Using craniofacial fluctuating asymmetry to examine the effects of sex, socioeconomic status, and early life experiences on adult age at death in industrial England

OBJECTIVES

Historical evidence from 18th- and 19th-century England suggests that industrialization's impacts on health were largely negative, especially among marginalized groups. However, available documentary evidence is often biased toward adult men and rarely sheds light on the experiences of other members of the population, such as women and children. Craniofacial fluctuating asymmetry (FA) can serve as a proxy measurement of developmental instability and stress during development. This study examines the associations among age, sex, socioeconomic status (SES), and FA in skeletal samples from industrial-era England.

MATERIALS AND METHODS

The sample for this study comes from four industrial-era cemeteries from England (A.D. 1711-1857). Geometric morphometric analyses of three-dimensional landmark coordinate data were used to generate a measure of FA for each individual (Mahalanobis distance). A three-way ANOVA was used to evaluate the impacts of sex, SES, and FA scores on adult age at death (n = 168).

RESULTS

Significant associations existed between age at death and SES (p = 0.004) and FA scores (p = 0.094). Comparisons of the estimated means indicated that age at death was consistently higher among high SES individuals and individuals with FA scores less than one standard deviation from the mean.

CONCLUSIONS

This study supports findings from previous studies that have suggested that the differences in resource access and environmental buffering generated by socioeconomic inequality can impact longevity and patterns of mortality among socioeconomic status groups. Likewise, stress in early life-evinced by craniofacial fluctuating asymmetry-can influence observed patterns of longevity in adults decades later.

The effect of sex and age on facial shape directional asymmetry in adults: A 3D landmarks-based method study

OBJECTIVES

Facial directional asymmetry research, including age-related changes, is crucial for the evaluation of treatment of craniofacial malformations/trauma in orthodontics, facial surgery and forensic sciences. The aim was to describe facial directional asymmetry (DA) in different age categories of adults using 3D methods. According to our hypothesis, facial shape DA (1) depends on sex; (2) differs among age groups; and (3) has wider variability in older age.

MATERIAL AND METHODS

A cross-sectional sample of healthy Czech adults without craniofacial trauma or anomalies consisted of 300 3D facial models (151 females). The age-range in the study was between 20-80 years. The shape asymmetry of 28 3D landmarks was evaluated using geometric morphometrics and multivariate statistics.

RESULTS

The manifestation of DA was similar in both sexes and in each age category; however, there were some statistical differences. In contrast to the ideal symmetrical face, the mean asymmetrical faces tended to create a slightly bent "C" shape of the midline. Therefore, the upper face was rotated slightly clockwise and the lower face counter-clockwise. The right eye was located slightly higher, with the nasal tip and mandibular region tilting to the left. Sex differences in facial DA were significant before the age of 40. DA was more significant in the youngest males than in the oldest, while the women's DA did not change.

CONCLUSIONS

The DA patterns were similar in both sexes and in all age categories (a slightly bent C shape of the midline); however, some significant local differences between male age groups were found. A significantly more pronounced asymmetry compared to other age groups was found only in the youngest males from 20 to 40 years. Moreover, significant sexual dimorphism of DA rapidly decreased after middle age, likely caused by the same age-related changes of the face during aging.

Testing different 3D techniques using geometric morphometrics: Implications for cranial fluctuating asymmetry in humans

This study aimed to test the performance of 3D digitizer, CT scanner, and surface scanner in detecting cranial fluctuating asymmetry. Sets of 32 landmarks (6 in the midline and 13 bilateral) were acquired from 14 archeological crania using a 3D digitizer, and from 3D models generated from a CT scanner and surface scanner using Viewbox 4. Levels of shape variation were analyzed in MorphoJ using Procrustes analysis of variance and Principal component analysis. Intra-observer error accounted for 1.7%, 1.8%, and 4.5% of total shape variation for 3D digitizer, CT scanner, and surface scanner respectively. Fluctuating asymmetry accounted for 15%-16% of total shape variation. Variation between techniques accounted for 18% of total shape variation. We found a higher level of missing landmarks in our surface scan data than for both 3D digitizer and CT scanner data, and both 3D model-based techniques sometimes obscured taphonomic damage. All three 3D techniques are appropriate for measuring cranial fluctuating asymmetry. We advise against combining data collected with different techniques.

