Spheno-occipital synchondrosis fusion in modern Americans

This study examines spheno-occipital synchondrosis fusion in the modern American population and presents age ranges for forensic use. The sample includes 162 modern individuals aged 5-25 years. The basilar synchondrosis was scored as open, closing, or closed via direct inspection of the ectocranial site of the suture. Transition analysis was used to determine the average ages at which an individual transitions from unfused to fusing and from fusing to fused. The maximum likelihood estimates from the transition analysis indicate that females are most likely to transition from open to closing at 11.4 years and males at 16.5 years. Females transition from closing to closed at 13.7 years and males at 17.4 years. The probability distributions associated with these maximum likelihood estimates were used to derive age ranges for age estimation purposes. These results reflect sexual dimorphism in basilar synchondrosis fusion and agree approximately with average age at pubertal onset.     

A Bayesian Approach to Age Estimation in Modern Americans from the Clavicle*

Abstract: Clavicles from 1289 individuals from cohorts spanning the 20th century were scored with two scoring systems. Transition analysis and Bayesian statistics were used to obtain robust age ranges that are less sensitive to the effects of age mimicry and developmental outliers than age ranges obtained using a percentile approach. Observer error tests showed that a simple three‐phase scoring system proved the least subjective, while retaining accuracy levels. Additionally, significant sexual dimorphism was detected in the onset of fusion, with women commencing fusion at least a year earlier than men (women transition to fusion at approximately 15 years of age and men at 16 years). Significant secular trends were apparent in the onset of skeletal maturation, with modern Americans transitioning to fusion approximately 4 years earlier than early 20th century Americans and 3.5 years earlier than Korean War era Americans. These results underscore the importance of using modern standards to estimate age in modern individuals.     

Thyroid Cartilage Ossification and Multislice Computed Tomography Examination: A Useful Tool for Age Assessment?

Abstract: Many authors have studied the thyroid cartilage ossification process using radiographic features for age estimation of individuals. Their results were various: Sugiyama reported excellent correlation coefficients between ossification rates and civil age, unlike most other authors. We hypothesized that recent advances in imaging techniques would enable more precise evaluation of the ossification of the thyroid cartilage. We retrospectively analyzed the CT scans of 312 French patients using postprocessing software to examine the pattern of thyroid cartilage ossification, calculating the ossified volume of the cartilage on 3D reconstructions. Pearson’s correlation coefficients for volume were 0.73 for men and 0.75 for women (standard error 18.02 and 17.06), indicating considerable inter‐individual variability. Although a correlation between civil age and morphological changes was found, these methods based on thyroid cartilage ossification were not accurate enough for the assessment of individual age.     

A Bayesian approach to estimate skeletal age-at-death utilizing dental wear

In the forensic context, teeth are often recovered in mass disasters, armed conflicts, and mass graves associated with human rights violations. Therefore, for victim identification, techniques utilizing the dentition to estimate the first parameters of identity (e.g., age) can be critical. This analysis was undertaken to apply a Bayesian statistical method, transition analysis, based on the Gompertz-Makeham (GM) hazard model, to estimate individual ages-at-death for Balkan populations utilizing dental wear. Dental wear phases were scored following Smith's eight-phase ordinal scoring method and chart. To estimate age, probability density functions for the posterior distributions of age for each tooth phase are calculated. Transition analysis was utilized to generate a mean age-of-transition from one dental wear phase to the next. The age estimates are based on the calculated age distribution from the GM hazard analysis and the ages-of-transition. To estimate the age-at-death for an individual, the highest posterior density region for each phase is calculated. By using a Bayesian statistical approach to estimate age, the population's age distribution is taken into account. Therefore, the age estimates are reliable for the Balkan populations, regardless of population or sex differences. The results showed that a vast amount of interpersonal variation in dental wear exists within the current sample and that this method may be most useful for classifying unknown individuals into broad age cohorts rather than small age ranges.     

Application of the Iscan method to two- and three-dimensional imaging of the sternal end of the right fourth rib

Age determination is a major field of interest in physical and forensic anthropology. Among the different methods based on macroscopic skeletal study, the Iscan method, which analyzes the sternal end of the right fourth rib, is one of the most reliable. We applied the Iscan method to two- and three-dimensional multislice computed tomography (MSCT) reconstructions of the sternal end of the right fourth rib on 39 ribs. The intra-observer variability on MSCT reconstructions was good (gamma coefficient equal to 0.86; value of the Krippendorff's alpha reliability equal to 0.79); inter-observer variability on MSCT reconstructions was also good (gamma coefficient ranging from 0.82 to 0.88; value of the Krippendorff's alpha reliability ranging from 0.78 to 0.86). We demonstrated excellent agreement between the results of analysis of bone samples and those of the two- and three-dimensional images, in particular regarding bone projections, morphology of the pit and of its rim. The accuracy of age estimation did not significantly differ between the Iscan method applied to dry bones and the same method applied to MSCT images. Determination of the Krippendorff's alpha reliability coefficient for the inter-error method confirmed the agreement between phase estimations obtained with the two methods (ranging from 0.55 to 0.71). The real civil age was comprised in 21 cases out of 36 for assessment performed on dry bones and in 23 cases out of 36 on MSCT reconstructions, which represented 58.3% and 63.9%, respectively. Use of MSCT reconstructions in forensic anthropology offers many advantages: no bone preparation, no damage to bone material, and the possibility of application to living individuals.     

