The influence of body size on adult skeletal age estimation methods

Accurate age estimations are essential to archaeological and forensic analyses. However, reliability for adult skeletal age estimations is poor, especially for individuals over the age of 40 years. This is the first study to show that body size influences skeletal age estimation. The ??can et al., Lovejoy et al., Buckberry and Chamberlain, and Suchey‐Brooks age methods were tested on 764 adult skeletons from the Hamann‐Todd and William Bass Collections. Statures ranged from 1.30 to 1.93 m and body masses ranged from 24.0 to 99.8 kg. Transition analysis was used to evaluate the differences in the age estimations. For all four methods, the smallest individuals have the lowest ages at transition and the largest individuals have the highest ages at transition. Short and light individuals are consistently underaged, while tall and heavy individuals are consistently overaged. When femoral length and femoral head diameter are compared with the log‐age model, results show the same trend as the known stature and body mass measurements. The skeletal remains of underweight individuals have fewer age markers while those of obese individuals have increased surface degeneration and osteophytic lipping. Tissue type and mechanical loading have been shown to affect bone turnover rates, and may explain the differing patterns of skeletal aging. From an archaeological perspective, the underaging of light, short individuals suggests the need to revisit the current research consensus on the young mortality rates of past populations. From a forensic perspective, understanding the influence of body size will impact efforts to identify victims of mass disasters, genocides, and homicides. Am J Phys Anthropol 156:35–57, 2015 © 2014 Wiley Periodicals, Inc.     

Variation and classification of human age patterns of mortality: analysis using competing hazards models

The structure of variation in human mortality patterns is explored using a five-parameter competing hazards model and standard multivariate taxonomic procedures. The data consist of 281 national life tables representing a wide range of environmental and cultural regions of the world. A general or average age pattern of mortality was generated for the entire sample using multiple regression procedures. A K mean cluster analysis conducted on the residuals of the regression analysis identified seven distinct models of mortality that differ in characteristic ways from the general pattern. Four of the seven clusters have age patterns of mortality similar to the north, east, south, and west regions of the Coale and Demeny model life tables. The remaining three clusters represent regions of the world and age patterns of mortality that are not represented in the Coale and Demeny model life tables.     

Model life table fitting by maximum likelihood estimation: a procedure to reconstruct paleodemographic characteristics from skeletal age distributions

A procedure is presented that uses the regression coefficients for the Coale and Demeny west model life tables to model selected demographic characteristics from skeletal age-at-death distributions. Model death distributions were constructed and compared to a given skeletal distribution, using methods of maximum likelihood estimation to determine the best fit. Two chi-square tests are employed to evaluate the degree of fit. The resulting model includes estimates of demographic characteristics including gross reproductive rate, crude birth rate and life expectancy. The procedure is applied to three archaeological skeletal samples as test cases: two from eastern North America and one from Mexico. These display a range of correspondence (between the best fitting model and the data) from good to poor. The proposed procedure is a potentially powerful tool for both reconstructing paleodemographic rates and illuminating differences between typical human patterns and those found in archaeological populations.     

Dental wear in the Libben population: Its functional pattern and role in the determination of adult skeletal age at death

Modal patterns of occlusal attrition are presented for the Libben population based on a sample of 332 adult dentitions. Maxillas and mandibles were reviewed independently by seriation prior to assessment of complete dentitions. The Spearman rank order coefficient for upper and lower dentitions was.96. Wear patterns are very similar to those reported by Murphy (1959a: Am. J. Phys. Anthropol. 17:167–178) for Australian aborigines. There were no significant sexual differences in wear rate. Dental wear is concluded to be a highly reliable and important indicator of adult age at death for skeletal populations if seriation procedures are employed.     

