Using multivariate adaptive regression splines to estimate subadult age from diaphyseal dimensions

Subadult age estimation is considered the most accurate parameter estimated in a subadult biological profile, even though the methods are deficient and the samples from which they are based are inappropriate. The current study addresses the problems that plague subadult age estimation and creates age estimation models from diaphyseal dimensions of modern children. The sample included 1,310 males and females between the ages of birth and 12 years. Eighteen diaphyseal length and breadth measurements were obtained from Lodox Statscan radiographic images generated at two institutions in Cape Town, South Africa, between 2007 and 2012. Univariate and multivariate age estimation models were created using multivariate adaptive regression splines. k‐fold cross‐validated 95% prediction intervals (PIs) were created for each model, and the precision of each model was assessed. The diaphyseal length models generated the narrowest PIs (2 months to 6 years) for all univariate models. The majority of multivariate models had PIs that ranged from 3 months to 5 and 6 years. Mean bias approximated 0 for each model, but most models lost precision after 10 years of age. Univariate diaphyseal length models are recommended for younger children, whereas multivariate models are recommended for older children where the inclusion of more variables minimized the size of the PIs. If diaphyseal lengths are not available, multivariate breadth models are recommended. The present study provides applicable age estimation formulae and explores the advantages and disadvantages of different subadult age estimation models using diaphyseal dimensions. Am J Phys Anthropol 154:376–386, 2014. © 2014 Wiley Periodicals, Inc.     

Technical note: Error in Olivier and Pineau's regression formulae for calculation of stature and lunar age from radial diaphyseal length in forensic fetal remains

Stewart ([1979] Essentials of Forensic Anthropology, pp. 128–131) cites five regression formulae presented by Olivier and Pineau ([1960] Ann. Méd. Lég. 40:141–144) for estimation of fetal stature from diaphyseal length. Of these formulae, one appears problematic: the formula for calculation of stature from the radius yields values which suggest the fetus has a much greater crown-heel (CH) length than do the remaining formulae for the diaphyses of other long bones. Moreover, when this stature estimate, so derived, is then inserted into these authors' earlier general formula for estimation of lunar age (Olivier and Pineau [1958] Arch. Anat. 6:21–28) the error is compounded. A fetus is now indicated to be nearly a trimester older than when the CH lengths obtained by the other long bone formulae are used. Accordingly, we believe this particular formula, unlike the others, is incorrect and should not be used to estimate lunar age from fetal remains. © 1996 Wiley-Liss, Inc.     

Formation of the permanent dentition in Arikara Indians: timing differences that affect dental age assessments

This report concerns one problem encountered with application of American white dental formation standards to age assessment of sub-adults of archaeological context. Dental ages for eight mandibular permanent teeth and maxillary central and lateral incisors of Arikara Indian immature skeletons were determined according to degree of crown or root mineralization. Ages assigned to the various teeth of the same individual were compared. They showed similarities as well as patterned differences. First premolar, second premolar, and mandibular incisor ages closely approximated one another. In relation to this complex, dental ages for maxillary incisors and mandibular second molars were older by 0.5 to 1.1 years. Developmental ages assigned to individuals on the basis of third molars showed relative advancement by more than 2 years. The systematic occurrence of these observations reflects more than just individual variability; it shows the presence of population differences in tooth-formation timing. Timing differences complicate assessment of dental ages needed for growth or demographic studies.     

Patterns of clavicular bilateral asymmetry in relation to the humerus: variation among humans