Assessments of bilateral asymmetry with application in human skull analysis

As a common feature, bilateral symmetry of biological forms is ubiquitous, but in fact rarely exact. In a setting of analytic geometry, bilateral symmetry is defined with respect to a point, line or plane, and the well-known notions of fluctuating asymmetry, directional asymmetry and antisymmetry are recast. A meticulous scheme for asymmetry assessments is proposed and explicit solutions to them are derived. An investigation into observational errors of points representing the geometric structure of an object offers a baseline reference for asymmetry assessment of the object. The proposed assessments are applicable to individual, part or all point pairs at both individual and collective levels. The exact relationship between the developed treatments and the widely used Procrustes method in asymmetry assessment is examined. An application of the proposed assessments to a large collection of human skull data in the form of 3D landmark coordinates finds: (a) asymmetry of most skulls is not fluctuating, but directional if measured about a plane fitted to shared landmarks or side landmarks for balancing; (b) asymmetry becomes completely fluctuating if one side of a skull could be slightly rotated and translated with respect to the other side; (c) female skulls are more asymmetric than male skulls. The methodology developed in this study is rigorous and transparent, and lays an analytical base for investigation of structural symmetries and asymmetries in a wide range of biological and medical applications.

A New Integrated Tool to Calculate and Map Bilateral Asymmetry on Three-Dimensional Digital Models

The observation and the quantification of asymmetry in biological structures are deeply investigated in geometric morphometrics. Patterns of asymmetry were explored in both living and fossil species. In living organisms, levels of directional and fluctuating asymmetry are informative about developmental processes and health status of the individuals. Paleontologists are primarily interested in asymmetric features introduced by the taphonomic process, as they may significantly alter the original shape of the biological remains, hampering the interpretation of morphological features which may have profound evolutionary significance. Here, we provide a new R tool that produces the numerical quantification of fluctuating and directional asymmetry and charts asymmetry directly on the specimens under study, allowing the visual inspection of the asymmetry pattern. We tested this show.asymmetry algorithm, written in the R language, on fossil and living cranial remains of the genus Homo. show.asymmetry proved successful in discriminating levels of asymmetry among sexes in Homo sapiens, to tell apart fossil from living Homo skulls, to map effectively taphonomic distortion directly on the fossil skulls, and to provide evidence that digital restoration obliterates natural asymmetry to unnaturally low levels.

Are entheseal changes and cross-sectional properties associated with the shape of the upper limb?

OBJECTIVES

Reconstruction of the activity of past human populations can be carried out using various skeletal markers; however, the relationship between these methods is not fully understood. Therefore, the main aim of this article is to analyze the relationship between entheseal changes, cross-sectional properties, and variability in the shape of the upper limb.

MATERIALS AND METHODS

The analyzed material consisted of CT images of 71 right scapulae, humeri, and ulnae belonging to the same individuals from a mediaeval population located in Poland. For each series of bones for the same individual, skeletal markers such as: cross-sectional properties, entheses and shape variation were assessed. Next, correlations between these three skeletal indicators were calculated.

RESULTS

In general, the models showed that only sex influences entheses. Multivariate regression revealed significant correlation only between ulnar auricular surface shape and two types of mean score for entheses.

DISCUSSION

The findings are inconsistent and stand in contradiction to other research; therefore, we suggest that an assessment of individual activity should be carried out, using as many post-cranial elements as possible and a variety of methods. This approach will ensure more accurate reconstruction of the activity levels and patterns of archeological groups.

