Sexual dimorphism in primates reflects evolutionary, ecological, and social pressures and varies widely across species, complicating its analysis. This study builds on previous research to investigate sexual dimorphism in the long bones of great apes, aiming to improve sex estimation and evaluate the effectiveness of various methods in classifying unsexed specimens.
Materials and Methods
External morphology of humeri and femora from modern great apes—including Homo, Pan, Gorilla, and Pongo—was analyzed using 3D anatomical landmarks and geometric morphometrics. Various statistical approaches and dimensionality reduction techniques were employed alongside classification methods, including supervised machine learning algorithms.
Results
Size, rather than shape, emerged as the main factor distinguishing male and female long bones in great apes—except in Pan, where dimorphism is minimal and classification accuracy remains low. Incorporating size improved classification accuracy for Gorilla, Pongo, and Homo, with results indicating strong dimorphism in Gorilla and Pongo, moderate dimorphism in Homo sapiens, and minimal dimorphism in Pan.
Discussion
This study shows that combining geometric morphometrics with machine learning can enhance sex classification of great ape long bones. Nonetheless, limitations such as small or imbalanced samples highlight the need for larger datasets and further research—including internal bone structure—to better understand skeletal dimorphism and its evolutionary drivers.
{"title":"External Long Bone Morphology as a Tool for Sex Identification in Great Apes: The Case of the Humerus and Femur","authors":"Julia Aramendi","doi":"10.1002/ajpa.70139","DOIUrl":"10.1002/ajpa.70139","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Sexual dimorphism in primates reflects evolutionary, ecological, and social pressures and varies widely across species, complicating its analysis. This study builds on previous research to investigate sexual dimorphism in the long bones of great apes, aiming to improve sex estimation and evaluate the effectiveness of various methods in classifying unsexed specimens.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>External morphology of humeri and femora from modern great apes—including <i>Homo</i>, <i>Pan</i>, <i>Gorilla</i>, and <i>Pongo</i>—was analyzed using 3D anatomical landmarks and geometric morphometrics. Various statistical approaches and dimensionality reduction techniques were employed alongside classification methods, including supervised machine learning algorithms.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Size, rather than shape, emerged as the main factor distinguishing male and female long bones in great apes—except in <i>Pan</i>, where dimorphism is minimal and classification accuracy remains low. Incorporating size improved classification accuracy for <i>Gorilla</i>, <i>Pongo</i>, and <i>Homo</i>, with results indicating strong dimorphism in <i>Gorilla</i> and <i>Pongo</i>, moderate dimorphism in <i>Homo sapiens</i>, and minimal dimorphism in <i>Pan</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>This study shows that combining geometric morphometrics with machine learning can enhance sex classification of great ape long bones. Nonetheless, limitations such as small or imbalanced samples highlight the need for larger datasets and further research—including internal bone structure—to better understand skeletal dimorphism and its evolutionary drivers.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145252018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hana Salahuddin, Andrea L. Waters-Rist, Fred J. Longstaffe
Objectives
Evaluate the effectiveness of compound-specific nitrogen isotope analysis of amino acids (CSIA-AA) in reconstructing early childhood diets and detecting episodes of stress. Examine (1) proline's potential for identifying breastfeeding and weaning; (2) the influence of physiological and pathological stress on AA δ15N; (3) the reliability of trophic position (TP) estimates from phenylalanine (Phe) and glutamate (Glx) δ15N during dietary transitions; and (4) mother-infant trophic enrichment factors (TEFGlx-Phe) as indicators of infant dietary protein quality.
Materials and Methods
Three mother-infant dyads provided fingernail clippings (n = 43) for CSIA-AA analysis pre- and post-birth, alongside dietary and health surveys.
Results
Proline δ15N was elevated by 2.4‰–3.5‰ in exclusively breastfed infants compared to their mothers and decreased by 2.2‰–4.1‰ during weaning. Phenylalanine δ15N showed large positive shifts (e.g., by 6.7‰) during maternal stress, despite being a source AA expected to remain stable. TP differences between mother-infant pairs were minimal (−0.2 to 0.1), except for one pair with higher infant TP (by 0.6–1.5). The calculated TEFGlx-Phe for infants ranged from −1.4‰ to 11.3‰.
