American Journal of Human Biology最新文献

Objectives

The sex ratio at birth (SRB), calculated as male divided by total live births, is an important indicator of population health. Typically, male live births slightly outnumber female live births. Population events, including pandemics, can alter the SRB, with effects sometimes evident 9 months post-event, potentially due to changes in sexual behavior and/or stress levels. This study investigates the impact of the COVID-19 pandemic on the SRB in the Republic of Ireland.

Methods

Publicly available monthly live birth data for Ireland were obtained from the Central Statistics Office for the period 2015 to 2021. Time series analysis predicted the SRB for 2020 using data from 2015 to 2019, with comparisons made between observed and predicted values.

Results

In December 2020, 9 months after the March 2020 COVID-19 declaration, the observed SRB sharply fell to 49.44% (97.80 males for every 100 females), below the 95% prediction interval of 50.31% to 52.15%, significantly deviating from the expected male predominance. December 2020 also recorded the lowest average daily number of births (n = 145) in the study period.

Conclusion

The sharp decline in the SRB in December 2020, alongside the lowest birth count, suggests reduced sexual intercourse at the population level, particularly in March 2020, aligning with recommendations from Ireland's Health Service Executive (HSE). The HSE advocated precautionary measures such as limiting partnered sex in March 2020 to mitigate the spread of COVID-19. These findings highlight the pandemic's potential impact on population dynamics and stress the importance of SRB monitoring as a low-cost and readily available health indicator, especially during national crises.

Objectives

The digit ratio (2D:4D) is a possible marker of prenatal hormone exposure. The purpose of this study was to explore the relationships between digit ratio (2D:4D) and anthropometric indexes in Chinese children and adolescents.

Methods

This study is a cross-sectional study. A school-based survey among 685 children and adolescents aged 8–15 years were conducted by stratified cluster sampling. The length of index finger (2D) and ring finger (4D) of the left hand, height, sitting height (ST), weight, chest circumference (CC), waist circumference (WC), hip circumference (HC), and abdominal skinfold thickness (AST) were measured. Pearson correlation and multivariate linear regression were used to analyze associations between 2D:4D and above indexes.

Results

In girls, 2D:4D was positively related to WC, AST, waist-to-height (WHtR), waist-to-hip ratio (WHR) after adjusting for ages (p < 0.05). The WC, AST, WHtR, and WHR among girls with 2D:4D ≥ 1 were significantly higher than those among girls with 2D:4D < 1, respectively (p < 0.05). However, there was no correlations between digit ratio (2D:4D) and above anthropometric indexes in boys (p > 0.05).

Conclusions

The 2D:4D was related to anthropometric indexes in girls, which suggests that the maternal prenatal hormone exposure might be related to the anthropometric indexes of their female offspring.

Objectives

The impacts of stress on inflammation, although hypothesized, have not been thoroughly examined, especially in relation to social and environmental factors and particularly within Black populations. This study aims to explore the biological mechanisms of embodiment linking stress and health to understand physiological changes in the body's response to psychological stress in a Nigerian population. Through a multidisciplinary approach, this study queries the relationship between stress, cortisol, and salivary C-reactive protein (sCRP), a biomarker of inflammation, while also validating the use of sCRP as a potential and accurate stress indicator in the field.

Methods

In this cross-sectional study, 138 passive drool saliva samples (n _female = 89 n _male = 49) were collected and assessed for sCRP and cortisol levels in adults. Participants also completed a short demographic survey and, to measure psychological stress, the General Health Questionnaire 12 (GHQ-12). Relationships between sCRP and stress-related variables (i.e., cortisol, GHQ-12, and demographic data) were assessed using Spearman's correlations, simple regression, multivariable linear regression, and exploratory factor analysis.

Results

sCRP levels ranged from 20.57 to 6879.41 pg/mL across all samples, with significant differences between female and male participants. The GHQ-12 was not a significant predictor of sCRP variability. However, socio-demographic factors such as body mass index (BMI), age, self-reported sex, ethnic identity, and cortisol were significant predictors, collectively explaining 24%–27% of the variation in sCRP.

Conclusion

Socio-demographic predictors like BMI, age, sex, and particularly ethnic group experience in Nigeria encapsulate aspects of embodied stress, that significantly affect sCRP variability.

Background

This study aims to examine the relationship between resting vagal-related heart rate variability (HRV) parameters and heart rate (HR) with resting metabolic rate (RMR) and respiratory exchange ratio (RER) in young adults.

Methods

A total of 74 young adults (22 ± 2 years old, 51 women) were included in this cross-sectional study. HRV was assessed using a HR monitor, whereas RMR and RER were determined by indirect calorimetry.

Results

Linear regression analyses showed a positive association between HR and RER in women (standardized β = 0.384, p = 0.008), while negative associations were observed between vagal-related HRV parameters and RER in women (β ranged from −0.262 to −0.254, all p ≤ 0.042). No significant association was found between the abovementioned physiological parameters in men.

Conclusion

Here, we show that HR is positively associated with RER in young women but not in men, while vagal-related HRV parameters are inversely related to RMR, therefore suggesting a potential sexual dimorphism between cardiac rhythm and its relationship with markers of cardiometabolic health status.

Trial Registration: ClinicalTrials.gov identifier: NCT02365129.

Objectives

Males, on average, are bigger and stronger than females. Hormonal differences during puberty are one reason given for this performance advantage. However, not all evidence supports that thesis. Our aim was to further this discussion by measuring early life changes between sexes (when hormones would be similar) in components of muscle function.

