American Journal of Biological Anthropology最新文献

{"title":"Missing Landmark Estimation Using Reverse Engineering: Challenges and Potential Solutions for the Study of Hominin Long Bones","authors":"Lloyd A. Courtenay,&nbsp;Julia Aramendi","doi":"10.1002/ajpa.70334","DOIUrl":"10.1002/ajpa.70334","url":null,"abstract":"<p>Fragmentary preservation represents a fundamental limitation in palaeoanthropological research, particularly for postcranial elements where symmetry cannot be exploited and large portions of bone are frequently missing. Although a wide range of virtual reconstruction methods exist, many rely on strong anatomical priors, localized interpolation, or reference specimens that risk biasing reconstructions toward predefined morphologies. The present study introduces a new approach for estimating the coordinates of missing landmarks, termed the Reverse Engineering (RE) approach. This method establishes mathematical relationships between morphological patterns observed in complete reference specimens and those preserved in reduced portions of each bone, allowing missing regions to be inferred from patterns of covariation rather than local geometric proximity. We demonstrate that the RE approach performs consistently across a range of reconstruction scenarios, including cases where substantial portions of bone are missing, and in empirical applications to Neanderthal femoral and humeral specimens. Importantly, reconstructed specimens retain morphological signal in subsequent morphometric analyses, regardless of the extent of missing data. While limitations remain, as is the case for all reconstruction methods applied to fragmentary fossil material, the RE approach offers a robust and flexible alternative that does not depend on symmetry or a single reference specimen. As such, it represents a valuable addition to the methodological repertoire available to palaeoanthropologists working with incomplete postcranial remains.</p>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13430587/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148664718","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":"Comparative Morphometric Analysis of the Pelvis of LB 1 (Homo floresiensis).","authors":"Kristi L Lewton, Ashley S Hammond, Nico Alamsyah, Sofwan Noerwidi, Thomas Sutikna, Matthew M Skinner, Matthew W Tocheri","doi":"10.1002/ajpa.70339","DOIUrl":"10.1002/ajpa.70339","url":null,"abstract":"<p><strong>Objectives: </strong>Although there has been copious research on the postcranial functional morphology of Homo floresiensis, there has been relatively little study of its pelvis and its implications for interpretations of H. floresiensis locomotion. Here we present the first comparative morphometric analysis of the pelvis of LB 1, the holotype of H. floresiensis, using data derived from high-resolution micro-CT scans and situated within a broad, Plio-Pleistocene hominin context. This includes a novel quantitative measure of iliac flare in hominins to assess the australopith-like qualities of the LB 1 pelvis described by previous studies.</p><p><strong>Materials and methods: </strong>In a sample of extant humans and African apes and 26 fossil hominin pelves, we quantified linear and angular pelvic traits, with a focus on features that should provide functional insights into H. floresiensis locomotor behavior, including ilium orientation angle and lower ilium length. Morphometric and allometric hypotheses were investigated using Kruskal-Wallis tests, principal component analysis, and least squares regression.</p><p><strong>Results: </strong>Univariate analyses demonstrate that all pelvic features of LB 1 (except for ischium length) are within the ranges of variation exhibited by Homo sapiens. Multivariate analysis reveals that the H. floresiensis pelvis shares similarities with those of other Pleistocene Homo and some australopith individuals.</p><p><strong>Discussion: </strong>Overall, our results suggest that the pelvis of LB 1 is more Homo-like than previously described. While the mix of primitive and derived traits in the postcrania of H. floresiensis makes functional inferences challenging, our results from the pelvis suggest a human-like form of terrestrial bipedalism in this species.</p>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 4","pages":"e70339"},"PeriodicalIF":2.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13504309/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148814236","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":"Cover & Editorial Board","authors":"","doi":"10.1002/ajpa.70274","DOIUrl":"https://doi.org/10.1002/ajpa.70274","url":null,"abstract":"","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.70274","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617345","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":"Livelihood and Dietary Transitions in Subsistence Populations of Northern Laos: Insights From Carbon and Nitrogen Stable Isotope Analysis","authors":"Ziyang Li,&nbsp;Mihoko Kibe,&nbsp;Yuki Mizuno,&nbsp;Masafumi Saitoh,&nbsp;Kohei Yamazaki,&nbsp;Hiroaki Masuoka,&nbsp;Satoko Kosaka,&nbsp;Kazumi Natsuhara,&nbsp;Kazuhiro Hirayama,&nbsp;Nouhak Inthavong,&nbsp;Sengchanh