Double lamellae in trabecular osteons: towards a new method for age estimation by bone microscopy.

The study of anatomical ageing has a dual purpose in biological anthropology. On the one hand, it can provide insights into age associated changes in the body and thus widen the understanding of human senescence; and on the other hand it can provide means of estimation of age at death. This paper explores normal ageing in the pattern of remodelling of trabecular bone in humans. The material consists of necropsies of bone from the ilium of 25 males. A 1 cm2 prism extending from the outer to the inner surface of the iliac bone was removed from men who had died with no clinical signs of diseases, which would usually affect bone structure and metabolism. The samples were cut, and studied by light microscopy at a magnification of 100 x. New trabecular bone is formed in disk-shaped osteons with a clear double lamellar structure. In each sample, the number of double lamellae in a mean of 21 complete osteons was counted. The mean number of lamellae was taken as the measurement of interest. The log of the mean counts was found to regress linearly and with no evidence for heteroscedacity on age. The correlation between the two was high and negative (r=-0.83, p<0.001). The material is too limited to provide a useful basis for age estimation as such, but the study demonstrates the potential for palaeodemographic application of the method.

Sex-related risks of trauma in medieval to early modern Denmark, and its relationship to change in interpersonal violence over time.

Skeletons from three Danish cemeteries, Sortebrødre, Tirup, and St. Mikkel, that collectively held 822 adults (>15 years) and spanned the medieval to early modern periods (ca. AD 1100-1610) show that men, in general, experienced more bone fractures than women. Men were three times more likely to have healed cranial vault and ulnar shaft fractures than women, with many of these bones presumably broken in interpersonal violence. More women, however, broke distal radii, presumably often the result of falls. Both sexes suffered more cranial fractures than modern Danes, with the proportional difference for men and women being about the same. The difference in cranial trauma frequencies between historic-period and modern Danes has implications for a decline over the past several centuries in interpersonal violence that scholars in other disciplines have inferred from historical sources.

Low bone mineral density in the femoral neck of medieval women: a result of multiparity?

An archaeological investigation of a medieval cemetery gave us the opportunity to investigate 49 Danish skeletons dating from 1000 to 1250 A.D. and to compare them with 298 contemporary Danes (aged 19-79 years) and assess the millennial trend in bone mineral density (BMD) in populations considered genetically closely related. BMD and bone mineral apparent density (BMAD) of the femoral neck were measured by dual-energy X-ray absorptiometry (DEXA) and transformed into z scores. BMD(zscore) was significantly lower in medieval women (-0.54 +/- 0.25, p = 0.04), whereas BMD(zscore) in medieval men was significantly higher (0.55 +/- 0.22, p = 0.02). In medieval women, BMD(zscore) tended to increase with age (r = 0.42, p = 0.07), whereas no change was seen in men (r = 0.19, not significant [n.s.]). Also, BMAD(zscore) was significantly elevated in medieval men (1.00 +/- 0.28, p < 0.01), but in medieval women no difference was found (-0.28 +/- 0.21, n.s.). However, the correlation between BMAD(zscore) and age was significant in the medieval women where it increased with advancing age (r = 0.49, p = 0.03). In conclusion, medieval women had lower BMD when compared with contemporary women, but this relationship was reversed in women who survived to older ages. In contrast, medieval men had significantly higher BMD as compared with contemporary men at all ages. The observed lower BMD in medieval women can be explained by the well-known selective mortality among the younger women. A high birth rate and prolonged periods of lactation are the main reasons for the observed increased mortality, and therefore can also very likely explain the associated low BMD. The increase in the incidence of osteoporosis in modern elderly women could possibly, or partially, be explained by the survival of women who would have died prematurely had they lived in earlier centuries.

[Continuously diminishing menarcheal age in Denmark]. / Et fortsat fald i menarchealderen i Danmark.

INTRODUCTION: The aim was to follow the development of the parameters of the distribution of age at menarche in Danish women in recent decades. MATERIAL AND METHODS: The study is based on retrospective data from six different samples with a total of 42,784 women, born in the period 1923-1973. RESULTS: We report a renewed decline in the mean menarcheal age in a large Danish sample after a period with a halt in the trend towards an earlier age at menarche in many North European countries. We find a continuously declining mean menarcheal age in Denmark in women born in the years 1964-1973. In a sample of textile workers born in the years 1939-1968 (n = 12,605) we find a higher mean menarcheal age of one year. DISCUSSION: The results indicate that menarcheal age is still delayed in certain groups in Denmark. It can therefore be expected that the menarcheal age will fall even more in the future.