Paleodemography of the Carlston Annis (Bt-5) Late Archaic skeletal population

The study presents a demographic assessment of the Carlston Annis (Bt-5) Late Archaic hunting and gathering population recovered from the banks of the Green River in west-central Kentucky. The shell midden habitation and cemetery site originally yielded the remains of 390 individuals. Radiocarbon dates place site occupation between 3,000 and 4,500 y.b.p. The skeletal sample consisted of 354 individuals ranging in age from 7 months in utero to 70 + years. Subadults were aged by seriation of dental and skeletal developmental criteria. Adult ages were determined by the multifactorial summary age method that employed 1) five indicators of adult skeletal age at death, 2) the procedure of age indicator seriation, and 3) differential weighting of age assessments as determined by principal components analysis. Adult sex diagnoses were based on qualitative assessment of pelvic and cranial morphological criteria. The Bt-5 life table analysis yields an E0 of 22.4 years, crude birth of 45, mean family size of 3.3, gross reproductive rate of 2.7, generation length of 26.6 years, and B of .076, indicating a healthy population with a substantial capability to replace succeeding generations. Survivorship profiles and demographic parameters that compare the Carlston Annis (Bt-5) and Indian Knoll (Oh-2) skeletal series are presented. Both populations display type II survivorship curves, with high infant mortality and early onset of elevated mortality rates in adults. Major differences between Bt-5 and Oh-2 demographic parameters concern adult sex ratio and adult age distribution over 30 years. These differences are interpreted to reflect census errors in the Oh-2 demographic reconstruction that were possibly introduced by selective methodological biases and/or taphonomic factors.     

Estimating age of mature adults from the degeneration of the sternal end of the clavicle

The sternal end of the clavicle has been illustrated to be useful in aging young adults, however, no studies have investigated what age‐related changes occur to the sternal end post epiphyseal fusion. In this study, three morphological features (i.e., surface topography, porosity, and osteophyte formation) were examined and scored using 564 clavicles of individuals of European ancestry (n = 318 males; n = 246 females), with known ages of 40+ years, from four documented skeletal collections: Hamann‐Todd, Pretoria, St. Bride's, and Coimbra. An ordinal scoring method was developed for each of the three traits. Surface topography showed the strongest correlation with age, and composite scores (formed by summing the three separate trait scores) indicated progressive degeneration of the surface with increasing chronological age. Linear regression analyses were performed on the trait scores to produce pooled‐sample age estimation equations. Blind tests of the composite score method and regression formulae on 56 individuals, aged 40+ years, from Christ Church Spitalfields, suggest accuracies of 96.4% for both methods. These preliminary results display the first evidence of the utility of the sternal end of the clavicle in aging older adult individuals. However, in the current format, these criteria should only be applied to individuals already identified as over 40 years in order to refine the age ranges used for advanced age. These findings do suggest the sternal end of the clavicle has potential to aid age estimates beyond the traditional “mature adult” age category (i.e., 46+ years), and provides several suggestions for future research. Am J Phys Anthropol 156:203–214, 2015. © 2014 The Authors American Journal of Physical Anthropology Published by Wiley Periodicals, Inc.     

An elusive paleodemography? A comparison of two methods for estimating the adult age distribution of deaths at late Classic Copan,Honduras

Comparison of different adult age estimation methods on the same skeletal sample with unknown ages could forward paleodemographic inference, while researchers sort out various controversies. The original aging method for the auricular surface (Lovejoy et al., 1985a) assigned an age estimation based on several separate characteristics. Researchers have found this original method hard to apply. It is usually forgotten that before assigning an age, there was a seriation, an ordering of all available individuals from youngest to oldest. Thus, age estimation reflected the place of an individual within its sample. A recent article (Buckberry and Chamberlain, 2002) proposed a revised method that scores theses various characteristics into age stages, which can then be used with a Bayesian method to estimate an adult age distribution for the sample. Both methods were applied to the adult auricular surfaces of a Pre-Columbian Maya skeletal population from Copan, Honduras and resulted in age distributions with significant numbers of older adults. However, contrary to the usual paleodemographic distribution, one Bayesian estimation based on uniform prior probabilities yielded a population with 57% of the ages at death over 65, while another based on a high mortality life table still had 12% of the individuals aged over 75 years. The seriation method yielded an age distribution more similar to that known from preindustrial historical situations, without excessive longevity of adults. Paleodemography must still wrestle with its elusive goal of accurate adult age estimation from skeletons, a necessary base for demographic study of past populations.     

