Rebeca García‐González

The obstetrical dilemma hypothesis (ODH) proposes an evolutionary trade‐off between obstetric requirements and locomotor performance. However, whether external pelvic breadth measures influence walking energetics during human growth remains poorly understood. This study quantified gross walking energy expenditure (WalkingEE) in juveniles and examined whether external pelvic breadth measures influence locomotor energetics during growth. Twenty‐eight healthy children and adolescents (8–17 years) completed treadmill walking trials at randomized speeds (2–6 km/h). Gross WalkingEE (kcal/24 h) was measured by indirect calorimetry, and anthropometric variables included body mass (BM), height, femur length, tibia length, bi‐iliac breadth (BIL), and bi‐trochanteric breadth (BITR). Forward stepwise multiple linear regression identified BM, walking speed, and BIL as the only significant predictors of WalkingEE ( R ² = 0.89, * p < 0.0001). BM and walking speed were positively associated with energy expenditure, whereas BIL showed a significant negative association, accounting for 43%, 31.5%, and −25.5% of the explained effect, respectively. These findings indicate that greater bi‐iliac breadth is associated with lower walking energy expenditure during growth. Moreover, the fact that bi‐trochanteric breadth was not retained in the final model, despite being used as a proxy more closely associated with obstetric dimensions, suggests that locomotor energetics and obstetric function may be at least partly independent. Overall, our findings are consistent with a more dynamic interpretation of the obstetrical dilemma hypothesis and provide new empirical support for the view that the human pelvis is a functionally modular structure shaped by multiple selective pressures.

The scarcity of infant human remains in prehistoric sites, combined with a historical lack of interest in the social and cultural roles of infants, has traditionally relegated the study of childhoo...

The preauricular sulcus has long been debated as a pelvic feature variably attributed to obstetric stress, ligamentous traction, and broader biomechanical processes. To clarify its determinants, we analyzed 409 adult individuals from three archeological and one early modern skeletal collection from the Iberian Peninsula, integrating graded sulcus expression with pelvic morphology, body size, and demographic context. Sulcus expression shows marked sexual dimorphism: females exhibit the full morphological spectrum, whereas males display limited variation and are overwhelmingly concentrated in the lowest grades. Hierarchical log‐linear models and ordinal logistic regression analyses indicate that preauricular sulcus presence is not associated with stature, body mass, or overall pelvic canal dimensions. Instead, inferior pelvic dimensions, particularly pubic length and outlet measures, emerge as the only consistent morphological predictors, with significant sex‐specific interactions restricted to the outlet. Neither population affiliation nor age at death modifies the association between sex and sulcus expression. Taken together, these results support a model in which the preauricular sulcus reflects sex‐specific biomechanical environments of the inferior pelvis rather than overall body size or population‐level variation. Within this framework, sulcus development is best interpreted as ligament‐mediated remodeling shaped by localized mechanical loading and hormonally mediated changes associated with pregnancy, while remaining robust across diverse biocultural contexts and mortality regimes.

This study investigates ontogenetic changes in human scapular morphology using three‐dimensional geometric morphometrics with whole‐bone and region‐specific analyses. The aim is to evaluate whether the scapula follows a regular developmental pattern and whether its functionally distinct components, the scapular spine (SS) and glenoid fossa (SGF), exhibit divergent growth trajectories indicative of modular development. This approach assesses interactions between global and local morphological change and explores the influence of size, biomechanics, and ossification timing on scapular development. We analyzed 3D surface scans of 127 scapulae from non‐adult and adult individuals from the medieval San Pablo Collection, Spain, and the documented Lisbon Collection, Portugal. Seven ontogenetic groups were defined using dental and chronological age. Landmark and semi landmark configurations were generated for the entire scapula, the scapular spine, and the glenoid fossa. Shape and form variation were examined using Generalized Procrustes Analysis and Principal Component Analysis. Across all regions, PC1 captured the main axis of ontogenetic variation, separating age groups in both shape and form space. Whole‐scapula analyses revealed a gradual developmental pattern, whereas regional analyses highlighted distinct trajectories. The scapular spine showed progressive curvature and torsion, likely reflecting muscular loading, while the glenoid fossa displayed more constrained changes linked to joint stabilization and ossification timing. These findings support a modular model of scapular growth, with regions responding to intrinsic developmental processes and extrinsic biomechanical influences. Integrating regional and whole‐bone analyses reveals developmental plasticity not detectable through global approaches alone, with implications for forensic, clinical, paleoanthropological, and bioarchaeological research.

