Estimation stature from X-rays of metacarpals in the Turkish population

Determination of stature is as important as the determination of sex and age when analyzing and identifying the remains of skeletons. Stature, in an approximate and widespread manner, is determined by the femur and tibia, i.e. those long bones that affect stature directly. However, when long bones are not available or when they are found in a very badly preserved condition that does not permit any estimation on stature, then other bones of the body can also be used for this purpose. The aim of this study is to determine stature with the help of metacarpals in the Turkish population. In this study, by using the X-ray films of metacarpal bones of 100 females and 100 males, regression equations have been set up for 5 metacarpal bones. The coefficients of correlation existing between the metacarpal bones and stature, together with the standard errors of these equations, have been intensively examined in this study. The results of studies conducted by other researchers such as Musgrave & Harneja (1978) and Meadows & Jantz (1992) have been compared with the results of our study. As a result of this comparison, the difference existing between them has been found to be significant according to the results of the t-test (p < 0.05, p < 0.01 and p < 0.001). The significance of such results proves that the general body characteristics and body proportions of populations are differing from each other and therefore specific regression equations for the different populations have to be set up.     

Evolving dispersal and age at death

Traditional, and often competing, theories on ageing agree that a programmed age at death must have arisen as a side effect of natural selection, and that it can have no adaptive value of its own. However, theoretical models suggest that ageing and programmed death can be adaptive. Travis J. M. J. suggested that if fecundity declines with age, a programmed age of death evolves through kin selection and that the nature of dispersal is crucial as it determines the degree of spatial structure and hence the strength of kin selection. Here, using a similar model, we consider the interplay between dispersal and age of death. We incorporate more realistic dispersal kernels and allow both dispersal and age of death to evolve. Our results show each trait can evolve in response to the other: earlier age of death evolves when individuals disperse less and greater dispersal distances evolve when individuals are programmed to die later. When we allow dispersal and age of death to evolve at the same time we typically find that dispersal evolves more rapidly, and that ageing then evolves in response to the new dispersal regime. The cost of dispersal is crucial in determining the evolution of both traits. We argue both that ageing is an overlooked ecological process, and that the field of gerontology could learn a lot from evolutionary ecology. We suggest that it is time to develop the field of ecological gerontology and we highlight a few areas where future work might be particularly rewarding.     

Estimation of stature in children from second metacarpal measurements.

On the basis of 552 boys and 542 girls aged 6 to 20 years, this study examines the estimation of stature from dimensions and maturity of second metacarpals by means of linear regression equations. A combination of length and width measurements provided a more accurate estimation than each measurement individually. When taken alone, length produced a more accurate estimation than width. Sex and age factors are useful for the estimation of stature, though these variables are often unknown in the isolated bone. The samples are divided into immature and mature groups (according to skeletal maturity). Regardless of sex, stature could be estimated from the metacarpal length and width with a standard error of 4.19 cm by means of a multiple linear equation in the immature group. The mature group should be considered with adults for this purpose. Thus, taking into account their skeletal maturity, living stature could be practically estimated from the second metacarpal with significant degrees of accuracy in children.     

Estimation of morbid risk and age at onset with missing information.

Investigators of genetic illnesses are currently employing life-table techniques to estimate the lifetime risk of disease and the age-at-onset distribution. This methodology assumes that onset ages are known for affected individuals and that censoring ages are known for unaffected individuals. We extend these methods to incorporate affected individuals with unknown onset ages and unaffected persons with unknown censoring ages and illustrate how conventional life-table methods can produce seriously biased estimates, particularly of lifetime risk. The methodology is not restricted to genetic illnesses and can be applied to more complex illnesses with unknown etiology. We present an example for Huntington disease, which is generally assumed to be a Mendelian autosomal dominant disease, yielding estimates of lifetime risk of .503 +/- .70 and mean onset age of 47.7 +/- 3.1 years for offspring with a single affected parent. When conventional life-table techniques are employed, these estimates are .238 +/- .032 and 43.2 +/- 2.2.     

Family similarities in the age at coronary death in familial hypercholesterolaemia.

