This commentary on Growth Rates and Life Histories in Twenty-Two Small-Scale Societies overviews the original publication and its contributions, and reviews advances in the field of human growth and development since its publication.
This commentary on Growth Rates and Life Histories in Twenty-Two Small-Scale Societies overviews the original publication and its contributions, and reviews advances in the field of human growth and development since its publication.
Total cholesterol is a risk factor for cardiovascular disease, yet little is known about how its age-related trajectory differs by lifestyle factors across adulthood.
We analyzed data from 8758 adults aged 40–80 years using NHANES from 2011 to 2020. Total cholesterol was measured via enzymatic analysis of serum samples. Physical activity was assessed using the Global Physical Activity Questionnaire, with participants classified as meeting or not meeting physical activity guidelines (≥ 150 min/week of moderate-to-vigorous activity). Weight status was determined by body mass index (BMI), categorized as healthy BMI (18.5–24.9 kg/m2) or overweight BMI (≥ 25.0 kg/m2). Time-varying effect modeling (TVEM) was used to estimate total cholesterol across age, stratified by physical activity and BMI category.
TVEM indicated that there were no significant differences in total cholesterol levels between physical activity groups across age. In contrast, individuals with an overweight BMI had higher total cholesterol levels than those with a normal BMI, with significant differences observed between ages 63 and 69.
These findings highlight late midlife as a turning point when excess body weight may exert a stronger influence on cholesterol regulation. Age-specific approaches to weight management may enhance cardiovascular disease prevention efforts.
This study aimed to describe inter-individual variation in growth velocity during puberty among Brazilian children, considering maturity status to better understand differences in the timing and intensity of growth spurts.
Longitudinal stature data from 398 Brazilian children (197 girls, 201 boys) aged 6–19 years, collected annually from 1997 to 2010, were analyzed. Growth and velocity curves were estimated using the SITAR model within a Bayesian framework. Maturity groups were classified based on the standard deviation of the estimated age at peak growth velocity, categorizing participants as early, average, or late maturers.
The mean age at peak growth velocity was 11.30 years for girls and 13.55 years for boys. Mean peak velocities were 8.38 and 9.52 cm/year, respectively. Pubertal takeoff occurred at 8.41 years for girls and 11.19 years for boys, with mean velocities of 5.85 and 5.43 cm/year. Early maturers exhibited earlier onset and higher growth velocities, while late maturers showed delayed growth for both sexes.
Considerable variability in growth velocity patterns during puberty was observed. Compared to Northern Hemisphere populations, Brazilian children experienced earlier and more intense pubertal growth spurts. These findings highlight the importance of accounting for maturational timing in physical education planning, training load management, and pediatric growth assessment.
In 2009 we published an article in the American Journal of Human Biology arguing for a developmental contribution to US racial inequities in cardiovascular disease (CVD), inspired by emerging evidence that stress during pregnancy reduces birth weight (BW) while also elevating offspring CVD risk. The 15 years since our piece was published provide an opportunity to update the status of the hypothesis. Although relevant studies are sparse, work to date has revealed an apparent paradox: although Black Americans have lower BWs and higher CVD rates, and even though lower BW elevates future CVD risk, studies generally report stronger inverse BW–CVD relationships in white compared to Black samples. Drawing on current understandings of intergenerational pathways, we propose an updated model that could help explain the weakening of BW–CVD relationships in Black Americans: Structural racism not only elevates CVD risk through pathways that reduce BW, as we originally emphasized, but also increases the likelihood of maternal weight gain and elevated glucose, which elevate offspring CVD risk but increase BW. We review newer evidence that these offsetting, “push–pull” effects on BW operate across the full BW spectrum. As a result, when BW is used as a marker, a dimension of CVD risk is rendered invisible, with the degree of invisibility proportionate to the strength of these opposing pathways. BW will thus be particularly uncoupled from CVD risk in minoritized US populations, who often face psychosocial stress but are also more likely to be exposed to environments that lead to weight gain and metabolic dysregulation.
