Estimation of adult skeletal age‐at‐death using the Sugeno fuzzy integral

Age‐at‐death estimation of an individual skeleton is important to forensic and biological anthropologists for identification and demographic analysis, but it has been shown that the current aging methods are often unreliable because of skeletal variation and taphonomic factors. Multifactorial methods have been shown to produce better results when determining age‐at‐death than single indicator methods. However, multifactorial methods are difficult to apply to single or poorly preserved skeletons, and they rarely provide the investigator with information about the reliability of the estimate. The goal of this research is to examine the validity of the Sugeno fuzzy integral as a multifactorial method for modeling age‐at‐death of an individual skeleton. This approach is novel because it produces an informed decision of age‐at‐death utilizing multiple age indicators while also taking into consideration the accuracies of the methods and the condition of the bone being examined. Additionally, the Sugeno fuzzy integral does not require the use of a population and it qualitatively produces easily interpreted graphical results. Examples are presented applying three commonly used aging methods on a known‐age skeletal sample from the Terry Anatomical Collection. This method produces results that are more accurate and with smaller intervals than single indicator methods. Am J Phys Anthropol 2010. © 2009 Wiley‐Liss, Inc.     

Cross-sectional geometric analysis of a foot bone assemblage from Mangaia, Cook Islands

This study describes a human foot bone assemblage from prehistoric Mangaia, Cook Islands in the context of diaphyseal cross-sectional strength measures. We use this sample to test the hypothesis that habitually unshod individuals who walk over rugged terrain will have stronger foot bones than a sample of habitually shod industrialized people. Specifically, we examine whether the Mangaian sample has a stronger size-adjusted metatarsal (MT) and phalangeal cross-sectional properties than the industrial sample, drawn from the Terry Collection. Contrary to expectations, residual analyses showed that most values of cross-sectional area (CA) and torsional resistance (J) of MTs 1-4 and the hallucal proximal phalanx (HPP) of the Mangaians are among those in the lower range of the Terry Collection sample. However, the bending strength ratios (Zy/Zx) of the Mangaian HPP are significantly greater than those of the Terry Collection. While characteristics such as forefoot shape variation between the sexes and among geographic populations cannot be ruled out as influential factors, cross-sectional properties of the hallucal proximal phalanges, but not the MTs, indicate terrain complexity in prehistoric populations.     

Age-at-death estimation in an Italian historical sample: A test of the Suchey-Brooks and transition analysis methods

A growing body of research is demonstrating increased accuracy in aging from a relatively new method, transition analysis. Although transition analysis was developed for paleodemographic research, a majority of subsequent studies have been in the forensic arena, with very little work in bioarchaeological contexts. Using the Suchey‐Brooks pubic symphysis phases, scored on a target sample of historic Italians from the island of Sardinia, we compare accuracy of aging between transition analysis combined with a Bayesian approach and the standard Suchey‐Brooks age ranges. Because of the difficulty in identifying a reasonable informative prior for bioarchaeological samples, we also compared results of both an informative prior and a uniform prior for age estimation. Published ages‐of‐transition for the Terry Collection and Balkan genocide victims were used in conjunction with parameters generated from Gompertz hazard models derived from the priors. The ages‐of‐transition and hazard parameters were utilized to calculate the highest posterior density regions, otherwise known as “coverages” or age ranges, for each Suchey‐Brooks phase. Each prior, along with the parameters, were input into cumulative binomial tests. The results indicate that the Bayesian approach outperformed the Suchey‐Brooks technique alone. The Terry Collection surpassed the Balkans as a reasonable sample from which to derive transition analysis parameters. This discrepancy between populations is due to different within phase age‐at‐death distributions that reflect differences in aging between the populations. These results indicate bioarchaeologists should strive to apply a Bayesian analysis when aging historic and archaeological populations by employing an informative prior. Am J Phys Anthropol 149:259–265, 2012. © 2012 Wiley Periodicals, Inc.     

Sex determination of fragmentary crania by analysis of the cranial base

The cranial base can be used to determine the sex of fragmentary or deformed skulls. An initial study used nine measurements taken from 100 crania in the Terry Collection. The sample was divided equally by race and sex. Six regression models were formulated that predicted correctly the sex of the sample with 71-90% accuracy. In a separate test, a control sample of 20 skulls, also drawn from the Terry Collection but not involved with formulating the regression equations, was correctly classified with 70-85% accuracy.     

