ANTHROPOLOGY APPS
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(hu)MANid Publications
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Introducing Human Mandible Identification [(hu)MANid]: A free, web-based GUI to classify human mandibles
ABSTRACT: Statistical programs have revolutionized the way in which forensic anthropologists conduct casework by allowing practitioners to use computationally complex analytics at the click of a button. Importantly, the products of these statistical programs are reproducible and contain measures of error or uncertainty, thereby strengthening conclusions. This paper is an introduction to (hu)MANid, a free, web-based application that uses linear and mixture discriminant function analyses to classify human mandibles into one of many worldwide and/or periodic reference groups. The mechanics, development, and use of the application will be discussed. Further, the program was tested against other software to compare model performances and classifications. Total correct classifications among the test cases and programs were identical. Ten mandibles were tested using both statistical procedures. Mixture discriminant analysis improved classification by an average of 9.3% and correctly identified three more mandibles than LDA. Therefore, we believe (hu)MANid will be an asset to the anthropological community. PDF
Evaluating mixture
discriminant analysis to classify human mandibles with (hu)MANid, a free, R-Based GUI
ABSTRACT: Increasingly over the last 30 years, anthropologists have been studying human skeletal variation using more complex data gathering tools and systems. Traditionally, Linear Discriminant Analysis (LDA) has been the hallmark statistical tool for classifying this variation into extant and extinct human populations. Criticisms of LDA in anthropology typically focus on the violation of multiple assumptions of the statistical approach. In this chapter, we explore using Mixture Discriminant Analysis (MDA) as an alternative to this traditional method, as it violates fewer assumptions and produces better classification rates. We utilize a new analytical program, (hu)MANid, to evaluate both statistical approaches for classifying the human mandible. (hu)MANid is a free, downloadable graphic user interface (GUI) now available to all practitioners.
Examining Interobserver Reliability of Metric and Morphoscopic Characteristics of the Mandible
ABSTRACT: Mandibular metric and morphological characteristics have long been used for sex and ancestry estimation. Currently, there are no large-scale studies examining interobserver agreement, particularly examining the role of observer experience. This study examines the interobserver agreement of six morphoscopic and eleven metric mandibular variables. Four observers with varied levels of experience scored 183 mandibles from the William M. Bass Donated Skeletal Collection. Absolute agreement and consistency were evaluated with the intraclass correlation coefficient (ICC). Additionally, technical error of measurement (TEM) and relative TEM (%TEM) were calculated for each metric variable. All analyses were conducted twice—once with all observers and again with only experienced observers. Results show mean morphoscopic agreement of 0.543 among all observers and 0.615 for experienced observers, and mean metric agreement of 0.886 among all observers and 0.911 for experienced observers. Further, no TEM exceeded 2 mm. All results were significant. PDF
Biological Affinity and Sex from the Mandible Utilizing Multiple World Populations
ABSTRACT: The goal of this study is to provide an "on the ground anthropologist" a suite of procedures by which to estimate biological affinity and determine sex of an unknown individual through the use of a relatively robust bone, the mandible. The study tests the idea that mandibular metrics and morphology can be used to accurately determine population affinity (and as a byproduct, sex) of an unknown specimen. Straightforward and easily understood processes (e.g. simple morphometric and morphoscopic scoring methods), without the need for relatively complex statistical manipulations, are presented. The study attempts to take a rather far-flung approach, incorporating world-wide populations, rather than just two or three groups. Further, if both morphometric and morphoscopic features are employed at the same time, smaller and smaller portions of the bone are all that may be needed to determine the biological profile of an individual via custom discriminant functions presented herein.