Recent advances in the study of cross‐sectional geometry have highlighted the value of ontogenetic data for understanding skeletal function, development, and biomechanics. While multiple protocols for extracting bone cross‐sections have been validated in limb long bones, the clavicle (despite its unique curvature and developmental trajectory) has received little methodological scrutiny. Critically, two main alignment strategies can be used to extract clavicular midshaft cross‐sections from 3D data, yet their comparability remains untested. This lack of standardization compromises the reproducibility and interpretability of clavicular cross‐sectional property (CSP) data, particularly in developmental studies. This study evaluates two published alignment protocols for clavicular CSP extraction in non‐adults: one that follows the natural curvature of the bone and one based on a standardized transverse plane. We analyzed high‐resolution computed tomography scans of 81 individuals (ages 0.5–20 years) from a medieval osteological collection. Midshaft cross‐sections were generated using both methods for each clavicle, and CSP variables were calculated. Comparative analysis involved linear regressions, Bland–Altman plots, and percent prediction error (%PE) to assess both systematic bias and the magnitude and direction of error between methods. While total area showed a significant proportional bias and %PE values exceeding the 5% acceptable error threshold, cortical subperiosteal area exhibited a consistent but non‐proportional bias, indicating uniform overestimation across specimens. Z _p and J showed the largest directional errors, reflecting greater sensitivity to alignment differences. These discrepancies are not merely numerical but reflect fundamental geometric divergences introduced by the alignment strategy. As a result, CSP values obtained from these two protocols are not directly interchangeable. Together, Bland–Altman and %PE analyses provide a robust framework for evaluating agreement and highlight where pooling data across alignment strategies may be justified and where it is not. Our findings underscore the importance of methodological consistency in clavicular cross‐sectional analyses. Given the anatomical complexity of the clavicle and its developmental plasticity, alignment strategy exerts a significant influence on derived CSP values. We recommend that future studies clearly report alignment criteria and avoid direct comparisons between datasets processed with different protocols.

Objectives: This study analyzes the relationship between femoral cross‐sectional geometric properties (CSGP) and the topographic features of Gran Canaria (Canary Islands, Spain) in the Amazigh population. We assess individual variation and differences by region (Inland vs. Coast) and sex to infer mobility patterns. Materials and Methods: The sample comprises 110 complete adult femora representing a minimum of 88 individuals from eight Amazigh period sites (5th–15th centuries ce ) located in both inland and coastal regions. Sex estimation was conducted using a combination of paleogenomic data, mathematical methods, and morphological traits. Geospatial analyses using GIS allowed us to estimate calculated catchment area (A) and average slope (AS) for each site. CSGP were obtained via CT at 20%–80% of bone biomechanical length. Results: Significant differences were found between inland and coastal sites in A and AS values. Regional variations in femoral geometry appeared primarily at mid‐proximal diaphyseal levels, with a tend coastal showing stronger femora and greater resistance to bending and torsional forces than inland individuals. Sex‐related differences were significant across most femoral levels, with males displaying larger areas and second moment of area than females. Discussion: Femoral CSGP in the Amazigh population of Gran Canaria indicates similar mobility patterns across regions, likely shaped by the island's rugged terrain, with a slightly higher mobility pattern observed in the coastal areas. Additionally, sex‐gender related differences in femoral properties suggest a higher mobility activity in males probably due to a division of labor.