Son preference remains a deeply rooted sociocultural phenomenon in Pakistan and plays a critical role in shaping fertility behavior. The study investigates the influence of son preference on fertility behavior, with a specific focus on birth intervals and the sex composition of existing children, within the context of marital structure (monogamous vs. polygynous unions) in Pakistan.
Using nationally representative data from the Pakistan Demographic and Health Survey (2012–2013 and 2017–2018), data are analyzed using Cox proportional hazards regression to assess the timing of subsequent births at parity three and linear regression to measure son preference. The sample size included 100 733 women of reproductive age (15–49 years), of whom 96 975 were in monogamous unions and 3758 were in polygynous unions.
The results demonstrate a persistent and significant son preference in fertility decisions. Women with fewer or no sons are more likely to proceed to another birth, as evidenced by shorter birth intervals. A key finding is that polygynous marriages are associated with both higher son preference and shorter birth intervals compared to monogamous unions. While rural polygynous women exhibit stronger son preference, urban polygynous women tend to have quicker transitions to the next birth. In contrast, monogamous women generally report longer birth intervals and lower levels of son preference, regardless of residence.
The study finds that polygynous marriages are associated with stronger son preference compared to their monogamous counterparts. While rural polygynous women exhibit a stronger son preference than urban polygynous women, the latter have shorter birth intervals.
This study was conducted to determine whether possible allometries in hand digit lengths have an effect on the observed sexual dimorphism in digit ratios.
The lengths of four digits from the second to the fifth digits on the right and left hands of 500 adult participants (250 males, 250 females) were measured and six different ratios were calculated. ANCOVA and regression analyses were used to examine the allometry effect.
The findings revealed that the sexual dimorphism that emerged in the right and left 2D:4D ratios was independent of the allometry effect. On the other hand, it was observed that the allometry effect emerged in the three digit ratios (right and left 2D:5D, left 3D:5D).
These results reveal that the allometry effect is not observed on the ratios calculated from the digits (2D and 4D) that are claimed to have formed under the influence of prenatal steroids, but it can be observed on the other digits.
Human Biology is a young science asking the oldest of questions: Who are we? From what did we evolve? How did we deal with threats to our existence? What physiological and morphological adaptations did we develop that allowed our survival and fitness through evolutionary time? In the 21st century, after over three million years of human evolutionary change, what biological characteristics allow us to deal with the existential onslaught that is now affecting our daily lives?
These questions are not just interesting in their own right, but their answers are fundamental to the future of our species and are critically important to addressing long-standing inequities in health outcomes among human populations around the world. Arguably, the most important characteristic of Homo sapiens is our ability to acquire and use knowledge to understand the world around us. In that acquisition, it is the identification of the problem, the sharing of the search, and the answers that allows our onward existence. Threats to the research that targets those specific questions are a threat to humanity.
Since the dawn of the enlightenment in the 17th century, the speed with which we have been able to acquire and use knowledge has gathered pace, requiring ever more sophisticated methods of the sharing and transfer of knowledge through education so that the next generation profits from our endeavors and continues the journey.
We believe that threats exist to the educational and research methods that are the basis of our academic freedom to explore existential questions. These threats to science and promotion of conspiracy theories must be identified and rejected.
The consequences of the actions by the Trump administration are being felt across academia, research institutions, international development agencies, and in the broader global scientific community. As international organizations of Human Biologists, we believe that our collective voice must be heard at this time of crisis to argue for and create a constructive future pathway and not one that destroys the very advantages that have made our species so successful. We believe that government policies that emphasize deregulation, budget cuts, and restrictions on research and global engagement in the health and life sciences are ultimately destructive and must be objected to at every juncture.
We join the voices of our colleagues internationally and through the American National Academies of Sciences, Engineering, and Medicine when we agree that while we hold diverse political beliefs, we are united as researchers in wanting to protect independent scientific inquiry for the future of our species.
