Variation in ontogenetic trajectories of limb dimensions in humans is attributable to both climatic effects and neutral evolution.

Previous studies showed that there is variation in ontogenetic trajectories of human limb dimensions and proportions. However, little is known about the evolutionary significance of this variation. This study used a global sample of modern human immature long bone measurements and a multivariate linear mixed-effects model to study 1) whether the variation in ontogenetic trajectories of limb dimensions is consistent with ecogeographic predictions and 2) the effects of different evolutionary forces on the variation in ontogenetic trajectories. We found that genetic relatedness arising from neutral (nonselective) evolution, allometric variation associated with the change in size, and directional effects from climate all contributed to the variation in ontogenetic trajectories of all major long bone dimensions in modern humans. After accounting for the effects of neutral evolution and holding other effects considered in the current study constant, extreme temperatures have weak, positive associations with diaphyseal length and breadth measurements, while mean temperature shows negative associations with diaphyseal dimensions. The association with extreme temperatures fits the expectations of ecogeographic rules, while the association with mean temperature may explain the observed among-group variation in intralimb indices. The association with climate is present throughout ontogeny, suggesting an explanation of adaptation by natural selection as the most likely cause. On the other hand, genetic relatedness among groups, as structured by neutral evolutionary factors, is an important consideration when interpreting skeletal morphology, even for nonadult individuals.

Technical note: A report on the Forensic Anthropology Database for Assessing Methods Accuracy.

We report on the functionality, available support, and research capability of the Forensic Anthropology Database for Assessing Methods Accuracy (FADAMA; DOJ DUBX0213). FADAMA is an online repository for case data from identified forensic skeletal cases. The goal of FADAMA is to address the lack of adequate measures for assessing accuracy and reliability of forensic anthropology methods. FADAMA requires users to apply for access with their university or organization credentials. Verified users may upload and download anonymized case data via the user interface, after signing a terms of service agreement outlining ethical behavior. Case data uploads require information about the actual biological profile of the decedent and the forensic anthropology estimations. Uploading case data takes approximately 15-25 min. FADAMA users currently have 85 methods to select from when entering case data, with the capability to add new methods as they are developed. Access to the database is free, and online video tutorials are available for users covering database functionality. Currently, the database houses anonymized case data for over 350 identified cases from across the U.S. Funding has been allocated for a database technician to assist offices with large caseloads to upload cases. As it stands, the database is easy to use, and maintains thoughtful tools to assist users. The power of the database to identify trends in both method accuracy and usage is apparent, and will continue to grow as more cases are added.

Allometric scaling and growth: Evaluation and applications in subadult body mass estimation.

OBJECTIVES: Previously developed methods in subadult body mass estimation have not been tested in populations other than European-American or African-American. This study uses a contemporary Taiwanese sample to test these methods. Through evaluating their accuracy and bias, we addressed whether the allometric relationships between body mass and skeletal traits commonly used in subadult body mass estimation are conserved among different populations. MATERIALS AND METHODS: Computed tomography scans of lower limbs from individuals aged 0-17 years old of both sexes were collected from National Taiwan University Hospital along with documented body weight. Polar second moment of area, distal femoral metaphyseal breadth, and maximum superior/inferior femoral head diameter were collected either directly from the scans or from reconstructed 3D models. Estimated body mass was compared with documented body mass to assess the performance of the equations. RESULTS: Current methods provided good body mass estimates in Taiwanese individuals, with accuracy and bias similar to those reported in other validation studies. A tendency for increasing error with increasing age was observed for all methods. Reduced major axis regression showed the allometric relationships between different skeletal traits and body mass across different age categories can all be summarized using a common fitted line. A revised, maximum likelihood-based approach was proposed for all skeletal traits. DISCUSSION: The results suggested that the allometric relationships between body mass and different skeletal traits are largely conserved among populations. The revised method provided improved applicability with strong underlying theoretical justifications, and potential for future improvements.

Considerations for age estimation accuracy: Method-derived outcomes and practitioner interpretations.

Recent research observed 92% accuracy for age-at-death estimations by U.S. forensic anthropologists. The present study compares this case report level accuracy to method level accuracy for the most commonly used methods in U.S. casework, drawing from the Forensic Anthropology Database for Assessing Methods Accuracy (FADAMA). Method application rate (i.e., how often a method is used in casework) was analyzed for n = 641 cases and identified 15 methods with an application rate >45 cases, and the present study focused further analyses on these 15 methods. Of the 15, only four yielded accuracies greater than or equal to the 92% documented for case-report level accuracy. The other 11 methods produced accuracy rates ranging from 54% to 91%, with six of these below 70% This disconnect between highly accurate age estimations at the case report level compared to the poor performance at method level suggests that practitioner interpretation and synthesis of the methods' outcomes is a critical step for increasing the accuracy rates of the age estimations as reported on the final case report. This inference was further supported by the study's results which indicated that practitioner interpretations of frequently used method combinations improve accuracy and age range width of age estimation. The study also performed a Fisher's Exact test to assess whether case report-level accuracy differed with the number of aging methods used in a case, and found no significant differences.

