Population Affinities Research Articles

Mitochondrial dynamics control of mitoKv1.3 during cell cycle progression.

The voltage-gated potassium channel Kv1.3 plays a crucial role in adipose tissue. Kv1.3 is involved in the development of obesity and diabetes, thus becoming a potential therapeutical target. Kv1.3 locates at the plasma membrane and at mitochondria, controlling cell proliferation and differentiation or apoptosis, respectively. While the plasma membrane targeting is by a COPII-dependent mechanism and driven by several forward-traffic motifs, little is known about the mitochondrial route. In this work, the mitochondrial Kv1.3 interactome was obtained in order to decipher the mitochondrial components that participate in mitoKv1.3 import pathway. We report for the first time that, although Kv1.3 is a multispanning protein with no defined N-terminal presequence, the channel follows an unconventional routing through the TIM23 complex. The targeting is mediated by the information encoded along the channel sequence and regulated by the cytosolic Hsp70/90 chaperon complex. Once in mitochondria, mitoKv1.3 shows a higher affinity for perinuclear populations. In addition, mitoKv1.3 expression is cell cycle-dependent, increasing at the G1/S phase. The development of a knocked-down preadipocyte cell line let us describe that Kv1.3 promotes the preadipocyte proliferation by regulating mitochondrial dynamics. Throughout the cell cycle, there are several fusion-fission events that are key for a correct proliferation. We found that Kv1.3 expression mediates the G1/S phase hyperfusion and, consequently, the hyperpolarization of mitochondria. Our results unravel the unconventional import pathway of Kv1.3 into the inner mitochondrial membrane. Moreover, it sheds light into Kv1.3 control of mitochondrial morphology and dynamics at the G1 phase fine-tuning proliferation. Supported by the Ministerio de Ciencia e Innovación (MICINN/AEI), Spain (PID2020-112647RB-I00 and 10.13039/501100011033) and European Regional Development Fund (FEDER).

A Non-Racial Approach to Assessing Group Membership of Victims in a Mass Grave Using Cranial Data

In some jurisdictions, race, ancestry, or population affinity have been used for historical and po-litical, rather than biological, reasons in forensic anthropology when identifying individuals. The approach persists even though the genetic and skeletal data clearly demonstrate that human variation does not cluster into these groups. For over 60 years, these methods have consistently performed poorly when independently tested using large samples. By racializing the deceased, these methods have further marginalized the living. However, there is a need in the investigation of genocide and human rights violations to demonstrate that a specific group was targeted. Without relying on the outdated typological concepts of human variation, in this paper we present preliminary results for a method that can be used in a mass grave context to demonstrate that a specific group was targeted. Using samples from two identified reference collections, we created subsamples from one relatively homogeneous collection to model various mass grave scenarios and used the relatively heterogenous sample from the other collection as a reference for com-parison. In scenarios that varied by sample size and sex, it was possible to determine that a specific group was targeted if the sample size in a hypothetical mass grave was greater than 25 for a multi-sex sample, when sex is not known, and a minimum of 14 if sex could be estimated.

Population affinity estimation on a Spanish sample: Testing the validity and accuracy of cranium and mandible online software methods

Population affinity estimation is an important step in the identification of unknown individuals. To ensure accurate results, validation studies of newly developed methods must be performed using different target populations and skeletal elements. This research aimed to determine the accuracy and reliability of population affinity estimation on a modern Spanish sample using two online software applications.The sample consisted of 114 adult individuals (51 males, 63 females) using 38 measurements and one angle from the skull and mandible. AncesTrees was used for craniometric measurements and (hu)MANid for mandibular variables with different classification models and probability thresholds being evaluated. The required parameters were inputted for each individual and statistics were generated to assess the accuracy of the estimation.AncesTrees performed with the greatest accuracy as the program correctly classified the sample as Southwestern European or European, with highest accuracies being 54.56% (trial 1), 86.05% (trial 2), 82.61% (trial 3), 34.55% (trial 4) and 100% (trial 5). (hu)MANid correctly classified the sample as being from white origin with accuracies ranging from 70.59% to 80% without considering correct sex estimation, while accuracy ranged between 62.75% and 80% accounting for estimated sex.Population affinity estimation may determine subsequent methods used in the construction of the biological profile. Our results demonstrated varying accuracy rates depending on the element and method, offering a critical view in relation to software applicability and validity. Reference populations and intrinsic and extrinsic factors can potentially influence the method accuracy and reliability. Future research should focus on the inclusion of underrepresented groups.