Discussion
Proline δ15N reliably tracks nutritional transitions, likely due to its role in arginine synthesis during infancy. The unexpected variability in δ15NPhe complicates its use in TP and dietary protein quality assessments. This variability may result from phenylalanine's slow turnover and delayed dietary incorporation during endogenous catabolism. TP is an unreliable marker of breastfeeding or weaning. TEFGlx-Phe for infants seems indicative of high dietary protein quality, but interpretations must consider the influence of non-dietary factors on δ15NPhe.
{"title":"Exploring Early Childhood Diet, Stress, Trophic Position and Dietary Protein Quality Using Amino Acid Nitrogen Isotope Compositions of Fingernail Keratin","authors":"Hana Salahuddin, Andrea L. Waters-Rist, Fred J. Longstaffe","doi":"10.1002/ajpa.70128","DOIUrl":"10.1002/ajpa.70128","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Evaluate the effectiveness of compound-specific nitrogen isotope analysis of amino acids (CSIA-AA) in reconstructing early childhood diets and detecting episodes of stress. Examine (1) proline's potential for identifying breastfeeding and weaning; (2) the influence of physiological and pathological stress on AA <i>δ</i><sup>15</sup>N; (3) the reliability of trophic position (TP) estimates from phenylalanine (Phe) and glutamate (Glx) <i>δ</i><sup>15</sup>N during dietary transitions; and (4) mother-infant trophic enrichment factors (TEF<sub>Glx-Phe</sub>) as indicators of infant dietary protein quality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>Three mother-infant dyads provided fingernail clippings (<i>n</i> = 43) for CSIA-AA analysis pre- and post-birth, alongside dietary and health surveys.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Proline <i>δ</i><sup>15</sup>N was elevated by 2.4‰–3.5‰ in exclusively breastfed infants compared to their mothers and decreased by 2.2‰–4.1‰ during weaning. Phenylalanine <i>δ</i><sup>15</sup>N showed large positive shifts (e.g., by 6.7‰) during maternal stress, despite being a source AA expected to remain stable. TP differences between mother-infant pairs were minimal (−0.2 to 0.1), except for one pair with higher infant TP (by 0.6–1.5). The calculated TEF<sub>Glx-Phe</sub> for infants ranged from −1.4‰ to 11.3‰.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>Proline <i>δ</i><sup>15</sup>N reliably tracks nutritional transitions, likely due to its role in arginine synthesis during infancy. The unexpected variability in <i>δ</i><sup>15</sup>N<sub>Phe</sub> complicates its use in TP and dietary protein quality assessments. This variability may result from phenylalanine's slow turnover and delayed dietary incorporation during endogenous catabolism. TP is an unreliable marker of breastfeeding or weaning. TEF<sub>Glx-Phe</sub> for infants seems indicative of high dietary protein quality, but interpretations must consider the influence of non-dietary factors on <i>δ</i><sup>15</sup>N<sub>Phe</sub>.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12505251/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study provides a proof-of-concept for incorporating evolutionary theory into forensic anthropology practice. Specifically, we test whether innominate measurements used in the DSP 2 sex-estimation method reflect known patterns of morphological integration and whether variable redundancy can be reduced without compromising classification accuracy.
Materials and Methods
Innominate measurements were obtained from published datasets totaling 3045 individuals. Principal component analysis (PCA) was used to identify clusters of measurements. Relative standard deviation of eigenvalues was used to assess the degree of morphological integration. Posterior probabilities of sex classification were computed using one variable per cluster (cluster-based approach) and compared to a randomly selected four-variable approach, consistent with the minimum recommended by the original study. Simulations were used to generate posterior distributions of accuracy and the percentage of samples reaching a decision threshold.
Results
Three distinct clusters of innominate measurements were identified, broadly corresponding to known modules of the innominate. The degree of morphological integration was higher within clusters than in the full measurement set or nonintegrated matrices. The cluster-based classification approach showed comparable accuracy (mean = 96.38%) to the randomized approach (mean = 95.64%) despite using only three variables. While fewer individuals were assigned a sex under the cluster-based method, the results demonstrated higher consistency.
Discussion
Results suggest that accounting for morphological integration can streamline sex estimation by reducing variable redundancy without compromising accuracy. This study demonstrates how evolutionary principles can improve the theoretical foundation of forensic anthropology methods and offers a framework for future method development grounded in evolutionary theory.