Investigating identification disparities in forensic anthropology casework.

Forensic anthropology is shifting to reflect on the impact of its practices within the criminal justice context in important ways. Here, we contribute to this essential work by examining how decedent demographics as well as estimations of biological profile components are related to identification trends in forensic anthropology cases. The study uses data from more than 1,200 identified and unidentified forensic anthropology cases from three agencies (together representing a nation-wide sample). We found the following: i) multivariate analyses indicated that decedent sex, age, and race and/or ethnicity are not related to case identification rates in the pooled United States sample, ii) when identification rate differences do occur, they appear to be smaller effects, more agency-specific, and/or related to the context of a particular agency, iii) for the agency-specific sample with available data, there was no consistent evidence for a discrepancy in the duration of an identification investigation based on a decedent's sex, age, or race and/or ethnicity, iv) forensic anthropological estimations of sex, age, and ancestry can improve the odds of identification for decedents, although these are small effects, and v) reporting an ancestry estimation does not appear to impact decedent race representation among resolved unidentified person cases. Although previous studies have identified demographic discrepancies in other areas of the criminal justice system, the results presented here suggest that decedent demographic estimation practices by forensic anthropologists in general do not appear to be related to discrepancies in identification trends, but more research is needed to examine whether these findings hold. Contextual factors and practices specific to each investigative agency likely contribute to identification trends.

Diversity in forensic sciences: Black, Indigenous, and People of Color (BIPOC) representation in different medicolegal fields in the United States.

The benefits of a diverse and inclusive working environment are well documented. This study examined forensic science literature, demographic data reported from professional organizations, and demographic surveys to compile information regarding racial and ethnic diversity within different subdisciplines of forensic science. Results showed that practitioners self-identified as Black or Hispanic were underrepresented in scientific fields closely related to forensic science. Moreover, Black, Indigenous, and People of Color (BIPOC) students were underrepresented at the undergraduate level, despite increasing college enrollments. This lack of representation may have consequences on knowledge production and innovation. By recognizing the current status of diversity in forensic science, this study is the first step toward mitigating the trend of underrepresentation. We encourage professional organizations to be transparent about the diversity in their membership and provide actual practitioner demographic statistics. These data are beneficial to studying the effects of underrepresentation and developing effective strategies to improve representation.

Forensic anthropology casework performance: Assessing accuracy and trends for biological profile estimates on a comprehensive sample of identified decedent cases.

The purpose of this study was to investigate the accuracy rates and trends in forensic anthropology casework concerning the estimation of the biological profile (sex, age, ancestry, and stature). Identified cases from the Forensic Anthropology Database for Assessing Methods Accuracy (FADAMA; n = 359) were analyzed to explore the following: accuracy rates per biological profile component, case-level performance in assessing the biological profile, and factors related to inaccuracy rates. Accuracy rates for the four biological profile components ranged from 83% to 98%, with sex estimation performing the best and stature performing the poorest. While the overall sex estimation inaccuracies were the lowest of any biological profile component, we found that females are missexed approximately ten times more often than males. Inaccurate age estimates were more frequently the result of overestimation than underestimation, while the trends are reversed for stature estimation. Regarding ancestry estimation performance, African American/Black and White decedents had the lowest inaccuracy rates, while Hispanic and Asian/Pacific Islander decedents demonstrated greater inaccuracy rates. When examining accuracy rates for each case, 81% of cases had no inaccurate biological profile estimates, while 17% and 2% inaccurately estimated one and two biological profile components, respectively. The demographic trends of identified forensic anthropology cases reflect the national unidentified decedent demographics. Biological profile accuracy rates were generally comparable to previous studies. The findings highlight the current status of forensic anthropologists' casework performance, with a greater amount of case-level inaccuracy rates than previously thought, and demonstrate the potential methodological and sampling strategies that could improve accuracy rates.

A Retrospective Study of Intentional Body Dismemberment in New York City: 1996-2017.

A review of New York City dismemberment cases occurring between 1996 and 2017 was conducted, which resulted in a total of 55 dismembered decedents in a 22-year period. Annual trends indicate an average of 2.5 dismembered decedents. Additional results show that 53% of cases involved transection only, 35% involved disarticulation only, and 13% involved a combination of both. When the entire body could be accounted for, the average number of body portions per case was 5.5. Frequent locations for dismemberment were the neck, shoulders, hips, and knees. Dismemberment locations showed a general trend of anatomical symmetry. Seventy-eight percent of the dismemberments involve disposal of body parts in an outside location. Eighty-four percent were concealed from view with some type of covering. The findings from New York City are compared with other studies.