Optosearch Publications
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Personal identification based on prescription eyewear
ABSTRACT: This study presents a web-based tool that can be used to assist in identification of unknown individuals using spectacle prescriptions. Currently, when lens prescriptions are used in forensic identifications, investigators are constrained to a simple ''match'' or ''no-match'' judgment with an antemortem prescription. It is not possible to evaluate the strength of the conclusion, or rather, the potential or real error rates associated with the conclusion. Three databases totaling over 385,000 individual prescriptions are utilized in this study to allow forensic analysts to easily determine the strength of individuation of a spectacle match to antemortem records by calculating the frequency at which the observed prescription occurs in various U.S. populations. Optical refractive errors are explained, potential states and combinations of refractive errors are described, measuring lens corrections is discussed, and a detailed description of the databases is presented. The practical application of this system is demonstrated using two recent forensic identifications. This research provides a valuable personal identification tool that can be used in cases where eyeglass portions are recovered in forensic contexts. PDF
Distribution of Ametropia among military beneficiaries
ABSTRACT: In addition to active duty military members and their dependents, retired military members and the members of their immediate families are eligible for eye care in military medical treatment facilities. We recorded refractive errors, age, sex, and race for 4,595 individual beneficiaries visiting optometry clinics at two U.S. Air Force medical treatment facilities during 2005 to 2006. Evaluation revealed most patients requiring optical correction were myopic, or near-sighted, and there was an increase in the degree of myopia between ages 4 and 23. That trend is reversed at age 30 and, by age 60, most patients are hyperopic, or far-sighted. Both trends were true for both sexes and all ethnicities studied. The degree of astigmatism was distributed similarly between races and age groups. Presbyopia occurred at similar ages and progressed at similar rates in all ethnicities and both sexes. PDF
Predicting Biological Profiles from Prescription Eyewear: A Pilot Study
ABSTRACT: When unidentified human remains are recovered, valuable evidence to determine identity often comes from the nonskeletal material associated with those remains. In light of this observation, the following study presents a test of the hypothesis that, in cases where prescription glasses are found in association with human remains or at a crime scene, data from those glasses may be used to estimate the wearer's age, sex, or race. The study utilized data from the prescription glasses or current eye exams of 97 volunteers. Each anonymous volunteer provided information about his or her age, sex, and race. An automated lens analyzer was used to read prescriptions from glasses provided by volunteers, and the glasses were then returned to volunteers using a drop-off box with an anonymous numbering system. Data collected from lenses and prescriptions were compared to two large databases comprised of eyeglass prescriptions from more than 12,000 individuals in a variety of age, sex, and racial categories. To attempt to estimate the age, sex, and race of the study volunteers from their prescriptions, three methods were applied. The results of the study indicate that one of the methods for estimating age within ±10 years had an 81% accuracy rate; age (±10 years) was correctly predicted in 100% of cases with bifocal prescriptions (n=31). Sex and race could not be estimated with sufficient accuracy using any of the three methods applied in this study. Although the study resulted in the null hypothesis in terms of estimating sex and race using prescription lenses, the ability to estimate an unknown individual's age would be useful in many cases, particularly in instances of advanced age, where traditional age estimation methods fare poorly. Such a method could also prove invaluable in the (albeit rare) instances where a perpetrator leaves glasses behind at a crime scene. PDF
Ocular detail and Ophthalmic appliances as potential aid in forensic identification
ABSTRACT: Ophthalmic appliances have been utilized in forensic identification. Additionally, ocular features may be of assistance in identification for live missing individuals and pre-decomposed deceased individuals. This paper discusses some ocular features and ophthalmic appliances potentially useful in identification. Venues of distribution regarding placement of potential identification features are also discussed (Iris biometrics has been discussed in a prior article and will not be addressed in this writing. PDF
Isolocate Publications
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Application of stable isotope forensics for predicting region of origin of human remains from past wars and conflicts