Methods

Fifty-one children (29 boys, 22 girls) completed this study. Forearm muscle size and strength were assessed three times with each time point being separated by approximately a year (2021–2023).

Results

There was no sex*time interaction for handgrip strength (p = 0.637). There was, however, a time (p < 0.001) and sex (p < 0.001) effect. Strength increased each year and boys were stronger than girls (difference of 1.5 [95% 0.7, 2.3] kg). There was no sex*time interaction for ulnar muscle thickness (p = 0.714) but there was a time (p < 0.001) effect. Muscle size increased each year but there was no evidence of a sex effect (p = 0.12; difference of 0.81 [95% −0.21, 1.8] mm). A strong positive within-participant correlation between muscle size and strength (r = 0.803 95% CI: [0.72, 0.86], p < 0.0001) was found across time.

Conclusion

Muscle size and strength increased together but this increase did not differ based on sex and boys were stronger than girls. Future work is needed to determine the reason for this difference in maximal strength. Any effect was seemingly present at the initial measurement (at the age of 4 years), since muscle size and strength did not change differently between boys and girls over time.

Objective

Human sexual dimorphism in physical strength manifests itself in men having a greater muscle mass than women, reflecting ancestral roles in competition, protection, and provisioning. Prenatal testosterone exposure, approximated via the second-to-fourth digit ratio (2D:4D), is linked to increased muscular strength in both sexes, indicating a developmental influence. Previous research has shown that both physical strength and 2D:4D have facial shape correlates, especially in men, but most studies have focused on Western populations and one trait. We therefore hypothesized a broader relationship between facial shape and both physical strength and 2D:4D.

Materials and Methods

In this study, we quantified the association between facial shape, handgrip strength (HGS), and 2D:4D in a non-Western Turkish sample (72 men, 55 women; Md = 22 y, SIR = 1.8 y) using two dimensional geometric morphometrics. Thirty-eight somatometric and 32 semi-landmarks were digitized on facial photographs taken in frontal view. Physical strength was assessed via handgrip strength (HGS), and the second digit length was divided by the fourth digit length to calculate 2D:4D.

Results

Both HGS and 2D:4D were significantly associated with shape in both sexes, but only in men did they explain a significant amount of facial variation. Thin-plates spline deformation grids and geometric morphometric morphs visualized the facial shape changes related to variations in handgrip strength, 2D:4D, and sexual dimorphism, enabling trait comparisons.

Conclusion

This study contributes a comparative sample from the Middle East, which is indispensable to discern universalities from Western peculiarities. It provides evidence to better understand the biological basis of facial traits, which can potentially serve as increasingly relevant social cues in today's online and digital environments.

Objectives

The regional population mortality patterns in China exhibit substantial geographical distribution characteristics. This paper aims to explore the impact and mechanisms of geographical environmental factors on regional population mortality patterns.

Methods

This study first utilized the data from China's Seventh Population Census to obtain mortality patterns for the 31 provincial-level administrative regions. Subsequently, a functional regression method was employed to explore the geographical environmental driving factors of regional mortality patterns.

Results

The study provides a detailed explanation of the mechanisms and marginal contributions of key geographical environmental factors at different age groups.

Conclusions

(1) The impact of geographical environmental factors on mortality patterns shows distinct phased characteristics. Mortality patterns before the age of 40 years are hardly influenced by geographical environmental factors, with a noticeable impact beginning at ages 40–69 years and reaching the maximum influence after the age of 70 years. (2) In mortality patterns at ages 40–69 years, average altitude have the most substantial impact, followed by extreme low-temperature days and PM2.5 concentration. In mortality patterns at ages 70–94 years, high-temperature days have the greatest influence, followed by the impact of SO₂ concentration. (3) In comparisons based on gender, socioeconomic factors, and geographical environmental factors, gender and urban–rural differences have the most significant impact on regional population mortality patterns, followed by the influence of other socioeconomic factors, with geographical environmental factors having a relatively smaller impact.

Objective

To analyze the changes in children's height, weight, BMI and rates of stunting and overweight and obesity over three periods: 1986–1987, 1996–1998, and 2023 for the community of Yalcoba in the Yucatan Peninsula.

Material and Methods

Four hundred forty (6-to-15 years) children measured in 2023 were compared with data obtained in 1986–1987 (n = 675) and 1996–1998 (n = 628). Z-scores of height and BMI were calculated to estimate percentages of stunting and high BMI-for-age (overweight and obesity). Comparisons of anthropometric parameters by sex and age groups between years of measurement were performed through one way ANOVAs.

Results

Differences in anthropometric parameters were significant in all age groups of both sexes. Boys measured in 2023 were, on average, 6.4 and 3.3 cm taller than boys measured in the 1980s and 1990s, respectively. Increases in girls were 12 and 7.3 cm, respectively. Average increases in weight of boys measured in 2023 were 7.9 kg compared to the 1980s and 5.8 kg compared to 1990s. Average increases in girls measured in 2023 were 11.3 kg compared to the 1980s, and 7.6 kg compared to the 1990s. Stunting between the 1980s and 1990s decreased by 15 percentage points and between the 1990s and 2023 decreased by 47 percentage points. The percent of children deemed overweight/obese during these periods increased from 8 to 12–50 by 2023.

Conclusion

Results reflect the overall trends seen in the Yucatan where stunting has decreased substantially but the numbers of overweight/obese youths have increased dramatically in the past 30 years.