Biological anthropology has long positioned foraging and often pastoralist populations as the most appropriate referent communities for the rigorous study of human behavior and evolution. With this, we have created a framework in which these communities exist in a world system that experiences the passage of time functionally differently than do individuals living in industrialized settings. Such thinking has come to structure our understanding of behavioral phenomena across time and space, encourage narrow interpretations of the relevance of various social processes, and constrain our ability to accurately imagine the full capacity of human behavioral variability. Our selective sampling persists despite the development of extra-genetic theoretical models that should be applicable in all communities. To meet even the most modest ends of this decolonial moment and for our science to continue expanding to include shifting landscapes resulting from increased globalization, it is necessary to move beyond assumptions about what has or has not changed in foraging communities, incorporate analyses about changes into research questions when appropriate, contend with observer bias in highly sampled communities, and expand research programs interested in human behavior and evolution to communities engaged in all kinds of economies and subsistence practices.
{"title":"Adjusting the Aperture: Decolonizing Time in Studies of Human Behavior and Evolution","authors":"Robin G. Nelson","doi":"10.1002/ajpa.70187","DOIUrl":"10.1002/ajpa.70187","url":null,"abstract":"<div>\u0000 \u0000 <p>Biological anthropology has long positioned foraging and often pastoralist populations as the most appropriate referent communities for the rigorous study of human behavior and evolution. With this, we have created a framework in which these communities exist in a world system that experiences the passage of time functionally differently than do individuals living in industrialized settings. Such thinking has come to structure our understanding of behavioral phenomena across time and space, encourage narrow interpretations of the relevance of various social processes, and constrain our ability to accurately imagine the full capacity of human behavioral variability. Our selective sampling persists despite the development of extra-genetic theoretical models that should be applicable in all communities. To meet even the most modest ends of this decolonial moment and for our science to continue expanding to include shifting landscapes resulting from increased globalization, it is necessary to move beyond assumptions about what has or has not changed in foraging communities, incorporate analyses about changes into research questions when appropriate, contend with observer bias in highly sampled communities, and expand research programs interested in human behavior and evolution to communities engaged in all kinds of economies and subsistence practices.</p>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145953299","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}
Although there is general agreement nowadays that the last common euprimate ancestor looked something like a diminutive mouse lemur or the Eocene primate Teilhardina, debate continues over the adaptive meanings of the synapomorphies that distinguished it from more primitive mammals. We review the background and history of the visual-predation theory of the origin of the order Primates, evaluate the objections and alternatives to it that have been put forward since it was first proposed in 1970, and conclude that with some corrections and additions, the visual-predation account continues to be the best available explanation for the origins of the euprimate synapomorphies. Nevertheless, the theory has implications that need to be tested through broad-based, multidisciplinary comparative research.
{"title":"The Visual-Predation Theory: A Binocular Look Backward","authors":"Matt Cartmill, Kaye Brown","doi":"10.1002/ajpa.70192","DOIUrl":"10.1002/ajpa.70192","url":null,"abstract":"<div>\u0000 \u0000 <p>Although there is general agreement nowadays that the last common euprimate ancestor looked something like a diminutive mouse lemur or the Eocene primate <i>Teilhardina</i>, debate continues over the adaptive meanings of the synapomorphies that distinguished it from more primitive mammals. We review the background and history of the visual-predation theory of the origin of the order Primates, evaluate the objections and alternatives to it that have been put forward since it was first proposed in 1970, and conclude that with some corrections and additions, the visual-predation account continues to be the best available explanation for the origins of the euprimate synapomorphies. Nevertheless, the theory has implications that need to be tested through broad-based, multidisciplinary comparative research.</p>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145946587","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}
Traits found in a skeletal sample are frequently used to infer qualities of the living population from which the skeletons were drawn. However, traits observed in a mortality sample may exhibit biological mortality bias in that they may not accurately represent the same traits in the living sample. The purpose of this research was to assess biological mortality bias in deciduous tooth emergence, a trait that is used to estimate chronological age in skeletal samples.