The analysis of fractures in skeletal populations with an example from the Libben site,Ottowa County,Ohio

A quantitative approach to the analysis of long-bone fractures in skeletal populations is presented. These kinds of data are shown to be valuable in interpreting various behavioral aspects of the population. An example of application is provided for the Libben population. Data from this group show that the overall fracture rate was high (there is a 45% chance of a long-bone fracture in any single individual) but lower than the rates observed in nonhuman primates by almost an order of magnitude when data are adjusted for years of risk. The data for Libben also suggest that traumatic child abuse was not practiced, that most fractures occur as a consequence of accident, that fracture risk was highest in the 10–25 and 45 + age categories, that care of patients was enlightened and skillful in this group, and that chance of fracture is largely determined by accumulated years of risk in the population (r = 0.97).     

A revised method of age determination using the os pubis, with a review and tests of accuracy of other current methods of pubic symphyseal aging

All current standardized methods of age determination using the os pubis were tested by blind assessment of a skeletal sample with documented ages (from the Todd collection; N = 96). No demographic data (sex, age, race, age composition) were known to the assessors prior to completion of the test. Results showed the Todd method to be more reliable than more recent component techniques and that all systems tended to underage. Therefore, modifications were made of the Todd system to eliminate this and other deficiencies, and a second test using a new sample was conducted (N = 109). The age distribution determined by the revised Todd method did not significantly differ from the actual age distribution of the second sample. Error due to race was nonsignificant. Biological stages of pubic metamorphosis are described and possible evolutionary specializations of the hominid symphysis are discussed. Revised standards for age determination are presented.     

Modulated expression of human peripheral blood microRNAs from infancy to adulthood and its role in aging

Accumulating evidence suggests a role for microRNAs (miRNAs) in regulating various processes of mammalian postnatal development and aging. To investigate the changes in blood‐based miRNA expression from preterm infants to adulthood, we compared 365 miRNA expression profiles in a screening set of preterm infants and adults. Approximately one‐third of the miRNAs were constantly expressed from postnatal development to adulthood, another one‐third were differentially expressed between preterm infants and adults, and the remaining one‐third were not detectable in these two groups. Based on their expression in infants and adults, the miRNAs were categorized into five classes, and six of the seven miRNAs chosen from each class except one with age‐constant expression were confirmed in a validation set containing infants, children, and adults. Comparing the chromosomal locations of the different miRNA classes revealed two hot spots: the miRNA cluster on 14q32.31 exhibited age‐constant expression, and the one on 9q22.21 exhibited up‐regulation in adults. Furthermore, six miRNAs detectable in adults were down‐regulated in older adults, and four chosen for individual quantification were verified in the validation set. Analysis of the network functions revealed that differentially regulated miRNAs between infants and adults and miRNAs that decreased during aging shared two network functions: inflammatory disease and inflammatory response. Four expression patterns existed in the 11 miRNAs from infancy to adulthood, with a significant transition in ages 9–20 years. Our results provide an overview on the regulation pattern of blood miRNAs throughout life and the possible biological functions performed by different classes of miRNAs.     

Age determination from dental microstructure in juveniles

The crypts outside St Bride's Church, London, contain a documented collection of skeletal remains dating from the mid-18th century. Some of these remains became mixed during post-war restoration work on the church. The worst example of such mixing involves ten infants that were boxed all together with their corresponding coffin plates. All the infants were aged between 1 and 4 years at death. Recognized skeletal aging criteria proved unsuccessful in identifying the bodies. A more precise method of age estimation was utilized in order to separate these individuals. Age was determined using the incremental markers found in dental microstructure which are thought to be formed in circadian and circaseptan rhythms. The resulting age estimates were compared with the real ages obtained from the coffin plates and death certificates. Confident identification was achieved in eight out of ten cases. This study illustrates the potential value of a little-known aging method in circumstances where commonly used methods have proved unsuccessful. © 1995 Wiley-Liss, Inc.     