Frontal Sinus Morphological and Dimensional Variation as Seen on Computed Tomography Scans.

Simple SummaryThe frontal sinus is an important cavity inside an individual’s forehead and has been used by forensic anthropologists to provide positive identifications due to its highly unique structure from person to person, yet researchers still do not fully understand why it forms as it does. This study examined the differences in both shape and size of the frontal sinuses of over 300 individuals from various ancestral backgrounds and assigned sexes to see if climate adaptations or sexual dimorphism might be driving factors. Results showed that shape was not dependent on where a person descended from nor their assigned sex at birth; however, dimensionally, these variables in combination do cause some significant variation. The results also speak to the idiosyncratic nature of the frontal sinus and bolster confidence in using morphological variations as a means of personal identification. While it is still unknown what causes the significant shape variation between individuals within the U.S., it appears that the frontal sinus is affected more by sexual dimorphism than by the ancestry of the individual.Frontal sinus variation has been used in forensic anthropology to aid in positive identification since the 1920s. As imaging technology has evolved, so has the quality and quantity of data that practitioners can collect. This study examined frontal sinus morphological and dimensional variation on computed tomography (CT) scans in 325 individuals for assigned sex females and males from African-, Asian-, European-, and Latin American-derived groups. Full coronal sinus outlines from medically derived CT images were transferred into SHAPE v1.3 for elliptical Fourier analysis (EFA). The dimensional data were measured directly from the images using the MicroDicom viewer. Statistical analyses—Pearson’s chi-square, ANOVA, and Tukey post hoc tests—were run in R Studio. Results indicated that 3.7% lacked a frontal sinus and 12.0% had a unilateral sinus, usually on the left (74.3%). Additionally, no statistically significant morphological clustering using EFA was found based on assigned sex and/or population affinity. However, there were statistically significant differences dimensionally (height and depth) when tested against assigned sex and population affinity, indicating that the interactive effects of sexual dimorphism and adaptive population histories influence the dimensions but not the shape of the frontal sinus.

The Application of Bony Labyrinth Methods for Forensic Affinity Estimation

Simple SummaryWhen human remains are recovered, it is important to identify the individual for multiple reasons, including reuniting the individual with family members. In cases when human remains are incomplete, it can be challenging to identify the individual. This research found a highly successful method for identifying a person’s affinity by using measurements of the inner ear cavity. Since the inner ear is housed in a bony region that survives extremely well, the potential for identifying human remains is exciting. Researchers developed functions that can identify with 90.8% and higher accuracy between three different population samples using measurements from the bony labyrinth alone. These methods are non-destructive and quick to make, and plug into the functions developed in this research. This research points to potential for this method and calls for additional samples to be added to the data base to help with more identifications in the future. Population affinity identification is important for reconstructing the biological profile of human skeletal remains. Most anthropological methods for predicting population affinity rely on complete crania or cranial parts. However, complete parts are frequently not found in forensic and bioarchaeological contexts. In contrast, the petrous portion of the cranium presents a unique rate of preservation in the field. Therefore, this study aimed to develop stepwise discriminant function formulae to determine population affinity using measurements on three-dimensional models of the human adult bony labyrinth. The sample utilised consisted of 30 German, 38 African Zulu, and 30 Oneota individuals. A total of four function equations were developed. The function involving all three populations presented an average accuracy of 90.8%. Mathematical equations were also derived to discriminate between Zulu and Germans (91.2%), Zulu and Oneota (95.5%), as well as Oneota and Germans (96.7%). These results indicate this new method of population affinity identification is highly successful, even with fragmentary remains.