Materials and Methods
Data on clinical tooth emergence were collected from longitudinal studies of Javanese, Guatemalan, and Bangladeshi children that included a living sample (those who survived through the study) and a mortality sample (those who died during the study). Parametric hazards analysis was used to test for differences in the timing of tooth emergence between the living and mortality samples.
Results
There were no significant differences between the living and mortality samples for Bangladesh and Java, although there was a trend toward delayed emergence in the Bangladesh mortality sample. The Guatemalan mortality sample exhibited advanced emergence of the posterior dentition for the mortality sample. No evidence of biological mortality bias was found in pooled analyses of the Bangladesh and Java samples or pooled analyses of all three samples.
Discussion
We found limited evidence that deciduous tooth emergence in a mortality sample (e.g., a skeletal series) would differ from the timing of emergence in the living population from which the mortality sample was drawn.
{"title":"Assessing Biological Mortality Bias From Deciduous Tooth Emergence","authors":"Darryl J. Holman, Chris J. Dolinski","doi":"10.1002/ajpa.70202","DOIUrl":"10.1002/ajpa.70202","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Traits found in a skeletal sample are frequently used to infer qualities of the living population from which the skeletons were drawn. However, traits observed in a mortality sample may exhibit biological mortality bias in that they may not accurately represent the same traits in the living sample. The purpose of this research was to assess biological mortality bias in deciduous tooth emergence, a trait that is used to estimate chronological age in skeletal samples.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>Data on clinical tooth emergence were collected from longitudinal studies of Javanese, Guatemalan, and Bangladeshi children that included a <i>living sample</i> (those who survived through the study) and a <i>mortality sample</i> (those who died during the study). Parametric hazards analysis was used to test for differences in the timing of tooth emergence between the living and mortality samples.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>There were no significant differences between the living and mortality samples for Bangladesh and Java, although there was a trend toward delayed emergence in the Bangladesh mortality sample. The Guatemalan mortality sample exhibited advanced emergence of the posterior dentition for the mortality sample. No evidence of biological mortality bias was found in pooled analyses of the Bangladesh and Java samples or pooled analyses of all three samples.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>We found limited evidence that deciduous tooth emergence in a mortality sample (e.g., a skeletal series) would differ from the timing of emergence in the living population from which the mortality sample was drawn.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12789964/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145946581","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}
Victoria A. Lockwood, François Druelle, Alicia Blasi-Toccacceli, Jean-Pascal Guéry, Guillaume Daver
Arboreal bipedalism is suggested as a precursor and adaptive locomotor mode for the immediate ancestor of hominin terrestrial bipedalism, yet detailed investigation of its locomotor biomechanics is hindered by its low frequency and observation difficulties in free-ranging hominoids. Further difficulties are faced in the creation and installation of a suitable experimental setup in natural settings. Captive studies may potentially reduce logistical issues, but data on arboreal bipedalism are scarce. We present an experimental design and protocol for collecting video data on arboreal bipedalism in captive primates, from which qualitative and quantitative gait data can be extracted. Our protocol increases the frequency of this rare behavior. Data were collected on six adult chimpanzees (three males, three females) at La Vallée des Singes, Romagne, France. The chimpanzees voluntarily engaged with a simulated arboreal foraging scenario consisting of two parallel PVC tubes and a high-value food reward. Five GoPro cameras recorded interactions with the experimental equipment. For validation of the effectiveness of our experimental design, protocol interactions were identified as successful (activity completed) or unsuccessful. All age and sex classes had successful interactions. Full strides were observed alongside the identification of two forms of arboreal bipedalism, forward-facing and sideways. This highlights the variation within the arboreal bipedalism locomotor category and the capacity for our experimental design to provide suitable data for gait parameter analysis and interspecies comparisons. Our protocol thus permits detailed investigation of arboreal bipedalism's role in the evolution of hominin bipedalism.