{"title":"Incorporating Evolutionary Theory Into Forensic Anthropology Methods and Practice: A Proof-of-Concept Study Using Skeletal Sex Estimation","authors":"An-Di Yim, Michala K. Stock, Allysha P. Winburn","doi":"10.1002/ajpa.70137","DOIUrl":"10.1002/ajpa.70137","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>This study provides a proof-of-concept for incorporating evolutionary theory into forensic anthropology practice. Specifically, we test whether innominate measurements used in the DSP 2 sex-estimation method reflect known patterns of morphological integration and whether variable redundancy can be reduced without compromising classification accuracy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>Innominate measurements were obtained from published datasets totaling 3045 individuals. Principal component analysis (PCA) was used to identify clusters of measurements. Relative standard deviation of eigenvalues was used to assess the degree of morphological integration. Posterior probabilities of sex classification were computed using one variable per cluster (cluster-based approach) and compared to a randomly selected four-variable approach, consistent with the minimum recommended by the original study. Simulations were used to generate posterior distributions of accuracy and the percentage of samples reaching a decision threshold.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Three distinct clusters of innominate measurements were identified, broadly corresponding to known modules of the innominate. The degree of morphological integration was higher within clusters than in the full measurement set or nonintegrated matrices. The cluster-based classification approach showed comparable accuracy (mean = 96.38%) to the randomized approach (mean = 95.64%) despite using only three variables. While fewer individuals were assigned a sex under the cluster-based method, the results demonstrated higher consistency.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>Results suggest that accounting for morphological integration can streamline sex estimation by reducing variable redundancy without compromising accuracy. This study demonstrates how evolutionary principles can improve the theoretical foundation of forensic anthropology methods and offers a framework for future method development grounded in evolutionary theory.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12501655/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145239853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Predrag Radović, Joshua Lindal, Petar Milovanović, Dušan Mihailović, Mirjana Roksandic
Objective
The cave site of Velika Balanica in Sićevo Gorge, Serbia, has previously yielded early Neanderthal dental remains from Layer 3a, dated by thermoluminescence to 285 ± 34 and 295 ± 74 ka. We describe and compare four additional dental specimens recovered from the Middle Pleistocene Layers 3a and 3b of the cave: a right I1 (BH-8), a right I2 (BH-7), an incisor crown fragment (BH-16), and a left M3 (BH-15).
Material and Methods
The fossil teeth were scanned using micro-computed tomography (μCT), and the resulting digital models were used to record dimensions and assess internal morphology, including the enamel–dentine junction (EDJ). Morphological traits were analyzed on both outer and internal surfaces. Dental measurements were compared to those of relevant hominin samples.
Results
BH-8 and BH-7 show large, robust crowns and roots, consistent with Pleistocene Eurasian hominins. Linear enamel hypoplasia is present in BH-8 and BH-16. BH-15 displays a continuous middle trigonid crest—a trait considered diagnostic of the Neanderthal lineage. Notably, BH-15 also presents an extreme case of taurodontism, as well as a severe antemortem tooth fracture accompanied by multiple pulp stones, which are rarely recorded in the hominin fossil record.
Discussion
These findings align with earlier results, reinforcing evidence for early Neanderthal presence at Velika Balanica around 300 ka. While Neanderthals may have been present in the region earlier, this represents the earliest dated evidence of their spread into the Balkans.
