American Journal of Human Biology最新文献

Objectives: Second to fourth digit ratio is widely known indicator of prenatal sex hormones proportion. Higher prenatal androgenization results in longer fourth finger and lower 2D:4D index. The aim of this study was to determine whether the 2D:4D digit ratio is associated with DNA methylation (DNAm) age dependently on sex.

Material and methods: The study included 182 adults (106 females and 76 males) with a mean age of 51.5 ± 13 years. The investigation consisted of three main parts: a survey, anthropometric dimensions measurements (fingers length) and methylome analysis using collected blood samples. Genome-wide methylation was analyzed using EPIC microarray technology. Epigenetic age and epigenetic age acceleration were calculated using several widely applied algorithms.

Results: Males with the female left hand pattern had more accelerated epigenetic age than those with the male pattern as calculated with PhenoAge and DNAmTL clocks.

Conclusions: Finger female pattern 2D:4D above or equal to 1 in males is associated with epigenetic age acceleration, indicating that prenatal exposure to estrogens in males may be related to aging process in the later ontogenesis.

Objective: Hot flashes (HFs) are experienced as sudden sensations of heat. We hypothesized that brown adipose tissue (BAT) activation could increase the likelihood of HFs in winter. The aim of this study was to test whether women with more BAT activity were more likely to experience self-reported or biometrically measured HFs.

Methods: Women aged 45-55 years (n = 270) participated in face-to-face interviews and anthropometric and ambulatory measures. Level of BAT activity was estimated from the difference in supraclavicular skin temperature measured by infrared thermography before and after cooling. Logistic regressions were applied to examine whether bothersome HFs (yes/no) during the past 2 weeks were associated with BAT activity, adjusting for menopausal status, childhood exposure to cold, waist/hip ratio, and self-reported health. Linear regressions were used to examine the frequency of self-reported and biometrically measured HFs during the study period and BAT activity, adjusting for potential confounders.

Results: Menopausal status, childhood exposure to cold, waist-to-hip ratio (WHR), and self-reported health were associated with both BAT activity and HFs. After adjusting for potential confounders, an increase in BAT activity almost tripled the likelihood of bothersome HFs (OR 2.84, 95% CI 1.26-6.43). In linear regressions, BAT activity was not associated with frequency of subjective or objective HFs during the study period, but childhood exposure to cold was associated with subjective HF report (β = 0.163, p = 0.010).

Conclusion: To our knowledge, this is the first study of BAT activation and HFs. Our results support a role for BAT activity in HF experience. Therefore, we encourage further examination of the role of BAT, as well as childhood exposure to cold, in HFs.

Objectives: Whether gemination or fusion, double teeth are rare worldwide, including Africa based on few published data. New cases from the continent are tallied, and anomalies potentially associated with double teeth are identified. These findings should interest a range of dental researchers.

Methods: The presence of double teeth was recorded in 97 modern and premodern North and sub-Saharan African samples (5631 inds.). They and coexistent anomalies are described relative to published examples. Prevalence was estimated as possible, using a Poisson model for 95% confidence intervals (CI).

Results: Three maxillary double teeth were identified: a primary left lateral incisor in a Nubian child (1938-1756 BC), permanent left central incisor in an adult Egyptian (3650-3500 BC), and permanent right central incisor in a modern (19th century) adult from Guinea. Each co-occurs, respectively, with a talon cusp, peg lateral incisor and, in the latter individual, second premolar crown variation with rotation, and third molar dens evaginatus. Double tooth prevalence is 0.048% (CI 0.001%-0.270%), with regional variation, in premodern, and 0.000% in modern North Africans. It is 0.000% for premodern and 0.048% for modern sub-Saharan Africans (0.008%-1.714%).

Conclusions: The double incisors are comparable to other global examples, indicative of common developmental processes during odontogenesis. Prevalence is lower than published modern rates, to suggest some exceptionality in Africans as reported earlier for other dental variants. Finally, though circumstantial, double teeth and accompanying anomalies may share an etiology. Continuing research overall, and in Africa specifically, will promote an improved understanding of double teeth formation and expression.

Introduction: In the context of adverse in utero environments, the fetal brain might be preserved at the expense of other tissues. This trade-off, brain sparing, has not been studied in the context of maternal infection. We investigated cases of maternal syphilis in the early 20th century and influenza during the 1918-1920 pandemic, in the Swiss city of Lausanne, a relatively high-income setting. We tested the brain sparing hypothesis, that head circumference is protected at the expense of birth weight.

Methods: A total of 8530 individual birth records from 1911 to 1922 from the University Maternity Hospital of Lausanne were used. We fitted generalized linear and additive linear models to explain how neonatal size varies under disease exposure.