Interrelationship between various aging methods,and their relevance to palaeodemography

Age estimations for 64 adult individuals from the Byzantine city of Rehovot-in-the-Negev were carried out using seven different aging methods. Correlation coefficients were calculated between five of the methods, which employed the following anatomical structures: teeth attrition rate, cranial sutures (closure stages), sternal end of ribs, symphysis pubis, and sacroiliac joints. Age estimations were checked against ‘summary age’ (Lovejoy et al., 1985a). Life tables were reconstructed based on summary ages and revised ages separately. It was found that ages obtained from the innominate bones correlated best with the summary age and showed less bias and inaccuracy, while ages obtained from the cranial sutures, showed the opposite. Reconstructing the ‘revised-age’ has no advantage over other aging methods when calculating demographic parameters.     

Relative tibia long bone growth in the Libben and Bt-5 prehistoric skeletal populations

Patterns of tibia long bone growth were examined for the Libben Late Woodland and Bt-5 Late Archaic hunter-gatherer skeletal groups. Subadults included in the analyses ranged in age from birth to 10 years. The primary goals were to identify potential differences in relative tibia growth and evaluate the extent to which such differences were concordant with demographic and epidemiological characteristics of the two groups. Methods used were designed to minimize the shortcomings of unknown age and sex of the skeleton, small sample sizes, and population differences in adult size attained. Results showed that Bt-5 preadolescent growth performance and health status in general were superior to those of the Libben group. Modifications in the rate and timing of Libben tibia growth occurred early and were primarily restricted to the weaning period. It is suggested that high levels of infectious disease experienced in the first years of life at Libben played a substantial role in the etiology of early long bone growth retardation, a greater prevalence of iron deficiency anemia in the childhood years, and elevated levels of subadult morbidity and mortality compared to Bt-5. Paleodemographic, paleoepidemiological, and modern comparative population data that support these inferences are discussed. No evidence of chronic malnutrition owing to dietary inadequacy was observed for either group. Alternatively, higher population density and greater degree of sedentism alone may have been responsible for elevated disease loads at Libben compared to low levels that were observed for the seasonally mobile semisedentary Bt-5 hunter-gatherers.     

A demographic analysis of skeletons from the Larson site (39WW2) Walworth County,South Dakota: Vital statistics

A life table methodology was used for paleodemographic analysis of skeletons from the Larson site (39WW2), an Arikara village and cemetery dated to circa A.D. 1750–1785. Vital statistics on mortality, survivorship, age-specific probability of death, life expectancy and crude mortality rate were derived from skeletal data. The population had an extremely high infant mortality rate and high rates of childhood mortality. The lowest probability of death was for adolescents. Mortality increased for young adults, ages 15–19. This increase was especially marked for females, the actual peak of adult female mortality was during ages 15–19. A second mode in the female mortality curve occurred at ages 35–39. The greatest percentage of male deaths was observed in the fourth decade, ages 30–34. Only 4.0% of the population attained the age of 50. The population crude death rate was 76 per thousand per year. This estimate, although high, is congruent with archaeological and historical sources which report a rapid Arikara population decline during the Post-Contact period. Causes of specific deaths appear to be linked to childbirth (affecting mother and infant), starvation, diseases especially tuberculosis, and intertribal warfare.     

Testing predictions of the programmed and stochastic theories of aging: Comparison of variation in age at death,menopause, and sexual maturation

One of the arguments against aging being programmed is the assumption that variation in the timing of aging-related outcomes is much higher compared to variation in timing of the events programmed by ontogenesis. The main objective of this study was to test the validity of this argument. To this aim, we compared absolute variability (standard deviation) and relative variability (coefficient of variation) for parameters that are known to be determined by the developmental program (age at sexual maturity) with variability of characteristics related to aging (ages at menopause and death). We used information on the ages at sexual maturation (menarche) and menopause from the nationally representative survey of the adult population of the United States (MIDUS) as well as published data for 14 countries. We found that coefficients of variation are in the range of 8–13% for age at menarche, 7–11% for age at menopause, and 16–21% for age at death. Thus, the relative variability for the age at death is only twice higher than for the age at menarche, while the relative variability for the age at menopause is almost the same as for the age at menarche.     

