Estimation and evidence in forensic anthropology: age-at-death

Development of a deep-learning algorithm for age estimation on CT images of the vertebral column

PURPOSE

The accurate age estimation of cadavers is essential for their identification. However, conventional methods fail to yield adequate age estimation especially in elderly cadavers. We developed a deep learning algorithm for age estimation on CT images of the vertebral column and checked its accuracy.

METHOD

For the development of our deep learning algorithm, we included 1,120 CT data of the vertebral column of 140 patients for each of 8 age decades. The deep learning model of regression analysis based on Visual Geometry Group-16 (VGG16) was improved in its estimation accuracy by bagging. To verify its accuracy, we applied our deep learning algorithm to estimate the age of 219 cadavers who had undergone postmortem CT (PMCT). The mean difference and the mean absolute error (MAE), the standard error of the estimate (SEE) between the known- and the estimated age, were calculated. Correlation analysis using the intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed to assess differences between the known- and the estimated age.

RESULTS

For the 219 cadavers, the mean difference between the known- and the estimated age was 0.30 years; it was 4.36 years for the MAE, and 5.48 years for the SEE. The ICC (2,1) was 0.96 (95 % confidence interval: 0.95-0.97, p < 0.001). Bland-Altman analysis showed that there were no proportional or fixed errors (p = 0.08 and 0.41).

CONCLUSIONS

Our deep learning algorithm for estimating the age of 219 cadavers on CT images of the vertebral column was more accurate than conventional methods and highly useful.

Estimating adult age categories in commingled skeletons with Transition Analysis 3

OBJECTIVES

We estimate adult age frequencies from Unar 1 and Unar 2, two late Umm an-Nar (2400-2100 BCE) tombs in the modern-day Emirate of Ras al-Khaimah, United Arab Emirates. These collective tombs each contained hundreds of skeletons in commingled, fragmented, and variably cremated states. Previous studies placed the vast majority of this mortuary community in a generalized "adult" category, as have most analyses of similar tombs from this period. We sought to test how adult age estimation methods compare in identifying young, middle, and old-age individuals in commingled assemblages.

MATERIALS AND METHODS

We employed Transition Analysis 3 (TA3) and traditional age estimation methods to generate adult age frequencies for each tomb. We compared these frequencies between tomb contexts as well as by method.

RESULTS

Unar 1 and Unar 2 had similar adult age frequencies within each method, but TA3 age frequencies included significantly more middle and older adult individuals than those generated by traditional methods.

DISCUSSION

These results support findings of earlier iterations of transition analysis in regard to sensitivity in old adult age estimation, compared with traditional methods. Our findings indicate a potential use of TA3 in reconstructing age frequencies and mortality profiles in commingled skeletal assemblages. Increasing our understanding of everyday life in the distant past necessitates better understandings of adult age, and here, we illustrate how age estimation method choice significantly changes bioarchaeological interpretations of aging in Bronze Age Arabia.

RESEARCH HIGHLIGHTS

Adult age estimation using TA3 revealed significantly more middle and older adults than traditional methods in two commingled tombs. Similar mean maximum likelihood point estimates by side and across skeletal elements were found between tombs.

Age estimation in the combined long bones and ribs by histomorphometry: Past, present, and future

Numerous age estimation methods in unidentified bone have been a long time developing for application in forensic anthropology. The histomorphometric technique is one of the alternative methods that relied upon the evaluation of the cortical bone microstructure over the lifespan as a result of the remodeling process in bone. Remodeling is a sophisticated event occurring from the coupled function of bone formation and resorption cells for maintaining mineral homeostasis and repairment of microdamage in bone tissue. Products derived from remodeling are primary changes in the osteon or haversian system in various regions in the cortical bone, including periosteum, endosteum, and trabecular bone. Throughout life, bone remodeling rate with osteon alteration can be predictable. In the forensic field, histological methods are getting more attention due to the unavailability of macroscopic methods. Histomorphometry approach can be accomplished in fragmentary or incomplete bone remains indicating the limited use of gross morphological methods. In addition, the microscopic methods can aid to increase the more accuracy of analyses and diminish the biased subjective assessment for determining age. Most histomorphometry method utilizes a cross-section of the midshaft of the long bones including the mandible, rib, and clavicle. This review provides the basic knowledge of bone biology and anatomy, several age-estimating methods of histology, and crucial factors for age methods. Studies regarding overall age determination methods from the past until now contribute to obtaining more benefits for developing methods of histomorphometry using human bone in forensic identification.