The Fall and Rise of Identified Reference Collection: It Is Possible and Necessary to Transition from a Typological Conceptualization of Variation to Effective Utilization of Collections

In some jurisdictions, race, ancestry or population affinity are part of the biological profile used in preliminary identification, for historical and political reasons. It is long overdue for forensic anthropologists to abandon this typological approach to human variation, regardless of the terms used. Using a sample (n = 105) selected from the Terry and Coimbra identified reference collections, a blind experimental approach is used to test several metric methods and versions of methods for group estimation (Fordisc 3.0 and 3.1, and AncesTrees), that rely on different statistical approaches (discriminant function analysis and random forest algorithms, respectively) derived from different reference samples (Howells’ data in AncesTrees and Fordisc 3.1, and different forensic subsamples in Fordisc 3.0 and 3.1). The accuracy for matching premortem documented group designation is consistently low (36 to 50%) across testing parameters and consistent with other independent tests. The results clearly show that a change in terminology, software updates, alternative statistics, expanded reference samples, and newer collections will not solve the underlying fundamental problems. It is possible and necessary to transition from a typological conceptualization of variation to the effective utilization of identified reference collections in Forensic Anthropology. In addition to the theoretical and methodological reasons, it is unethical for forensic anthropologists to continue to use on the deceased methods that do not work and that serve only to further exclude and marginalize the living.

The Ethics of Sourcing a Cadaver Population–A Perspective from South Africa

We cannot deny the early, turbulent unethical history of the sourcing of human bodies for dissection during the 18th and 19th Centuries, but we most certainly can learn from the past. While the International Federation for the Associations of Anatomists (IFAA) has recommended ethical guidelines for the sourcing of bodies from donors only (IFAA, 2021), many institutions around the world have not been able to fulfil these recommendations. In South Africa, as an ethical imperative, most departments of anatomy have converted from the use of unclaimed bodies (although legal by South African law) to body donor programs which are founded on ethics and informed consent. South Africa has a diverse multicultural population derived from four main population groups (Black, Coloured, White and Indian) with health sciences classes being made up of predominantly Black students. As a consequence of the transformation from the use of unclaimed bodies to donor programs, the population diversity of the more recent cadaver populations has been impacted and White bodies now predominate. This transformation of the cadaver population will in time also impact the large skeletal collections in South Africa which are used for teaching and research by both local and international researchers. The change in the cadaver population with respect to population affinity particularly, may also impact our students and how they view the body they dissect. In South Africa and Africa, a number of factors including religious and cultural practices have a bearing on the diversity of the donors in donor programs. Donor programs are extremely important from the ethical perspective, and so too is the informed consent aligned to registration for these programs. In considering establishing diversity in the cadaver population of our donor programs for the future, some of the questions which should be pondered by South African anatomists and anatomists in general are: Is it important to have a body donor cohort that is representative of the demographics of the student population? How do we overcome the religious and cultural challenges which are prevalent in some of the population in order to maintain a donor program that is based on sound ethical behaviour and which is representative of the population at large? In addition, will anatomists be able to maintain ethical standards of sourcing bodies in the light of unexpected crises such as the recent pandemic? There is no doubt that in South Africa, widespread communication, educational programs and community outreach, particularly through the traditional leaders of each community, would assist with increasing the diversity of the donors.ReferenceIFAA. 2012. International Federation of Anatomical Associations. Federative International Committee on Ethics and Medical Humanities (FICEM). Recommendations of good practice for the donation and study of human bodies and tissues for anatomical examination. Plexus 2012: 4‐5.

Adult Skeletal Age-at-Death Estimation through Deep Random Neural Networks: A New Method and Its Computational Analysis.

Simple SummaryAge-at-death is of paramount importance in forensic analysis of skeletal remains. In addition to sex, stature, and population affinity, it constitutes baseline information in the identification process of deceased individuals. Despite its long tradition, in anthropological research age-at-death estimation poses many challenges and unanswered questions. It is undisputedly among the most difficult tasks of the forensic anthropologist and its results are often subject to a lackluster performance. In this study, we assessed computationally the efficiency of a holistic approach to skeletal age estimation based on a new proposal for macroscopic examination and the use of machine learning-based models for data analysis. Our results suggest that this approach is key for accurate and efficient age-at-death estimation based on skeletal remains analysis.Age-at-death assessment is a crucial step in the identification process of skeletal human remains. Nonetheless, in adult individuals this task is particularly difficult to achieve with reasonable accuracy due to high variability in the senescence processes. To improve the accuracy of age-at-estimation, in this work we propose a new method based on a multifactorial macroscopic analysis and deep random neural network models. A sample of 500 identified skeletons was used to establish a reference dataset (age-at-death: 19–101 years old, 250 males and 250 females). A total of 64 skeletal traits are covered in the proposed macroscopic technique. Age-at-death estimation is tackled from a function approximation perspective and a regression approach is used to infer both point and prediction interval estimates. Based on cross-validation and computational experiments, our results demonstrate that age estimation from skeletal remains can be accurately (~6 years mean absolute error) inferred across the entire adult age span and informative estimates and prediction intervals can be obtained for the elderly population. A novel software tool, DRNNAGE, was made available to the community.