Determination of age at death in human skeletal remains: A comparison of two techniques

Reliable palaeodemographic reconstruction is dependent upon accurate determination of age at death in human skeletal remains. Two methods, Todd (Todd, 1920, 1921) and Suchey-Brooks (Katz & Suchey, 1986), which use morphological changes of theos pubis as an indicator of age at death, were applied to a sample of Central California Indians. Life tables were constructed and the two data sets were compared. Differences between the two data sets were evident when life expectancies, mean ages, and survivorship curves were compared. Because both methods were developed using male samples, only the male data were considered valid. In a comparison between the two male data sets it became apparent that the differences lie in the upper decades depending upon which method was used. In an attempt to rectify the difference in age ranges between the two methods, a conversion of Todd phases into equivalent Suchey-Brooks phases (Katz & Suchey, 1986) was employed. Applications and limitations of both methods are discussed and it is suggested that the Suchey-Brooks method is to be perferred.     

男性青少年脂肪组织分布与相对骨龄的关系——Fels追踪研究

本文对Fels追踪研究中8—17岁男性青少年的相对骨龄与脂肪分布类型之间的关系做了分析。按体重/身高~2调整后,如用每个年龄的三种皮褶厚度(ST)指数的均值表示脂肪分布类型的话,8—12岁时,脂肪分布类型呈外周型分布,但13岁后开始朝向心型发展呈全身性分布。如用肩胛下ST/(肩胛下ST+肱三头肌区ST)的比例表示的话,那么14—17岁时,相对骨龄早者(简称早组)与相对骨龄晚者(简称晚组)相比,前者有较明显的向心型分布倾向。13—14岁时,早组的上述比值的年增长明显大于晚组。但是,按脂肪分布类型指数等级的基线和体重/身高~2调整之后,7、11或14岁时的相对骨龄不能预测17岁时的脂肪分布类型指数的等级。所以,我们可以得出这样的结论:如按本文的比例指数加以定量的话,脂肪分布类型与男性青少年的相对骨龄只有微弱的关系。他们的脂肪分布类型可能与其它成熟指征(如男性青春期的第二性征)有明显的关系。     

First rib metamorphosis: its possible utility for human age-at-death estimation.

Human first ribs demonstrate predictable, sequential changes in shape, size, and texture with increasing age, and thus, can be used as an indicator of age at death. Metamorphosis of the first rib's head, tubercle, and costal face was documented in a cross-sectional sample of preadult and adult first ribs of known age at death from the Hamann-Todd skeletal collection (Cleveland Museum of Natural History, Cleveland, Ohio). Blind tests of the usefulness of the first rib as an age indicator were conducted, including tabulation of intraobserver and interobserver inaccuracies and biases. First rib age estimates show inaccuracies and biases by decade comparable to those generated by other aging techniques. Indeed, the first rib method is useful as an isolated age indicator. When used in conjunction with other age indicators, the first rib improves the quality of summary age assessments.     

Paleodemographic age‐at‐death distributions of two Mexican skeletal collections: A comparison of transition analysis and traditional aging methods

Traditional methods of aging adult skeletons suffer from the problem of age mimicry of the reference collection, as described by Bocquet‐Appel and Masset (1982). Transition analysis (Boldsen et al., 2002) is a method of aging adult skeletons that addresses the problem of age mimicry of the reference collection by allowing users to select an appropriate prior probability. In order to evaluate whether transition analysis results in significantly different age estimates for adults, the method was applied to skeletal collections from Postclassic Cholula and Contact‐Period Xochimilco. The resulting age‐at‐death distributions were then compared with age‐at‐death distributions for the two populations constructed using traditional aging methods. Although the traditional aging methods result in age‐at‐death distributions with high young adult mortality and few individuals living past the age of 50, the age‐at‐death distributions constructed using transition analysis indicate that most individuals who lived into adulthood lived past the age of 50. Am J Phys Anthropol 152:67–78, 2013. © 2013 Wiley Periodicals, Inc.