and interethnic interaction in an ethnically structured Amazonian population. We show that, among indigenous Matsigenka, interethnic education with colonial Mestizos is more strongly associated with Mestizo-typical norms than even extensive interethnic experience in commerce and wage labor is. Using ethnographic observations, we show that all five of the proposed mechanisms of norm adoption may contribute to this effect. However, of these mechanisms, we argue that changes in relative bargaining power are particularly important for ethnic minorities wishing to preserve distinctive norms while engaging in interethnic interaction in domains such as education. If this mechanism proves applicable in a range of other ethnographic contexts, it would constitute one cogent explanation for when and why ethnically structured cultural variation can either persist or erode given frequent, and often mutually beneficial, interethnic interaction.

Phylogenetic inference based on language is a vital tool for tracing the dynamics of human population expansions. The timescale of agriculture-based expansions around the world provides an informative amount of linguistic change ideal for reconstructing phylogeographies. Here we investigate the expansion of Arawak, one of the most widely dispersed language families in the Americas, scattered from the Antilles to Argentina. It has been suggested that Northwest Amazonia is the Arawak homeland based on the large number of diverse languages in the region. We generate language trees by coding cognates of basic vocabulary words for 60 Arawak languages and dialects to estimate the phylogenetic relationships among Arawak societies, while simultaneously implementing a relaxed random walk model to infer phylogeographic history. Estimates of the Arawak homeland exclude Northwest Amazonia and are bi-modal, with one potential homeland on the Atlantic seaboard and another more likely origin in Western Amazonia. Bayesian phylogeography better supports a Western Amazonian origin, and consequent dispersal to the Caribbean and across the lowlands. Importantly, the Arawak expansion carried with it not only language but also a number of cultural traits that contrast Arawak societies with other lowland cultures.

Gastric cancer is one of the most lethal types of cancer and its incidence varies worldwide, with the Andean region of South America showing high incidence rates. We evaluated the genetic structure of the population from Lima (Peru) and performed a case-control genetic association study to test the contribution of African, European, or Native American ancestry to risk for gastric cancer, controlling for the effect of non-genetic factors. A wide set of socioeconomic, dietary, and clinic information was collected for each participant in the study and ancestry was estimated based on 103 ancestry informative markers. Although the urban population from Lima is usually considered as mestizo (i.e., admixed from Africans, Europeans, and Native Americans), we observed a high fraction of Native American ancestry (78.4% for the cases and 74.6% for the controls) and a very low African ancestry (<5%). We determined that higher Native American individual ancestry is associated with gastric cancer, but socioeconomic factors associated both with gastric cancer and Native American ethnicity account for this association. Therefore, the high incidence of gastric cancer in Peru does not seem to be related to susceptibility alleles common in this population. Instead, our result suggests a predominant role for ethnic-associated socioeconomic factors and disparities in access to health services. Since Native Americans are a neglected group in genomic studies, we suggest that the population from Lima and other large cities from Western South America with high Native American ancestry background may be convenient targets for epidemiological studies focused on this ethnic group.

ABSTRACT Objective: To discuss the fundamental aspects in the establishment of preventive measures to tackle covid-19 among indigenous people in view of the motivations for seeking health care in villages of the Terra Indígena Buriti, Mato Grosso do Sul, Brazil. Methods: Theoretical-reflective study based on assumptions of the National Health System and previous ethnographic research that enabled the identification of the motivations to seek health care in Buriti villages. Results: Indigenous people seek health centers for health care programs assistance, treatment of cases they cannot resolve and to chat. Such motivations were the basis for discussing the indigenization process in the confrontation of the new coronavirus pandemic in indigenous lands. Final considerations: The motivations for seeking health care show the physical and social vulnerability of the Terena ethnicity. The effectiveness of the social isolation measure in the villages depends on the dialogue with indigenous leaders, professional engagement and intersectoral actions. RESUMO Objetivo: Discutir aspectos fundamentais no estabelecimento de medidas preventivas no enfrentamento da covid-19 entre indígenas frente às motivações para busca dos serviços de saúde nas aldeias da Terra Indígena Buriti, Mato Grosso do Sul, Brasil. Métodos: Estudo teórico-reflexivo fundamentado nos pressupostos do Sistema Único de Saúde e em pesquisa etnográfica prévia, que possibilitou identificar as motivações para a procura do serviço de saúde nas aldeias Buriti. Resultados: Os indígenas buscam unidades de saúde para atendimento de programas de atenção à saúde, tratamento para casos que não conseguem resolver e para conversar. Tais motivações fundamentaram a discussão do processo de indigenização do enfrentamento da pandemia do novo coronavírus em terras indígenas. Considerações finais: As motivações para procura do serviço de saúde mostram a vulnerabilidade física e social da etnia Terena. A efetividade da medida de isolamento social nas aldeias depende do diálogo com lideranças indígenas, engajamento dos profissionais e ações intersetoriais. RESUMEN Objetivo: Discutir los aspectos fundamentales en el establecimiento de medidas preventivas para abordar el covid-19 entre los pueblos indígenas ante las motivaciones para buscar servicios de salud en los pueblos de la Terra Indígena Buriti, Mato Grosso do Sul, Brasil. Métodos: Estudio teórico-reflexivo basado en supuestos del Sistema Único de Salud y en una investigación etnográfica previa. Resultados: Los pueblos indígenas buscan unidades de salud para recibir asistencia en programas de salud, tratamiento de casos que no pueden resolver y charlar. Tales motivaciones fueron la base para discutir el proceso de indigenización en el enfrentamiento de la pandemia de coronavirus en tierras indígenas. Consideraciones finales: Las motivaciones para buscar el servicio de salud evidencian la vulnerabilidad física y social de la etnia Terena. La efectividad de la medida de aislamiento social depende del diálogo con líderes indígenas, compromiso profesional y acciones intersectoriales.