Fluctuating body asymmetry in young Polish women in relation to childhood socioeconomic status

The aim of this study was to analyse the relationship between childhood socioeconomic conditions and body asymmetry in young Polish women. The study measured fluctuating asymmetry (FA), which refers to small random deviations from perfect symmetry in bilaterally paired body structures. Data were obtained from 620 female students aged from 19 to 25 years recruited from Jagiellonian University in Cracow, Poland. The research was carried out in the period from January 2016 to May 2017. A composite fluctuating asymmetry (cFA) of the women was calculated using five bilateral body traits. The lengths and widths of the women’s ears, lengths of their 2nd and 4th digits and wrist widths of the right and left sides of the body were measured twice using standard methodology. The following data were collected in a questionnaire: degree of urbanization of the woman’s place of residence during childhood, number of older siblings, parental education and woman’s dominant hand. The results showed a tendency for FA to fall with an increase in parental education, and to rise with an increase in number of older siblings. The level of FA was significantly lower in women from rural areas than in those from cities. The results of the study show that FA in early adulthood is significantly associated with socioeconomic status during childhood, and confirm that the level of FA in adulthood may be a good indicator of stress factors in the early stages of development.

Three-dimensional geometry of human tibial anterior curvature in chronologically distinct population samples of Central Europeans (2900 BC - 21st century AD)

Several lines of bioarchaeological research have confirmed the gradual decline in lower limb loading among past human populations, beginning with the transition to agriculture. The goal of this study was to assess whether human tibial curvature reflects this decline, with a special emphasis on the time-span during which the pace of technological change has been the most rapid. Our study is the first (1) to apply longitudinal curvature analysis in the antero-posterior (A–P) and medio-lateral (M–L) planes to the human tibia, and (2) that incorporates a broad temporal population sample including the periods of intensification of agriculture, urbanization and industrialization (from 2900 BC to the 21^st century AD; N = 435) within Czech territories. Using three-dimensional geometric morphometrics, we investigated whether anterior tibial curvature mirrors assumed diminishing lower limb loading between prehistoric and industrialized societies and explored its shape in all three dimensions. Results showed the continuous trend of A–P straightening of the shaft. This straightening was associated with a relative sigmoidal curve accentuation in the M-L plane. Given the timescale involved and the known phenomenon of declining mobility, such adaptive changes in bone geometry can be interpreted in terms of the diminishing biomechanical demands on the tibia under different living conditions.

Three-dimensional geometry of human tibial anterior curvature in chronologically distinct population samples of Central Europeans (2900 BC - 21st century AD)

Several lines of bioarchaeological research have confirmed the gradual decline in lower limb loading among past human populations, beginning with the transition to agriculture. The goal of this study was to assess whether human tibial curvature reflects this decline, with a special emphasis on the time-span during which the pace of technological change has been the most rapid. Our study is the first (1) to apply longitudinal curvature analysis in the antero-posterior (A-P) and medio-lateral (M-L) planes to the human tibia, and (2) that incorporates a broad temporal population sample including the periods of intensification of agriculture, urbanization and industrialization (from 2900 BC to the 21^st century AD; N = 435) within Czech territories. Using three-dimensional geometric morphometrics, we investigated whether anterior tibial curvature mirrors assumed diminishing lower limb loading between prehistoric and industrialized societies and explored its shape in all three dimensions. Results showed the continuous trend of A-P straightening of the shaft. This straightening was associated with a relative sigmoidal curve accentuation in the M-L plane. Given the timescale involved and the known phenomenon of declining mobility, such adaptive changes in bone geometry can be interpreted in terms of the diminishing biomechanical demands on the tibia under different living conditions.

Developmental stability and environmental stress: A geometric morphometrics analysis of asymmetry in the human femur

OBJECTIVES

The evaluation of developmental stability (DS) by measuring fluctuating asymmetry (FA), a bioindicator of general cumulative stress, is an approach that has often been used to characterize health status in past populations. New techniques of geometric morphometrics now enable a better appreciation of FA than before, with a more refined quantification of variation. The aim of our study is to determine the effectiveness of geometric morphometrics analyses of asymmetry in the human femur for the study of individual DS and inferring health status of human populations.

