Previous studies have suggested that maternal childhood trauma (MCT) may influence infant temperament, but the underlying physiological mechanisms remain unclear. This study sought to confirm the involvement of breast milk cortisol in the link between MCT and infant temperament. The study sample included 90 mother–infant dyads recruited from the urban Polish population. MCT was assessed based on the Early Life Stress Questionnaire (ELSQ) and infant temperamental factors (surgency/extraversion, negative affectivity, and orienting/regulation) using the Infant Behavior Questionnaire-Revised at 12 months of life. Cortisol was assayed in milk samples collected at 5 months of life using the ELISA method. Based on the ELSQ median, the sample was divided into low and high MCT groups. The ANCOVA models with milk cortisol as a covariant were run to check the effect of low versus high MCT on infant temperament. We found a positive association between milk cortisol and orienting/regulation. Surprisingly, the low and high MCT groups did not significantly differ in milk cortisol. Furthermore, we found that MCT was unrelated to any infant temperamental factor. While recent literature on the association between milk cortisol and infant temperament is inconsistent, our results suggest that high orienting/regulation might be an adaptation to adverse environments such as stress. Moreover, the infant's temperament appears to be more responsive to the current exposition to maternal stress than her experience of traumatic stress.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
The study provides a detailed explanation of the mechanisms and marginal contributions of key geographical environmental factors at different age groups.
(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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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).
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%).
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.
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.
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.
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).
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.
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