ABSTRACT: The application of stable isotope analysis has provided novel approaches for provenancing unidentified human remains from forensic contexts. Stable isotope ratios measured in human tissues provide a record of the foods consumed during life as well as the geographic location where drinking water or food was obtained. This study begins with an overview of the application of stable isotope analysis for provenancing human remains, followed by three cases that illustrate how chemical signatures in bone reflect a probable region of origin. Using stable carbon and nitrogen isotopes of human bone, we test whether human skeletal remains recovered by the Joint POW/MIA Accounting Command-Central Identification Laboratory (JPAC-CIL, or CIL) reflect a geographic origin within North America or Asia. Stable carbon and nitrogen isotopes of human bone collagen and stable carbon isotopes of bone apatite reflect consumption of food resources that are expected to vary between world regions due to cultural dietary differences. Based on the isotopic differences, a testable hypothesis of geographic origin can be applied, determining if the remains are more likely of a U.S. service person or of an indigenous local. We believe that this approach can provide useful information for narrowing search parameters in unidentified persons cases; can contribute to human rights cases where an unknown individual is thought to originate from a different geographic area; and, in human remains cases of unknown geographic provenience, can determine whether a person is local or nonlocal. PDF
Addressing data comparability in the creation of combined data sets of bioapatite carbon and oxygen isotopic compositions
ABSTRACT: Before amalgamating published isotope data, comparability should be demonstrated. This paper compares carbon and oxygen isotopic compositions of 30 enamel samples measured by two laboratories. The aims were to see what, if any, isotopic variation was observed, to determine the causes as needed and to correct if possible. Bioapatite was acidified at 90°C in 2006 and at 26°C in 2017, while δ values were corrected via one-point normalization in 2006 and by two-point normalization in 2017. One case (of the 30) produced different δ values between the analysis dates, suggesting contamination. Repeated carbon isotope ratio measurements were not meaningfully different. Repeated oxygen isotope ratio measurements were significantly different, even following correction for acid-carbonate fractionation at different temperatures and the renormalization of 2017 δ values using one point; however, differences were not meaningful for interpretations. Results were used to calculate real interpretative differences (RIDs) for comparing enamel bioapatite as 0.6‰ for δ13C values and as 1.6‰ for δ18O values. PDF
Basic principles of stable isotope analysis in humanitarian forensic science
OVERVIEW: Isotope ratios of hydrogen (H), carbon (C), nitrogen (N), oxygen (O), sulfur (S), strontium (Sr), and lead (Pb) act as "nature's recorders." Once the isotope ratios within a tissue—such has hair, nail, bone, or tooth enamel—have been measured, they can be translated into information about geographic life trajectories and dietary patterns of an individual. This information can aid in the process of identification, typically by eliminating scenarios but potentially by revealing life history details that could be included in a public appeal for information. This book chapter provides background and applications of stable isotope analysis in the context of humanitarian forensic science to illustrate the contribution isotopic profiling can make to an investigation of an unidentified decedent. It also describes a few of the isotopic tools and data resources currently available to forensic investigators.
Application of stable isotope analysis for provenancing human remains recovered from Asia and the Pacific. PDF
A large-scale evaluation of intraperson isotopic variation within human bone collagen and bioapatite. PDF
General Isotope Papers
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The use of stable isotopes in postconflict forensic identification
Stable isotope ratio analysis is becoming an extremely important tool for the forensic investigator. It can be particularly useful in missing persons investigations to help establish an unknown's identity by potentially reconstructing an individual's geolocational history, determining the number of individuals present in a case, and linking/separating remains from commingled assemblages. In this review article, we explore several main themes related to the use of stable isotopes in postconflict forensic identification. First, we describe what stable isotopes are and how global isotopic variation arises in human tissues via natural processes and cultural practices. Next, we discuss the selection of appropriate human tissue samples for examination based on testable hypotheses. We provide guidance on the options that exist for isotope sample preparation, analysis, and data handling; and finally, we examine which sample quality measures and quality assurance approaches should be used in isotope data reporting and interpretation. These themes are primarily presented to help the isotope data consumer understand the benefits and limitations of the technique that might not be apparent when sending samples to and receiving results from a high throughput, contract isotope testing laboratory. Real world examples of forensic stable isotope ratio analysis are provided within the article to highlight many of the concepts, particularly in regard to identification applications. PDF
Calculation and Interpretation of Inter-laboratory Variation in Isotope Delta (δ) Values Using Real Interpretative Differences