MATERIALS AND METHODS

We conducted a comparative analysis between two diachronic populations of distinct and known health status. Two samples of 70 pairs of adult femurs from individuals of comparable age range and sex were selected and CT-scanned. For each 3D reconstruction, two sets of 27 landmarks were digitized to quantify and minimize the effect of measurement error on the evaluation of FA.

RESULTS

While the measurement of FA in femoral centroid size seemed comparable between the samples, the amount of FA in femoral shape differed. Individuals who experienced high levels of environmental stress presented higher intra-individual variation. In parallel, results did not reveal any significant differences in DS between sexes or age groups.

DISCUSSION

The geometric morphometrics analysis of femoral asymmetry was effective for distinguishing two populations. After considering various factors of influence, genetics and biomechanics seem to have a limited impact on the results. Expressing FA appears to be normal but dependent on the disturbances of DS produced by environmental stress.

Comparison of cranial fluctuating asymmetry between normal and pathological specimens from a modern Thai skeletal group

The purpose of this study was to compare fluctuating asymmetry (FA) levels across cranial modules of normal and pathological cranial specimens. It was examined whether pathological specimens have significantly higher FA scores than normal specimens in cranial regions affected by a developmental disorder. For this study, a modern Thai skeletal sample from Chulalongkorn University was analyzed. Ninety-two cranial landmarks were digitized on 66 adult and eight sub-adult normal specimens and on five pathological specimens including two adults with abnormal palates, two sub-adults with craniosynostosis, and one sub-adult with natal absence of nasal bones. In sub-adults, FA scores of specimens with developmental disorders were significantly higher than normal specimens in the entire cranium (p = 0.041) and vault (p = 0.025). However, comparisons excluding specimen with coronal craniosynostosis were not statistically significant. In adult specimens, comparisons of FA scores in each separate cranial module were also not statistically significant. These results suggest that elevated cranial FA may not be confined to the specific cranial region with the developmental disorder.

Bilateral asymmetry of the humerus in Neandertals, Australian aborigines and medieval humans

OBJECTIVES

Bilateral asymmetry of diaphyseal shape and size may be a reflection of relative activity levels and patterns of habitual biomechanical stress in the upper arms of Neandertals and Homo sapiens. The main purpose of our study was to assess the level of directional asymmetry of humeral cross sections in Neandertals, recent Australian aborigines, and medieval farmers.

MATERIALS AND METHODS

Indices of directional and absolute asymmetry (%DA and %AA) of humeral cross-sectional properties in Neandertals and recent Homo sapiens were calculated. Evenly distributed semilandmarks around the external and internal borders of cortical bone were digitized in the course of computed tomography for analysis of shape differences between sides of the body.

RESULTS

The medieval farmers were characterized by significant %DA and %AA for polar second moment of area (J), ratio of maximum to minimum second moments of area, and ratio of antero-posterior to medio-lateral bending strength. In Australian aborigines, only J in males shows significant %DA and %AA, while Neandertals exhibit no significant asymmetry of any cross-sectional properties. Differences in cross-sectional shape between sides of the body were established in all three analyzed groups.

DISCUSSION

High levels of directional asymmetry of cross-sectional shape and properties in medieval farmers may be caused by the performance of more physically demanding tasks using one side of the body from an early age in that population. Various patterns of asymmetry in Neandertals and modern humans may be caused by different habitual behaviors during growth, eco-geographic patterns in body proportions, genetic factors, and differences in ontogeny.