Results: Influenza reduced head circumference and birth weight among livebirths similarly, by -0.11 and -0.14 standard deviation (SD) units respectively. Conversely, for syphilis-exposed infants, head circumference was affected more than birth weight (-0.61 SD vs. -0.46 SD). Stillborn infants exposed to syphilis experienced a much greater reduction in head circumference (-1.92 SD) than liveborn infants. After adjustment for gestational age, these findings persisted in the case of influenza, but the effects of syphilis were reduced. Furthermore, half of syphilis-exposed infants were born before term, suggesting that lower infant size was partly mediated by shorter gestation. Nevertheless, head circumference among stillbirths exposed to syphilis was still substantially reduced, even after adjustment for gestational age (-1.26 SD).

Conclusion: Our findings do not support the brain sparing hypothesis. Moreover, the substantial reduction in head circumference among syphilis-exposed fetuses might help explain why a quarter of them were stillborn.

Objectives: Human childrearing is cooperative, with women often able to achieve relatively high fertility through help from many individuals. Previous work has documented tremendous socioecological variation in who supports women in childrearing, but less is known about the intracultural correlates of variation in allomaternal support. In the highly religious, high-fertility setting of The Gambia, we studied whether religious mothers have more children and receive more support with their children.

Methods: We randomly sampled 395 mothers and 745 focal children enrolled in the Kiang West (The Gambia) Longitudinal Population Study cohort. Structured interviews asked mothers who and how often people invest in their children, and about their religious practices. Data were collected at participants' homes on electronic tablet-based long-form surveys and analyzed using the Bayesian hierarchical models.

Results: Religiosity was weakly associated with women's higher age-adjusted fertility. Maternal religiosity was negatively related to maternal investment in focal children, but positively associated with total allomaternal support. Specifically, a woman's religiosity was positively associated with allomaternal support from matrilineal kin, other offspring, and affinal kin, but unrelated to paternal, patrilineal, and non-kin investment.

Conclusions: These results suggest that higher fertility among religious mothers may be supported by high levels of investment from biological and affinal kin. Matrilineal kin, other siblings, and affinal kin seem to be the most responsive to a woman's religiosity. Our findings cast doubt on interpretations of women's religious behaviors as signals of fidelity, and instead suggest they may be part of strategies to enable collective allomaternal resources and higher relative fertility.

Introduction: Locus of control (LoC) refers to one's expectation that life outcomes and (mis)fortune are driven largely by one's own actions or abilities (internal LoC) or by external factors (e.g., powerful others, chance; external LoC). There is a large literature demonstrating an association between internal LoC and positive mental health outcomes. However, this research is conducted mostly in high-income, Global North settings, with limited consideration of cross-cultural variability. This short report explores how LoC relates to mental health when considered in a less-studied context: in a setting of stark structural violence and in relation to supernatural agents.

Methods: I conducted a community-based survey in rural Haiti (n = 322) that assessed sent spirit-related locus of control (LoC-S) and mental health.

Results: Among individuals experiencing higher levels of daily stressors, depressive and anxiety symptoms were high regardless of LoC-S. However, for individuals facing low-to-moderate daily stressors, external LoC-S (believing one does not have control in relation to sent spirits) was associated with lower depressive and anxiety symptoms, though this interaction did not hold for anxiety after controlling for covariates. Though initially a nonintuitive finding, I contextualize this outcome in relation to ethnographic work in Haiti, showing that the ability to explain misfortune via the supernatural world can serve as a form of blame displacement.

Conclusion: In a context where extreme structural violence means that individuals realistically have little control over their lives, an external LoC better reflects lived experience, helping explain the association with better mental health outcomes.

Objectives: Parents' healthy behaviors are important for both their health and role models for their children. The purpose of this study was to evaluate adherence to the three recommendations associated with health in the Canadian 24-h movement or Japanese physical activity (PA) guidelines and their relationship with weight status (underweight or obesity) in Japanese parents.

Methods: This cross-sectional study included 425 mothers and 237 fathers. Meeting the 24-h movement guidelines was defined as: ≥150 min/week of moderate-to-vigorous PA (MVPA) (Canada) or at least 60 min/day of MVPA (Japan), ≤8 h/day of sedentary time which includes ≤3 h of recreational screen time, and 7 to 9 h/night of sleep. MVPA and sedentary time were accelerometer-determined while screen time and sleep duration were self-reported.

Results: The prevalence of mothers meeting all three recommendations was 30.6% using Canadian PA guidelines and 20.7% using Japanese PA guidelines, while that of fathers was 10.6% and 8.0%, respectively. Mothers not meeting the sedentary behavior recommendation had a lower odds ratio and those not meeting Japanese PA recommendations had a higher odds ratio for underweight compared to mothers meeting the recommendations, adjusted for age and area socioeconomic status.

Conclusions: The screen time recommendation and Japanese PA recommendation were associated with underweight in mothers. None of the recommendations was associated with weight status in fathers. Further research is needed to understand the relationships among movement behaviors and weight status, particularly among Japanese women, whose routine behaviors, such as household activities, may be misclassified by a questionnaire.