geoFOR: A collaborative forensic taphonomy database for estimating the postmortem interval.

Accurately assessing the postmortem interval (PMI), or the time since death, remains elusive within forensic science research and application. This paper introduces geoFOR, a web-based collaborative application that utilizes ArcGIS and machine learning to deliver improved PMI predictions. The geoFOR application provides a standardized, collaborative forensic taphonomy database that gives practitioners a readily available tool to enter case information that automates the collection of environmental data and delivers a PMI prediction using statistically robust methods. After case submission, the cross-validating machine learning PMI predictive model results in a R² value of 0.82. Contributors receive a predicted PMI with an 80% confidence interval. The geoFOR database currently contains 2529 entries from across the U.S. and includes cases from medicolegal investigations and longitudinal studies from human decomposition facilities. We present the overall findings of the data collected so far and compare results from medicolegal cases and longitudinal studies to highlight previously poorly understood limitations involved in the difficult task of PMI estimation. This novel approach for building a reference dataset of human decomposition is forensically and geographically representative of the realities in which human remains are discovered which allows for continual improvement of PMI estimations as more data is captured. It is our goal that the geoFOR data repository follow the principles of Open Science and be made available to forensic researchers to test, refine, and improve PMI models. Mass collaboration and data sharing can ultimately address enduring issues associated with accurately estimating the PMI within medicolegal death investigations.

Craniofacial asymmetry as a marker of socioeconomic status among undocumented Mexican immigrants in the United States.

This study examines levels of fluctuating asymmetry (FA) in Mexican residents, U.S. residents, and undocumented border crossers (UBCs) from Mexico to the United States. Craniofacial structures develop symmetrically under ideal circumstances; however, during periods of developmental stress random deviations from perfect symmetry, or FA, can occur. It is hypothesized that the UBC sample would represent individuals of a lower socioeconomic status (SES) who experienced higher stress levels during development, and that these individuals would consequently have higher levels of FA. Three-dimensional cranial landmarks were collected from 509 individuals representing the three resident groups. Geometric morphometric methods were used to calculate an FA score for each individual. The FA score provides a distance measure that is a scalar measure of the magnitude of FA in each individual. The results show that the difference in the means of the FA scores between UBCs and U.S. residents is 0.43 (p = 0.02), with UBCs showing significantly higher levels of FA compared to U.S. residents. Moreover, Mexican residents' FA levels are intermediate between and not significantly different from the other two samples. These results suggest that levels of FA may prove useful for reconstructing individuals' social and economic circumstances, and that craniofacial asymmetry provides a suitable biological marker for analyzing differences in SES among different groups.

An Examination of the Differential Effects of the Modern Epidemiological Transition on Cranial Morphology in the United States and Portugal.

This research examines the pattern of secular change in the cranial morphology of two populations experiencing the epidemiological transition associated with decreased mortality rates in children, followed by declines in infant mortality and subsequent increases in adult longevity. The two samples examined in this study come from US and Portuguese individuals. The epidemiological transition occurred at different times in the United States and Portugal, with Portugal entering into the transition later than the United States. The results of the study show that the US and Portuguese samples experienced significant changes in cranial morphology during the approximately 150 years under study. In all of the samples the cranial base morphology changes significantly over time. However, the pattern of change in the US and Portuguese samples varies in the other regions of the crania. The US samples exhibit significant changes associated with the posterior cranial fossa, which experiences the greatest growth during the fetal period and the first year of life. Conversely, in the Portuguese samples the region of the cranium that shows the greatest change is in the face and lateral cranial base, which experiences the greatest growth from three to nine years. This differential pattern may reflect differences in changing mortality patterns in the two countries. During the period under study the United States had already proceeded through the early stages of the epidemiological transition, and improvements in the juvenile mortality and juvenile growth had occurred previously. Subsequently, the United States experienced significant declines in infant mortality, and the regions of the crania that exhibit the greatest changes occur in area with maximum growth velocity under one year. However, Portugal entered into the epidemiological transition later than the United States and therefore the greatest changes in growth occurred during the juvenile period, which is reflected in the adult morphology in this group. This study demonstrates the utility of variation in growth patterns in different cranial regions to document changes in the demographic parameters in two different populations.