Influence of physiological stress on the presence of hypoplasia and fluctuating asymmetry in a medieval population from the village of Sypniewo

This study aims to estimate the levels of physiological stress in the medieval rural population of Sypniewo by evaluating patterns of fluctuating asymmetry (FA) and enamel hypoplasia (EH), and provide information on the influence of physiological stress during the prenatal and perinatal period on early childhood development. Stress is defined as any external or internal condition that challenges homeostasis of an organism. FA is associated with physiological stress occurring mainly during prenatal development and early childhood. The level of FA is thought to reflect the intensity of the stressor(s). EH is caused by physiological stress such as nutritional instability during the first years of life. The studied material consisted of 126 skulls from the village of Sypniewo (Poland). Cranial radiographs were taken in postero-anterior (P-A) and basal views. The images were scanned and calibrated. Measurements of the cranium were used to estimate FA. The presence of EH was assessed using standard anthropological methods The highest levels of FA were observed in the region of the cranial base. EH was observed in 29% of individuals from the rural skeletal series. There was no statistically significant correlation between FA and EH occurrence or between sex and the studied stress indicators.

Developmental instability and its relationship to mental health in two historic Dutch populations

This study aimed to assess the magnitude and patterns of fluctuating asymmetry as an indicator of developmental instability between two urban archeological Dutch populations. The sample comprised of 209 adult individuals representing the general population of Alkmaar, the Netherlands, dating to the 18th to early 19th century (Grote Kerk, n=134), and a psychiatric hospital sample of the 19th to early 20th century (Meerenberg, n=75). Fluctuating asymmetry was assessed from left and right measurements recorded from various traits on the cranium, mandible, and dentition. Three non-specific skeletal indicators of stress were documented to aid in the interpretation of the differences in asymmetry. No significant difference in developmental instability, as reflected by fluctuating asymmetry, was apparent between the two populations. However, individuals who presented with skeletal lesions indicative of stress were significantly more asymmetric than individuals who did not present with any of the lesions. The observed frequencies of the pathological changes and socio-economic history suggest that the two populations experienced similar levels of stress, even though the source and duration of the stress might have been different. The possibility that the mentally institutionalized are not as developmentally unstable as suggested by previous research should be considered.

Socioeconomic Status Is Not Related with Facial Fluctuating Asymmetry: Evidence from Latin-American Populations

The expression of facial asymmetries has been recurrently related with poverty and/or disadvantaged socioeconomic status. Departing from the developmental instability theory, previous approaches attempted to test the statistical relationship between the stress experienced by individuals grown in poor conditions and an increase in facial and corporal asymmetry. Here we aim to further evaluate such hypothesis on a large sample of admixed Latin Americans individuals by exploring if low socioeconomic status individuals tend to exhibit greater facial fluctuating asymmetry values. To do so, we implement Procrustes analysis of variance and Hierarchical Linear Modelling (HLM) to estimate potential associations between facial fluctuating asymmetry values and socioeconomic status. We report significant relationships between facial fluctuating asymmetry values and age, sex, and genetic ancestry, while socioeconomic status failed to exhibit any strong statistical relationship with facial asymmetry. These results are persistent after the effect of heterozygosity (a proxy for genetic ancestry) is controlled in the model. Our results indicate that, at least on the studied sample, there is no relationship between socioeconomic stress (as intended as low socioeconomic status) and facial asymmetries.

Diachronic changes in size and shape of human proximal tibia in Central Europe during the latest 1200 years

During the past twelve centuries, the stature of Central European inhabitants has increased significantly with corresponding changes in the size of lower limb bones. The aim of our study was to determine whether these changes have occurred strictly in relation to size or if the shape of skeletal structures has been altered simultaneously. Diachronic size and shape changes in the proximal part of tibia in a Central European population (Czech Republic) were studied using geometric morphometrics (principal components analysis, Hotelling's test, linear discriminant analysis). The study sample consisted of 183 three-dimensional (3D) models of adult tibiae dating to the early Middle Ages (N=65), early 20th century (N=60), and from a modern Czech population (N=57). A positive secular trend in size manifested only between the two modern Czech populations (the 20th century vs. the 21st century), a time range shorter than one century. By contrast, landmark-based shape analyses revealed significant differences in tibial morphology over the three periods covered in the study. In particular, progressive changes were observed in the position of tibial tuberosity (shifted medially), the inclination of the line connecting tuberosity with anterior edge of the tibial plateau (sloped down), the reshaping of the lower back condyle boundary (shifted posteriorly), and reshaping of the medial contour of the medial condyle (shifted anteriorly). Changes in the shape of the proximal tibial extremity across the chronologically distinct groups indicated the existence of discreet but convincing microevolutionary trends involving this anatomical structure.