An examination of the meaning of cranial discrete traits for human skeletal biological studies

Discrete traits are of increasing interest in comparative skeletal biological research. Characteristics justifying their use have been investigated primarily in mice, however. Using 72 discrete variants, 321 human skulls from the Terry Collection of known race, sex and age have been studied. Significant sex and age differences were detected. Inter-trait correlation was found to be at a low but significant overall level. Multivariate comparison with conventional craniometric analysis was undertaken on subdivisions of the sample, and distance based on metric and nonmetric data were concordant. It is concluded, on the basis of these findings and the discontinuous variant frequency distributions, that discrete traits in isolation are not of paramount value to skeletal genetic studies, but may be vital in comparison and conjunction with other types of data in analyzing the population genetics of extinct groups.     

Multiple discriminant function analysis of sex and race in the postcranial skeleton

Terry Collection femora and innominates of 260 American Whites and Blacks (65 males and 65 females of each race) were analyzed by multiple discriminant function analysis. A stepwise procedure produced three optimal discriminant functions using 15 of our 32 measurements. These functions correctly identified 95% of the sample. The first two-one for sex and one for race-are statistically and biologically significant and form the basis of our analysis. The sexing function manifested both size and shape elements. Prominent among the former was joint size--acetabular diameter and epicondylar diameter of the femur. The shape elements included form of the greater sciatic notch and of the inferomedial aspect of the pubic body. The racing function highlighted a pattern of greater innominate dimensions, exclusive of the acetabular joint, in Whites. This was in contrast to the greater length of the Black femur. Overall, the function seems to express the established differences between the races in the ratio of lower limb length to torso length. While these functions have been applied successfully to forensic cases with confirmed identifications, questions regarding the breadth of applicability of discriminant functions make it desirable to validate our results on new material from the Terry and other collections.     

Cultural patterns of trauma among 19th-century-born males in cadaver collections

Comprehending violence among bioarchaeological and historical groups is a topic of recent interest among biological anthropologists. This research examines trauma among African American and Euro-American males of low socioeconomic status born between 1825 and 1877. A total of 651 male skeletons from the Cobb, Terry, and Hamann-Todd anatomical collections were macroscopically evaluated for skeletal trauma, based on the presence of fractures and weapon-related wounds, and statistically analyzed according to ancestry, birth (Antebellum, Civil War, Reconstruction), combined ancestry - birth, and collection cohorts. Results indicated that African Americans and Euro-Americans expressed ethnic differences in regard to interpersonal violence. To interpret these disparities, documentary data were used to reconstruct the socioeconomic and cultural environment of these individuals. This research emphasizes the importance of evaluating skeletal data within the context of class, culture, and environment so that behavioral patterns observed in the skeleton can be better understood.     

Test of the Lamendin aging method on two historic skeletal samples

The Lamendin aging method involves the quantification of root translucency and the attachment position of the periodontal membrane. It was developed using recent medical-examiner specimens, and was tested on modern skeletal samples such as the Terry Collection (Lamendin et al. [1992] J. Forensic Sci. 37:1373-1379; Prince and Ubelaker [2002] J. Forensic Sci. 47:107-116). The method may be one of the most useful for estimating age after the mid-30s. The current study is an evaluation of the Lamendin criteria on two historic skeletal samples from Britain. Both the Christ's Church Spitalfields and St. Bride's Church collections represent documented skeletal samples that were interred in the 18th and 19th centuries. In total, 1,188 teeth from 220 adult individuals were examined from these two collections. The Lamendin method requires measuring total root length (cementoenamel junction to apex), gingival regression (cementoenamel junction to periodontal ligament attachment), and root translucency (root apex to maximum level of root translucency) on the labial surface of single-rooted teeth. Our results indicate that postmortem factors affect the applicability of the Lamendin technique to archaeological and historical samples. In particular, root translucency disappears with time, or is obscured by unknown postmortem taphonomic effects related to the length of interment or postmortem environment. Thirty-five percent of our sample showed no root translucency, indicating that caution is required when applying this method to archaeological or historical remains. The mean error of age estimates for Spitalfields and St. Bride's was higher than in the original study of Lamendin et al. ([1992] J. Forensic Sci. 37: 1373-1379), and higher than in the test by Prince and Ubelaker ([2002] J. Forensic Sci. 47:107-116) of the Lamendin method on the Terry Collection.     