How Do Drugs Affect the Skeleton? Implications for Forensic Anthropology.

Simple SummaryForensic anthropologists analyze human remains to assist in the identification of the deceased, predominantly by assessing age-at-death, sex, stature, ancestry and any unique identifying features. Whilst methods have been established to create this biological profile of the skeleton, these may be influenced by a number of factors. This paper, for the first time, provides an overview from a reading of the clinical and pharmacological literature to explore whether the intake of drugs can affect the skeleton and whether these may have implications for forensic anthropology casework. In effect, drugs such as tobacco, heroin, and prescription medications can alter bone mineral density, can increase the risk of fractures, destroy bone and changes to the dentition. By considering how drugs can affect the skeleton, forensic anthropologists can be aware of this when attempting to identify the deceased.Forensic anthropologists rely on a number of parameters when analyzing human skeletal remains to assist in the identification of the deceased, predominantly age-at-death, sex, stature, ancestry or population affinity, and any unique identifying features. During the examination of human remains, it is important to be aware that the skeletal features considered when applying anthropological methods may be influenced and modified by a number of factors, and particular to this article, prescription drugs (including medical and non-medical use) and other commonly used drugs. In view of this, this paper aims to review the medical, clinical and pharmacological literature to enable an assessment of those drug groups that as side effects have the potential to have an adverse effect on the skeleton, and explore whether or not they can influence the estimation of age-at-death, sex and other indicators of the biological profile. Moreover, it may be that the observation of certain alterations or inconsistencies in the skeleton may relate to the use of drugs or medication, and this in turn may help narrow down the list of missing persons to which a set of human remains could belong. The information gathered from the clinical and medical literature has been extracted with a forensic anthropological perspective and provides an awareness on how several drugs, such as opioids, cocaine, corticosteroids, non-steroidal anti-inflammatory drugs, alcohol, tobacco and others have notable effects on bone. Through different mechanisms, drugs can alter bone mineral density, causing osteopenia, osteoporosis, increase the risk of fractures, osteonecrosis, and oral changes. Not much has been written on the influence of drugs on the skeleton from the forensic anthropological practitioner perspective; and this review, in spite of its limitations and the requirement of further research, aims to investigate the current knowledge of the possible effects of both prescription and recreational drugs on bones, contributing to providing a better awareness in forensic anthropological practice and assisting in the identification process of the deceased.

Repeatability of a morphoscopic sex estimation technique for the mental eminence on micro-focus X-ray computed tomography models

• Scoring the mental eminence trait on virtual 3D models is challenging. • A personal affinity for assessing virtual 3D models of bone may play a role. • Scores 1 and 5 were easier to score on virtual 3D models than intermediate expressions. • A more detailed definition of the mental eminence trait could be useful. Walker's sex estimation method is based on five morphoscopic features of the human skull. This study aimed at testing the repeatability of one of the five traits, the mental eminence, visually on three-dimensional (3D) models, compared to the traditional, tactile scoring approach on bone. The sample comprised 105 mandibles from the Pretoria Bone Collection and their respective virtual 3D models, obtained from micro-focus X-ray computed tomography (micro-XCT) scans. Four observers independently scored the bones first, followed by the virtual 3D modality. Intra- and interobserver errors (interOE and intraOE) were performed with Fleiss’ and Cohen's Kappa, respectively. We calculated the intermodality agreement per observer with Wilcoxon Signed-Rank tests. The intraOE was moderate on bone (κ=0.448) and substantial on 3D (κ=0.799), while the Fleiss’ Kappa test for the interOE resulted in slight agreement both on bone (κ=0.163) and 3D (κ=0.169) irrespective of level of experience. All Wilcoxon Signed-Rank test P -values were significant. The application of the morphoscopic sex estimation for the mental eminence to micro-XCTs could be a matter of personal affinity as the level of experience did not play a role in the results. The expression of the mental eminence trait being population-specific, the individual's population affinity should be considered when sex is estimated in South African skeletons. It remains unclear whether the slight agreement between observers is due to the unreliability of the trait for sex estimation or whether the modalities are not easily interchangeable.