Sexual Dimorphism of the Human Tibia through Time: Insights into Shape Variation Using a Surface-Based Approach

In this paper we present a three-dimensional (3D) morphometrical assessment of human tibia sexual dimorphism based on whole bone digital representation. To detect shape-size and shape differences between sexes, we used geometric morphometric tools and colour-coded surface deviation maps. The surface-based methodology enabled analysis of sexually dimorphic features throughout the shaft and articular ends of the tibia. The overall study dataset consisted of 183 3D models of adult tibiae from three Czech population subsets, dating to the early medieval (9-10th century) (N = 65), early 20th century (N = 61) and 21st-century (N = 57). The time gap between the chronologically most distant and contemporary datasets was more than 1200 years. The results showed that, in all three datasets, sexual dimorphism was pronounced. There were some sex-dimorphic characteristics common to all three samples, such as tuberosity protrusion, anteriorly bowed shaft and relatively larger articular ends in males. Diachronic comparisons also revealed substantial shape variation related to the most dimorphic area. Male/female distinctions showed a consistent temporal trend regarding the location of dimorphic areas (shifting distally with time), while the maximal deviation between male and female digitized surfaces fluctuated and reached the lowest level in the 21st-century sample. Sex determination on a whole-surface basis yielded the lowest return of correct sex assignment in the 20th-century group, which represented the lowest socioeconomic status. The temporal variation could be attributed to changes in living conditions, the decreasing lower limb loading/labour division in the last 12 centuries having the greatest effect. Overall, the results showed that a surface-based approach is successful for analysing complex long bone geometry.

Early Life Conditions and Physiological Stress following the Transition to Farming in Central/Southeast Europe: Skeletal Growth Impairment and 6000 Years of Gradual Recovery

Early life conditions play an important role in determining adult body size. In particular, childhood malnutrition and disease can elicit growth delays and affect adult body size if severe or prolonged enough. In the earliest stages of farming, skeletal growth impairment and small adult body size are often documented relative to hunter-gatherer groups, though this pattern is regionally variable. In Central/Southeast Europe, it is unclear how early life stress, growth history, and adult body size were impacted by the introduction of agriculture and ensuing long-term demographic, social, and behavioral change. The current study assesses this impact through the reconstruction and analysis of mean stature, body mass, limb proportion indices, and sexual dimorphism among 407 skeletally mature men and women from foraging and farming populations spanning the Late Mesolithic through Early Medieval periods in Central/Southeast Europe (~7100 calBC to 850 AD). Results document significantly reduced mean stature, body mass, and crural index in Neolithic agriculturalists relative both to Late Mesolithic hunter-gatherer-fishers and to later farming populations. This indication of relative growth impairment in the Neolithic, particularly among women, is supported by existing evidence of high developmental stress, intensive physical activity, and variable access to animal protein in these early agricultural populations. Among subsequent agriculturalists, temporal increases in mean stature, body mass, and crural index were more pronounced among Central European women, driving declines in the magnitude of sexual dimorphism through time. Overall, results suggest that the transition to agriculture in Central/Southeast Europe was challenging for early farming populations, but was followed by gradual amelioration across thousands of years, particularly among Central European women. This sex difference may be indicative, in part, of greater temporal variation in the social status afforded to young girls, in their access to resources during growth, and/or in their health status than was experienced by men.

Geometric morphometrics: does the appearance of the septal aperture depend on the shape of ulnar processes?