Studies of directional asymmetry in the human upper limb have extensively examined bones of the arm, forearm, and hand, but have rarely considered the clavicle. Physiologically, the clavicle is an integrated element of the upper limb, transmitting loads to the axial skeleton and supporting the distal bones. However, clavicles develop in a manner that is unique among the bones of the upper limb. Previous studies have indicated that the clavicle has a right-biased asymmetry in diaphyseal breadth, as in humeri, radii, ulnae, and metacarpals, but unlike these other elements, a left-biased length asymmetry. Few studies have assessed how clavicular asymmetry relates to these other bones of the upper limb. Bilateral directional asymmetry of the clavicle is examined in relation to the humerus in a large, geographically diverse human sample, comparing lengths and diaphyseal breadths. Dimensions were converted into percentage directional (%DA) and absolute (%AA) asymmetries. Results indicate that humans have same-side %DA bias in the clavicles and humeri, and contralateral length %DA between these elements. Diaphyseal breadths in both clavicles and humeri are more asymmetric-both in direction and amount-than lengths. Differences in diaphyseal asymmetry are shown to relate to variation in physical activities among groups, but a relationship between activity and length asymmetry is not supported. This further supports previous research, which suggests different degrees of sensitivity to loading between diaphyseal breadths and maximum lengths of long bones. Differences in lateralized behavior and the potential effects of different bone development are examined as possible influences on the patterns observed among human groups.     

Adult stature and age at menarche in Zapotec-speaking communities in the Valley of Oaxaca,Mexico, in a secular perspective

Adult stature and the age at menarche among individuals from Zapotec-speaking communities in the Valley of Oaxaca in southern Mexico are considered in a secular perspective. Four sets of observations are utilized: (1) adult stature in males and females from five rural communities; (2) age at menarche in adult women and school girls from a single rural community; (3) earlier studies of adult stature in the Valley of Oaxaca; and (4) estimated stature from long bones excavated in various archaeological sites in the Valley of Oaxaca. There were no significant differences among the five communities for stature; hence, the data were pooled for analysis and comparison. Results of linear regression of stature and stature adjusted for the estimated effects of aging after 30 years of age on year of birth indicate negligible secular changes in either sex. Comparisons with statures from earlier surveys, the earliest dates to 1899, also indicate negligible changes. When adult women are grouped according to age, there are no differences in mean ages at menarche between the older and younger women. Mean age at menarche for the total adult sample is 14.53 ± 0.08 years, which compares favorably with the probit estimate for school girls, 14.70 ± 0.32 years. These results thus suggest virtually no secular change in adult size and maturity of the Zapotec-speaking population in the Valley of Oaxaca over the past 80 years. Differences in stature between contemporary populations and estimated statures from long bones from several archaeological sites in Oaxaca are small, and thus suggests little secular change over the past one to two–thousand years.     

Age determination of pre- and postnatal skeletons with special reference to current methodological aspects]

From the remains of ten fetal and neonatal skeletons the standard methods of age estimation by means of dental and osseous criteria as well as diaphyseal length were applied and discussed. The ratio of long bone lengths and change of proportions during the first and second half of pregnancy is a useful indicator for the stage of maturation.     

Estimating diaphyseal length from fragmentary subadult skeletal remains: Implications for palaeodemographic reconstructions of a southern Ontario ossuary

Fragmentary skeletal remains are a significant problem for osteologists attempting to reconstruct individuals or populations. This problem is further aggravated by sites yielding commingled remains, such as are recovered from the large protohistoric and historic ossuaries from southern Ontario, for which individual methods of age estimation and sex determination cannot be used concurrently. While some attention has been given to the estimation of long bone length from fragmentary, adult remains, little attention has been given to the equally important problem of fragmentary long bones in subadult assemblages. Analysis of data on diaphyseal length is a crucial aspect of reconstructing subadult palaeodemographic profiles, particularly for ossuary collections where dental remains are not associated with individuals and are often less represented than long bones. Such analysis also aids in the assessment of conditions of past population health. This study reports the results of several regression techniques used to estimate diaphyseal length from shaft-end breadths. Data collected from two southern Ontario ossuary samples were compiled to calculate the regression equations. Reliability of these equations and implications for palaeodemographic profiles are discussed. © 1996 Wiley-Liss, Inc.     