{"title":"New Middle Pleistocene Hominin Dental Remains From Velika Balanica, Serbia","authors":"Predrag Radović, Joshua Lindal, Petar Milovanović, Dušan Mihailović, Mirjana Roksandic","doi":"10.1002/ajpa.70133","DOIUrl":"10.1002/ajpa.70133","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objective</h3>\u0000 \u0000 <p>The cave site of Velika Balanica in Sićevo Gorge, Serbia, has previously yielded early Neanderthal dental remains from Layer 3a, dated by thermoluminescence to 285 ± 34 and 295 ± 74 ka. We describe and compare four additional dental specimens recovered from the Middle Pleistocene Layers 3a and 3b of the cave: a right I<sup>1</sup> (BH-8), a right I<sub>2</sub> (BH-7), an incisor crown fragment (BH-16), and a left M<sub>3</sub> (BH-15).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Material and Methods</h3>\u0000 \u0000 <p>The fossil teeth were scanned using micro-computed tomography (μCT), and the resulting digital models were used to record dimensions and assess internal morphology, including the enamel–dentine junction (EDJ). Morphological traits were analyzed on both outer and internal surfaces. Dental measurements were compared to those of relevant hominin samples.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>BH-8 and BH-7 show large, robust crowns and roots, consistent with Pleistocene Eurasian hominins. Linear enamel hypoplasia is present in BH-8 and BH-16. BH-15 displays a continuous middle trigonid crest—a trait considered diagnostic of the Neanderthal lineage. Notably, BH-15 also presents an extreme case of taurodontism, as well as a severe antemortem tooth fracture accompanied by multiple pulp stones, which are rarely recorded in the hominin fossil record.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>These findings align with earlier results, reinforcing evidence for early Neanderthal presence at Velika Balanica around 300 ka. While Neanderthals may have been present in the region earlier, this represents the earliest dated evidence of their spread into the Balkans.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12498494/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145233433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The evolution of modern humans in southern China during the Late Pleistocene is still poorly known. Well-preserved human fossils are scarce, and their chronological framework is often unclear or debated. We report two human teeth (M1 and M2) embedded in mandibular fragments from two individuals, recovered from Jianshan Cave. An integrated approach based on a secured stratigraphic and chronological framework has been employed. We test the hypothesis that these teeth exhibit stronger affinities to those of modern humans than to other Late Pleistocene hominins by using morphological comparisons and 3D imaging-based analyses.
Materials and Methods
We applied AMS 14C dating of charcoals, OSL of sediments, and U-series dating of fossils for chronological constraints. Conventional morphological description and metric analysis were used. In addition, diffeomorphic surface matching analyses of the enamel-dentine junction shape were conducted.
Results
The Jianshan teeth were dated to 33.5–19.5 ka. All analyses indicate that they belong to Homo sapiens. They exhibit similarities and differences with teeth from other sites, highlighting the morphological diversity of Late Pleistocene humans in southern China. Given the significant differences in lithic assemblages between Jianshan Cave and Bailiandong, it is possible that multiple waves of modern human dispersal in the region occurred during MIS 3–2.
Discussion
With this study, Jianshan joins the short list of MIS 3–2 paleoanthropological sites in attesting to the evolution of modern humans in southern China. More evidence with precise dating is needed before more elaborate interpretations can be proposed.
{"title":"Modern Human Dentognathic Remains From MIS 3–2 of Jianshan Cave, Southern China","authors":"Shengnan Yu, Clément Zanolli, Ping Lai, Qingfeng Shao, Yanyan Yao, Hua Liang, Jiemei Zhong, Jiazhi Li, Qizhi Jiang, Wei Liao, Zhongping Lai, Wei Wang","doi":"10.1002/ajpa.70138","DOIUrl":"10.1002/ajpa.70138","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>The evolution of modern humans in southern China during the Late Pleistocene is still poorly known. Well-preserved human fossils are scarce, and their chronological framework is often unclear or debated. We report two human teeth (M<sub>1</sub> and M<sub>2</sub>) embedded in mandibular fragments from two individuals, recovered from Jianshan Cave. An integrated approach based on a secured stratigraphic and chronological framework has been employed. We test the hypothesis that these teeth exhibit stronger affinities to those of modern humans than to other Late Pleistocene hominins by using morphological comparisons and 3D imaging-based analyses.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>We applied AMS <sup>14</sup>C dating of charcoals, OSL of sediments, and U-series dating of fossils for chronological constraints. Conventional morphological description and metric analysis were used. In addition, diffeomorphic surface matching analyses of the enamel-dentine junction shape were conducted.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The Jianshan teeth were dated to 33.5–19.5 ka. All analyses indicate that they belong to <i>Homo sapiens</i>. They exhibit similarities and differences with teeth from other sites, highlighting the morphological diversity of Late Pleistocene humans in southern China. Given the significant differences in lithic assemblages between Jianshan Cave and Bailiandong, it is possible that multiple waves of modern human dispersal in the region occurred during MIS 3–2.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>With this study, Jianshan joins the short list of MIS 3–2 paleoanthropological sites in attesting to the evolution of modern humans in southern China. More evidence with precise dating is needed before more elaborate interpretations can be proposed.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145233456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Delaney J. Glass, Jessica Godwin, Josefin Koehn, Eleanna Bez, Margaret Corley, Rana Dajani, Kristin Hadfield, Catherine Panter-Brick, Claudia Valeggia, Melanie Martin
Objectives
Puberty is regulated by the hypothalamic–pituitary–adrenal (HPA) and gonadal (HPG) axes. It has been proposed that if HPA and HPG coactivate during pubertal development, the hormones cortisol and testosterone would be positively coupled during puberty and decoupled postpuberty. Our objective was to test for hormonal coupling in less-studied, non-Western populations.
