Objective: Evaluating the relationships between the shape and biomechanical function of bone cross-sections can contribute novel insights towards human functional and evolutionary morphology. However, this research involves unique analytical and statistical challenges when comparing complex and multidimensional shape data to multivariate biomechanical variables. We developed the CSGM package in the R programming language to streamline statistical hypothesis testing on the geometric properties and shape of bone cross-sections, offering unique interactive and informative visualization plots. This package uses a variety of popular statistical inferential techniques including correlation, covariation, classification, and prediction. By applying a novel nested hypothesis testing approach, users can efficiently analyze complex morphofunctional relationships in parallel.

Materials and Methods: We present various functions within the CSGM package that can analyze and visualize three-dimensional shape relationships. In addition, we highlight dedicated functions which evaluate pairwise relationships between bone cross-sectional shape and biomechanically relevant variables. The effectiveness of this automated hypothesis testing approach is demonstrated through the use of two associated, complex datasets generated from cross-sections of the mandibular corpus in three modern human collections.

Results: The functions of our package helped reveal prominent shape asymmetry in the study sample which also asymmetrically impacts the bending resistances and breaking strength properties of the mandibular corpus.

Discussion: The CSGM package offers a series of functions that can test morphofunctional relationships by incorporating a nested hypothesis modeling approach to statistical analysis and interactive graphic visualizations. Thus, CSGM is a useful and powerful analytical toolkit to interpret complex data relationships.

Secular changes in the physical growth of children in the 20th century have been examined largely between cohorts of boys or men, with fewer studies examining changes among girls/women or both sexes. Sex-specific growth trajectories and differential cultural treatment of the sexes can affect how girls and boys respond to changes in the ontogenetic environment. This study examined secular change in height (cm) and weight (kg) in affluent Portuguese school children from three periods over the 20th century: an early (1913–1916), middle (1929–1943), and late (1992–2012) period. Anthropometric data was taken from medical records and archives of two boarding schools located in or near Lisbon: the Colégio Militar for boys and the Instituto de Odivelas for girls. Height and weight data were collated from over 1349 children (over 825 boys and 524 girls), aged to 10 to 17 years. Height and weight were plotted against age for the three periods to assess secular changes and sex differences in the secular trend. Results indicate a similar pattern of secular change across boys and girls, wherein children measured in the late period demonstrated an increase in height and weight, with the greatest increase occurring between the middle and late periods. The increase in height and weight can be attributed to changes to the socioeconomic environment in Portugal after the 1960s, but particularly after the democratic transition of 1974. This includes population-wide improvements in living standards, sanitation, decreased disease load, access to medical care and improved quantity and quality of nutrition. Cultural-based preferential treatment of boys may have taken place, as boys increased more in relative and absolute height and weight.

Objective: This study examines the radiological and dry bone manifestations of diagnosed leukemia in a child who lived prior to the advent of modern cancer treatment.

Materials: The skeleton of a 9-year-old girl who died of myeloid leukemia in Lisbon, Portugal in the 1940s.

Methods: Lesions were identified and documented through macroscopic analysis. Selected skeletal elements were imaged using radiography, mammography, and computed tomography.

Results: Osteolytic lesions were observed on the petrous portion, humerus, ilia, ischia, pubis, sacrum, tibiae, femora, and humeri. New bone formation was observed at the margins of osteolytic lesions on some bones including both ilia. Diffuse porosity on the frontal bone, the palate, several vertebrae, and the tarsals was also noted.

Conclusions: The lesions present in the child, both osteolytic and porotic, as well as new bone formation, are consistent with the clinically known radiological and dry bone effects of childhood leukemia.

Significance: This case is one of the few examples of potentially diagnosed childhood leukemia with observable dry bone lesions prior to the modern era of cancer treatment and can serve as a reference for diagnosis of suspected cases in the archaeological record.

Limitations: While the cause of death was documented as myeloid leukemia, it is possible that the medical diagnosis was incorrect.

Suggestions for future research: Further research using confirmed dry bone cases of leukemia and the environmental and societal factors potentially associated with the disease in the past.