树栖两足动物被认为是人类陆生两足动物直系祖先的先驱和适应性运动模式，但其运动生物力学的详细研究受到其频率低和在散居人科动物中观察困难的阻碍。进一步的困难是在自然环境中创建和安装合适的实验装置。圈养研究可能会潜在地减少后勤问题，但关于树栖两足动物的数据很少。我们提出了一种实验设计和方案，用于收集圈养灵长类动物树栖两足行走的视频数据，从中可以提取定性和定量的步态数据。我们的协议增加了这种罕见行为的频率。研究人员在法国罗马的La vallsamade des Singes收集了6只成年黑猩猩（3只雄性，3只雌性）的数据。黑猩猩自愿参与模拟的树上觅食场景，包括两个平行的PVC管和一个高价值的食物奖励。五台GoPro相机记录了与实验设备的相互作用。为了验证我们实验设计的有效性，协议交互被确定为成功（活动完成）或不成功。所有年龄和性别的班级都有成功的互动。在鉴定两种形式的树栖两足动物（向前和侧向）的同时，观察到完整的步幅。这突出了树栖两足动物运动类别的差异，以及我们的实验设计为步态参数分析和物种间比较提供合适数据的能力。因此，我们的方案允许详细调查树栖两足动物在人类两足动物进化中的作用。
{"title":"A New Experimental Protocol for Assessing Hominoid Assisted Arboreal Bipedalism","authors":"Victoria A. Lockwood, François Druelle, Alicia Blasi-Toccacceli, Jean-Pascal Guéry, Guillaume Daver","doi":"10.1002/ajpa.70189","DOIUrl":"10.1002/ajpa.70189","url":null,"abstract":"<p>Arboreal bipedalism is suggested as a precursor and adaptive locomotor mode for the immediate ancestor of hominin terrestrial bipedalism, yet detailed investigation of its locomotor biomechanics is hindered by its low frequency and observation difficulties in free-ranging hominoids. Further difficulties are faced in the creation and installation of a suitable experimental setup in natural settings. Captive studies may potentially reduce logistical issues, but data on arboreal bipedalism are scarce. We present an experimental design and protocol for collecting video data on arboreal bipedalism in captive primates, from which qualitative and quantitative gait data can be extracted. Our protocol increases the frequency of this rare behavior. Data were collected on six adult chimpanzees (three males, three females) at La Vallée des Singes, Romagne, France. The chimpanzees voluntarily engaged with a simulated arboreal foraging scenario consisting of two parallel PVC tubes and a high-value food reward. Five GoPro cameras recorded interactions with the experimental equipment. For validation of the effectiveness of our experimental design, protocol interactions were identified as successful (activity completed) or unsuccessful. All age and sex classes had successful interactions. Full strides were observed alongside the identification of two forms of arboreal bipedalism, forward-facing and sideways. This highlights the variation within the arboreal bipedalism locomotor category and the capacity for our experimental design to provide suitable data for gait parameter analysis and interspecies comparisons. Our protocol thus permits detailed investigation of arboreal bipedalism's role in the evolution of hominin bipedalism.</p>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12789990/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145946559","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}
Courtney P. Orsbon, Nicholas J. Gidmark, Callum F. Ross
Objectives
Swallowing biomechanics in primates and other mammals is poorly understood, and the effect of hyoid descent on swallowing biomechanics lacks experimental interrogation. In macaques, which share similar swallowing kinematics with humans, the base of the tongue and the food bolus are hypothesized to be driven into the oropharynx by a hydraulic mechanism, at the core of which is elevation and protraction of the hyoid. Here, the musculoskeletal mechanisms driving these hyoid movements are experimentally evaluated in macaque primates.
Materials and Methods
We integrate XROMM-based measures of mandibular, cranial, and hyolingual kinematics with electromyography of suprahyoid and lingual muscles to evaluate the underlying kinetics of swallowing.
Results
All suprahyoid muscles rotate during swallowing and tongue base retraction. Hyoid elevation and protraction are powered by concentric activation and rotation of posterior mylohyoid and both digastric muscle bellies, followed by concentric activation of geniohyoid muscle. Genioglossus is predominantly active early in swallowing.