Materials and Methods
We analyzed longitudinal and cross-sectional data from marginalized populations: Indigenous Qom/Toba females in Argentina (n = 46, 777 urine samples) and Syrian/Jordanian youth (n = 768, dried blood spots). We used Bayesian hierarchical models to assess the hypothesis that cortisol and testosterone are positively coupled during puberty but decouple at later stages.
Results
We found positive, age-specific cortisol–testosterone coupling among adolescents in both populations, with patterns varying by age and sex. Coupling increased across pubertal ages but did not decline at older ages, contradicting the expectation that there is hormonal de-coupling.
Discussion
This is the first study to demonstrate positive cortisol–testosterone coupling across adolescence in two socio-ecologically distinct, non-Western populations. While hormonal decoupling was not observed, coupling patterns suggest population-level differences in pubertal timing. These findings challenge assumptions derived from Western-based research and underscore the need for global, context-sensitive models of adolescent development.
{"title":"Positive Cortisol–Testosterone Hormonal Coupling Among Adolescents in Argentina and Jordan","authors":"Delaney J. Glass, Jessica Godwin, Josefin Koehn, Eleanna Bez, Margaret Corley, Rana Dajani, Kristin Hadfield, Catherine Panter-Brick, Claudia Valeggia, Melanie Martin","doi":"10.1002/ajpa.70134","DOIUrl":"10.1002/ajpa.70134","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Puberty is regulated by the hypothalamic–pituitary–adrenal (HPA) and gonadal (HPG) axes. It has been proposed that if HPA and HPG coactivate during pubertal development, the hormones cortisol and testosterone would be positively coupled during puberty and decoupled postpuberty. Our objective was to test for hormonal coupling in less-studied, non-Western populations.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>We analyzed longitudinal and cross-sectional data from marginalized populations: Indigenous Qom/Toba females in Argentina (<i>n</i> = 46, 777 urine samples) and Syrian/Jordanian youth (<i>n</i> = 768, dried blood spots). We used Bayesian hierarchical models to assess the hypothesis that cortisol and testosterone are positively coupled during puberty but decouple at later stages.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We found positive, age-specific cortisol–testosterone coupling among adolescents in both populations, with patterns varying by age and sex. Coupling increased across pubertal ages but did not decline at older ages, contradicting the expectation that there is hormonal de-coupling.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>This is the first study to demonstrate positive cortisol–testosterone coupling across adolescence in two socio-ecologically distinct, non-Western populations. While hormonal decoupling was not observed, coupling patterns suggest population-level differences in pubertal timing. These findings challenge assumptions derived from Western-based research and underscore the need for global, context-sensitive models of adolescent development.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.70134","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145207832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ian Towle, Kristin L. Krueger, Kazuha Hirata, Mugino O. Kubo, Anderson T. Hara, Joel D. Irish, Carolina Loch, Matthew R. Borths, Luca Fiorenza
Objectives
In clinical settings, non-carious cervical lesions (NCCLs) are often linked to abrasion, erosion, abfraction, or a combination of these factors. In archaeological and paleontological remains, the most common NCCL is the “toothpick groove,” yet little is known about the occurrence of these and other NCCLs in wild non-human primates.
Materials and Methods
Here, we examine 531 individuals from 27 wild extant and extinct anthropoid primate taxa for NCCLs. Macroscopic examinations were followed by microwear and tissue-loss analyses using multiple imaging techniques, including stereoscopic microscopy, confocal laser, handheld digital microscopy, and 3D tissue loss analysis.