Researchers have long speculated about the evolutionary benefits of religiosity. One explanation for the evolution of religious ritual is that rituals signal commitment to co-religionists. As a major domain of prosocial behaviour, alloparental care – or care directed at children by non-parents – is a plausible benefit of religious signalling. The religious alloparenting hypothesis posits that parents who signal religious commitment receive greater alloparental support. Prior research on religiosity, cooperation, and allocare tends to treat individuals as isolated units, despite the inherent collective nature of religious cooperation. Here, we address this limitation in a survey-based study of 710 parents in rural Bangladesh. Instead of focusing only on mothers, we consider the interplay between both mothers and fathers in eliciting allocare, and leverage variation in the covertness of religious rituals to test a key mechanistic assumption linking religious ritual with cooperation. We find that parents who practice religious rituals more frequently receive greater alloparental support from co-religionists. This effect is moderated by parent gender, as well as variation in the visibility of religious rituals. Women’s private practices positively affect only those alloparents with whom they share a household, whereas men’s public practices positively affect alloparents more broadly.

Estimating age as accurately as possible in older adults (50 years and above) remains a challenge. Dental methods such as the pulp/tooth area ratio developed by Cameriere et al. have shown promising results in different populations. However, their applicability across forensic contexts remains underexplored. This study evaluates the repeatability and validity of the Cameriere method in a contemporary U.S. sample using cone-beam computed tomography (CBCT) scans. A total of 136 mandibular canines, 89 first premolars, and 82 second premolars from 146 individuals were analyzed. Intra- and inter-observer reliability were evaluated using technical error of measurement (TEM), relative TEM (rTEM), and intraclass correlation coefficients (ICC). Method accuracy was assessed using mean residuals, mean absolute residuals, and the percentage of individuals within the 95 % prediction interval. The method exhibited overall poor performance: only 46.90–58.33 % of individuals true age fell within the 95 % prediction interval. Performance was inconsistent across different age groups: individuals under 30 and over 60 years of age had greater prediction error. Mean absolute residuals were 13.52 years for the canine, 15.37 years for the first premolar, and 15.03 years for the second premolar. All teeth showed negative mean residuals indicating overall underestimation of the individuals’ ages. While tooth area measurements showed acceptable repeatability, pulp cavity measurements exceeded acceptable error thresholds, suggesting observer experience plays a critical role in the application of this method. We discuss the implications of our results for understanding the limitations of this method in forensic casework in the U.S. and other populations.

Research demonstrates that religious people are trusted more, receiveand provide more cooperation, and have larger cooperative networks.This line of research also suggests, that religious prosociality is notalways parochial, and often extends to people outside of a religiousingroup. Here, we test whether the intensity of religious practiceassociates with received support from coreligionists and/or non-coreligionists among a sample of American mothers. Specifically, wetest the association between self-reported behavioral religiosity ofreligious (here Christian) and non-religious mothers from the GreaterPittsburgh area, USA, and the frequency of emotional support (Nmothers= 517, Nsupporters = 1999) and housework help (Nmothers = 447, Nsupporters= 997) they received from Christian and non-religious supporters. Wefound that maternal religiosity was positively associated with thefrequency of housework help received from Christian supporters, butnot from non-religious supporters. We did not find evidence for anassociation between maternal religiosity and emotional supportreceived from religious nor non-religious supporters. We interpret ourresults through the lens of religious signaling theory

Among humans, paternal investment has been shown to enhance both fertility and offspring survival. While psychological and ecological influences on human paternal investment are relatively well documented, cultural influences remain less well understood. It has been proposed that religion can be an important socio-cultural factor shaping paternal investment. First, religions often instill pro-family values in fathers, potentially increasing their investment. Second, if religions promote pro-family values in mothers, these values may be communicated through religious behaviours, encouraging greater paternal investment. Alternatively, fathers may use maternal religiosity as a strategic cue of maternal pro-family commitment to reduce their own investment, shifting responsibility to mothers. To evaluate these hypotheses, we analyse data from 1238 children under 17 years old across 822 households in India and Bangladesh. Our findings suggest that in India, paternal religiosity is positively associated with fathers’ housework assistance and emotional support to mothers. In Bangladesh, maternal religiosity is positively associated with paternal emotional support to mothers and child provisioning. In both countries, maternal religiosity positively associates with paternal investment among the most religious fathers. These findings indicate that religion plays a complex role in paternal investment, shaped by the interplay of parental religiosity and socio-ecological context.