Identifying biological affinities of Holocene northern Iberian populations through the inner structures of the upper first molars

Neolithisation was a relatively fast process that affected both the interior and coastal zones of the Iberian Peninsula, but it was also a heterogeneous process that had diverse impacts on genomic and cultural diversity. In the Late Neolithic–Chalcolithic, a change in funerary practices, cultural material and trade networks occurred, and genomic heterogeneity decreased, suggesting human mobility and genetic admixture between different Iberian populations. Dental morphology has emerged as an effective tool for understanding genomic variability and biological affinities among ancient human populations. But, surprisingly, less attention has been paid to the morphological traits of inner dental tissues in Holocene European populations and their utility for the study of population dynamics. We applied 3D geometric morphometric methods on the enamel-dentine junction (EDJ) of the first upper molars to explore the biological affinities of north-eastern Iberian Peninsula populations from the Late Neolithic–Chalcolithic to the Bronze Age. Our results show that the EDJ morphologies of the northern Iberian Peninsula populations were generally homogeneous, indicative of genetic admixture as a result of human mobility and exchange networks. However, differences in the EDJ traits in remains from the Can Sadurní site are indicative of distant biological affinities with nearby populations. Additionally, the hypocone associated dentine area and the position of the trigon dentine horns relative to each other on the occlusal surface best describe the variability found among the samples studied. This study highlights the utility of EDJ morphology as a genetic proxy in Holocene population dynamic studies when paleogenomic studies are absent.

What Are We Really Estimating in Forensic Anthropological Practice, Population Affinity or Ancestry?

While American forensic anthropologists often state that they estimate ancestry, is that what they are really estimating? Although typological terminology, the oids, was replaced with continental terminology, the change was linguistic rather than substantive. The American population is comprised largely of immigrants. Genetic data suggests a high degree of admixture within American population groups. Further, data from documented skeletal collections suggest that Americans have undergone secular changes. Our paper addresses the uniqueness of the American population as compared to ancestral continental and geographic origin groups to address what it is that forensic anthropologists are really estimating, ancestry or something else? We conclude, based on uniqueness of American population groups, that what forensic anthropologists are estimating is best described as affinity, a term that indicates similarity and is not exclusively attached to definitions of race and ethnicity.

Self- Reported Ancestry and Craniofacial SNPs: Assessing Correspondence with Implications for Forensic Case Analysis and Reporting

Genotype-phenotype studies increasingly link single nucleotide polymorphism (SNPs) to the dimensions of the face for presumed homogeneous populations. To appreciate the significance of these findings, it is essential to investigate how these results differ between the genetic and phenotypic profiles of individuals. In prior work, we investigated the connection between SNPs previously iden-tified as informative of soft tissue expression and measurements of the craniofacial skeleton. Using matched genetic and skeletal informa-tion on 17 individuals who self-identified as White with presumed common continental ancestry (European), we obtained significant Spearman correlations for 11 SNPs. In the present study, we looked at self-identified ancestry to understand the intersectional background of the individual’s phenotype and genotype. We integrated our samples within a diverse dataset of 2,242 modern Americans and applied an unsupervised model-based clustering routine to 13 craniometrics. We generated a mean estimate of 69.65% (±SD = 18%) European ances-try for the White sample under an unsupervised cluster model. We estimated higher quantities of European ancestry, 88.5%–93%, for our subset of 17 individuals. These elevated estimates were of interest with respect to the distribution of population-informative SNPs; we found, for example, that one of our sampled self-identified White individuals displayed SNPs commonly associated with Latin American populations. These results underscore the complex interrelationship between environment and genetics, and the need for continued research into connections between population affinity, social identity, and morphogenetic expression.