Discussion
Morphology, function, and coordination of suprahyoid and lingual muscles are especially important determinants of swallowing performance in macaques, and probably humans. Here, we characterize suprahyoid muscle biomechanics within a dynamic framework of architectural gear ratios and pulley systems that optimize hyoid elevation velocity to quickly “prime the pump” and subsequent hyoid protraction power and/or force to drive the hydraulic mechanism of tongue base retraction. Because of muscle rotation, primate hyolingual muscle function is particularly dependent on hyoid posture and muscle geometry, which may have important implications for the evolution of swallowing biomechanics in human evolution.
{"title":"Primate Swallowing Is Powered by Both Rotation and Contraction of Suprahyoid Muscles","authors":"Courtney P. Orsbon, Nicholas J. Gidmark, Callum F. Ross","doi":"10.1002/ajpa.70195","DOIUrl":"10.1002/ajpa.70195","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Swallowing biomechanics in primates and other mammals is poorly understood, and the effect of hyoid descent on swallowing biomechanics lacks experimental interrogation. In macaques, which share similar swallowing kinematics with humans, the base of the tongue and the food bolus are hypothesized to be driven into the oropharynx by a hydraulic mechanism, at the core of which is elevation and protraction of the hyoid. Here, the musculoskeletal mechanisms driving these hyoid movements are experimentally evaluated in macaque primates.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>We integrate XROMM-based measures of mandibular, cranial, and hyolingual kinematics with electromyography of suprahyoid and lingual muscles to evaluate the underlying kinetics of swallowing.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>All suprahyoid muscles rotate during swallowing and tongue base retraction. Hyoid elevation and protraction are powered by concentric activation and rotation of posterior mylohyoid and both digastric muscle bellies, followed by concentric activation of geniohyoid muscle. Genioglossus is predominantly active early in swallowing.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>Morphology, function, and coordination of suprahyoid and lingual muscles are especially important determinants of swallowing performance in macaques, and probably humans. Here, we characterize suprahyoid muscle biomechanics within a dynamic framework of architectural gear ratios and pulley systems that optimize hyoid elevation velocity to quickly “prime the pump” and subsequent hyoid protraction power and/or force to drive the hydraulic mechanism of tongue base retraction. Because of muscle rotation, primate hyolingual muscle function is particularly dependent on hyoid posture and muscle geometry, which may have important implications for the evolution of swallowing biomechanics in human evolution.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12789991/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145949254","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}
{"title":"We Already Know a Bit About the Evolution of Love…","authors":"Adam Bode","doi":"10.1002/ajpa.70201","DOIUrl":"10.1002/ajpa.70201","url":null,"abstract":"","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145935393","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}
Chunxiang Li, Jian Li, Anaer, Shizhu Gao, Yang Xu, Maolin Ye, Linhai Cai, Yinqiu Cui
Objectives
The Qijia culture (2300–1500 bce) in northwest China's Gansu-Qinghai region facilitated prehistoric exchanges between East Asia and the Eurasian steppe, yet its population origins and demographic dynamics remain unclear. We investigate the maternal genetic diversity, ancestry, and regional impact of the Qijia people to clarify their role in the prehistoric peopling of East Asia.
Materials and Methods
We analyzed 29 complete mitochondrial genomes from Qijia-associated individuals, comparing them with a comprehensive dataset of ancient and modern Eurasian populations using haplogroup assignment, phylogenetic analysis, and population genetic statistics.
Results
The Qijia population exhibits a dual ancestry structure, deriving from millet-farming groups from the Middle Yellow River (Shimao/Yangshao/Longshan cultures) and pastoralist populations from the Eastern Eurasian steppe. Notably, our analysis reveals little to no detectable contribution from Western Eurasia, despite archaeological evidence of cultural exchange. Key haplogroups, particularly F1g and D4j1b, link the Qijia people to modern Tibeto-Burman speakers (e.g., Tibetans and Qiangic groups), supporting a model of southward migration via the Tibetan-Yi Corridor. The presence of southern haplogroup F1a1a may indicate limited northward gene flow into the region.