Alloparental care—care provided to children who are not one’s offspring—is ubiquitous across human populations. Empirical research reveals socioecological variation in who cares for children, but less attention has been paid to the type of care provided. To better understand the fitness outcomes of different forms of alloparental care, or allocare, we categorize such care into two broad forms based on economic cost structures: additive cost and declining marginal cost allocare. Additive cost allocare requires alloparents to pay equal costs for each child to whom care is provided, while declining marginal cost allocare entails reduced costs for additional children beyond the first. Given this general typology, we investigate how fitness is impacted by the type of allocare provided in socioecological conditions of scarcity or abundance. Results of an agent-based model indicate that allocare has fitness benefits in nearly all circumstances, but the impact of cost structures depends on resource availability. In contexts of abundance, the cost structure of allocare does not matter as individuals’ reproductive success is instead constrained by fertility and mortality more than the availability of resources or time. In conditions of scarcity, however, the greatest increases in reproductive success are achieved when allocare has a declining marginal cost structure. This is due to an economy of scale permitting alloparents to scale up their care at discounted rates. Consequently, we expect allocare practices to exhibit these patterns cross-culturally: in contexts of scarcity allocare is anticipated to be focused on practices with declining marginal cost structures and to be much less variable than in contexts of abundance. We discuss several ethnographic examples that are consistent with the overall findings of our simulations, and we conclude with recommendations for future modeling and empirical work on allocare.

The social isolation resulting from governments’ responses to the COVID-19 pandemic likely limited support available to mothers. Evidence suggests tasks like childcare and domestic work fell disproportionately on mothers during the pandemic, with consequences for their wellbeing. We explore how the pandemic affected emotional and practical support available to mothers between March and August 2020 and whether changes in support are associated with changes in their paid work and mental health. Data were collected in August 2020 from 1528 UK and US mothers with at least one child under 5-years using a cross-sectional survey and are analysed using regression models. Women’s in-person contact with support networks decreased, while virtual interactions increased. Most mothers experienced a ‘nuclearization’ of in-person support: childcare from fathers and siblings increased or remained constant but decreased from the grandparental generation. Women receiving less support during the pandemic had higher odds of reducing participation in paid work. Associations between support and mental health are limited. We also identify women who concurrently experienced reduced support and increased need for help, representing a particularly vulnerable group. The nuclearization of maternal social networks likely increased physical and emotional pressures on the immediate family, risking parental burnout and affecting reductions in female participation in paid labour. There is a need for reliable and affordable childcare options that help reduce women’s burden of unpaid care labour, allowing them to re-enter (or remain in) paid labour.

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.

In low fertility settings, religious people tend to have larger families than non-religious people. One way religious individuals may achieve larger relative family sizes is through support from their families. In this paper, we investigate the relationships between religiosity, kin contact, allomaternal investment from relatives, and fertility in two high income low fertility settings: the United Kingdom and the United States. Data for this pre-registered research come from an online survey of 609 women living in the US and 919 women living in the UK, recruited through Prolific, who answered questions about their religious practices, childbirth histories, social networks, and allomaternal networks. We find that, compared with less religious peers, more religious women: 1) have more geographically diffuse kin networks (particularly in the UK) but have social networks that are equally kindense; 2) receive more allomaternal support from kin beyond their partner, particularly help with household tasks, though the countries differ in the exhibited relationship between religiosity and partner support; and 3) have higher fertility in both countries. We do not find strong evidence for a mediating role of allomaternal support on the relationship between religiosity and fertility. Our study highlights important variation in the relationship between religion and fertility across two high income low fertility countries and raises new questions about the role that religion plays in allomaternal support networks in these settings.