Adult females and pubic bone growth

Previous research (Tague [1994] Am. J. Phys. Anthropol. 95:27–40) has shown an age effect in pubic bone length among adult women. Tague found that in three prehistoric Native American skeletal samples, women aged 18–24 had a significantly shorter linea terminalis than did women aged 25 and older. The purpose of this research is to determine whether such a difference can be discerned in other female skeletal samples. Three female skeletal samples were used in this analysis: 75 African-American and 42 European-American females aged 18–39 from the Hamann-Todd Collection (collected between 1893 and 1938; Iscan, 1990) and 99 African-American females aged 18–39 from the Terry Collection (collected between 1914 and 1965; Cobb, 1933; Iscan, 1990). Several chord measurements of pubic bone length along the linea terminalis were analyzed by one-tailed t-tests of the separate samples subdivided into two age groups: 18–24 and 25–39 years. Of 15 comparisons between age groups, none differed significantly by age group within each sample. It is concluded that the observed significant difference in pubic bone length in the Native American female skeletal samples cannot be replicated in other samples and that there is no age effect on pubic bone length in the samples tested in this analysis. Tague's findings reflect either the occurrence of late menarche in prehistoric populations or differential survivorship. Am J Phys Anthropol 106:323–328, 1998. © 1998 Wiley-Liss, Inc.     

The estimation of sex on the basis of the talus and calcaneus

The present report records and describes sexual dimorphism of the talus and calcaneus in American Blacks and Whites from the Terry Collection housed in the Smithsonian Institution, Washington, D.C. The greater amount of sexual dimorphism was observed in the talus, where 81 percent of the study sample could be accurately sexed. Four discriminant functions based on measurements from the talus and/or the calcaneus allowed sexing 79 to 89% of the study sample accurately. The techniques developed were then applied to two North American Indian samples, and sex of the individuals in these samples was assessed with the same degree of accuracy.     

Application of the anatomical method to estimate the maximum adult stature and the age‐at‐death stature

This study focuses on the age adjustment of statures estimated with the anatomical method. The research material includes 127 individuals from the Terry Collection. The cadaveric stature (CSTA)–skeletal height (SKH) ratios indicate that stature loss with age commences before SKH reduction. Testing three equations to estimate CSTA at the age at death and CSTA corrected to maximum stature from SKH indicates that the age correction of stature should reflect the pattern of age‐related stature loss to minimize estimation error. An equation that includes a continuous and linear age correction through the entire adult age range [Eq. (1)] results in curvilinear stature estimation error. This curvilinear stature estimation error can be largely avoided by applying a second linear equation [Eq. (2)] to only individuals older than 40 years. Our third equation [Eq. (3)], based on younger individuals who have not lost stature, can be used to estimate maximum stature. This equation can also be applied to individuals of unknown or highly uncertain age, because it provides reasonably accurate estimates until about 60/70 years at least for males. Am J Phys Anthropol 152:96–106, 2013. © 2013 Wiley Periodicals, Inc.     

Sex assessment using the proximal tibia

The proximal end of the human tibia is sexually dimorphic. Tibial condyles from 100 individuals in the Hamann-Todd Collection were measured. Regression equations retrodicted known sex with 86-95% accuracy. A test sample of 20 individuals also from the Hamann-Todd Collection was classified with 85-100% accuracy. A sample of 20 prehistoric individuals provisionally sexed by using crania and innominate bones was classified with 85-100% agreement. Thus, the proximal tibia may be useful in determining the sex of a skeleton.     

The mylohyoid bridge of pre-Columbian Peruvians

The frequency of expression of the mylohyoid bridge was studied in the skeletal remains of 122 Pre-Columbian Peruvians. The incidence in this population was found to be 17.6% as compared to an incidence of 15.4% found in a similar size sample population of American Negroes and a 16.1% incidence in a population of American Whites from the Terry Collection. No significant differences as to the incidence of the mylohyoid bridge were found as to the side of occurrence or between deformed and undeformed crania. A mylohyoid bridge was found in a younger individual (6 years) than had previously been reported. Females showed a significantly higher incidence of this trait in all three populations studied. A similar incidence of the mylohyoid bridge in Pre-Columbian and Mongoloid peoples adds support to the theory of a Mongoloid origin of these people. The mylohyoid bridge is considered to be a significant genetic marker which along with other such markers could be of value in population studies.     