Age estimation from iliac auricular surface using Bayesian inference and principal component analysis: a CT-based study in an Indian population

Age estimation constitutes one of the pillars of human identification. The auricular surface of the ilium presents as a durable and robust structure within the human skeletal framework, capable of enabling accurate age estimation in older adults. Amongst different documented auricular age estimation methods, the Buckberry-Chamberlain method offers greater objectivity through its component-based approach. The present study aimed to test the applicability of the Buckberry-Chamberlain method in an Indian population through a CT-based examination of the auricular surface. CT scans of 435 participants undergoing CT examinations following the advice of their treating physicians were scrutinized for different age-related auricular changes. Three of the five morphological features described by Buckberry-Chamberlain could be appreciated on CT scans, and thus further statistical analysis was restricted to these features. Transition analysis coupled with Bayesian inference was undertaken individually for each feature to enable age estimation from individual features, while circumventing age mimicry. A Bayesian analysis of individual features yielded highest accuracy percentages (98.64%) and error rates (12.99 years) with macroporosity. Transverse organization and apical changes yielded accuracy percentages of 91.67% and 94.84%, respectively, with inaccuracy computations of 10.18 years and 11.74 years, respectively. Summary age models, i.e. multivariate age estimation models, derived by taking this differential accuracy and inaccuracy into consideration yielded a reduced inaccuracy value of 8.52 years. While Bayesian analysis undertaken within the present study enables age estimation from individual morphological features, summary age models appropriately weigh all appreciable features to yield more accurate and reliable estimates of age.

Mixed cumulative probit: a multivariate generalization of transition analysis that accommodates variation in the shape, spread and structure of data

Biological data are frequently nonlinear, heteroscedastic and conditionally dependent, and often researchers deal with missing data. To account for characteristics common in biological data in one algorithm, we developed the mixed cumulative probit (MCP), a novel latent trait model that is a formal generalization of the cumulative probit model usually used in transition analysis. Specifically, the MCP accommodates heteroscedasticity, mixtures of ordinal and continuous variables, missing values, conditional dependence and alternative specifications of the mean response and noise response. Cross-validation selects the best model parameters (mean response and the noise response for simple models, as well as conditional dependence for multivariate models), and the Kullback-Leibler divergence evaluates information gain during posterior inference to quantify mis-specified models (conditionally dependent versus conditionally independent). Two continuous and four ordinal skeletal and dental variables collected from 1296 individuals (aged birth to 22 years) from the Subadult Virtual Anthropology Database are used to introduce and demonstrate the algorithm. In addition to describing the features of the MCP, we provide material to help fit novel datasets using the MCP. The flexible, general formulation with model selection provides a process to robustly identify the modelling assumptions that are best suited for the data at hand.

Forensic age estimation in males by MRI based on the medial epiphysis of the clavicle

Increasing cross-border migration has brought forensic age assessment into focus in recent decades. Forensic age estimation is based on the three pillars: physical and medical constitution, bone age, and tooth age. Part of the bone age examination includes the assessment of the medial end of the clavicles when the hand bones are already fully developed and a minority must be excluded. Recent research has brought MRI to the forefront as a radiation-free alternative for age assessment. However, there exits only a few studies with large sample size regarding the clavicles and with controversies about staging, motion artifacts, and exclusion based on anatomic norm variants. In the current prospective study, 338 central European male individuals between 13 and 24 years of age underwent MRI examination of the sternoclavicular region. Development was assessed by three blinded raters according to the staging system described by Schmeling et al. and Kellinghaus et al. and related to age by descriptive statistics and transition analyses with a cumulative probit model. In addition, reliability calculations were performed. No statistically significant developmental difference was found between the left and right clavicles. Inter-rater agreement was only moderate, but intra-rater agreement, on the other hand, was good. Stage 3c had a minimum age of 19.36 years and appears to be a good indicator of proof of majority. The minimum age of stage 4 was lower compared with other studies, 20.18 years, and therefore seems not to be an indicator of age of 21 years. In conclusion, we confirmed the value of clavicular MRI in the age estimation process. The transition analysis model is a good approach to circumvent the problems of age mimicry and samples that are not fully equilibrated. Given the moderate agreement between raters, a consensus reading is recommended.

Paleodemography: From archaeology and skeletal age estimation to life in the past

Much of paleodemography, an interdisciplinary field with strong ties to archaeology, among other disciplines, is oriented toward clarifying the life experiences of past people and why they changed over time. We focus on how human skeletons contribute to our understanding of preindustrial demographic regimes, including when changes took place that led to the world as we know it today. Problems with existing paleodemographic practices are highlighted, as are promising directions for future work. The latter requires both better age estimates and innovative methods to handle data appropriately. Age-at-death estimates for adult skeletons are a particular problem, especially for adults over 50 years that undoubtedly are mistakenly underrepresented in published studies of archaeological skeletons. Better age estimates for the entirety of the lifespan are essential to generate realistic distributions of age at death. There are currently encouraging signs that after about a half-century of intensive, and sometimes contentious, research, paleodemography is poised to contribute much to understandings of evolutionary processes, the structure of past populations, and human-disease interaction, among other topics.