ABSTRACT: Building on applications in anthropology, the use of stable isotope ratio analysis of human bone collagen to investigate an individual's life history is becoming more commonplace in the forensic science community. Careful consideration of the resultant isotope delta (δ) values, particularly in regard to their accuracy and reliability, is paramount when introducing isotope data into the U.S. court system. In this study, we use a simple framework to calculate real interpretative difference (RID) values for collagen ("col") and assess isotope data comparability for sample analysis (RIDanalysis) as well as sample preparation/analysis combined (RIDcombined). The RIDcombined values of 0.59‰ for δ13Ccol and 0.91‰ for δ15Ncol are similar to more complex, published calculations of inter-laboratory variability in the stable isotope analysis of skeletal remains, but they are easier to calculate and intuitively elegant. The RIDcombined as well as RIDanalysis values presented here allow users to examine multiple sources of inter-laboratory isotopic variation (preparation, analysis, and both together) in a two-step process whereby a RID value is constructed and then tested. Implementation of this RID approach will provide surety for the legal and research communities in forensic applications of stable isotope ratio analysis. PDF
Using bone bioapatite yield for quality control in stable isotope analysis applications
ABSTRACT: Since the late 1970s, stable isotope analysis of bone has become a routine method in archaeological science for reconstructing an individual's life history. There is published guidance for assessing bone quality prior to stable isotope analysis, including measurement of bioapatite molecular structure, collagen yield, and collagen element content. This study investigated bioapatite yield as an additional quality indicator. Bioapatite and collagen were extracted from 182 modern (20th Century) and 272 prehistoric (5420–230 cal BP) human skeletal elements. As expected, modern remains were well-preserved, with ranges of 3–28% for collagen yield and 3.1–3.4 for the atomic carbon-to-nitrogen (C:N) ratio; bioapatite yield ranged from 21% to 63%. There was a significant, but only fair, negative correlation between bioapatite and collagen yields of modern samples (r = -0.31, p ‹ 0.0001). Conversely, no correlation was observed between bioapatite and collagen yields of prehistoric samples, suggesting preservation of one is not indicative of preservation of the other. Prehistoric sample condition was evaluated by measuring the infrared splitting factor (IR-SF) to evaluate bioapatite crystallinity and the carbonate-to-phosphate (C/P) ratio to measure carbonate concentration; yield and C:N ratio were used to evaluate collagen condition. Prehistoric samples in the best condition had bioapatite yields between 29% and 62%, within the range of modern samples. In contrast, prehistoric samples in poor condition had significantly higher bioapatite yields, suggesting diagenetic addition of material. The range of bioapatite yields from modern bone samples, 21–63%, is proposed as the least conservative acceptable threshold for screening bone prepared for stable isotope analysis. PDF
Recent applications of isotope analysis to forensic anthropology
ABSTRACT: Isotope analysis has become an increasingly valuable tool in forensic anthropology casework over the past decade. Modern-day isotopic investigations on human remains have integrated the use of multi-isotope profiles (e.g. C, N, O, H, S, Sr, and Pb) as well as isotopic landscapes ("isoscapes") from multiple body tissues (e.g. teeth, bone, hair, and nails) to predict possible region-of-origin of unidentified human remains. Together, data from various isotope analyses provide additional lines of evidence for human identification, including a decedent's possible region-of-birth, long-term adult residence, recent travel history, and dietary choices. Here, we present the basic principles of isotope analysis and provide a brief overview of instrumentation, analytical standards, sample selection, and sample quality measures. Finally, we present case studies that reflect the diverse applications of isotope analysis to the medicolegal system before describing some future research directions. As shown herein, isotope analysis is a flexible and powerful geolocation tool that can provide new investigative leads for unidentified human remains cases. PDF
Odontosearch
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Establishing personel identification based on specific patterns of missing, filled and unrestored teeth
ABSTRACT: The primary goal of this research is to examine the overall utility of nonradiographic dental records for the establishment of indi-vidual identifications. It was found that even without radiographic lines of comparison, charts and notes that accurately detail a missing individual's antemortem dental condition can be essential for establishing an identification. Based on an analysis of two large datasets, individual dental patterns were determined to be generally unique, or at least very uncommon. Through this type of empirical comparison, it is possible to establish a strong, quantifiable association with a missing individual. The results of this research indicate that a definitive number of points of concordance do not need to be established in dental identification cases. Each case must be assessed individually. The critical factor is to remove subjective judgment calls from dental comparisons. This research has proposed a new method of empirical comparison that allows forensic odontologists to derive objective frequency information regarding the occurrence of specific dental patterns in the general population. The method is similar to that used for mtDNA casework, and a computer program (OdontoSearch) has been developed to make the technique accessible. It was found that even a small number of common dental characteristics may produce a very rare dental pattern, a point that may be counterintuitive to many forensic odontologists.
PDF, Part I
PDF, Part II