Results
NCCLs were identified in 21 individuals, indicating a prevalence of 4% within the sample. The distribution of NCCLs was uneven, with multiple cases concentrated in certain taxa and populations, but they are identified in all major groupings (e.g., Platyrrhini, Cercopithecidae, Hominoidea). Two distinct lesion types were identified: (1) localized U-shaped lesions with internal parallel striations, indicative of regular contact with abrasive materials (i.e., attrition or abrasion); and (2) smooth, shallow lesions characterized by tissue loss along the recessed gum line, indicative of a multifactorial process that may involve acid erosion.
Discussion
Several attrition/abrasion NCCLs resembled or have characteristic features of “toothpick grooves” known from hominin samples, suggesting the need for further comparative analyses between human and non-human primates. The absence of abfraction lesions supports the view that abfraction may be related to contemporary human behaviors. These findings emphasize the value of non-human primate data for interpreting NCCLs in both contemporary and ancient human populations.
{"title":"Non-Carious Cervical Lesions in Wild Primates: Implications for Understanding Toothpick Grooves and Abfraction Lesions","authors":"Ian Towle, Kristin L. Krueger, Kazuha Hirata, Mugino O. Kubo, Anderson T. Hara, Joel D. Irish, Carolina Loch, Matthew R. Borths, Luca Fiorenza","doi":"10.1002/ajpa.70132","DOIUrl":"10.1002/ajpa.70132","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>In clinical settings, non-carious cervical lesions (NCCLs) are often linked to abrasion, erosion, abfraction, or a combination of these factors. In archaeological and paleontological remains, the most common NCCL is the “toothpick groove,” yet little is known about the occurrence of these and other NCCLs in wild non-human primates.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>Here, we examine 531 individuals from 27 wild extant and extinct anthropoid primate taxa for NCCLs. Macroscopic examinations were followed by microwear and tissue-loss analyses using multiple imaging techniques, including stereoscopic microscopy, confocal laser, handheld digital microscopy, and 3D tissue loss analysis.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>NCCLs were identified in 21 individuals, indicating a prevalence of 4% within the sample. The distribution of NCCLs was uneven, with multiple cases concentrated in certain taxa and populations, but they are identified in all major groupings (e.g., Platyrrhini, Cercopithecidae, Hominoidea). Two distinct lesion types were identified: (1) localized U-shaped lesions with internal parallel striations, indicative of regular contact with abrasive materials (i.e., attrition or abrasion); and (2) smooth, shallow lesions characterized by tissue loss along the recessed gum line, indicative of a multifactorial process that may involve acid erosion.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>Several attrition/abrasion NCCLs resembled or have characteristic features of “toothpick grooves” known from hominin samples, suggesting the need for further comparative analyses between human and non-human primates. The absence of abfraction lesions supports the view that abfraction may be related to contemporary human behaviors. These findings emphasize the value of non-human primate data for interpreting NCCLs in both contemporary and ancient human populations.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12477751/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145186989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The objective of this study is to test the hypothesis that variation in hallucal metatarsal divergence and tarsometatarsal joint morphology reflects mobility and stability across hominoids using a comparative morphological approach.
Methods
The comparative sample includes 896 3D models of extant hominoid first metatarsals, second metatarsals, intermediate cuneiforms, and medial cuneiforms representing 224 individuals across 10 taxa. The variables include the hallucal metatarsal divergence angle, articular surface areas, curvatures, and joint congruence indices. Linear modeling and information criteria were used to evaluate taxon, locomotor frequency, and ecology and locomotion effects.
Results
Extant hominoids vary in a predictable manner based on their ecological and locomotor differences. Humans and eastern gorillas have morphologies suggestive of a less divergent, less mobile hallux, whereas orangutans and hylobatids fall on the opposite end of the morphological spectrum. The models using a graded ecology and locomotion predictor variable substantially outperform those using binary locomotor predictors based on frequencies of arboreality and terrestriality.
Conclusions
The morphology of the hominoid hallucal tarsometatarsal joint reflects variation in ecology and locomotion. A large-bodied, forest-living ecological niche may select for hallucal grasping features in taxa that spend a large proportion of their locomotor budget on the ground because foraging for preferred foods and avoiding predators relies on vertical climbing, which is a relatively infrequent but potentially selectively advantageous locomotor behavior of African apes.