DXAGE 2.0 - adult age at death estimation using bone loss in the proximal femur and the second metacarpal

The accurate age at death assessment of unidentified adult skeletal individuals is a critical research task in forensic anthropology, being a key feature for the determination of biological profiles of individual skeletal remains. We have previously shown that the age-related decrease of bone mineral density (BMD) in the proximal femur could be used to assess age at death in women (Navega et al., J Forensic Sci 63:497-503, 2018). The present study aims to generate models for age estimation in both sexes through bone densitometry of the femur and radiogrammetry of the second metacarpal. The training sample comprised 224 adults (120 females, 104 males) from the "Coimbra Identified Skeletal Collection," and different models were generated through least squares regression and general regression neural networks (GRNN). The models were operationalized in a user-friendly online interface at https://osteomics.com/DXAGE2/ . The mean absolute difference between the known and estimated age at death ranges from 9.39 to 13.18 years among women and from 10.33 to 15.76 among men with the least squares regression models. For the GRNN models, the mean absolute difference between documented and projected age ranges from 8.44 to 12.58 years in women and from 10.56 to 16.18 years in men. DXAGE 2.0 enables age estimation in incomplete and/or fragmentary skeletal remains, using alternative skeletal regions, with reliable results.

Adult Skeletal Age-at-Death Estimation through Deep Random Neural Networks: A New Method and Its Computational Analysis

Age-at-death assessment is a crucial step in the identification process of skeletal human remains. Nonetheless, in adult individuals this task is particularly difficult to achieve with reasonable accuracy due to high variability in the senescence processes. To improve the accuracy of age-at-estimation, in this work we propose a new method based on a multifactorial macroscopic analysis and deep random neural network models. A sample of 500 identified skeletons was used to establish a reference dataset (age-at-death: 19–101 years old, 250 males and 250 females). A total of 64 skeletal traits are covered in the proposed macroscopic technique. Age-at-death estimation is tackled from a function approximation perspective and a regression approach is used to infer both point and prediction interval estimates. Based on cross-validation and computational experiments, our results demonstrate that age estimation from skeletal remains can be accurately (~6 years mean absolute error) inferred across the entire adult age span and informative estimates and prediction intervals can be obtained for the elderly population. A novel software tool, DRNNAGE, was made available to the community.

Validation of a post-mortem computed tomography method for age estimation based on the 4th rib in a French population

Age estimation is a key factor for identification procedure in forensic context. Based on anthropological findings, degenerative changes of the sternal extremity of the 4th rib are currently used for age estimation. These have been adapted to post-mortem computed tomography (PMCT). The aim of this study was to validate a post-mortem computed tomography method based on a revision of the Iscan's method on a French sample. A total of 250 PMCT (aged from 18-98 years (IQR 36-68 years, median 51 years); 68 (27%) females) from the Medicolegal Institute of Paris (MLIP) were analyzed by two radiologists. The sternal extremity of 4th right rib was scored using method adapted from Iscan et al. Weighted κ was used to evaluate intra- and inter-observer reliability and Spearman correlation was performed to evaluate relationship between age and score. Confidence intervals for individual prediction of age based on 4th rib score and sex were computed with bootstrapping. The intra-observer reliability and inter-observer reliability were almost perfect (weighted κ = 0.85 [95%CI: 0.78-0.93] and 0.82 [95%CI 0.70-0.96] respectively). We confirmed a high correlation between the 4th rib score and subject age (rho = 0.72, p < 0.001), although the confidence intervals for individual age prediction were large, spanning over several decades. This study confirms the high reliability of Iscan method applied to PMCT for age estimation, although future multimodal age prediction techniques may help reducing the span of confidence intervals for individual age estimation.Trial registration: INDS 0,509,211,020, October 2020, retrospectively registered.

Contribution of the use of clavicle bone density in age estimation

Age estimation is an essential element in the field of forensics and is also of judicial interest in forensic medicine of the living. Despite all the methods, age estimation is often imprecise with many biases, especially in mature individuals. The main objective of our study is to assess the correlation between age and computed tomography bone mineral density of the medial end of the clavicle. A sample of 180 chest multi-slice computed tomography scans without contrast injection performed in living individuals, with suspected respiratory infection, aged 15 to 100 years was used. Bone density measurement was performed on the medial meta-epiphyseal region of the clavicles. A significant negative correlation was found between bone density and age of individuals (p-value < 0.05). The mean absolute error was calculated for men at 13.4 years and 13.1 years for women, which was associated with an absence of bias. Good precision of the estimate for both sexes was also calculated on a subgroup of individuals whose age was greater than 40 years, with average absolute errors of about 12 years, which was associated with an absence of relative error. In view of our preliminary results, the study of bone density of the medial end of the clavicle could be of interest in the estimation of age. Several studies will be necessary to evaluate the reproducibility of these results on independent bone samples and in the estimation of age in the living individual.