Design and evaluation of a bioreactor with application to forensic burial environments.

Existing forensic taphonomic methods lack specificity in estimating the postmortem interval (PMI) in the period following active decomposition. New methods, such as the use of citrate concentration in bone, are currently being considered; however, determining the applicability of these methods in differing environmental contexts is challenging. This research aims to design a forensic bioreactor that can account for environmental factors known to impact decomposition, specifically temperature, moisture, physical damage from animals, burial depth, soil pH, and organic matter content. These forensically relevant environmental variables were characterized in a soil science context. The resulting metrics were soil temperature regime, soil moisture regime, slope, texture, soil horizon, cation exchange capacity, soil pH, and organic matter content. Bioreactor chambers were constructed using sterilized thin-walled polystyrene boxes housed in calibrated temperature units. Gravesoil was represented using mineral soil (Ultisols), and organic soil proxy for Histosols, horticulture mix. Gravesoil depth was determined using mineral soil horizons A and Bt2 to simulate surface scatter and shallow grave burial respectively. A total of fourteen different environmental conditions were created and controlled successfully over a 90-day experiment. These results demonstrate successful implementation and control of forensic bioreactor simulating precise environments in a single research location, rather than site-specific testing occurring in different geographic regions. Bone sections were grossly assessed for weathering characteristics, which revealed notable differences related to exposure to different temperature regimes and soil types. Over the short 90-day duration of this experiment, changes in weathering characteristics were more evident across the different temperature regimes rather than the soil types. Using this methodology, bioreactor systems can be created to replicate many different clandestine burial contexts, which will allow for the more rapid understanding of environmental effects on skeletal remains.

Assessing the relationship between fluctuating asymmetry and cause of death in skeletal remains: a test of the developmental origins of health and disease hypothesis.

OBJECTIVES: This study examines the relationship between craniofacial fluctuating asymmetry and cause of death in an identified skeletal collection. This study tests the Developmental Origins of Health and Disease hypothesis using fluctuating asymmetry as the measure of developmental instability. METHODS: The skeletal sample used in this study comes from Lisbon, Portugal, and individuals in the sample were born between 1806 and 1935. This represents a period during which Lisbon was beginning to undergo the modern health transition, in which mortality from infectious disease began to decline while mortality from degenerative diseases began to increase. Approximately equal numbers of individuals in the sample died from infectious diseases, such as tuberculosis, and from degenerative diseases. Fluctuating asymmetry is examined using three-dimensional landmark data collected from 392 individuals with documented causes of death. Landmark data may provide a more robust measure of fluctuating asymmetry, although it has not often been used in studies of fluctuating asymmetry in human skeletal samples. RESULTS: The results of the study show that individuals who died from degenerative diseases have higher rates of fluctuating asymmetry compared to individuals who died from infectious diseases. Males also exhibit higher rates of fluctuating asymmetry compared to females. CONCLUSIONS: The results of this study confirm earlier findings that early development has a significant impact on adult health outcomes. Furthermore, the results suggest that fluctuating asymmetry in skeletal samples may offer a means of testing the Developmental Origins of Health and Disease hypothesis.

Secular changes in craniofacial morphology of the Portuguese using geometric morphometrics.

This study examines patterns of secular change in cranial morphology in the New Lisbon collection, a documented skeletal collection from Lisbon, Portugal with birth years from 1806 to 1954. This period represents a time when Lisbon was undergoing increased urbanization and population growth, as well as changes in mortality and fertility patterns. Previous studies from the U.S., Europe, and Japan have reported significant secular changes in cranial morphology over the past 200 years. In the current study, secular changes were analyzed using three-dimensional geometric morphometrics methods. The results from this study demonstrate a significant change in cranial morphology over the roughly 150-year period. Allometry was rejected as a causal factor of this change because there was no association found between temporal change and size. The pattern of temporal change is similar to that observed in other populations in the U.S., Europe, and Japan, including decreased facial breadth and a more inferiorly placed cranial base. This study, along with previous research, suggests a similar pattern of change occurs in genetically and geographically diverse populations experiencing modern environmental conditions. We argue that because the secular changes are focused in the cranial base, a region of the skull that experiences a relatively early growth curve, changes related to declines in childhood morbidity and mortality are likely important factors related to the observed changes.