{"title":"Hominoid Hallucal Metatarsal Divergence and Tarsometatarsal Joint Morphology","authors":"Thomas C. Prang","doi":"10.1002/ajpa.70129","DOIUrl":"10.1002/ajpa.70129","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>The objective of this study is to test the hypothesis that variation in hallucal metatarsal divergence and tarsometatarsal joint morphology reflects mobility and stability across hominoids using a comparative morphological approach.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The comparative sample includes 896 3D models of extant hominoid first metatarsals, second metatarsals, intermediate cuneiforms, and medial cuneiforms representing 224 individuals across 10 taxa. The variables include the hallucal metatarsal divergence angle, articular surface areas, curvatures, and joint congruence indices. Linear modeling and information criteria were used to evaluate taxon, locomotor frequency, and ecology and locomotion effects.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Extant hominoids vary in a predictable manner based on their ecological and locomotor differences. Humans and eastern gorillas have morphologies suggestive of a less divergent, less mobile hallux, whereas orangutans and hylobatids fall on the opposite end of the morphological spectrum. The models using a graded ecology and locomotion predictor variable substantially outperform those using binary locomotor predictors based on frequencies of arboreality and terrestriality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The morphology of the hominoid hallucal tarsometatarsal joint reflects variation in ecology and locomotion. A large-bodied, forest-living ecological niche may select for hallucal grasping features in taxa that spend a large proportion of their locomotor budget on the ground because foraging for preferred foods and avoiding predators relies on vertical climbing, which is a relatively infrequent but potentially selectively advantageous locomotor behavior of African apes.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145186850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There is a paradigm in Iranian archeology that a mass migration of nomads from the steppe north of the Caspian Sea to the Central Iranian Plateau occurred around the beginning of the Iron Age, leading to the domination of a mobile pastoral economy in the region. Such a hypothesis was tested through strontium isotope analysis of recently excavated human remains from the cemetery of Estark-Joshaqan, dated from the Late Bronze to Early Iron Age (c. 1800–800 BCE).
Materials and Methods
We measured the 87Sr/86Sr ratio in human dental enamel of 23 individuals from Estark and six individuals from nearby sites: Tepe Sialk (Parthian period) and Bidgol (Early Islamic period), all located near Kashan, Iran, and compared them to the local strontium isoscape based on 39 modern plant samples collected in the region.
Results
Available evidence does not support the hypothesis of permanent long-distance migration from a region with a different strontium isotope signature. Mobility was similarly low in the Late Bronze Age and the Early Iron Age, although the local resource exploitation pattern may have shifted slightly between these periods.
Discussion
There is no clear indication of nomadism, and most likely, people from Estark were agropastoralists, using a relatively limited area for grazing their livestock. Our results open a new perspective in the research of the ‘dark age’ in the Central Iranian Plateau preceding the formation of the Median state.
{"title":"Patterns of Mobility in Iranian Central Plateau at the Transition From the Bronze Age to the Iron Age: Research on Strontium Isotope Ratios in Human Remains From Estark-Joshaqan","authors":"Joanna Trębicka, Javad Hosseinzadeh, Arkadiusz Sołtysiak","doi":"10.1002/ajpa.70130","DOIUrl":"https://doi.org/10.1002/ajpa.70130","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>There is a paradigm in Iranian archeology that a mass migration of nomads from the steppe north of the Caspian Sea to the Central Iranian Plateau occurred around the beginning of the Iron Age, leading to the domination of a mobile pastoral economy in the region. Such a hypothesis was tested through strontium isotope analysis of recently excavated human remains from the cemetery of Estark-Joshaqan, dated from the Late Bronze to Early Iron Age (c. 1800–800 <span>BCE</span>).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>We measured the <sup>87</sup>Sr/<sup>86</sup>Sr ratio in human dental enamel of 23 individuals from Estark and six individuals from nearby sites: Tepe Sialk (Parthian period) and Bidgol (Early Islamic period), all located near Kashan, Iran, and compared them to the local strontium isoscape based on 39 modern plant samples collected in the region.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Available evidence does not support the hypothesis of permanent long-distance migration from a region with a different strontium isotope signature. Mobility was similarly low in the Late Bronze Age and the Early Iron Age, although the local resource exploitation pattern may have shifted slightly between these periods.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>There is no clear indication of nomadism, and most likely, people from Estark were agropastoralists, using a relatively limited area for grazing their livestock. Our results open a new perspective in the research of the ‘dark age’ in the Central Iranian Plateau preceding the formation of the Median state.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"188 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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