Palaeodemography of the Nasca valley: reconstruction of the human ecology in the southern Peruvian coast

This study is based on skeletons and mummies belonging to 582 individuals excavated at sites of Pueblo Viejo, Cahuachi, Estaqueria and Atarco in the Nasca valley, South Coast of Peru. Archaeological evidence distinguishes three cultural phases: Nasca (400 BC-550 AD), Wari (600-1100 AD) and Chincha (1100-1412 AD). Since the Chincha human remains were too exiguous (27 individuals), only Nasca and Wari were considered. For the Nasca population, sex ratio was 113 men to 100 women (53% of males); for the Wari population, sex ratio was 117 men to 100 women (54% of males). The palaeodemographic data show that the infant mortality rate was 33@1000 for Nasca and 105@1000 for Wari. Life expectancy was 38-43 years for Nasca and 31-36 years for Wari. Death percentages in all the age groups increased from Nasca to Wari phase. ANOVA and t-test for paired comparison were applied in order to examine if dental and bone ages were statistically different. Long bones and teeth showed an allometric development, and the age estimated from the tooth formation and eruption was generally higher than the age estimated from the maximum lengths of long bones. The anthropological study of the Nasca valley skeletal populations confirmed the archaeological hypothesis of worse conditions of the Wari population in comparison with the previous Nasca people.     

Comparison of Tanner-Whitehouse and Greulich-Pyle methods in a large scale Danish Survey

In Denmark no systematic investigation of skeletal development had been made prior to this investigation which involved 1009 school children aged 7–18 years in a transverse examination. The skeletal age was estimated according to the American atlas of Greulich-Pyle. The English system of Tanner-Whitehouse was also applied. In this latter method the stage of development of 20 selected bones in the hand and wrist is rated on a scale of 8 (in one case 9) possible stages. Each bone is awarded points according to its stage of development. These points are totalled for the 20 bones and reference to a table gives the skeletal age. The problem with this system is that the later stages of carpal bone development cannot be reliably placed on the scale. Their point system is calculated in such a way that a difference of one stage in rating of a single carpal bone in older children would give rise to a difference of up to two years in the skeletal age estimation. For younger children the method is, however, quite reliable. The investigation has shown that Greulich-Pyle's atlas can be applied to Danish children of 7-18 years of age provided that a correction of six months is made. A variable error of about four months was found when using Greulich-Pyle compared to about two months with Tanner-Whitehouse.     

Testing the quality of nonadult Bayesian dental age assessment methods to juvenile skeletal remains: the Lisbon collection children and secular trend effects

Age estimation of nonadult skeletons from archaeological or forensic contexts has relied heavily on modern schedules of dental formation developed on samples of children of affluent populations. Although genetic factors have been considered to have had the greatest influence on population differences in dental development, increased interest has been placed on the role of environmental influences, such as differences in socioeconomic status and secular trends. This study evaluates the quality (i.e., accuracy and reliability) of two Bayesian dental age estimation methods to a sample of identified child skeletons from the Lisbon collection (20th century Portugal). The two Bayesian methods are developed on a reference sample of modern children from France, Ivory Coast, Iran, and Morocco. The test sample from Lisbon, compared to the reference sample, is separated by over 50 years of secular trends and comprises a lower socioeconomic segment. The two Bayesian methods show that the Lisbon children are consistently 1-year behind in dental age compared to the modern children of the reference sample. Environmental factors largely explain the differences between dental and chronological age in historic samples of nonadults.     

Lion (Panthera leo) demographics in the south-western Kgalagadi Transfrontier Park

Changes in demographic features of the lion population in the south-western Kgalagadi Transfrontier Park cause conservation concern. The ratio between adult males and females changed from 1♂:2♀ to 1♂:1♀ over a 32-year period (1977–2010). This is atypical for undisturbed lion populations. We evaluated mechanisms that on their own or together could explain the trend by using both a discrete- and continuous-time capture–recapture model to analyse 2 years of individual-based observation data (May 2013–June 2015). Although most vital rates were within expected parameters, shifts in the sex structure remained similar to that reported for sub-adults previously. The population comprised of 26.9% cubs and juveniles (<2 years), 14.2% sub-adults (2–4 years) and 59% adults (>4 years). Litters had equal sex ratios at first detection. Birth rates were lower (0.44 cubs per female per year) than between 1998 and 2001 (0.69 cubs per female per year). The continuous model indicated a higher survival effect for female cubs, while both models showed higher survival rates/effects for sub-adult and adult females relative to males. However, the sex ratio for sub-adults was male-biased. The shift in demographic signals may associate with changes in age-related immigration rates of sub-adult males.     