Statement of Editorial Independence: The views expressed here are solely those of the authors and do not necessarily represent those of the publisher.
More than any other scholar in our field, Professor Roy J. Shephard's research has shaped and transformed our understanding of the biology and health of circumpolar populations. His long-term research among the Inuit of Igloolik, Canada has provided the field of human biology with foundational insights into how human populations adapt to arctic climates, and how the transition to a market-oriented lifestyle erodes fitness and metabolic health. Shephard was the prime architect of early research done in the Canadian Arctic as part of the Human Adaptability Program (HAP) of the International Biological Programme (IBP) in the 1960s and early 1970s. After the original IBP studies, Shephard and collaborator Andris Rode continued their research in Igloolik through the early 1990s. This long-term research provided some of the first clear evidence on how the process of acculturation and lifestyle change erodes physical development and metabolic health among Indigenous populations of the north. This paper provides an overview of the major findings and insights from Roy Shephard and colleagues' research in Igloolik and highlights how these contributions are shaping ongoing research on the biology and health of circumpolar populations.
To analyze the influence of sociodemographic factors and BMI-based nutritional status on the somatic maturity of Mexican children.
BMI-based nutritional status and maturity offset by the Moore-II method were estimated. Information on age, sex, weight, height of 2- to 18-year-old children and adolescents, household socioeconomic status, and geographic region were obtained from the 2012 and 2018 databases of the National Health and Nutrition Survey (ENSANUT), National Institute of Public Health (INSP), and the National Institute of Statistics and Geography (INEGI) in Mexico. Saturated log-linear and logistic regression models were used to evaluate the associations among the variables. The association between the prevalence of excess weight (BMI-based overweight and obesity) and age, transforming the logistic model to a linear model using the logit function, was estimated.
The prevalence of overweight and obesity showed a cubic correlation with age and maturity offset in both sexes. In boys, the highest prevalence was observed at ages 12–14 years, which coincides with the peak height velocity. In girls, the highest prevalence occurred at ages 14–15 years, with this trend being stronger than in boys; additionally, overweight and obesity prevalence peaks at −2 and −1 years from APHV in boys, and between 0 and 2 years from APHV in girls. Children from rural areas, lower socioeconomic levels, and those from the southern region had a higher probability of late somatic maturity.
Socioeconomic and geographic factors play important roles in shaping nutritional status and somatic maturation patterns in Mexican children. Health and nutrition intervention programs and strategies for children and adolescents, based on these factors, are recommended.
In growing humans, densitometric scans of whole-body bone mass “less head” are recommended to circumvent the excessive contribution of youths' proportionally larger heads but potentially inflate inter-scan variation and least significant change due to measurement error. We aimed to determine biological benchmarks for achievement of adult head-body proportions in a sample of US females.
Annual whole-body dual energy x-ray absorptiometry (DXA) scans tracked growth, maturation, and bone mass accrual in a prospective longitudinal cohort of girls for up to 19 years (baseline age 7–15 years). We used cubic smoothing spline mixed effects models to generate chronological and gynecological age-based curves for head versus whole-body bone mass proportions (ratios). Females with ≥ 3 annual scans were included (n = 148, age 7–30 years).
Models yielded trajectories extending beyond observed age at peak bone mass for our sample. From age 18 years, “adult” mean of means for head vs. whole-body bone mass proportions was 0.204 (n = 66: 95% confidence interval = 0.198–0.210). Individual proportions stabilized to “adult” mean levels circum-menarche (n = 124: mean = 0.198; 95% confidence interval = 0.194–0.202). The minimum age for 95% confidence intervals overlapping with adult values was 12 years, circum-peak height velocity (n = 120: mean = 0.211; 95% confidence interval = 0.207–0.216).
In US girls with diverse activity exposures, head vs. whole-body bone mass proportions are “adult” from menarche onward; an “adult” age threshold of 12 years, or age at peak height velocity, may be used in the absence of extreme maturational delay to evaluate whole-body bone mass including the head.
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