MORPHOSCOPIC AND MORPHOMETRIC METHODS FOR SORTING COMMINGLED HUMAN REMAINS Popi Th. Chrysostomou 1,2 ; Tim J. U. Thompson 1 ; and John E. Byrd 3 1 School of Science & Engineering; 2 Cyprus Department of Antiquities; 3 Defense POW/MIA Accounting Agency 1. Introduction The commingling of human remains is a scientific challenge commonly encountered in both medicolegal and bioarchaeological settings. Despite the frequent occurrence of commingled remains, research on sorting methodologies remains relatively limited even though the segregation of elements to form complete or nearly complete individuals is an unquestionably important component not only for the analysis, but also the identification and return of human remains. Unfortunately, the heavy reliance on observer experience for the visual segregation of remains has produced a method that is currently as much an art as it is a science. 1.1 Definition of Commingled Remains The term “commingled remains” refers to the intermixing of body parts or skeletal elements of one or more individuals and is typically attributed to human activity or other taphonomic processes. Reported cases of commingling often relate to mass executions in armed conflicts, aircraft accidents, terrorist attacks, dismembered homicide cases, animal scavenging, archaeological ossuaries and museum collections. Figure 1. The photograph on the left illustrates a commingled case as accessioned by the examining anthropologist. Further to analysis, it was established that the commingled remains represented a minimum number of nine individuals. The photographs on the right illustrate the remains of four different individuals after reconstruction and sorting analyses. 1.2 Aims and Objectives The aim of the study is the development of validated methodologies for sorting commingled remains. The objectives of the research include:  the study of mechanical and functional attributes to understand human asymmetry and allometry;  the correlation of morphometric attributes in isometric and allometric relationships;  the detailed description of macroscopic methods for sorting commingled remains;  the development of new osteometric sorting models;  the provision of correct classification rates for sorting techniques. 2. Materials and Methods 3. Examples of Sorting Techniques The research involves all human dental and skeletal elements, with the exception of ear ossicles and hyoids. Observations are being made on approximately 600 skeletons recovered in situ or found in caskets in both modern and archaeological contexts in Cyprus, and were not commingled with other individuals’ remains. The majority of the individuals under examination are males, while the age range of individuals in the study includes all age categories from neonates to senile individuals. Performance indicators (sensitivity, specificity, classification accuracy, error rate, positive predictive value and predictive value negative) will be calculated for each method based on 50 sets of skeletal remains. 3.1 Cranium-Atlas Articular Reassociation Technique The reassociation of the first cervical vertebra (atlas) of the spinal column with the occipital bone of the cranium can be accomplished via examination of the atlanto-occipital joints. These joints are formed by the concave superior articular facets located on the lateral masses of the atlas and the convex facets of the occipital condyles. The present method introduces specific criteria for evaluating the association between an atlas and a cranium, namely by focusing on the size, shape, tropism, directionality and in-between distance of the two atlanto-occipital joints (Fig. 2). Figure 2. Examples of good-fitness articulations between atlases and crania. A: illustrates congruence in articular surface curvatures between the elements; B: illustrates expected size differences – occipital condyles can have extended articular facets to accommodate atlar movement; C: illustrates intra-distances used in the study – the distances marked as (a) and (c) should correspond to the distances marked as (b) and (d), respectively. D: the distances marked as (e) and (f) may vary. Note that in photographs C and D, the atlar articular facet exhibits a double-facet shape, while its corresponding occipital surface is singled-facet (red arrows). This feature often erroneously confuses analysts as to the good fitness of articulation. A B C D 3.2 Ulna-Radius Metric Reassociation Technique The reassociation of an articulating ulna and radius (forearm) can be accomplished via examination of isometric or near-isometric relationships. The present method introduces new metric variables for associating an ulna and a radius as seen in Fig. 3. Figure 3. Current models for ulnae and radii examine their maximum lengths and shaft diameters (measurements shown in red). These variables however are influenced by other biomechanical factors. The present model relies on articular distances (measurements shown in yellow) which offer improved discriminating power for grouping elements belonging to the same individual. 4. Discussion and Conclusions For additional information contact Popi Chrysostomou Email: P.Chrysostomou@tees.ac.uk Poster available for download at: independent.academia.edu/PopiChrysostomou The topic of commingled human remains has received very little attention within the realms of both physical and forensic anthropology, despite the somewhat increased research interest observed during the past decade. The present research aims to provide tools for a more active and efficient use of anthropological means during the analysis of commingled remains. Several hypotheses are investigated regarding the morphological and osteometric relations of nearly all osseous and dental elements of the human skeleton. The expected outcome is the development of coherent, scientifically-based visual and metric sorting techniques based on standardized, replicable, and validated methods in accordance with the post-Daubert forensic science best practices. Proposed method Current methods