[Suicide among patients with apoplexy. An epidemiological study]. / Selvmord hos patienter med apopleksi. En epidemiologisk undersøgelse.

The purpose of this study was, on the basis of a cohort of patients with a discharge diagnosis of stroke (ICD8 code: 430-438) diagnosed in the period 1.4.1973-31.12.1989 in a representatively selected area of Denmark (County of Funen), to estimate whether or not the risk of suicide in stroke patients was increased compared to the background population, i.e. the total population of the County of Funen. The patients were followed for causes of death until end of 1989. Standard Mortality Ratios for suicide standardized for age and sex in male and female stroke patients were calculated. A total of 37,869 stroke patients were included in the study, 140 committed suicide in the study period (80 females and 60 males). Standard Mortality Ratio for suicide was significantly increased for all stroke patients. For women below 49 years and from 50-59 years Standard Mortality Ratios were 1376 and 1378 respectively. For men below 49 years and from 50-59 years Standard Mortality Ratios were 656 and 580 respectively. The suicides did not occur at any specific time-point after the stroke. The results of this study emphasize the need, concurrently with improvements in prevention and treatment of stroke, to improve the care of patients suffering from the impairment of a stroke. This is a continuous process, and studies are needed in order to decide how this is best done.

[Age at menarche among schoolgirls in Odense. Is age at menarche still decreasing in Denmark?]. / Menarkalderen blandt skolepiger i Odense. Falder menarkalderen fortsat i Danmark?

The average age at the menarche has decreased from the 1850s to the 1950s. It is controversial whether there has been a continued decrease since the 1950s. The object of this investigation is to illustrate whether this trend has continued into the 1980s. This study is based on the ages at the menarche as recalled by 908 girls aged 14-16 years in 40 schools in Odense. The information was obtained during intervals of differing lengths and consequently, the parameters of the distribution of the age at the menarche were estimated in a randomly grouped normal distribution. The average age at the menarche was found to be the same throughout the municipality (13.27 years; 95% confidence limit 13.20-13.35). The variations were found to be significantly differentiated by the type of school district. The variations were low in the suburbs and in the surrounding rural districts, higher in the inner city areas and highest among girls attending private schools. Compared with the results from other recent Danish studies, these findings suggest a halt in the decline of the average age at the menarche, which may be temporary.

[Discrepancies between diagnosed asthma, asthma-like symptoms and a test for abnormal lung function]. / Manglende overensstemmelse mellem diagnosticeret asthma, asthmalignende symptomer og test for abnorm luftvejsfunktion.

For the diagnosis of asthma, it is neither clear to which degree various tests and symptoms identify the same subjects nor how these characteristics are best combined. We assessed the interrelationship between physician-diagnosed asthma, asthma-like symptoms and abnormal airway function in a population based sample of 495 12-15 year old schoolchildren. Participants filled in a questionnaire and underwent baseline spirometry (FEV1%), provocation with treadmill exercise (EXE) and with inhaled methacholine (PD15), and monitoring of peak expiratory flow (PEF) twice daily for two weeks. Most symptomatic subjects with any test positive were identified by PD15 alone (75%) or in combination with PEF monitoring (89%). Although interest agreement was weak (kappa < 0.40 for all pairs), significant associations were found between PD15 and EXE, between PEF and EXE and between FEV1% and PD15. However, PEF variability and methacholine responsiveness seem to identify different varieties of airway pathophysiology, and the combined use of the two tests may be helpful as an epidemiological screening tool for asthma.

Diversity in auxology: between theory and practice. Proceedings of the 18th Aschauer Soiree, 13th November 2010.

Auxology has developed from mere describing child and adolescent growth into a vivid and interdisciplinary research area encompassing human biologists, physicians, social scientists, economists and biostatisticians. The meeting illustrated the diversity in auxology, with the various social, medical, biological and biostatistical aspects in studies on child growth and development.