Discussion
The Qijia culture likely served as a genetic “melting pot” and a subsequent source population, illustrating demographic processes that were distinct from mere cultural diffusion. Its dual origins reflect a convergence of agricultural expansion from the Central Plains and pastoralist movements from the north. Furthermore, its profound genetic connections to Tibeto-Burman groups highlight its enduring legacy in shaping the genetic landscape of modern populations in Southwest China.
{"title":"Ancient Mitochondrial Genomes Reveal the Maternal Diversity and Genetic Influence of the Qijia Culture in Prehistoric Eastern Asia","authors":"Chunxiang Li, Jian Li, Anaer, Shizhu Gao, Yang Xu, Maolin Ye, Linhai Cai, Yinqiu Cui","doi":"10.1002/ajpa.70196","DOIUrl":"10.1002/ajpa.70196","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>The Qijia culture (2300–1500 <span>bce</span>) in northwest China's Gansu-Qinghai region facilitated prehistoric exchanges between East Asia and the Eurasian steppe, yet its population origins and demographic dynamics remain unclear. We investigate the maternal genetic diversity, ancestry, and regional impact of the Qijia people to clarify their role in the prehistoric peopling of East Asia.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>We analyzed 29 complete mitochondrial genomes from Qijia-associated individuals, comparing them with a comprehensive dataset of ancient and modern Eurasian populations using haplogroup assignment, phylogenetic analysis, and population genetic statistics.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The Qijia population exhibits a dual ancestry structure, deriving from millet-farming groups from the Middle Yellow River (Shimao/Yangshao/Longshan cultures) and pastoralist populations from the Eastern Eurasian steppe. Notably, our analysis reveals little to no detectable contribution from Western Eurasia, despite archaeological evidence of cultural exchange. Key haplogroups, particularly F1g and D4j1b, link the Qijia people to modern Tibeto-Burman speakers (e.g., Tibetans and Qiangic groups), supporting a model of southward migration via the Tibetan-Yi Corridor. The presence of southern haplogroup F1a1a may indicate limited northward gene flow into the region.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>The Qijia culture likely served as a genetic “melting pot” and a subsequent source population, illustrating demographic processes that were distinct from mere cultural diffusion. Its dual origins reflect a convergence of agricultural expansion from the Central Plains and pastoralist movements from the north. Furthermore, its profound genetic connections to Tibeto-Burman groups highlight its enduring legacy in shaping the genetic landscape of modern populations in Southwest China.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145913216","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}
{"title":"With Thanks","authors":"Trudy R. Turner","doi":"10.1002/ajpa.70198","DOIUrl":"10.1002/ajpa.70198","url":null,"abstract":"","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145913236","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}
Faye S. Harwell, Janine L. Brown, Stephen Paris, Nicole P. Boisseau, Erin Kane, Tri Wahyu Susanto, Endro Setiawan, Cheryl D. Knott
Objectives
Male and female primates experience different ecological and reproductive constraints, which often lead to differences in how they allocate energy. Since testosterone promotes muscle growth, male primates generally possess greater relative muscle mass than females. Orangutans exhibit a rare phenomenon called male bimaturism, where there are two adult male morphs. Male orangutans reach adulthood as the unflanged morph and may transition to the flanged morph during their lifetime. Here, we investigated muscle mass differences of wild and captive orangutans among the age-sex classes while accounting for flange status.
Methods
Estimated lean body mass (ELBM) can be obtained by comparing urinary creatinine (CR) residuals using specific gravity (SG). We analyzed 2329 urine samples collected from 51 orangutans under human care and 279 samples from 29 wild Bornean orangutans at Gunung Palung National Park, Borneo, Indonesia.
Results
In both datasets, flanged males had the greatest mean ELBM followed by females and unflanged males. Flanged males had significantly greater ELBM than adult females and unflanged males in both captive and wild environments.
Conclusions
Flanged males have greater ELBM than unflanged males, suggesting increased energetic investment in muscle mass. Differences in body composition likely reflect the distinctive reproductive strategies and behavioral niches utilized by the two morphs. Flanging is an energetically costly process to undergo and maintain and is associated with a costly reproductive strategy. Because of these sex/morph differences, we recommend indexing urine samples against SG to avoid potential sex biases when indexing with CR.