Performance of three mathematical models for estimating age-at-death from multiple indicators of the adult skeleton

The mathematical method which will achieve the most accurate and precise age-at-death estimate from the adult skeleton is often debated. Some research promotes Bayesian analysis, which is widely considered better suited to the data construct of adult age-at-death distributions. Other research indicates that methods with less mathematical complexity produce equally accurate and precise age-at-death estimates. One of the advantages of Bayesian analysis is the ability to systematically combine multiple indicators, which is reported to improve the age-at-death estimate. Few comparisons exist between Bayesian analysis and less complex mathematical models when considering multiple skeletal indicators. This study aims to evaluate the performance of a Bayesian approach compared to a phase-based averaging method and linear regression analysis using multiple skeletal indicators. The three combination methods were constructed from age-at-death data collected from 330 adult skeletons contained in the Raymond A Dart and Pretoria Bone Collections in South Africa. These methods were tested and compared using a hold-out sample of 30 skeletons. As is frequently reported in literature, a balance between accuracy and precision was difficult to obtain from the three selected methods. However, the averaging and regression analysis methods outperformed the Bayesian approach in both accuracy and precision. Nevertheless, each method may be suited to its own unique situation-averaging to inform first impressions, multiple linear regression to achieve statistically defensible accuracies and precisions and Bayesian analysis to allow for cases where category adjustments or missing indicators are necessary.

Metric forensic anthropology decisions: Reliability and biasability of sectioning-point-based sex estimates

Subjective decisions make human cognitive processes more susceptible to bias and error. Specifically, research indicates that additional context biases forensic anthropologists' morphological analyses. To address whether metric analyses are also subject to bias, we conducted a pilot study in which 52 experienced osteologists measured a difficult-to-classify human femur, with or without additional contextual information. Using a metric sectioning-point sex-estimation method, participants provided a sex estimate for individual skeletal element(s) and, when given multiple elements, the combined skeletal assemblage. Control group participants (n = 24) measured only the femur. In addition to the femur, bias group participants (n = 28) either measured a female humerus and viewed a female-biasing photograph (n = 14) or measured a male humerus and viewed a male-biasing photograph (n = 14). We explored whether the experts in the different groups would differ in: (1) femoral measurements; (2) femoral sex-estimation conclusions; and (3) final sex-estimation conclusions for the skeletal assemblage. Although the femoral measurements and femoral sex estimates were comparable across groups, the overall sex estimates in the female-biased group were impacted by contextual information-differing from both the control and male-biased groups (p < 0.001). Our results demonstrate that cognitive bias can occur even in metric sex-estimation conclusions. Specifically, this occurred when the metric data and single-element sex estimates were synthesized into an overall estimate. Thus, our results suggest that metric methods are most vulnerable to bias when data are synthesized into an overall conclusion, highlighting the need for bias countermeasures and comprehensive statistical frameworks for synthesizing metric data to mitigate the effects of cognitive bias.

The accuracy and reliability of the Suchey-Brooks pubic symphysis age estimation method: Systematic review and meta-analysis

Suchey-Brooks method has been studied many times with varying reports of accuracy and reliability. A systematic review and meta-analyses were utilized to quantitatively determine the accuracy and reliability of the Suchey-Brooks (S-B) method. A systematic search of PubMed and EBSCO health and medical databases was performed. Meta-analyses were performed to quantify the relationship between actual known age at death and the S-B method using Spearman's Rho and Pearson's r for (1) combined males and females estimates, (2) male-only estimates, and (3) female-only estimates. Overall correlation coefficient using Cohen's kappa, Spearman's Rho, and Pearson's r was also calculated to determine the interrater and intrarater reliability using the S-B method. Eighteen studies classified as moderate-to-high methodological quality met the inclusion criteria. The sample sizes were different for the combined male and female (n = 2620), male-only (n = 2602), and female-only (n = 1431) meta-analyses. The effect size of the age at death meta-analyses was large and significant for combined males and females (Spearman's Rho = 0.62; Pearson's r = 0.65), male-only (Spearman's Rho = 0.77; Pearson's r = 0.75), and female-only (Spearman's Rho = 0.71; Pearson's r = 0.71). The overall correlation coefficients of the interrater (Kappa = 0.76; Spearman's Rho = 0.73; Pearson's r = 0.80) and intrarater (Kappa = 0.81; Spearman's Rho = 0.91; Pearson's r = 0.83) reliability meta-analyses were large and significant. A significant degree of heterogeneity was present in all meta-analyses, with minimal evidence of publication bias. The meta-analyses results suggest the S-B method is highly reliable with a moderate-to-high degree of accuracy. Our results also identified sample size and accuracy differences between male and female individuals.