Limb bone bilateral asymmetry: variability and commonality among modern humans

Humans demonstrate species-wide bilateral asymmetry in long bone dimensions. Previous studies have documented greater right-biases in upper limb bone dimensions--especially in length and diaphyseal breadth--as well as more asymmetry in the upper limb when compared with the lower limb. Some studies have reported left-bias in lower limb bone dimensions, which, combined with the contralateral asymmetry in upper limbs, has been termed "crossed symmetry." The examination of sexual dimorphism and population variation in asymmetry has been limited. This study re-examines these topics in a large, geographically and temporally diverse sample of 780 Holocene adult humans. Fourteen bilateral measures were taken, including maximum lengths, articular and peri-articular breadths, and diaphyseal breadths of the femur, tibia, humerus, and radius. Dimensions were converted into percentage directional (%DA) and absolute (%AA) asymmetries. Results reveal that average diaphyseal breadths in both the upper and lower limbs have the greatest absolute and directional asymmetry among all populations, with lower asymmetry evident in maximum lengths or articular dimensions. Upper limb bones demonstrate a systematic right-bias in all dimensions, while lower limb elements have biases closer to zero %DA, but with slight left-bias in diaphyseal breadths and femoral length. Crossed symmetry exists within individuals between similar dimensions of the upper and lower limbs. Females have more asymmetric and right-biased upper limb maximum lengths, while males have greater humeral diaphyseal and head breadth %DAs. The lower limb demonstrates little sexual dimorphism in asymmetry. Industrial groups exhibit relatively less asymmetry than pre-industrial humans and less dimorphism in asymmetry. A mixture of influences from both genetic and behavioral factors is implicated as the source of these patterns.     

Cremated human and animal remains of the Roman period--microscopic method of analysis (Sepkovcica, Croatia)

Human and animal cremated osteological remains from twelve graves of Roman Period from archaeological site Sepkovcica near Velika Gorica (Turopolje region, NW Croatia) were analysed. Beside the content of urns and grave pits, fillings of grave vessels like bowls, pots and amphoras from twentytwo grave samples were included in this study. The preservation of osteological and dental remains of human and animal origin was very poor, majority of fragments hardly reach lengths of 10 mm. Weight of each specimen barely exceeds 100 g per person. Apart from traditional macroscopic methods of analysing cremated remains, microscopic method for determination of age at death was also tested. Fragments of femoral bone diaphysis of eighteen persons whose remains had been found on the site were analysed. Person's age at death was presented in the range of five or ten years, and the long bone fragments of a child (infants) were detected. Taxonomic position for each analysed specimen was determined by microscopic analysis of animal cremated bones. Analysis results confirm validity of microscopic method in determination of age at death for human remains and taxonomic qualification of cremated animal remains from archaeological sites.     

Associations between the rates of maturation and growth in the short bones of the hand

Serial radiographs of the hand-wrist were used to analyze the associations within bones between the rates of change in skeletal maturity, diaphyseal and epiphyseal lengths and diaphyseal width. In previous studies of these children, it has been shown that these rates are linear in relation to chronological age. The associations between the rates of change in these parameters were analyzed using the slopes (b values) for regression lines flitted to the data in each child. In individual bones, most of the correlation coefficients were moderate to low; some were negative. For most associations in each sex they were relatively high for metacarpal II. The rates of skeletal maturation and diaphyseal elongation were correlated more highly in the girls than in the boys but the rates of skeletal maturation and epiphyseal elongation were correlated more highly in the boys. When bones were considered in groups, relatively high correlations were noted for the metacarpals and ray II, lower correlations were common for the middle and distal phalanges. There was no evidence of real neighborhood effects but marginal effects were present.     