{"title":"Sex Differences in Estimated Lean Body Mass of Captive and Wild Orangutans","authors":"Faye S. Harwell, Janine L. Brown, Stephen Paris, Nicole P. Boisseau, Erin Kane, Tri Wahyu Susanto, Endro Setiawan, Cheryl D. Knott","doi":"10.1002/ajpa.70173","DOIUrl":"10.1002/ajpa.70173","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Male and female primates experience different ecological and reproductive constraints, which often lead to differences in how they allocate energy. Since testosterone promotes muscle growth, male primates generally possess greater relative muscle mass than females. Orangutans exhibit a rare phenomenon called male bimaturism, where there are two adult male morphs. Male orangutans reach adulthood as the unflanged morph and may transition to the flanged morph during their lifetime. Here, we investigated muscle mass differences of wild and captive orangutans among the age-sex classes while accounting for flange status.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Estimated lean body mass (ELBM) can be obtained by comparing urinary creatinine (CR) residuals using specific gravity (SG). We analyzed 2329 urine samples collected from 51 orangutans under human care and 279 samples from 29 wild Bornean orangutans at Gunung Palung National Park, Borneo, Indonesia.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>In both datasets, flanged males had the greatest mean ELBM followed by females and unflanged males. Flanged males had significantly greater ELBM than adult females and unflanged males in both captive and wild environments.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Flanged males have greater ELBM than unflanged males, suggesting increased energetic investment in muscle mass. Differences in body composition likely reflect the distinctive reproductive strategies and behavioral niches utilized by the two morphs. Flanging is an energetically costly process to undergo and maintain and is associated with a costly reproductive strategy. Because of these sex/morph differences, we recommend indexing urine samples against SG to avoid potential sex biases when indexing with CR.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145901146","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}
Hamadou Oumarou Hama, Michel Drancourt, Philip Slavin, Florent Sebbane
Objectives: Emerging genomic evidence has identified ancestral strains of Yersinia pestis in ancient human populations, which has sparked debates about its pathogenic role in later Neolithic societies. Here, we review published evidence linking anthropological and biological data reflecting the past natural history of Y. pestis infection.
Materials and methods: Review of reported ancient Y. pestis genomes, paleomicrobiological, archaeological, and ecological data related to ancient plague.
Results and discussion: While some researchers attributed the Scandinavian Neolithic population decline to plague epidemics, we argue that early Y. pestis strains were more likely associated with outbreaks of food-borne enteritis rather than flea-borne plague. This hypothesis is supported by genetic, archaeological, and ecological analyses, which indicate that Y. pestis evolved key flea-borne transmission mechanisms only later in its history.
{"title":"Commentary on Seersholm Et al.: Yersinia pestis Infection Is Not Synonymous With Deadly Plague in Neolithic Scandinavia.","authors":"Hamadou Oumarou Hama, Michel Drancourt, Philip Slavin, Florent Sebbane","doi":"10.1002/ajpa.70200","DOIUrl":"https://doi.org/10.1002/ajpa.70200","url":null,"abstract":"<p><strong>Objectives: </strong>Emerging genomic evidence has identified ancestral strains of Yersinia pestis in ancient human populations, which has sparked debates about its pathogenic role in later Neolithic societies. Here, we review published evidence linking anthropological and biological data reflecting the past natural history of Y. pestis infection.</p><p><strong>Materials and methods: </strong>Review of reported ancient Y. pestis genomes, paleomicrobiological, archaeological, and ecological data related to ancient plague.</p><p><strong>Results and discussion: </strong>While some researchers attributed the Scandinavian Neolithic population decline to plague epidemics, we argue that early Y. pestis strains were more likely associated with outbreaks of food-borne enteritis rather than flea-borne plague. This hypothesis is supported by genetic, archaeological, and ecological analyses, which indicate that Y. pestis evolved key flea-borne transmission mechanisms only later in its history.</p>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"189 1","pages":"e70200"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145991080","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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