Age estimation based on computed tomography exploration: a combined method

Despite an extensive number of existing methods, age estimation of human remains is still an unsolved matter in the field of forensic anthropology, especially when it comes to mature adults. The specific aim of this work was to propose a combined method for age estimation, for forensic purposes, by coupling the Suchey-Brooks method and the measure of the pubic bone density. For this purpose, we used an independent test sample comprising 339 CT scans of living individuals aged 15 to 99 years old. Measurement of bone density and staging according to the Suchey-Brooks phases were performed, followed by estimation of ages based on a combined method and an existing virtual reference sample. Results highlighted a significant negative correlation between bone density and age. Good accuracy was obtained for the measurement of pubic bone density for age estimation of men and women, especially concerning mature adults, with an absolute error ranging from 9 to 16 years for all individuals. The authors propose a practical combined method consisting of, first, allocating phases according to the scannographic approach of the Suchey-Brooks method. For phases I to IV, the age estimation is given using the Suchey-Brooks method. For phases V to VI, the pubic bone density measurement is used. Further study will be needed to assess the reproducibility of these results on cadavers and dry bones, as the post-mortem process could interfere with the measurement of mineral bone density.

An epidemiological approach to the analysis of cribra orbitalia as an indicator of health status and mortality in medieval and post-medieval London under a model of parasitic infection

OBJECTIVES

Many individuals living in medieval and post-medieval London suffered issues with sanitation, food insecurity, infectious disease, and widespread exposure to parasites from a multitude of sources, causing increased risk of death for many inhabitants. We examine this stressful environment and its relationship with various demographic and temporal dimensions, using cribra orbitalia (CO) as an indicator of stress, to model an increased risk of dying under the expectations of our proposed parasitic model of infection.

MATERIALS AND METHODS

We analyze the relationship between CO and mortality across seven medieval and post-medieval cemeteries from London by the covariates of sex, status, and age-at-death. A survival analysis (Cox regression) and a binomial logit estimated hazard and odds ratios of dying with CO across age-at-death, sex, status, and time-period within single statistical models. In addition, we provide new Bayesian age-at-death estimates for post-medieval samples.

RESULTS

The models show the rate of CO decreased over time and age-at-death, regardless of sex or status; post-medieval individuals were ~72% less likely to die with lesions than their medieval counterparts. Further, individuals with CO had ~1% decrease in risk of dying with CO per year of age.

DISCUSSION

These results suggest increased mortality risk for those with lesions indicative of anemia (CO), and selective mortality of younger individuals during the medieval period. Despite sex-specific nutritional and occupational hazards, and status-based access to resources, the prevalence of CO was similar across sex and status, which suggests living with parasitic infection that caused anemia was an everyday reality for medieval and post-medieval Londoners.

Bone age estimation with the Greulich-Pyle atlas using 3T MR images of hand and wrist

The age estimation of the hand bones by means of X-ray examination is a pillar of the forensic age estimation. Since the associated radiation exposure is controversial, the search for ionizing radiation-free alternatives such as MRI is part of forensic research. The aim of the current study was to use the Greulich-Pyle (GP) atlas on MR images of the hand and wrist to provide reference values for assessing the age of the hand bones. 3T hand MR images of 238 male participants between the ages of 13 and 21 were acquired using 3D gradient echo sequences (VIBE, DESS). Two readers rated the images using the X-ray-based GP atlas method. A descriptive analysis and a transitional analysis were used for the statistical processing of the data. The agreement between and within the raters was assessed. In addition, a comparison was made with the chronological age and with X-ray studies. The descriptive analysis and the transition analysis showed similar results. Both evaluations showed good agreement with X-ray studies. The comparison with the chronological age showed a difference of 0.37 and 0.54 years for the two readers. The age estimate based on the cross-validated transition analysis showed a mean error of -0.28 years. Inter- and intra-rater agreement were good. In summary, it can be concluded that age estimation of hand bones with MR images is routinely applicable with the GP atlas as an alternative without ionizing radiation. However, in order to reduce the estimation error, a multi-factorial assessment based on examinations of several body regions is still recommended.