This study investigated the presence and expression of medullary contractions—defined as reductions in the medullary area (MA)—during adolescence, with particular focus on sex‐specific patterns and regional variability within the femur. We assessed changes in cortical area (CA) and MA both in absolute terms and relative to total cross‐sectional area (TA) at two anatomical locations: the femoral midshaft and midneck. By integrating developmental and structural indicators, we aim to explore how the hormonal surge associated with pubertal maturation influences femoral cross‐sectional geometry, providing novel insights into life‐history processes as recorded in skeletal remains. The study sample included 75 femora (46 non‐adults and 29 adults) from the medieval population of San Pablo Monastery (Burgos, Spain, 14th–18th centuries). Individuals were assigned to one of four maturity groups based on dental and skeletal indicators. Sex estimation was performed macroscopically for adults and late adolescents, and via enamel peptide analysis (amelogenin) for younger individuals. Cross‐sectional properties (including TA, CA, and MA) were extracted from CT scans at the midshaft and midneck. Multiple linear regression models (log‐transformed variables) were used to assess the relationship between MA/CA and TA, testing to evaluate the effects of sex and skeletal maturity. At the midneck, both CA and MA increased with TA, with medullary expansion being more pronounced in females with larger bones, likely reflecting the influence of pelvic morphology and femoral neck orientation. In contrast, at the midshaft, TA was not generally associated with MA; however, interactions revealed that females and adults exhibited steeper increases in MA relative to TA, despite having smaller medullary cavities. Although CA was generally higher in adult females, its proportional increase with TA was attenuated, especially at the midshaft. These patterns reflect a shared trend toward medullary contraction, differentially modulated by anatomical region and biomechanical context. Our findings provide evidence for medullary contractions during late adolescence, particularly in females; however, their expression varies by anatomical region. The midneck shows more morphological plasticity, likely reflecting regional loading asymmetries, whereas the midshaft displays canalization with modulated trajectories in larger bones. Proximity to peak bone mass appears critical for detecting this process, which may be transient and obscured in cross‐sectional studies. Future studies should increase the sampling of late‐adolescent females and integrate pelvic proxies and other bones to better understand the timing and biomechanics of medullary contractions.

Objectives: Locomotion is fundamental to the survival of our species. The most comfortable walking speed may be the most efficient for allocating conserved energy for other functions. However, whether preferred (PLS) and optimal (OLS) speeds align in children and adolescents remains unclear. This study aimed to determine whether OLS and PLS are similar in children and adolescents and how anthropometry influences both speeds and their differences. Materials and Methods: Eleven females and 17 males (8–17 years of age) were anthropometrically characterized. Five treadmill walking pace tests were used to identify the OLS and U‐shaped relationship between energy expenditure and speed ( χ ² CoT), indicating walking flexibility. Additionally, PLS was self‐selected using the same protocol. Differences between OLS and PLS were calculated (mean difference [MD]). Results: No significant sex differences in anthropometry and speed‐related variables were found. OLS, PLS, and their MD in the pooled sample were 3.05 ± 0.13, 2.46 ± 0.51, and 0.60 ± 0.46, respectively, with significant differences between OLS and PLS ( p < 0.0001). Femur length (FL), Bi‐iliac breadth (BIL), and χ ² CoT explained variance in OLS, PLS, and MD, respectively, in the forward stepwise regression models. Discussion: Unlike adults, OLS and PLS are not interchangeable in children and adolescents. Participants with lower χ ² CoT (greater flexibility) can select comfortable speeds farther from OLS without energetic penalty. Taller individuals with longer femurs and wider hips might have biomechanical advantages in reaching higher OLS and PLS, but this reduces flexibility. These traits, along with the growth and development pattern of Homo sapiens , may reflect evolutionary advantages relevant to interspecies competition.

Objectives: This study evaluated the influence of genetic diversity, subsistence strategies, age at death, and their interplay on the prevalence of linear enamel hypoplasias (LEHs) in the indigenous populations of the Canary Islands. Additionally, we test the predictive adaptive hypothesis and the plasticity/constraint hypothesis within this unique archeological context.Methods: LEH incidence, age of occurrence, and the number of stress episodes were assessed macroscopically in a sample of 409 individuals from six of the seven islands comprising the Canarian archipelago during the pre‐contact or Indigenous period (2nd–15th century cal CE). Statistical comparisons were made using chi‐square and Fisher's exact tests to evaluate LEH prevalence across populations and age groups within each island. To control for potential demographic confounding, hierarchical log‐linear (HLL) analysis was applied to explore the combined influence of age, sex, and island of origin on LEH prevalence. Model fit was assessed using likelihood‐ratio chi‐square tests.Results: Statistically significant differences were found between Gran Canaria and Tenerife, and between them and La Palma. Sexual differences in LEH prevalence were observed among individuals from Gran Canaria and within specific age groups in the other populations. In all indigenous populations, the number of individuals with LEH decreased in the oldest age groups.Conclusions: Our findings suggest that subsistence strategies explain the differences observed among the islands in terms of the various analyzed variables. All the data suggest that the plasticity/constraint hypothesis best fits the Indigenous populations of the Canary Islands, with males being more affected by environmental conditions than females.