In a combined Norwegian and British study of the age at death from coronary heart disease of heterozygotes for familial hypercholesterolaemia (FH) the correlation coefficients within families for 43 sib pairs was 0-70 and for 14 first cousin pairs 0-61. There was no significant correlation between the age at death and serum cholesterol concentration in either series. The intrafamilial correlations suggest that information about the age at death from coronary heart disease in heterozygotes within families may have some prognostic value and may also be interpreted as evidence for genetic heterogeneity in FH.     

Reconstruction of paleodemographic characteristics from skeletal age at death distributions: perspectives from Hitotsubashi, Japan

This is a demographic exploration of the city of Edo, which reveals the changes that accompanied its urbanization and analyzes the skeletal remains of 207 individuals from a specific site in Tokyo (Hitotsubashi), using several paleodemographic approaches. A comparison of the three methods employed herein suggests that the Bayesian and maximum likelihood estimation techniques provide more plausible mortality patterns than the direct method of age estimation because the direct method of age estimation relies on published age intervals for the auricular surface and that would account for the underestimation of old people relative to the other two methods. Analyses using these new approaches indicate a short life span tendency for the people of Hitotsubashi. Although we cannot rule out methodological problems of adult-age estimation, one plausible interpretation of that life expectancy is an inadequate food supply and a poor public health situation. This study suggests that, in Tokugawa Japan, urbanization might have imposed health risks, increasing the risk of mortality. Analysis of demographic data from Hitotsubashi has refined our understanding on the impact of urbanization on the Edo period, and presents new perspectives on paleodemography in Japan.     

Interobserver error in macroscopic methods of estimating age at death from the human skeleton

This research evaluates the interobserver error when the macroscopic methods recommended by American and European anthropologists to estimate age at death of a skeleton, were applied to a sample of the Terry Collection (Smithsonian Institution, Washington D.C.). Although no statistical differences among observers were found for any of these methods, small dissimilarities suggest that techniques using a narrower scale of categories produce greater agreement among researchers. The present study is within a wider research project designed to evaluate the accuracy of these methods, when applied to an identified (age known) sample of 963 skeleton from the Terry Collection.     

A comparison of two methods for the microscopic determination of age at death.

The precision and accuracy of the Kerley and Ahlqvist-Damsten microscopic methods of age determination are compared. Both methods were applied to the same sample of 40 femoral thin sections of documented age at death. The results indicate that (1) both methods can be used with equal precision, as suggested by comparable observer errors; and (2) the Kerley method produces overall more accurate age estimates. The low previously published standard error of the Ahlqvist-Damsten method (6.71 years) apparently results from the uneven age distribution and small size (20) of their sample.     

Effects of social class,sex, and region of residence on age at death from cystic fibrosis.

To determine the time trend in age at death from cystic fibrosis and the independent effects of social class, sex, and region of residence mortality data for England and Wales from 1959 to 1986 were analysed. Median age at death increased from 6 months in 1959 to 17 years in 1986 and was higher in most years from 1970 in male patients (by one to six years) and in social classes with non-manual occupations (by one to 12 years). Independent odds ratios for death above the median age for the year of death (calculated for years from 1974, when regions of residence were coded by regional health authority area) were 1.47 (95% confidence interval 1.16 to 1.87) in male compared with female patients and 2.75 (2.16 to 3.52) in non-manual compared with manual social classes. The independent odds of death at above the median age also varied significantly among regions of residence by a ratio of up to 2.67. Social class, sex, and region of residence are all potential determinants of survival of patients with cystic fibrosis. Social class is particularly likely to confound the effect of management in specialist centres on survival.     

Median age at death as an indicator of premature mortality

The median age at death from certain diseases was calculated for each year for 1969-85 and compared with that at death from all causes. The results indicated the impact of these diseases in terms of premature mortality and changes over time. Cancer was a more important cause of premature mortality among women than among men. For cancer of the cervix the median age at death increased appreciably whereas for cancer of the lung in women it slightly decreased. The median age at death is easy to calculate, does not require standardisation, and has a useful role.     