Many theories have been suggested to explain the etiology of septal apertures (SA) of the humerus. The influence of genes, the size of ulnar processes, joint laxity, and bone robusticity, have been discussed; however, the problem has not yet been solved. The main aim of this study was to examine the influence of ulnar and humeri shape on septal aperture formation, using geometric morphometric analyses. Skeletal material from an early-mediaeval cemetery located in Western Poland was used. The material comprised two groups: (1) ulnae and humeri with septal apertures, (2) ulnae and humeri without septal apertures. From a CT image, three-dimensional reconstructions were obtained for all bones. Then, 25 landmarks were distributed on each proximal end of the ulnae and 30 landmarks on the distal ends of the humeri. Shape differences between ulnae in joints with and without SA were significant for the left and right sides of the body. The shapes of the left and right distal ends of humeri with SA differed significantly from those without SA. Similar results were obtained for the right side of the body. Ulnae from joints with SA were characterized by a more pronounced olecranon process, a smaller articulated coronoid process and a more tightly curved trochlear notch than ulnae from joints without SA. Humeri with SA included wider and deeper olecranon fossae and smaller and less curved articular surfaces. These results partly coincide with the results of other research indicating the influence of olecranon processes on lamina perforation.

The prevalence and distribution of dental caries in four early medieval non-adult populations of different socioeconomic status from Central Europe

OBJECTIVES

The aim of the study was to map the dental health status in non-adult individuals and to verify whether and how the existence of caries in the non-adult age group is associated with the different socio-economic status of early medieval populations.

MATERIAL AND METHODS

We studied the dental remains from the acropolis of the Mikulčice settlement agglomeration, where members of the higher social classes were buried, and from the Mikulčice hinterland. Overall, we evaluated 2544 teeth/3714 alveoli of deciduous dentition and 1938 teeth/2128 alveoli of permanent dentition. We determined the number of individuals with dental caries (i.e., caries frequency index, F-CE) and the proportion of teeth/alveoli with caries/ante-mortem tooth loss (i.e., caries intensity index, I-CE).

RESULTS

We found no statistical significant difference in the F-CE values between the Mikulčice hinterland and the acropolis. In addition, we found no statistically significant difference in the proportion of teeth with carious lesions (I-CE) either in the case of deciduous dentition or in the case of permanent dentition between the hinterland and the acropolis. In the case of permanent dentition, the statistically significant highest proportion of carious lesions (I-CE) was found in Mikulčice I (p ≤ 0.05). We confirmed an increase in the rate of caries with age.

CONCLUSIONS

The level of caries at all of the studied medieval locations was very low. We presume that lifestyle and the associated dietary habits and hygienic practices of the individuals or population groups had a greater influence on dental caries than did the socio-economic status of these individuals.

Canalization and developmental instability of the fetal skull in a mouse model of maternal nutritional stress

Nutritional imbalance is one of the main sources of stress in both extant and extinct human populations. Restricted availability of nutrients is thought to disrupt the buffering mechanisms that contribute to developmental stability and canalization, resulting in increased levels of fluctuating asymmetry (FA) and phenotypic variance among individuals. However, the literature is contradictory in this regard. This study assesses the effect of prenatal nutritional stress on FA and among-individual variance in cranial shape and size using a mouse model of maternal protein restriction. Two sets of landmark coordinates were digitized in three dimensions from skulls of control and protein restricted specimens at E17.5 and E18.5. We found that, by the end of gestation, maternal protein restriction resulted in a significant reduction of skull size. Fluctuating asymmetry in size and shape exceeded the amount of measurement error in all groups, but no significant differences in the magnitude of FA were found between treatments. Conversely, the pattern of shape asymmetry was affected by the environmental perturbation since the angles between the first eigenvectors extracted from the covariance matrix of shape asymmetric component of protein restricted and control groups were not significantly different from the expected for random vectors. In addition, among-individual variance in cranial shape was significantly higher in the protein restricted than the control group at E18.5. Overall, the results obtained from a controlled experiment do not support the view of fluctuating asymmetry of cranial structures as a reliable index for inferring nutritional stress in human populations.