Strengthening the role of forensic anthropology in personal identification: Position statement by the Board of the Forensic Anthropology Society of Europe (FASE)

In this position statement, the Board members of the Forensic Anthropology Society of Europe (FASE) argue that forensic anthropology methods can be used as means of personal identification, particularly in situations with limited availability of traditional identification methods (i.e. dactyloscopy, odontology, and molecular genetic analysis). This statement has been issued taking into account the international migration crises related to thousands of deaths worldwide, in which the utility of these traditional means of identification has been sporadic to non-existent. The statement is however not limited to deaths related to the migration crises, as similar problems may occur in fatalities en masse such as in natural disasters and armed conflicts, and on a smaller scale in cases of homeless or otherwise socioeconomically disadvantaged persons. The number of reports on personal identification based on sound anthropological methodology is increasing in the scientific literature. However, more research is needed to develop evidence-based standard operating procedures and statistical frameworks. It remains essential to raise awareness among forensic practitioners, law enforcement, and judiciary professionals on the utility of forensic anthropology in cases where it can provide sufficient information for identification.

Technical note: age estimation by using pubic bone densitometry according to a twofold mode of CT measurement

In forensic anthropology, age estimation is a major element in the determination of a biological profile and the identification of individuals. Thus, many anatomical structures have been studied, such as the pubic symphysis, which is a source of major interest due to its late maturation. One of the most well-known methods of assessment is the Suchey-Brooks (SB) system based on the morphological characteristics of the pubic symphysis. The aim of this study was to propose linear regression formulae in order to deduce chronological age from bone density, using both Hounsfield unit (HU), and mean bone density (mBD) values of the pubic symphysis. Moreover, we intended to test the reliability and then to explore the feasibility of using HU instead of mBD values for age estimation. We built retrospectively a reference sample of 400 pubic symphyses using computed tomography at a French hospital and a test sample of 120 pubic symphyses. Equations were created to establish linear regression models for age estimation. Inaccuracy and bias were calculated for individuals aged more or less than 40 years. We highlighted homogeneous mean absolute errors for both HU and mBD values, most of them being less than 10 years. Moreover, we reported a moderate overestimation for younger individuals and a very small underestimation for older individuals. This study proposes a correlation between the bone density and age of individuals with a valuable level of reliability. Finally, HU measurements seem to be suitable for linking bone density with the age of individuals in forensic practice.

Survival analysis of the Black Death: Social inequality of women and the perils of life and death in Medieval London

OBJECTIVES

Described as an indiscriminate killer by many chroniclers, the Black Death descended on London during the 14th century. To best understand the pattern of transmission among demographic groups, models should include multiple demographic and health covariates concurrently, something rarely done when examining Black Death, but implemented in this study to identify which demographic groups had a higher susceptibility. Female predisposition to the Black Death was also explored, focusing on whether social inequality added to vulnerability.

MATERIALS AND METHODS

Three attritional cemeteries from the Wellcome Osteological Research Database were compared with the Black Death cemetery, East Smithfield. A Cox proportional hazards regression estimated hazards ratios of dying of the Black Death, using transition analysis ages-at-death as the time variable, and sex and frailty as covariates. Additionally, a binomial logistic regression generated odds ratios for age-at-death, sex, and frailty.

RESULTS

The Cox model produced a significant hazards ratio for individuals deemed frail. Similarly, the logit model calculated significantly increased odds ratios for frail individuals, and decreased odds for individuals aged 65+.

DISCUSSION

The older individuals were not undergoing growth during times of great stress in London pre-dating the Black Death epidemic, which may explain the decreased odds of contracting the Black Death. Further, although women dealt with social inequality, which partially led to the demographic puzzle of the Medieval "missing" women, women's susceptibility to infection by the Black Death was not increased. The phenomenon of the missing women may be due to a combination of factors, including infant and child mortality and preservation.

Bone histomorphometry of the clavicle in a forensic sample from Albania

Forensic assessment of skeletal material includes age estimation of unknown individuals. When dealing with extremely fragmented human remains that lack macro-features used in age estimation, histological assessment of the skeletal elements can be employed. Historically, microscopic methods for age assessment used by forensic anthropologists have been available since 1965. Several skeletal elements have been used for this purpose. Among them, the clavicle has garnered very little attention. The purpose of this study is to explore the validity of clavicular histomorphometry as an age marker in a modern Balkan sample. This study examined a modern clavicular autopsy sample from Albania. The sample consisted of 33 individuals of known age and cause of death. Data were collected for micro-anatomical features including osteon population density (OPD) and cortical area. Intra- and inter-observer errors were assessed through technical error of measurement (TEM) and R coefficient. A validation study was performed in order to test the accuracy of existing histological formulae. Regression analysis was run to developed age prediction models with the best models tested through cross-validation and the comparison between OPD for the Albanian sample and a European-American sample examined. Intra- and inter-observer error TEM results demonstrated values falling within the limits of acceptance. The existing histological methods did not perform accurately on the sample under study. Regression equations for Albanians produced age estimations deviating 8 and 11 years from known age. Cross-validation on the most accurate regression formula which includes OPD as a single variable demonstrated similar mean errors. Statistically significant differences were observed between the Albanian and the European-American population when the two samples were compared. The research presented is the fifth article published and the fifth population explored on clavicular microstructure. The potential of histology to estimate age on the Albanian population is shown here; however, population effect, diet and health status might be considered. Further inclusion of individuals will corroborate our preliminary findings.

