Age-at-Death Estimation for Modern Populations in Mexico and Puerto Rico Through the Use of 3D Laser Scans of the Pubic Symphysis

Reliable age-at-death estimates from the adult skeleton is of fundamental importance in forensic anthropology, as it contributes to the identity parameters used in a medico-legal death investigation. However, reliable estimates are made difficult by the fact that many traditional aging methods are dependent upon a set of population-specific criteria derived from individuals of European and African descent. The absence of information on the potential differences in the aging patterns of underrepresented, especially Hispanic populations, may hinder our efforts to produce useful age-at-death estimates. In response to these concerns, this study explores the utility of currently available aging techniques, and explores the need, if any, for population- specific aging method among Hispanic groups. The current study obtained data from two skeletal collections representing modern individuals of Mexican and Puerto Rican origin. Five newly developed computational-shape based techniques utilizing 3D laser scans of the pubic symphysis and one traditional bone-to-phase technique were examined. A validation test of all computational and traditional methods was implemented, and new population-specific equations using the computational algorithms were generated and tested against a sub-sample. Estimated mean ages from the traditional and computational techniques were compared in order to offer practical recommendations for age estimation on cases of Hispanic identity and, in particular, cases presumed to be of Mexican or Puerto Rican individuals. Results from this study suggest that traditional and computational aging techniques applied to the pubic symphysis perform the best with individuals within 35-45 years of age. Levels of bias and inaccuracy increase as chronological age increases, with overestimation of individuals under 35 years of age, and underestimation of individuals over 45 years of age. New regression models provided error rates comparable, and in some occasions, outperformed the original computational models developed on White American males, but age estimates did not significantly improve. This study has shown that population specific models do not necessarily improve age estimates in Hispanic samples. Results do suggest that computational methods can ultimately outperform the Suchey Brooks method and provide improvement in objectivity when estimating age-at-death in Hispanic samples

Selective mortality in middle-aged American women with Diffuse Idiopathic Skeletal Hyperostosis (DISH).

OBJECTIVE:A mortality sample of white American male and female skeletons was examined to illustrate a simple means of identifying skeletal conditions associated with an increased risk of dying relatively early in adulthood and to determine if males and females with Diffuse Idiopathic Skeletal Hyperostosis (DISH) displayed the same general age-specific pattern of mortality. METHODS:Age-specific probability distributions for DISH were generated from 416 white Americans who died from the 1980s to the present, and whose remains were donated to the University of Tennessee Forensic Anthropology Center. The age-specific frequency of DISH is analyzed using an empirical smoothing algorithm. Doing so allows for the identification of deviations (i.e., local maxima) from monotonically increasing age-specific probabilities. RESULTS:In females (N = 199), there is a peak in the frequency of individuals with DISH around 60 years of age where 37.0% of the individuals have DISH. It is matched only by the frequency (38.7%) in the oldest females, those over 85 years old. In contrast, DISH frequencies for males (N = 217) increase monotonically with advancing age, reaching 62.5% in the ≥86 years age group. There was an association between DISH and high body weight in women, particularly those who died before they reached the age of 75. CONCLUSIONS:Early-onset DISH in white American women is associated with an increased risk of dying indicated by a local maximum in the probability curve. Should this finding be replicated in additional mortality samples and the reason DISH is associated with early death is established, beyond being heavy, this radiologically visible ossification of the spine could be a potential component of health-monitoring programs for middle-aged women

Not by the Book: Observations of Delayed Oviposition and Re-Colonization of Human Remains by Blow Flies

Postmortem interval estimations can be complicated by the inter-individual variation present in human decomposition. Forensic entomologists may especially face challenges interpreting arthropod evidence in scenarios that are not “by the book”, or that vary in unexpected ways. Therefore, it is important to report instances where blow fly colonization does not align with expected soft tissue decomposition as blow fly larvae are often used to produce a time of colonization (TOC) estimation to infer a minimum PMI. We followed the decomposition and blow fly activity of three human donors at the Anthropology Research Facility (University of Tennessee). Delayed oviposition occurred on one donor 115 d post-placement, whereas two donors experienced blow fly re-colonization after cessation of the consumption phase, one 22 d and one more than 200 d after blow fly larvae were last observed. A null hypothesis model tested whether the entomological TOC and anthropological total body score (TBS) estimations encompassed the time of placement (TOP) for each donor. While the null hypothesis was rejected for all TOC estimations, it could not be rejected for the TBS estimations. We discuss how the non-linear nature of human decomposition can pose challenges to interpreting blow fly evidence and suggest that forensic entomology practitioners should recognize these limitations in both research endeavors and applied casework

Soil elemental changes during human decomposition.

Mammalian decomposition provides pulses of organic matter to the local ecosystem creating ephemeral hotspots of nutrient cycling. While changes to soil biogeochemistry in these hotspots have been described for C and N, patterns associated with deposition and cycling of other elements have not received the same attention. The goal of our study was to evaluate temporal changes to a broad suite of dissolved elements in soils impacted by human decomposition on the soil surface including: 1) abundant mineral elements in the human body (K, Na, S, P, Ca, and Mg), 2) trace elements in the human body (Fe, Mn, Se, Zn, Cu, Co, and B), and 3) Al which is transient in the human body but common in soils. We performed a four-month human decomposition trial at the University of Tennessee Anthropology Research Facility and quantified elemental concentrations dissolved in the soil solution, targeting the mobile and bioavailable fraction. We identified three groups of elements based on their temporal patterns. Group 1 elements appeared to be cadaver-derived (Na, K, P, S) and their persistence in soil varied based upon soluble organic forms (P), the dynamics of the soil exchange complex (Na, K), and gradual releases attributable to microbial degradation (S). Group 2 elements (Ca, Mg, Mn, Se, B) included three elements that have greater concentrations in soil than would be expected based on cadaver inputs alone, suggesting that these elements partially originate from the soil exchange (Ca, Mg), or are solubilized as a result of soil acidification (Mn). Group 3 elements (Fe, Cu, Zn, Co, Al) increased late in the decomposition process, suggesting a gradual solubilization from soil minerals under acidic pH conditions. This work presents a detailed longitudinal characterization of changes in dissolved soil elements during human decomposition furthering our understanding of elemental deposition and cycling in these environments