Self- Reported Ancestry and Craniofacial SNPs: Assessing Correspondence with Implications for Forensic Case Analysis and Reporting

Genotype-phenotype studies increasingly link single nucleotide polymorphism (SNPs) to the dimensions of the face for presumed homogeneous populations. To appreciate the significance of these findings, it is essential to investigate how these results differ between the genetic and phenotypic profiles of individuals. In prior work, we investigated the connection between SNPs previously iden-tified as informative of soft tissue expression and measurements of the craniofacial skeleton. Using matched genetic and skeletal informa-tion on 17 individuals who self-identified as White with presumed common continental ancestry (European), we obtained significant Spearman correlations for 11 SNPs. In the present study, we looked at self-identified ancestry to understand the intersectional background of the individual’s phenotype and genotype. We integrated our samples within a diverse dataset of 2,242 modern Americans and applied an unsupervised model-based clustering routine to 13 craniometrics. We generated a mean estimate of 69.65% (±SD = 18%) European ances-try for the White sample under an unsupervised cluster model. We estimated higher quantities of European ancestry, 88.5%–93%, for our subset of 17 individuals. These elevated estimates were of interest with respect to the distribution of population-informative SNPs; we found, for example, that one of our sampled self-identified White individuals displayed SNPs commonly associated with Latin American populations. These results underscore the complex interrelationship between environment and genetics, and the need for continued research into connections between population affinity, social identity, and morphogenetic expression.

Bipartite parietal bone

This study reports the first case of the bipartite parietal bone in the Croatian modern and archaeological population. We have examined 458 skulls from Multi-Slice Computed Tomography (MSCT) images and found only one case of this trait (0.22%; 95%CI 0.01%-1.21%). The bone exhibiting an additional suture was the left parietal; the type of the trait was complete, horizontal, and asymmetrical. Some additional sutural bones were observed, including asterion and lambda ossicle and two lambdoid ossicles. Among the other epigenetic variants, parietal, zygofacial, oval, and mastoid foramina, frontal grooves, supratrochlear notch, and condylar canal were visible. The principal components analysis (PCA) of features extracted from the frontal, lateral, and posterior view of 110 female crania using a convolutional neural network (CNN) for image analysis demonstrated that the skull deviated from the average female skull in the population. The visual and metric examination of the skull showed ultrabrachycephaly, mild lateral deformational plagiocephaly, and depression on the posterior part of the skull. The rarity of this case in the Croatian population indicated that this variant could be interesting for both clinicians and forensic anthropologists, as it can be used as means of comparative identification. Further studies will show its importance in assessing population affinities and relations inside the graveyards.

Missing and murdered indigenous women and girls in Canada: a new population affinity assessment technique to aid in identification using 3D technology

As of 2015, 204 cases of missing and murdered Indigenous women and girls (MMIWG) remained unsolved in Canada, making it a major concern for Canadian Indigenous communities, who are still pressing for the resolution of these cases. In forensic anthropology, the assessment of population affinity can be useful to help identify victims. Population affinity, previously referred to as ancestry, is evaluated based on morphological analyses, which examine the size and shape of skeletal features, and metric analyses, which utilise skeletal measurements. However, morphological analyses strongly depend on an anthropologist’s experience with human variation, which makes the analyses particularly challenging to reproduce and standardise. The purpose of this study is to improve the rigour of morphological analyses by using 3D technology to quantify relevant cranial nonmetric population affinity traits. As there is currently little morphological data available for the Canadian Indigenous population, this research aims to develop a new technique that could aid in the identification of MMIWG. The study comprised a total of 87 adult female crania, including 24 of Canadian Inuit origin, 50 of European descent and 13 of African descent. The samples were imaged using photogrammetry, then analysed using a 3D shape analysis in 3DS Max. Results show that this method is satisfactory in correctly evaluating population affinity with an accuracy of 87.36% (jackknifed: 80.46%) and an average repeatability of 97%. Unfortunately, the small Canadian Indigenous sample size impacted the applicability of the results and further research will be required before the technique can be used to aid in the identification of MMIWG in Canada.

Island Biogeography Revisited: Museomics Reveals Affinities of Shelf Island Birds Determined by Bathymetry and Paleo-Rivers, Not by Distance to Mainland.