Ossification of laryngeal structures as indicators of age

As the role of forensic anthropologists expands to the medical examiner setting, their expertise is being applied beyond the traditional dry skeletal material. In such scenarios radiographic techniques can be applied when maceration is not appropriate. This study explores the use of radiographic analysis of laryngeal structures for age-at-death determination. Isolated human laryngeal structures (n = 104) from individuals between the ages of 15 and 89 were removed at autopsy and radiographically examined. The cricoid and individual regions of the thyroid cartilage were scored according to degree of ossification, and the relationship between age and degree of ossification statistically examined. A previously published study on age-determination from thyroid ossification by Cerny was assessed for accuracy. The results of the study indicate that although a consistent sequence in the ossification of laryngeal structures exists, variations in timing does not permit narrow age range estimates. Consequently the method presented by Cerny is inaccurate and should not be used in the forensic setting.     

Utility of the Frontonasal Suture for Estimating Age at Death in Human Skeletal Remains*

Abstract: This project evaluated the utility of the frontonasal suture for estimating age at death. Utilizing human remains of known age at death with varying degrees of fusion, curated at the American Museum of Natural History in New York City and the Smithsonian Institution’s National Museum of Natural History in Washington, DC, data were collected from the ectocranial surface of 522 crania; 68 of these were sagittally sectioned, allowing collection of internal data and observation of suture closure through the bone. Degree of ectocranial suture closure does not significantly predict age, even when sex and ancestry are accounted for. Suture closure progression data were converted into a Hershkovitz ratio (sum of the measurement of open portion divided by the total suture length), and regression models demonstrate that the effect of age accounts for only 13% of variation in suture closure.     

Age at Death Estimation Using Multislice Computed Tomography Reconstructions of the Posterior Pelvis*

Abstract: Thanks to recent advances, computed tomography is now seen as a tool of great value in the field of physical anthropology. In this study, we focused on the posterior pelvis and the auricular surface and evaluated the accuracy of 3D reconstructions of the auricular surface, using a methodology derived from a previous study by Lovejoy et al. We also looked for trabecular bone criteria expressing age‐related changes. Forty‐six coxal bones were scanned, and scoring of macroscopic criteria showed a good agreement between 3D reconstructions and photographs, especially for transverse organization (k = 0.90). The changes occurring in the posterior part of the sacropubic trabecular bundle were evaluated on CT reconstructions via three new criteria, which exhibited a good intra‐ and inter‐observer agreement (k = 0.77–0.89), and were particularly useful in identifying older subjects. We concluded that these CT‐evaluated trabecular bone criteria are promising and yield useful information about age at death.     

RUS-CHN图谱骨龄评价法用于推侧青少年年龄

目的探讨RUS-CHN(RC)图谱评价法用于13~18岁青少年年龄推侧的应用价值。方法4 424名(男2 272,女2 152)13~18岁正常城市汉族青少年,以简化RUS-CHN法建立手腕骨发育等级图谱。另以1 048名(男530,女518)13~18岁青少年为检验样本,比较不同方法骨龄与生活年龄的差异。结果RUS-CHN图谱法可仅评价桡骨、尺骨远端和第III指的4块掌指骨骺。检验样本中男14~17岁、女13~16岁年龄组,RC图谱法骨龄与生活年龄之间的差异均无统计学显著性(W ilcoxon符号秩和检验,P>0.05),对男18岁、女17岁组出现显著性差异的可能原因进行了讨论。结论RUS-CHN图谱法骨龄适用于男13~18岁、女13~17岁青少年的年龄推测。     

Analysis of age-at-death estimation through the use of pubic symphyseal data

The question of whether age parameters derived from an American population will reliably estimate age-at-death for East European skeletal populations is important since the ability to accurately estimate an individual's age-at-death hinges on what standard is used. A reference sample of identified individuals with known ages-at-death from the regions of the Former Yugoslavia (n = 861) is used to determine the age structure of victims and serves as the prior in the Bayesian analysis. Pubic symphyseal data in the manners of Todd (Am J Phys Anthropol, 3 [1920], 285; Am J Phys Anthropol, 4 [1921], 1) and Suchey-Brooks (Am J Phys Anthropol, 80 [1986], 167) were collected for n = 296 Balkan males and females and for n = 2078 American males and females. An analysis of deviance is calculated using an improvement chi-square to test for population variation in the aging processes of American and East European populations using proportional odds probit regression. When males and females are treated separately, there is a significant association among females and the population (df = 1, chi-square likelihood ratio = 15.071, p = 0.001). New age estimates for Balkan populations are provided and are based on the calculated age distribution from the Gompertz-Makeham hazard analysis and the ages-of-transition. To estimate the age-at-death for an individual, the highest posterior density regions for each symphyseal phase are provided.