Growth variation, final height and secular trend. Proceedings of the 17th Aschauer Soiree, 7th November 2009.

Growth and body height have always been topics interesting to the public. In particular, the stupendous increase of some 15-19cm in final adult height during the last 150 years in most European countries (the "secular trend"), the concomitant changes in body and head proportions, the tendency towards early onset of sexual maturation, the changes in the age when final height is being reached, and the very recent trend in body mass index, have generated much scientific literature. The marked plasticity of growth in height and weight over time causes problems. Child growth references differ between nations, they tend to quickly become out of date, and raise a number of questions regarding fitting methods, effects caused by selective drop-out, etc. New findings contradict common beliefs about the primary importance of nutritional and health related factors for secular changes in growth. There appears to be a broad age span from mid-childhood to early adolescence that is characterised by a peculiar insusceptibility. Environmental factors that are known to influence growth during this age span appear to have only little or no impact on final height. Major re-arrangements in height occur at an age when puberty has almost been completed and final height has almost been reached, implying that factors, which drive the secular trend in height, are limited to early childhood and late adolescence.

Geographical distribution of some Danish surnames: reflections of social and natural selection.

Geographical differences in the frequencies of eight common surnames in Jutland (Denmark) are analysed using data from telephone directories of 121 exchanges. All the names showed a significant geographical surplus variance, which was divided into trend and patchiness components reflecting the history of the names. The surplus variance of surnames with restricted areas of origin was dominated by a large trend component; for surnames with an originally more even distribution, the patchiness component was dominant. The patterns of distribution were affected by processes which modelled natural selection with linkage disequilibrium. The combined patchiness within the clusters of exchanges gave information about patterns of local migration and level of social integration in the communities. Areas situated in boundary regions show high levels of patchiness.

Season of birth and recalled age at menarche.

All 8th-form schoolgirls from the municipality of Odense in Denmark were asked at what age they reached menarche, and 886 girls (97.6%) gave this information. There is no evidence for seasonality in the time of birth but for far more girls than expected menarche occurred during winter or summer and fewer than expected during spring and autumn. This pattern appears primarily in girls living in the suburbs and was not seen in those living in central Odense. The seasonality appears to be brought about by differences in mean age at menarche according to time of the year at birth.

PIP: This study examines seasonality of age of menarche among 908 schoolgirls 14-16 years in 1987 from Odense, Denmark and seasonality of birth. A medial examination was provided and information received from 69% (611) on the month of menstruation, 16.9% (150) on the season, and 9.7% (86) who were premenarcheal. The GLM, 3.77, statistical package was used to estimate the mean and variance of data which were treated as grouped observations from a normal distribution. The results show seasonality for time at menarche (x2=40.99, df=3,p.005), and confirms Hungarian findings. Winter and summer are the expected seasons of menarche. There was no seasonality to the birthrate (x2=2.85, df=3,p.4) even when subdivided by type of district, and no interaction between season of birth and season of menarche (x2=10.05,db=9,p.3). Month of birth and month of menarche were also unrelated 9x2=1.06,df=1,p.03). In a Fourier method of analysis of the means of age at menarche, the fit of the curve shows that the mean age at menarche is low for girls in November, December, May, June, and July, and higher in February, March, August, September, and October. The major new findings is that the cause of menarche seasonality is the different mean age of menarche of girls born in different seasons. The results also do not appear to be a consequence of outliers in the peak months (March-September). 2 way analysis of variance for variances and mean was used to analyze months of menarche by 4 seasons (Feb-Apr, May-July, Aug-Oct, Nov-Jan) and district for possible social effects. The results were a statistically significant effect of seasonal differences and season/district interaction on mean age at menarche. Variances are significantly different due to larger variance for age at menarche among girls attending private school (var=1.70,db=91) than public schools (var=1.241, db=783). This reflects the diversity in the private population which is less well off and ethnically more diverse and less exposed to changing weather conditions. It appears that there are ecological differences between living in a suburb and in an inner city area that alters the biological response to it.

Epidemiological approach to the paleopathological diagnosis of leprosy.