Cranial suture closure as an age indicator: A review

Cranial suture closure has been recognized for over a century as a useful trait for age estimation. Although this indicator has become a standard feature of age assessment protocols in skeletal remains, serious questions have been raised about its reliability. This article attempts to provide a comprehensive review of cranial suture closure as an age indicator from several perspectives, including its anatomy and history, as well as issues relating to validation, statistics, and the potential of technological advancements to improve outcomes. We further suggest a path forward for the use of cranial suture closure as an estimator of age. Although its unreliability has been widely reported, cranial suture closure still appears to have value as an aging method, and it is hoped that the information contained in this article can serve as a stepping stone toward more effective use of this indicator. The cranium is often more durable than other skeletal elements in both archaeological and forensic circumstances, so maximizing the effectiveness of cranial indicators is an important goal. It is hoped that recent advancements in technology and in analytical approaches to the cranial sutures could breathe some new life into this feature as an indicator of age.

A Review of Bomb Pulse Dating and its Use in the Investigation of Unidentified Human Remains

In cases where there is limited antemortem information, the examination of unidentified human remains as part of the investigation of long-term missing person's cases is a complex endeavor and consequently requires a multidisciplinary approach. Bomb pulse dating, which involves the analysis and interpretation of 14C concentration, is one technique that may assist in these investigations by providing an estimate of year of birth and year of death. This review examines the technique of bomb pulse dating and its use in the identification of differentially preserved unknown human remains. Research and case studies implementing bomb pulse dating have predominantly been undertaken in the Northern Hemisphere and have demonstrated reliable and accurate results. Limitations were, however, identified throughout the literature. These included the small sample sizes used in previous research/case studies which impacted on the statistical significance of the findings, as well as technique-specific issues. Such limitations highlight the need for future research.

Evaluation of the Enhanced Computational Methods of Estimating Age-at-Death Using the Pubic Symphyses of a White South African Population

To address problems of reproducibility related to current age estimation methods, the enhanced computational Methods (ECM) were previously developed using a sample of white North American male pubic symphyses and showed promise in improving current techniques. However, given the evidence of sex and population differences in the onset of age markers, this study set out to test the ECM on a white South African sample. The sample consisted of 184 well-preserved os coxae from individuals of known age and sex. Pubic symphyseal surfaces were scanned using the Artec Spider 3D scanner, processed using Artec Studio 10 and analyzed using forAge. Point estimates of age were then compared to the true age of each individual. Results indicate that the ECM performed poorly in a white South African population, with consistent underestimation of age-at-death and weak positive correlations with true age. Despite the low correlations, the ECM did, however, reduce observer error.

Age estimation in forensic anthropology: methodological considerations about the validation studies of prediction models

There is currently no clear consensus on how to calculate, express, and interpret the error when validating methods for age estimation in forensic anthropology. For this reason, it is likely that researchers are commonly drawing erroneous or confusing conclusions about the existence of population differences or the need to design new and increasingly complex estimation methods. In recent years, many researchers have highlighted these limitations. They propose new lines of research focused on the use of rigorous statistics and new technologies for the development of methods for estimating age. Our main objective in this study is to contribute to the strengthening of these novel ideas, for which we show the existing empirical evidence about the inadequacy of some age estimation methods in calculating, expressing, and interpreting the errors obtained. With this aim, a total of 500 simulations have been performed, in which hypothetical research teams develop and validate methods for age estimation. The data employed in this study was obtained from the "Centers for Disease Control and Prevention (CDC) Growth Charts: United States" released in 2000. The charts relate age with height, weight, and head circumference of US male children. Five learning algorithms have been employed as age estimators. We have performed three experiments in which the following aspects have been analyzed: frequency with which "negative" results can be obtained in the validation studies; which are the most appropriate criteria to compare and select the age estimation methods; and what analysis should be employed to carry out the validation studies. The results show possible errors in the interpretation of validation studies as a consequence of the confusion of statistical concepts. To conclude, we made a proposal of "good practices" for the correct calculation, expression, and interpretation of the error when validating age estimation methods in forensic anthropology.