Kounnavong,&nbsp;Minoru Yoneda,&nbsp;Shinsuke Tomita,&nbsp;Masahiro Umezaki","doi":"10.1002/ajpa.70326","DOIUrl":"https://doi.org/10.1002/ajpa.70326","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Rural populations in northern Laos have experienced dramatic socioeconomic transformation driven by national policies and regional economic integration, substantially influencing their self-sufficient livelihoods. To investigate how these changes have manifested in local subsistence contexts, we compared hair carbon and nitrogen isotope values between two populations representing swidden- and paddy-farming systems, and assessed how isotopic variations reflect the differences in subsistence practices and degrees of livelihood transformation. By analyzing commonly consumed foodstuffs, we provide the first isotopic dataset of foods from northern Laos and baselines for interpreting human tissue isotope values.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Scalp hair and food samples and sociodemographic data were collected from the study villages. In total, 175 hair and 69 food samples were analyzed. Multiple linear regression analyses were used to examine associations with subsistence/economic and dietary variables. Rice–hair isotopic offsets were calculated to qualitatively assess dietary patterns.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Hair <i>δ</i>¹⁵N was higher in the paddy-farming village than in the swidden-farming village. In the swidden-farming village, individuals who shifted to paddy cultivation showed higher <i>δ</i>¹⁵N and lower <i>δ</i>¹³C values than those who primarily practiced swidden cultivation. In the paddy-farming village, individuals with greater market involvement exhibited higher hair <i>δ</i>¹³C values. The rice–hair offsets suggested elevated market food consumption among paddy field cultivators.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>The differences in hair isotope values between (sub)populations can be attributed to isotopic variations in rice, the staple food, and to the differences in market participation. Market integration can lead to an increase in hair <i>δ</i>¹³C, but the overall isotopic outcome is highly context dependent.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.70326","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148647920","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":"From Optimism to Opportunity: New Perspectives on the Osteological Paradox","authors":"Clare McFadden,&nbsp;Amy Anderson,&nbsp;Lucie Biehler-Gomez,&nbsp;Rachael Brown,&nbsp;Kathryn E. Marklein,&nbsp;Sammuel Sammut,&nbsp;Bronwyn Wyatt,&nbsp;Samantha L. Yaussy","doi":"10.1002/ajpa.70331","DOIUrl":"https://doi.org/10.1002/ajpa.70331","url":null,"abstract":"<p>The Osteological Paradox has had an immeasurable impact on bioarchaeology. It has spurred introspection, increased scientific rigor, and encouraged a suite of new and valuable approaches and methods to deal with the challenges it raises. Contrastingly, it has also been perceived as insurmountable, or a problem that simply needs to be acknowledged but not dealt with. In this synthesis, we discuss past and current approaches to the Osteological Paradox, the promise we believe agent-based modeling holds for future research, and broadly contextualize the Paradox within a philosophically optimistic outlook. Our synthesis represents a range of diverse perspectives from bioarchaeology and philosophy, and seeks to identify a path forward. We conclude that the Osteological Paradox represents a springboard more than a hurdle; one that continues to propel the discipline forward and supports the ongoing integration of new technologies to answer questions about past societies.</p>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.70331","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148647921","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":"Functional Differences in Muscle Architecture Across the Pelvis and Hind Limb of Primates","authors":"Emma Guimaraes,&nbsp;Evie Vereecke,&nbsp;Ashleigh L. Wiseman","doi":"10.1002/ajpa.70329","DOIUrl":"https://doi.org/10.1002/ajpa.70329","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Understanding the architectural diversity of primate musculature is essential for interpreting locomotor function and reconstructing evolutionary adaptations. This study examines whether interspecific differences in pelvic and hind limb muscle architecture reflect functional differentiation among major muscle groups.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>We present detailed dissection data from six primate species, alongside a large sample of additional specimens collected from previous studies. We quantify fascicle length, pennation angle, muscle mass, and physiological cross-sectional area across the hind limb and pelvis in each species. We assessed whether differences in muscle architecture were consistent across functional groups and taxa. Differences in muscle architecture were analyzed across functional groups, muscles, and species, with architectural specialization interpreted in functional terms, e.g., reflecting relative emphasis on force, power, displacement, or generalist/stabilizing roles.