Biodemography and Social Biology最新文献

In this study I examine local variation in the timing and magnitude of the excess mortality hump, which is the period in adolescence and in young adulthood when mortality rates spike in young men due to an increase in risk-taking behaviors believed to result from a surge of testosterone production and subsequent aggressive, impulsive behaviors. Using an ecological framework and data on all-cause mortality in the United States between 2000 and 2018, I test the hypothesis that dimensions of the local population structure will exacerbate testosterone production and intraspecific competition among young men, which in turn leads to behaviors that elevate the risk of death. This hypothesis is supported by the data. I find that the age at the peak of the excess mortality hump is younger in counties where the sex ratio skews toward males and where population density is high. Additionally, I find that the overall magnitude of the peak of the excess mortality hump is greater in counties where the sex ratio skews toward males.

This study explores the short-term relationships between sex ratio at birth and late fetal mortality in Italy from 1910 to 2016. As the leading scholars' attention traditionally focused on long-term trends and variations in the sex ratios at birth among different populations, less interest regarded short-term fluctuations as they were mainly seen as an effect of random variability. We detrended the national series of males proportion among live births and stillbirths by their medium-term component to consider the annual deviations from a normal trend. After controlling for fertility tendencies and wars effects, regression models seem to show the effects of stillbirth on the proportion of male newborns. A sensitivity analysis was also carried out to assess the effects of the perinatal deaths on the proportion of males at birth, combining stillbirths and early neonatal losses to control the possible misspecification between stillborn infants and early neonatal deaths. The significance of late fetal mortality reflects the mortality excess among male fetuses during the intrauterine life, showing evidence for the in utero hypothesis selection.

Studies of the current Chilean population performed using classical genetic markers have established that the Chilean population originated primarily from the admixture of European people, particularly Spaniards, and Amerindians. A socioeconomic-ethno-genetic cline was established soon after the conquest. Spaniards born in Spain or Chile occupied the highest Socioeconomic Strata, while Amerindians belonged to the lowest. The intermediate strata consisted of people with different degrees of ethnic admixture; the larger the European admixture, the higher the Socioeconomic Level. The present study of molecular genomic markers sought to calculate the percentage of Amerindian admixture and revealed a finer distribution of this cline, as well as differences between two Amerindian groups: Aymara and Mapuche. The use of two socioeconomic classifications - Class and Socioeconomic Level - reveals important differences. Furthermore, Self-reported Ethnicity (self-assignment to an ethnic group) and Self-reported Ancestry (self-recognition of Amerindian ancestors) show variations and differing relationships between socioeconomic classifications and genomic Amerindian Admixture. These data constitute a valuable input for the formulation of public healthcare policy and show that the notions of Ethnicity, Socioeconomic Strata and Class should always be a consideration in policy development.

This paper investigates the association between advanced maternal age and under-5 mortality and morbidity in Turkey, and is the first such study in the country to use a sibling comparison model to analyze this phenomenon. The study is based on data obtained from the 2013 Turkey Demographic and Health Survey, and analyzes the association of advanced maternal age with: (1) under-five mortality, using Cox proportional hazard models and their stratified versions to compare sibling groups born to the same mother in the 1978-2013 period, and (2) under-five morbidity; specifically, being born with low birth weight, stunting, underweight, and wasting based on between- and within-sibling groups models for the 2008-2013 period. Overall, our findings suggest that the hazard of under-5 mortality increases as maternal age increases. We conclude that period effects have failed to reverse the impeding effects of advanced maternal age on child mortality. Between-sibling group models indicate a positive but close to null association between advanced maternal age and child morbidity in general, although these positive associations vanish once we apply within-sibling group models. This result can be partially attributed to our controlling for unobserved characteristics specific to sibling groups, in addition to other methodological differences.

Few studies have examined the biosocial pathways linking socioeconomic status (SES) to accelerated aging in a population-based sample of southern US women. Even fewer have examined the importance of chronic compared to perceived stress in linking SES to women's salivary telomere length (STL). Using data from a probability-based sample of 156 US women and structural equation modeling, we examined three pathways - chronic stress exposure, stress appraisal, and coping behavior - linking SES to STL. SES was positively associated with STL (β_TE = 0.16, p < .05). Everyday discrimination was negatively associated with STL (β_DE = -0.21, p < .05), but perceived stress was positively associated with STL (β_DE = 0.20, p < .05). Current smoking decreased STL (β_DE = -0.19, p < .01). Perceived stress acted to suppress the negative relationship of chronic stress exposure on STL. Given the dearth of STL studies that include measures of both perceived and chronic stress, our study supports the importance of disentangling stress measures and a biosocial approach to the study of accelerated aging.

This study investigates two sources of education effects on obesity - achieved educational attainment and inherited genetic endowment for education. In doing so, we accomplish two goals. First, we assess the role of genetic confounding in the association between education and health. Second, we consider the heterogeneity in the extent to which genetic potential for education is realized, and we examine its impact on obesity. Data come from the National Longitudinal Study of Adolescent to Adult Health. Using a polygenic score approach, we find that, net of genetic confounding, holding a college degree is associated with a lower likelihood of obesity. Moreover, among individuals who hold a college degree, those with a high education polygenic score (a greater genetic propensity to succeed in education) are less likely to be obese than those with a relatively low education polygenic score. However, when individuals with a high education polygenic score do not have a college degree, their risk of obesity is similar to that of non-college-educated individuals with a low education polygenic score, suggesting that the effect of genetic endowment for education on obesity is conditional on college education.

Birth seasonality is a phenomenon whereby populations can be characterized by a single month or season in which births peak. While non-human animal research suggests that seasonal birth-pulses are related to variation in climate and local energy availability, social scientists debate the mechanisms responsible for it in humans. Here we investigate the role of precipitation, temperature, and energy availability on seasonal conception and birth pulses using a historical dataset from the Baja California peninsula - a hot, arid desert that experiences seasonal climatic fluctuations associated with the North American Monsoon. Analyses suggest that 1) local energy availability had a negative relationship with conception pulses; and 2) birth pulses had a positive relationship with local energy availability and a negative relationship with temperature. Taken together, our analyses suggest that women timed conceptions when local energy availability was lowest (challenging expectations of conception rates as simply reflecting ecological influences on female fecundity), so that children were born during the seasonal "green-up" associated with the North American Monsoon. Given our results, we speculate that birth seasonality represents a form of traditional ecological knowledge to improve neonate health and wellbeing.