Age determination on long bones in a skeletal subadults sample (b-12 years)

The skeletal age on the basis of the diaphyseal length of long bones was assessed. To this aim a sample of subadults skeleton, dated to last century, coming from the cemetery of Bologna was studied. The sample is composed by 79 males and 70 females between 0 and 12 years, whose chronological age and sex are known. Some information can be obtained by the means, standard deviation and graphs of the specimens grouped in age classes. The comparison with other studies confirms the interest of using standards based on direct measurements on long bones of known age and similar to the skeletal populations under study.     

Determination of adult stature from metatarsal length

The results of a study to determine the value of foot bones in reconstructing stature are presented. The data consist of length measurements taken on all ten metatarsals as well as on cadaver length from a sample of 130 adults of documented race, sex, stature, and, in most cases, age. Significant correlation coefficients (.58-.89) are shown between known stature and foot bone lengths. Simple and multiple regression equations computed from the length of each of these bones result in standard errors of estimated stature ranging from 40-76 mm. These errors are larger than those for stature calculated from complete long bones, but are approximately the same magnitude for stature calculated from metacarpals and fragmentary long bones. Given that metatarsals are more likely to be preserved unbroken than are long bones and given the ease with which they are accurately measured, the formulae presented here should prove useful in the study of historic and even prehistoric populations.     

Distribution and ontogenetic shifts in habitat and abundance of the temperate western blue groper, Achoerodus gouldii (Richardson)

Densities of juveniles western blue groper Achoerodus gouldii on exposed coasts of South Australia were slightly greater on granite than other substrata and increased with increasing bottom relief and declined with depth and increasing exposure. Sub-adults were in higher density on schists than on other substrata, and densities increased with increasing bottom relief, and declined with depth, increasing exposure and increasing algal canopy cover. Adults were in higher densities on schists, and abundances increased with depth and bottom relief. At a mesoscale A. gouldii was absent from gulfs and sheltered bays, except near their entrances, while at offshore islands juveniles were rare, sub-adults were in lower abundance, and adults in greater abundance, compared with mainland coasts. It is hypothesized that sub-adults may swim up to 60 km from settlement locations to exposed areas and to offshore islands. At a geographic scale, abundances of all three size classes of A. gouldii declined significantly from west to east over 2000 km of coast from the centre of the species' range to its eastern edge. Although A. gouldii is a protected species over part of its range, abundance of sub-adults and adults was significantly reduced by fishing, as shown by an index of fishing intensity. The mean size of sub-adult A. gouldii was also correlated with this index, suggesting that the observed geographic trend in sub-adult and adult abundance may be contributed to by fishing. Simulation showed that a high instantaneous fishing mortality rate of 0·8 per annum could explain the maximum observed reductions in mean size of sub-adult A. gouldii .     

Dietary protein level and skeletal development in the golden Syrian hamster

The hamster was used as a model for investigating the effect of low, moderate, and high protein intake (12, 18, and 36% casein) on bone mineral content. Animals fed the low level of protein between 3 and 8 months of age had a reduction in the weight of all skeletal components measured, with the exception of the diaphyseal portion of the long bones. Diaphyseal weight and calcium remained significantly lower when expressed as a percentage of body weight. However, urinary calcium excretion was not lower than that of animals consuming an adequate protein intake. Ingesting a high protein diet resulted in a significant increase in urinary calcium excretion, and a reduced amount of both mineral and organic material in the diaphyses. We conclude that long-term consumption of a high protein ration led to the development of a mild osteoporotic condition in the hamster which was limited to the diaphyseal portions of the long bones.     

Communalities for rates of diaphyseal elongation of short bones of the hand of children with Down syndrome

Communality indices for rates of elongation of diaphyses of short bones of the hand were computed from serial data for children with Down syndrome, 7 to 14 years of age. Communalities were larger for adjacent than for nonadjacent bones and also larger for bones grouped in rows rather than rays of the hand. This pattern is similar to that reported for normal children. Communality indices for rates of diaphyseal elongation for girls with Down syndrome were lower than those of boys with Down syndrome and normal children.