American Journal of Human Biology最新文献

The Shuar Health and Life History Project (established in 2005) is an interdisciplinary, integrated field and laboratory research project with the Indigenous Shuar population in Amazonian Ecuador. Grounded in human biology, behavioral ecology, evolutionary psychology, evolutionary medicine, and global health, the SHLHP has three key research foci: (1) To identify how market integration (via effects on diet, pathogen exposure, lifestyle, etc.) impacts Shuar health and well-being; (2) To investigate (using evolutionary life history theory) how lifetime phenotype and health are shaped by adaptive energy allocation between competing life tasks; and (3) To test hypothesized human psychological and demographic adaptations, including aspects of sociality that are central to the evolutionary success of our species. To address these foci, the SHLHP has established long-term and mutually beneficial relationships with the Shuar and local collaborators, resulting in community-engaged data collection with more than 3500 participants and a wide range of research publications and policy contributions over the past 20 years. This special issue of the American Journal of Human Biology showcases 10 original SHLHP articles that span much of the project's intellectual breadth and represent important advances for understanding human biology, life history, and health. To serve as an introduction, here we provide essential background on the Shuar and the SHLHP, overview the ten included special issue articles, and discuss key research and impact goals for the next 20 years of the SHLHP.

Objectives: Altitude shapes human morphology as highland populations must cope with cold and hypoxic environments. Although Andean highlanders have been proposed to exhibit larger and deeper ribcages, this idea is mainly based on research using disarticulated skeletal elements or non-South American controls. The objective of this research is to study 3D ribcage configuration of native South American populations considering altitude and worldwide ribcage variation.

Methods: Ribcages of 37 adult South Americans (17 highlanders, 20 lowlanders) were reconstructed and analyzed using 3D geometric morphometrics. Shape variation was assessed through Procrustes MANOVA and PCA, while centroid size was used to test for size differences. Comparisons were also made with a sample of 92 adult worldwide lowlanders.

Results: South American highlanders and lowlanders show similar ribcage shapes, both exhibiting a deeper thorax than worldwide lowlanders. No significant differences in absolute ribcage size were detected between South American highlanders and lowlanders. However, a marked sexual dimorphism was observed in both groups, with males having wider and significantly larger ribcages than females.

Conclusions: The pronounced ribcage depth in native South Americans could represent a population-specific trait maintained through long-term interactions, potentially advantageous in high-altitude settings but neutral in the lowlands. In addition, we propose that South American highlanders have a larger ribcage relative to their smaller body size compared to lowlanders. Finally, the larger and stockier male ribcage morphology in South Americans supports the notion of greater respiratory capacity and metabolic demands in males.

Objectives: Dysregulations of the hypothalamic-pituitary-adrenal (HPA) axis have been linked to adverse health outcomes such as obesity, cardiovascular disease, and diabetes. While research on the HPA axis is growing, few studies have examined whether different types of stressors affect HPA functioning differently, and none have done so in small-scale subsistence populations. To do so, we measured HPA axis activity and various kinds of stressors among the Tsimane of Bolivia, a population with more traditional lifestyles and stressors including low caloric intake, social conflict, and market integration.

Methods: Participants were adults from three different Tsimane communities (n = 129, 57% women). For each participant, urinary cortisol (n_samples = 303), corrected for specific gravity, was measured once at waking and at least once later on the same day to measure the diurnal slope. One hundred and twenty-five participants completed a questionnaire on culturally relevant psychosocial stressors in the Tsimane such as food insecurity, social conflicts, and economic problems. Multilevel Bayesian multivariate models assessed associations between stressor scores and cortisol levels.

Results: Diurnal variation in the HPA axis was differentially associated with each type of stressor. Food insecurity was associated with higher morning levels (median r_intercept = 0.08, p _> 0= 0.73) and a steeper diurnal slope (median r_slope = -0.19, p _< 0 = 0.83), while economic problems were associated with lower waking levels and shallower slopes (median r_intercept = -0.05; p _< 0 = 0.64, median r_slope = 0.12, p _> 0= 0.72). Higher morning levels and steeper slopes were also associated with better self-rated health (median r_intercept = 0.06; p _< 0 = 0.66, median r_slope = -0.10, p _> 0 = 0.71).

Conclusion: While many of these associations had high statistical uncertainty due to wide posterior distributions, the results overall emphasize complex relationships between perceived stressors and diurnal cortisol rhythms among a small-scale subsistence-based society. Future work employing longitudinal designs and higher-resolution sampling will be needed to clarify these trends.

This toolkit paper describes the value of including pollutant measurements in human biology research and describes considerations to implement such research. Human biologists study populations that are exposed to a variety of pollutants including metals and organic compounds used in agriculture and pest control. These pollutants can affect biological outcomes investigated by human biologists. Considering the impact of one or more of these pollutants in our investigations involves careful attention to properties of each pollutant and how the body metabolizes and stores them. Assessing exposure to many metals and organic compounds is best done by bio-sampling, usually of blood, but other media include hair, fingernails, and urine. Appropriate sampling media differ by pollutant but many found in the bloodstream may be collected together though not necessarily stored in the same way and not analyzed in the laboratory by the same method. A team approach is recommended as specialized knowledge of the proper sampling, handling, and analysis of each toxicant is needed. Choosing a laboratory should consider at a minimum the range of congeners measured, the minimum detection level, and the turnaround time for results required for the analysis. Study participants are likely to be interested in their toxicant exposure. The distribution of results should include careful description and interpretation to allow non-scientists to understand and take action if needed. Litigation by study participants against polluters is possible making it necessary to scrupulously preserve records of collection and analysis for possible court subpoena.

Objectives: The purpose of this study was to summarize the evidence regarding possible differences in areal bone mineral density (aBMD) and bone mineral content (BMC) across racial and ethnic groups of children and adolescents.

Methods: A systematic review was conducted using five electronic databases, supplemented by complementary searches of reference lists. Studies should have used dual-energy x-ray absorptiometry to assess bone mass in children and adolescents (aged ≤ 19 years) with no special clinical conditions.

Results: Of the 1791 articles initially identified, 26 were included. Whites had lower aBMD/BMC than Blacks in 60.2% (47/78) of the analyzed results. In racial/ethnic groups that did not include Blacks, aBMD/BMC values were lower when compared to Blacks or ethnic groups that included Blacks in 80.0% (8/10) of possible results. Most findings indicated a paucity of evidence regarding differences in aBMD/BMC between Whites and Asians, Pacific Islanders, Hispanics, and Mexican-Americans (percentage of results ≤ 50.0%).

Conclusions: Based on the findings, it can be concluded that White children and adolescents have lower bone mass values compared to their Black peers. Racial and ethnic groups that do not include Black individuals also exhibit lower bone mass values compared to Black children and adolescents. Additionally, there appears to be no difference in bone mass between White children and adolescents and their Asian, Pacific Islander, Hispanic, and Mexican-American counterparts.