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Our results reveal conserved configurations in load-bearing muscles, but marked divergence in others, particularly in knee and hip musculature. Notably, muscle specialization was more conserved between species with similarity in their ecology/locomotor mode than between those who are closely related, indicating that muscle architecture is closely linked to habitual hind limb function.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>These findings suggest that patterns of pelvic and hind limb muscle specialization across primates are driven primarily by ecological and locomotor function, rather than evolutionary relatedness. The dataset provides a detailed, anatomically grounded resource for future comparative and biomechanical studies of primate hind limb function.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 4","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.70329","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617396","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":"No More Sneaking Around: The Changing Terminology of Orangutan Male Reproductive Strategies","authors":"Alexandra E. Kralick","doi":"10.1002/ajpa.70252","DOIUrl":"10.1002/ajpa.70252","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Orangutans exhibit male bimaturism, characterized by pronounced variation among adult males. Early research framed this variation as age-based morphs with two alternative reproductive tactics (ARTs), contrasting “sneak and rape” subadults with “consort and combat” adults. Subsequent research demonstrated that males previously labeled as subadults can remain unflanged well into adulthood, and both types of males mate with and without force, leading to a revised ART framework: flanged males “sit, call, and wait” while unflanged males “go, search, and find.” This study examines how these frameworks have been taken up and represented over time in the scholarly literature.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>A bibliometric analysis of 810 publications which use orangutan and morph- and strategy-based keywords identified 124 relevant publications which were coded by morph and strategy classification and analyzed for temporal trends.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The “subadult” and “sneak and rape” terminology is no longer dominant in peer-reviewed primatology; yet, these imprecise frameworks persist, particularly outside of primatology in the secondary literature regarding the evolution of human male aggression.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>The persistence of the “sneak and rape” framework does not reflect empirical evidence, as primatology now distinguishes male morphs without defining them by sexual aggression. Nor can it be explained by disciplinary lag alone, as some studies update the term from subadult to unflanged male while retaining outdated behavioral framing. Instead, selective uptake aligns with broader narratives in human evolution that naturalize male aggression and female vulnerability, underscoring the need to clarify primatological frameworks that inform interpretations of human evolution.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.70252","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148456969","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":"The Interrelation Among Allometry, Phylogeny, and Diet in the Molar Cervix","authors":"Zana R. Sims","doi":"10.1002/ajpa.70321","DOIUrl":"10.1002/ajpa.70321","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Root surface morphology has been used to examine functional signals related to diet and taxonomic affinities in primates with varying degrees of success. The aim of this study is to determine if the use of the functionally significant root cervix can enhance our understanding of these relationships in catarrhines.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>Two-dimensional (2D) semilandmark points were collected using cross sections taken from the cervix of all three mandibular molar positions in a sample of extant catarrhines (<i>n</i> = 68). Multivariate regression was used to examine the influence of size on Procrustes aligned data. Standard and phylogenetic principal component analyses were performed for each molar position. Phylogenetic generalized least squares (PGLS) were used to correct for nonindependence.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Allometric effects were statistically significant (<i>p</i> &lt; 0.05) but weak for each position (<i>M</i>₁ = 0.096, <i>M</i>₂ = 0.064, <i>M</i>₃ = 0.062). Phylogenetic signal, multivariate <i>K</i>, was significant for each molar but less than expected under Brownian motion (<i>K</i>_mult &lt; 1). PGLS removed all functional signal related to dietary ecology at <i>M</i>₁ for phylogenetically aligned PCA (PACA) and phylogenetic PCA (pPCA) components. These signals were diminished but not eliminated at <i>M</i>₂ (PACA) and <i>M</i>₃ (pPCA).