Island biogeography is one of the most powerful subdisciplines of ecology: its mathematical predictions that island size and distance to mainland determine diversity have withstood the test of time. A key question is whether these predictions follow at a population-genomic level. Using rigorous ancient-DNA protocols, we retrieved approximately 1,000 genomic markers from approximately 100 historic specimens of two Southeast Asian songbird complexes from across the Sunda Shelf archipelago collected 1893–1957. We show that the genetic affinities of populations on small shelf islands defy the predictions of geographic distance and appear governed by Earth-historic factors including the position of terrestrial barriers (paleo-rivers) and persistence of corridors (Quaternary land bridges). Our analyses suggest that classic island-biogeographic predictors may not hold well for population-genomic dynamics on the thousands of shelf islands across the globe, which are exposed to dynamic changes in land distribution during Quaternary climate change.

Testing the Homogeneity of “White”

The purpose of estimating each part of the biological profile is to reduce the number of missing persons for comparison with unknown human remains. To serve this purpose each part must: 1) derive from information garnered from the remains, and 2) provide information that missing person’s community will generally agree describes them. Observer and statistical error, sampling error, and the disconnect between biological and social categories are all associated with each step of estimation, and can render aspects of the biological profile useless, or even harmful, to the ultimate goal of identification. Here, we examine patterns of phenetic variation within a group usually treated as homogeneous, European-descended populations in the United States and Australia, usually described as “White” (n = 365). We analyzed dental morphological data for biological distances and using several classification techniques. We find that structure exists among these groups. Accuracy of classification of individuals from contemporary Tennessee approaches forensic significance, compared to samples from New York, Ohio, and Australia. These results point out that researchers commonly seek structured variation among some populations but not others. We examine this point, and make recommendations to the field to change our approach to the estimation of population affinity so that it reflects the biological variation associated with social meaning relevant in local communities. Additionally, our approach to population affinity should be iterative, reflecting cultural changes over time, and reflexive, aware and responding to our own biases.

Craniometric Variation in a Regional Sample from Antioquia, Medellín, Colombia

Population affinity estimation is frequently assessed from measurements of the cranium. Traditional models place individuals into discrete groups―such as Hispanic―that often encompass very diverse populations. Current research, including this study, challenges these assumptions using more refined population affinity estimation analyses. We examine craniometric data for a sample of individuals from different regions in Antioquia, Colombia. We first assessed the sample to understand intraregional variation in cranial shape as a function of birthplace or a culturally constructed social group label. Then, pooling the Colombian data, we compare cranial variation with global contemporary and prehistoric groups. Results did not indicate significant intraregional variation in Antioquia; classification models performed poorly (28.6% for birthplace and 36.6% for social group). When compared to other groups (American Black, American White, Asian, modern Hispanic, and prehistoric Native American), our model correctly classified 75.5% of the samples. We further refined the model by separating the pooled Hispanic sample into Mexican and Guatemalan samples, which produced a correct classification rate of 74.4%. These results indicate significant differences in cranial form among groups commonly united under the classification “Hispanic” and bolster the addition of a refined approach to population affinity estimation using craniometric data.

Sex Estimation Using Geometric Morphometrics

Creating and testing efficient techniques for the sex estimation of modern human skeletal remains has been a significant focus in biological anthropology. It is well established that the innominate, particularly the pubic bone, is a sexually dimorphic part of the human skeleton, but prone to fragmentation. Using modern pubic bones of known age and sex, this study aims to capture shape differences using geometric morphometrics (GMM) to test classification accuracy of segments of the pubic bone. The sample consists of 70 left adult pubic bones from the William M. Bass Donated Skeletal Collection, with 35 males and 35 females of mixed age and population affinity. Landmarks were placed on the dorsal surface of the pubic body and ischiopubic ramus to capture their overall shape in two dimensions, so the study is easily replicable and applicable. The scans were separately run through a generalized Procrustes, principal components (PCA), and canonical linear discriminant function analysis (DFA). The DFA results show high classification accuracy for the pubic body (94% males, 100% females) and the ischiopubic ramus (100% females, 97% males), with the PCA DFA allowing a researcher to explore specific shape changes driving the differentiation between groups. GMM was able to quantify and successfully discriminant the shape changes between males and females for small elements of the pubis, which can be applied to fragmentary remains and future morphological methods.