Researchers in the biological and behavioural sciences are increasingly conducting collaborative, multi-sited projects to address how phenomena vary across ecologies. These types of projects, however, pose additional workflow challenges beyond those typically encountered in single-sited projects. Through specific attention to cross-cultural research projects, we highlight four key aspects of multi-sited projects that must be considered during the design phase to ensure success: (1) project and team management; (2) protocol and instrument development; (3) data management and documentation; and (4) equitable and collaborative practices. Our recommendations are supported by examples from our experiences collaborating on the Evolutionary Demography of Religion project, a mixed-methods project collecting data across five countries in collaboration with research partners in each host country. To existing discourse, we contribute new recommendations around team and project management, introduce practical recommendations for exploring the validity of instruments through qualitative techniques during piloting, highlight the importance of good documentation at all steps of the project, and demonstrate how data management workflows can be strengthened through open science practices. While this project was rooted in cross-cultural human behavioural ecology and evolutionary anthropology, lessons learned from this project are applicable to multi-sited research across the biological and behavioural sciences.

Existing child stature estimation methods have a number of disadvantages. This paper addresses some of these limitations by developing regression-based stature estimation formulae that are more generic and inclusive. A sample of 142 individuals under 12 years of age from the Hamann—Todd Human Osteological Collection and the New Mexico Decedent Images Database were used to generate five least squares linear regression formulae to estimate stature from the diaphyseal length of long bones. All models showed excellent fits to the data (R2 close to or at 0.98), and internal validation confirmed the stability and accuracy of model parameters. External validation was performed using a sample of 14 individuals from the Lisbon Collection and the Victoria Institute of Forensic Medicine. Overall, the humerus provides the most accurate estimate of stature, but the femur and tibia showed the greatest coverage. These formulae can be used in a variety of contexts and are not dependent on group affiliation, including sex.

Objectives: Biological mortality bias is the idea that individuals who comprise skeletal samples (non-survivors) are a specific subset of the overall population, who may have been exposed to greater stress during life. Because of this, it is possible that studying growth in a skeletal population misrepresents the growth and health of survivors in that population. Using a modern sample, this study investigates whether biological mortality bias in growth may be present in archaeological skeletal samples.

Materials and methods: Postmortem computed tomography scans of 206 children aged under 13 years were collected from two institutions in the United States and Australia. The sample was separated into children who died from natural causes as proxies for non-survivors and from accidental causes as proxies for survivors. Differences in long bone length for age were assessed through analysis of covariance (ANCOVA) and z-score analysis, and these results were compared with studies linking anthropometrics and mortality risk in nonindustrialized societies.

Results: Differences in growth favoring survivors were greater for girls than for boys and seemed to increase over age. The effect in nonindustrialized societies was 1.5 to 5 times the magnitude of that in our contemporary sample.

Conclusions: A greater growth delay in girls than in boys has been documented in historical identified collections, and skeletal samples consistently become more stunted relative to modern standards over the course of growth. Our findings on biological mortality bias could explain part of these growth delays and impact interpretations of past ontogenetic environments.

In high-income, low-fertility (HILF) settings, the mother’s partner is a key provider of childcare. However, it is not clear how mothers without partners draw on other sources of support to raise children. This paper reports the findings from a survey of 1532 women in the United Kingdom and the United States, in which women described who provided childcare for a focal child and how frequently they did so. We use multivariate Bayesian regression models to explore the drivers of support from partners, maternal kin, and other allomothers, as well as the potential impact of allomothering on women’s fertility. Relative to mothers who are in a stable first marriage or cohabitation, mothers who are unpartnered rely more heavily on fewer maternal kin, use more paid help, and have networks which include more non-kin helpers. Repartnered mothers received less help from their partners in the UK and less help from maternal kin in both countries, which US mothers compensated for by relying on other helpers. While repartnered mothers had higher age- adjusted fertility than women in a first partnership, allomaternal support was not clearly related to the mother’s fertility. These findings demonstrate the importance of partners but also of allomothering more broadly in HILF settings.