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The influence of size on the morphology of the root cervix is limited and does not impact functional signals related to either phylogeny or diet. Observed morphological variation of the root cervix is driven in part by both phylogeny and diet. However, these variables share a strong relationship, and more work is needed to disentangle the two.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.70321","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148457007","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":"Comparable Overall Copulation Rates Yet Rank-Biased Access to Likely Fertile Females in Male Bonobos at Wamba","authors":"Kazuya Toda,&nbsp;Furuichi Takeshi","doi":"10.1002/ajpa.70318","DOIUrl":"https://doi.org/10.1002/ajpa.70318","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Female bonobos (<i>Pan paniscus</i>) resume sexual swellings in the early postpartum stage and exhibit prolonged sexual receptivity. Despite the simultaneous availability of receptive females, genetic evidence reveals a pronounced male reproductive skew in this species. We investigated how male bonobos allocate mating effort to females in the likely fertile window (LFW) versus non-conceptive phases based on their dominance rank and dynamic party-level competitive situations.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>We conducted all-day focal animal sampling on adult and adolescent bonobos in a free-ranging group at Wamba. Female fertile windows were estimated using the end of the maximal swelling phase. Generalized linear mixed models were used to analyze rank-related mating patterns.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Overall copulation rates did not differ across male dominance ranks. However, higher-ranking males secured a disproportionate share of copulations with LFW females. At the party level, higher-ranking males preferentially copulated with LFW females when present, whereas lower-ranking males were more likely to copulate with non-LFW females as the number of LFW females increased.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>Our findings add evidence that the pronounced male reproductive skew in bonobos is driven by rank-biased access to fertile females rather than total mating frequency. Subordinate males likely redirect mating effort toward receptive but non-conceptive females rather than directly contesting with dominants over fertile females or forming consortships. This flexible shift in mating targets represents an alternative tactic that allows subordinates to marginally increase their participation in sperm competition despite high monopolization by dominants or to develop affiliative relationships with numerous females for future mating advantages.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.70318","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467266","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":"Deconstructing Biological Sex by Fuzzifying Osteological Sex: Implications for Theoretically Informed Practice","authors":"Donovan M. Adams,&nbsp;Katherine M. Lane","doi":"10.1002/ajpa.70311","DOIUrl":"https://doi.org/10.1002/ajpa.70311","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>In forensic and bioarchaeological contexts, sex is estimated as part of the biological profile. However, current methods limit estimation to binary and discrete categories of female and male, reinforcing biological normalcy and normative conceptions of sex and gender, while excluding non-binary variation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A subset of cranial and postcranial metric data of assigned females (<i>n</i> = 603) and assigned males at birth (<i>n</i> = 1101) was used from the Forensic Data Bank. Unsupervised Possibilistic Fuzzy C-Means (UPFCM), a fuzzy clustering technique, was used to explore natural, rather than constructed, patterns in the cranial, postcranial, and combined datasets.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>38,691 models were generated using various parameter combinations. Optimal models identified were a six-cluster model for the combined and postcranial data and a two-cluster model for the combined and cranial data. For the optimal models, many individuals were identified as “outliers,” especially for the cranial models, based on low typicality degrees. Clustering reflects bimodal variation with overlap between assigned females (AFAB) and assigned males at birth (AMAB) in their cluster of highest membership as well as distribution in degrees of membership across clusters. Membership reflected significant intra- and interindividual variation in sex expression.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Fuzzy logic, which allows individuals to partially belong to multiple groups, offers an approach that aligns with the complexity of sex-related variation. This research demonstrated that fuzzy principles can shift sex frameworks from binary to bimodal and continuous models, offering a means to address issues of biological normalcy and the harmful, rigid constructions of sex and gender it produces.</p>\u0000 </section>\u0000 </div>","PeriodicalId":29759,"journal":{"name":"American Journal of Biological Anthropology","volume":"190 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467265","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}