In paleopathology it is usually assumed that modern diagnostic criteria can be applied to infectious diseases in the past. However, as both the human species and populations of pathogenic microorganisms undergo evolutionary changes, this assumption is not always well-founded. To get valid estimates of the frequency (the point prevalence at death) of leprosy in skeletal samples, sensitivity, specificity, and sample frequency must be estimated simultaneously. It is shown that more than three symptoms must be evaluated in at least three samples in order to reach estimates with well-described properties. The method is applied to three skeletal samples from Medieval Denmark; the samples were scored for the presence of seven osteological conditions indicating leprosy. For the osteological conditions, sensitivity varied from 0.36-0.80, and specificity from 0.58-0.98. The frequency of leprosy in the three samples was: Odense (a lepers' institution), 0.98, 95% CI 0.64-1.00; Malmö (urban cemetery), 0.02, 95% CI 0.00-0.07; and Tirup (rural cemetery), 0.36, 95% CI 0.23-0.46. It is concluded that it is indeed possible to estimate disease frequencies without reference to modern standards, and that leprosy occurred with widely differing frequencies in different segments of the Medieval population in southern Scandinavia.

Body proportions in a medieval village population: effects of early childhood episodes of ill health.

The purpose of this paper is to widen the observational basis for analysing growth patterns. To reach this aim measurements taken on skeletons from a small Danish village, Tirup, are analysed in relation to evidence for ill health in early childhood (age 1-6 years, inclusive). Enamel hypoplasia is taken as the indicator of health problems in this age range. It is found that episodes of ill health in childhood played no part in the formation of adult size. In order to analyse size independent aspects of adult morphology shape related variables like residual height and principal component scores were analysed. It is found that the episodes of ill health leading to hypoplasia did indeed change the score on some size independent linear combinations of the raw measurements. It is concluded that the kind of stress in childhood leading to enamel hypoplasia probably modified the relationship between long bone lengths and stature. It appears that the association between vertebral body breadth measurements and living height is--at least in part--brought about by episodes of ill health in early childhood.

Time to pregnancy--a model and its application.

Biological fertility is poorly measured by the number of children born in industrially advanced societies. The time elapsing from when a couple decides to have a child to clinically recognizable pregnancy is a useful alternative. Time to pregnancy can be collected in broad categories in large samples. A model for condensing important information from such data is presented, which fits several large samples of reported waiting times. It is shown that multiparous women conceive more quickly than primiparous women.

PIP: Biological fertility is poorly measured by the number of children born in industrially advances societies. The deliberate intervention in human reproduction in many European countries has led to a declining fertility that is no gauge on the ability to reproduce which is of considerable epidemiological interest. Time to pregnancy can be collected in broad categories in large samples. A model condensing important information from such data is presented. In the model it is assumed that mean waiting time to pregnancy is constant for each couple but differs among couples, and that conceptions take place in continuous time (i.e. conceive not only once in each menstrual cycle). The data analyzed consisted of 3 studies where subjects replied to the question 'for how long did you try to become pregnant before you succeeded?'. 2 studies involved Danish mothers who recently gave birth and 1 study questioned pharmacy assistants who gave birth to a single live-born child. The model presented fits several large samples of reported waiting times. It is shown that multiparous women conceive more quickly than primiparous women. The model fits short and moderate waiting times but not long and very long waiting times.

Distribution of age at menopause in two Danish samples.

We analyzed the distribution of reported age at natural menopause in two random samples of Danish women (n = 176 and n = 150) to determine the shape of the distribution and to disclose any possible trends in the distribution parameters. It was necessary to correct the frequencies of the reported ages for the effect of differing ages at reporting. The corrected distribution of age at menopause differs from the normal distribution in the same way in both samples. Both distributions could be described by a mixture of two normal distributions. It appears that most of the parameters of the normal distribution mixtures remain unchanged over a 50-year time lag. The position of the distribution, that is, the mean age at menopause, however, increases slightly but significantly.

Relationship between biological and social aspects of sexual maturity among young Danes.