Estimation of gestational age from study of amniotic fluid and clinical assessment.

Study of 108 samples of amniotic fluid obtained between 28 and 42 weeks'' gestation from 101 patients revealed that in normal pregnancies the creatinine concentration, lecithin/sphingomyelin (L/S) ratio and percentage of fat cells correlated better with the gestational age of the newborn--assessed by clinical criteria--than did the bilirubin and sodium concentrations. A creatinine concentration of 1.75 mg/dL or more, an L/S ratio of 4 or more and a fat cell percentage of 10 or more correlated significantly with a gestational age of 37 weeks or more. In abnormal pregnancies (those with obstetric or medical complications, or both) the mean creatinine concentration in the amniotic fluid was significantly less than expected for gestational age in fetal dysmaturity and greater than expected when the mother had diabetes. The mean L/S ratio in the amniotic fluid was elevated when the mother had hypertension or smoked and in cases of fetal dysmaturity or long interval between rupture of the membranes and delivery, whereas it was significantly lower than normal when the mother had diabetes. The mean bilirubin concentration in the amniotic fluid was significantly lower than normal when the mother had hypertension. When the mother had diabetes, maturity of the fetal lung, liver, skin and brain appeared to be delayed, according to the values for the amniotic fluid constituents.     

Determination of age at death: assessment of an algorithm of age prediction using numerical three-dimensional CT data from pubic bones

The determination of age at death is an important part of physical and forensic anthropology. Because of resistance to decomposition and the simplicity/accuracy ratio, the direct observation of the os pubis by Suchey-Brooks phase analysis is the preferred reference system for determination of age at death. We propose an age-prediction system using a pubic symphysis numerical database obtained from CT x-ray through quantification of age-linked parameters. Our system increases the accuracy of age estimation and at the same time preserves the integrity of the archeological material.     

Revisions in the microscopic method of estimating age at death in human cortical bone.

Problems recently discovered in the Kerley method of estimating age at death from cortical microstructure are discussed. Kerley's original data have been re-analyzed to produce new regression equations and to document the original field size.     

Flexible parametric modeling of survival from age at death data: A mixed linear regression framework

Many long-lived vertebrate species are under threat in the Anthropocene, but their conservation is hampered by a lack of demographic information to assess population long-term viability. When longitudinal studies (e.g., Capture-Mark-Recapture design) are not feasible, the only available data may be cross-sectional, for example, stranding for marine mammals. Survival analysis deals with age at death (i.e., time to event) data and allows to estimate survivorship and hazard rates assuming that the cross-sectional sample is representative. Accommodating a bathtub-shaped hazard, as expected in wild populations, was historically difficult and required specific models. We identified a simple linear regression model with individual frailty that can fit a bathtub-shaped hazard, take into account covariates, allow goodness-of-fit assessments and give accurate estimates of survivorship in realistic settings. We first conducted a Monte Carlo study and simulated age at death data to assess the accuracy of estimates with respect to sample size. Secondly, we applied this framework on a handful of case studies from published studies on marine mammals, a group with many threatened and data-deficient species. We found that our framework is flexible and accurate to estimate survivorship with a sample size of 300 . This approach is promising for obtaining important demographic information on data-poor species.     

Estimation of age structure in anthropological demography.

The past decade has produced considerable debate over the feasibility of paleodemographic research, with much attention focusing on the question of reliability of age estimates. We show here that in cases where age is estimated rather than known, the traditional method of assigning individuals to age classes will produce biased estimates of age structure. We demonstrate the effect of this bias both mathematically and by computer simulation, and show how a more appropriate method from the fisheries literature (the "iterated age length key") can be used to estimate age structure. Because it is often the case that ages are also estimated for extant groups, we suggest that our results are relevant to the general field of anthropological demography, and that it is time for us to improve the statistical basis for age structure estimation. We further suggest that the oft noted paucity of older individuals in skeletal collections is a simple result of the use of inappropriate methods of age estimation, and that this problem can be rectified in the future by using maximum likelihood estimates of life table or hazard functions incorporating the uncertainty of age estimates.