Correlation between pubic bone mineral density and age from a computed tomography sample

In forensic anthropology, the estimation of age at death is mainly required to establish a biological profile and facilitate individual identification. The Suchey-Brooks (SB) system represents one of the most commonly used and tested methods of assessment based on the morphological characteristics of the pubic symphysis. However, this method has certain drawbacks, including frequently inaccurate estimation for older individuals. The aim of this work was to test the evolution of pubic bone mineral density (BMD) according to age, especially for individuals over 40 years old. We retrospectively studied pubic bones from males (n = 88) and females (n = 113) over 40 years of age undergoing clinical multi-slice computed tomography (MSCT) in a French hospital between November 2017 and April 2018. The results revealed a significant negative correlation between BMD and age for males (R = -0.62) and females (R = -0.55). The intra- and inter-observer reliabilities of the phase allocation were moderate for males (kappa values at 0.72 and 0.65) and strong for females (kappa values at 0.93 and 0.86). Moreover, a significant difference in BMD between stages 6-1 and 6-2 for males was observed. We hypothesize that BMD might help improve the reliability of the SB system for older individuals. In addition to the pubic bone, numerous other anatomical regions such as the area of Ward could represent interesting areas of study in order to relate bone density to age.

Age estimation using bone mineral density in South Africans

The use of bone mineral density (BMD) to predict age-at-death in skeletal remains provides a usable alternative to other methods because the values obtained are not observer-dependent. The aim of this study was to investigate the usability of BMD to estimate age in South African populations, and to assess inter-population variation and sex-specific differences in BMD values from the proximal end of the femur. In order to estimate age, regression analysis was done for the construction of population dependent formulae. The sample comprised of a total of 123 femora of black and white South Africans. DXA scans were performed using the Hologic Discovery system. Data analysis was done by employing independent-samples t-tests and correlation/regression analyses. The results indicated a statistically significant difference between black and white South Africans. Male groups were also significantly different from one another, but black and white females showed no significant differences. Linear regression analysis revealed a significant correlation between BMD values and age for the white population and the combined sample, but not for the black population. Bootstrapping were employed to confirm validity of the results. In conclusion, this study showed that the use of DXA measurements of the femur for estimating age may be used for the estimation of age-at-death in white South Africans, but more research is needed to better understand the relationship between bone mineral density and age in black South Africans.

Age assessment by Demirjian's development stages of the third molar: a systematic review

OBJECTIVES

Radiographic evaluation of the wisdom teeth (third molar) formation is a widely used age assessment method for adolescents and young adults. This systematic review examines evidence on the agreement between Demirjian's development stages of the third molar and chronological age.

METHODS

We searched four databases up until May 2016 for studies reporting Demirjian's stages of third molar and confirmed chronological age of healthy individuals aged 10-25 years. Heterogeneity test of the included studies was performed.

RESULTS

We included 21 studies from all continents except Australia, all published after 2005. The mean chronological age for Demirjian's stages varied considerably between studies. The results from most studies were affected by age mimicry bias. Only a few of the studies based their results on an unbiased age structure, which we argue as important to provide an adequate description of the method's ability to estimate age.

CONCLUSION

Observed study variation in the timing of Demirjian's development stages for third molars has often been interpreted as differences between populations and ethnicities. However, we consider age mimicry to be a dominant bias in these studies. Hence, the scientific evidence is insufficient to conclude whether such differences exist.

KEY POINTS

• There is significant heterogeneity between studies evaluating age assessment by Demirjian's third molar development. • Most of the studies were subject to the selection bias age mimicry which can be a source of heterogeneity. • Presence of age mimicry bias makes it impossible to compare and combine results. These biased studies should not be applied as reference studies for age assessment.

A Study on the Asymmetry of the Human Left and Right Pubic Symphyseal Surfaces Using High-Definition Data Capture and Computational Shape Methods

The pubic symphysis is among the most commonly used bilateral age indicators. Because of potential differences between right and left sides, it is necessary to investigate within-individual asymmetry, which can inflate age estimation error. This study uses 3D laser scans of paired pubic symphyses for 88 documented White males. Scan data are analyzed by numerical shape algorithms, proposed as an alternative to traditional visual assessment techniques. Results are used to quantify the within-individual asymmetry, evaluating if one side produces a better age-estimate. Relationships between the asymmetry and advanced age, weight, and stature are examined. This analysis indicates that the computational, shape-based techniques are robust to asymmetry (>80% of paired differences are within 10 years and >90% are within 15 years). For notably more asymmetric cases, differences in estimates are not associated with life history factors. Based on this study, either side can be used for age-at-death estimation by the computational methods.