Representative samples of 286 young Danish women and 336 young men aged 16-20 years were interviewed in 1984-1985 about menarcheal age and age at 1st sexual intercourse. The medium age at menarche was 13.13 years. Altogether 212 (74%) of females and 225 (70%) of males were sexually experienced. Among females the medium age at sexual debut is related to that at menarche in the 4 cohorts investigated where it was possible to estimate both variables. Consequently, the behavioral aspects of sexual maturity among females is heavily influenced by this purely biological index of maturation. Although the median age at 1st sexual intercourse could only be estimated in 3 of the male cohorts an indication of association between the median ages at sexual debut is clear, and they seem to follow the median age of menarche closely. The interrelationship between this biological factor (menarche) and a social event (1st sexual intercourse) indicates a causality in sexual development of young contemporary Danes.

Waiting time to pregnancy and pregnancy outcome among Danish workers in the textile, clothing, and footwear industries.

The relationship between time from planned to achieved pregnancy and pregnancy outcome has been studied in a group of 18,658 workers in the textile, clothing and footwear industries. Information on pregnancy outcome and delay in conception in the period 1979-84 was collected by self administered questionnaires in 1985. The response rate was 70.3%. During the study period there had been 5,171 live births and 708 spontaneous abortions. Information on delay in conception was collected in broad categories. The data were analysed by means of a newly developed statistical parametric model in order to collect all possible information from the highly grouped data. Median waiting time before a pregnancy which ended in spontaneous abortion was 1.68 times longer than median waiting time before a pregnancy leading to a live birth. There seems to be a correlation between the length of the waiting time and abortion.

PIP: This study examined, in a cohort of 18,658 women members 40 years of age in the textile, clothing, and footwear national union in 1985 in Denmark, the time span between planned and achieved pregnancy as it relates to pregnancy outcome. The response rate of the self-administered questionnaire was 70.3%. Information on all pregnancies between 1979 and 1984 was collected. Outcome data revealed 5171 pregnancies and 708 spontaneous abortions. Distribution of waiting times was modeled using Boldsen and Schaumburg techniques and assumes constant conception probability. Differences were represented by a gamma distribution with defined alpha and beta parameters. the results show that the waiting times resulting in spontaneous abortion are more likely to be unknown (chi square = 5.49, df = 1, p.05). There is a high likelihood that unplanned pregnancies result in spontaneous abortion (odds ration = 2.72, 95% confidence interval = 1.93-3.77). Abortion risk expected values closely approximate observed values of pregnancy resulting in spontaneous abortion. The median waiting time span for a pregnancy leading to spontaneous abortion is 1.68 times the median waiting time for pregnancy with a live birth. The risk of spontaneous abortion increases with the length of waiting time. Social conditions such as heavy smoking regimes, exposure to industrial chemicals, and lower educational levels may partially explain the results. There was a longer waiting time before conception also. A similar study among pharmacy assistants showed that outcome of pregnancy was unrelated to waiting time. Pregnancies may be considered unplanned more often when spontaneous abortion results, and may bias results. The long waiting times may mean impaired conception or very early pregnancy loss or an unknown biological explanation. Further research is suggested on other groups of women and waiting times.

Childhood conditions and adult height.

Self-reported height and childhood conditions among 1711 Danish male general workers born between 1923 and 1940 were analysed. No significant associations were found between adult height and father's occupation, growing up with both parents, paternal unemployment, sickness among the parents, parents receiving disability pension, economical problems in childhood, area of residence in childhood, and years at school. The study therefore provides no support for the hypothesis that poor childhood conditions are the cause of low adult height in this socially very homogeneous sample.

The distribution of stature among Danish conscripts in 1852-56.

Stature measurements on large samples of unselected 22-year-old Danish males from the period 1852-56 are analysed. Data are given for 18 rural counties and the City of Copenhagen. The distribution of stature deviates significantly and systematically from Normality in all counties. A mixture of two Normal distributions with equal variances describes the empirical distribution of stature in the 18 rural counties and explains important aspects of the distribution of stature in the City of Copenhagen. This mixed structure of the population is accomplished by a factor reducing the mean stature of a fraction of the population by nearly 20 cm. The factor generating this mixed population is probably genetic and inbreeding may play a major part in raising the frequency of affected persons to the observed values, 0.2-2%. The mean stature of the majority of the population and the mixing proportion show significant geographical variation. The frequency of the small subpopulation is generally highest in the least-developed main province, Jutland, and lower on the islands, particularly in and around the City of Copenhagen. On the Zealand group of islands the mean stature of the majority of the population is highest in the most developed area, whereas the reverse occurs in Jutland.