Assessment of race from the pelvis

Racial assessment of human postcranial skeletal remains has been a major concern for forensic and skeletal anthropologists. Materials (N = 400) of the present study are from the Terry Collection and consist of 100 black and white American pelves of both sex with known age and race. Measurements were taken from the articulated pelves. Results of discriminant function analysis indicate classificatory accuracy may be as high as 88%. Transverse pelvic breadth contributes more to the function than biiliac breadth and antero-posterior height. The females are more easily assessed racially than males. Although a highly reliable classification is produced, the results of the study should be employed with caution, as samples were of questionable nutritional status and of low socioeconomic class.     

A comparative study of metric and non-metric traits in a series of modern crania

The purpose of this study is to question the utility of non-metric traits as predictors of age, race, and sex by comparing a group of non-metric variables with a group of metric variables. Twelve metric variables and 15 nonmetric variables were scored on 317 crania from the Terry Collection at the U. S. National Museum, and later statistically evaluated with a number of multivariate analysis programs and a stepwise discriminant program. The metric variables were found to be significant sex and race discriminators, where-as the non-metric variables were non-significant. The non-metric variables were found to be better age discriminators than the metric variables, even though neither could be classified as highly significant. It was concluded that non-metric traits by themselves have very little discriminatory value and should be used instead to supplement other osteological measurements and observations.     

Shape variation of the human pollical distal phalanx and metacarpal

Human distal pollical phalanx form has been associated with tool manufacture, and the broad tuft of this bone in Neanderthals has been suggested to be a climatic adaptation and/or an aid to a tremendously powerful grip. A wide first metacarpal head has also been proposed to be useful in distinguishing tool-dependent hominids from those less reliant on tools. In order to contribute to an evaluation of these hypotheses variation in first metacarpal and distal phalanx shape is explored among samples of modern humans and compared to that of fossil hominids. Modern humans are from the Terry Collection, Larsen Bay, a Chinese-Alaskan cemetery, Egypt, and Sully and Mobridge. Hominid fossils include AL 333w-39, SKX 5016, SK 84, Stw 294, OH 7, several Neanderthals, Skhūl 4 and 5, and Predmostí 3. Analysis involves length-width ratios, regressions of distal phalanx tuft width on base width and of metacarpal head width on length, and pattern profiles based on Z-scores with reference to the Larsen Bay sample. Larsen Bay individuals are robust, while Terry "blacks," Egyptians, and Chinese-Alaskan males tend to be gracile. Fossil hominids are most distinctive for distal phalanx radioulnar tuft and mid-shaft widths relative to length. Security of grip is one plausible explanation. While most modern samples are positively allometric for tuft width relative to base width, the Larsen Bay and fossil hominid samples are not; thus caution is advised in accepting a base-tuft width comparison as a tool-dependence marker. Separation from modern humans is not easily achieved with metacarpal measures, but the Hadar metacarpal has distinctively narrow radioulnar head width ratios. While first metacarpal head expansion among hominids may plausibly be related to tool manufacture, other activities that place stress on the metacarpophalangeal joint should also be considered.     

Two Methods for reconstructing the empirical mortality profile

This paper goes one step beyond the age determination of the individual skeleton. It presents two methods for the reconstruction of the distribution of the age at death in a sample of skeletons. It is shown that the maximum likelihood method, in spite of certain weaknesses, is superior to the traditionally used proportional method, especially in situations when the analyzed sample consists of skeletons with very different conditions of preservation and thus age intervals of differing lengths. The maximum likelihood method eliminates a bias towards increased average age at death which is introduced by the proportional method. An analysis of an empirical example indicates that the difference between results obtained using the two methods increases with increasing age.     

Corrigenda to “estimation of stature from long limb bones of American Whites and Negroes,” American Journal Physical Anthropology (1952)

The amount of disparity between the lengths of the radii and ulnae of 177 Negro female skeletons of the Terry Collection was questioned. An error was found and corrections have been made in the relevant statistics and tables.