Response of bone and enamel formation to nutritional supplementation and morbidity among malnourished Guatemalan children

Association between Short Stature at Grade 1 and Permanent Teeth Caries at Grade 6 in Elementary School Children in Japan: A Population-Based Cohort Study

Short stature in children is a marker of low nutritional status and has been suggested to be associated with dental caries. However, longitudinal studies on this topic are scarce. Data from a longitudinal study of elementary school children in Adachi City, Tokyo, Japan, were analyzed. In 2015, caregivers of children at grade 1 answered questionnaires, and information on dental caries and height measured at school health checkups was merged and followed to grade 6 (N = 3576; follow up rate = 83.3%). The association between short stature at grade 1 (-2.01 standard deviation (SD)--3.00 SD, or <-3.00 SD in height-for-age according to the World Health Organization criteria) and the number of decayed, missing, or filled permanent teeth (DMFT) at grade 6 was examined using multivariable Poisson regression with robust standard error. After adjusting for confounders, children with a short stature at grade 1 had a higher DMFT number at grade 6: the mean ratios (95% confidence interval) were 1.17 (0.89-1.54) and 2.18 (1.03-4.64) for children with a height-for-age -2.01 SD--3.00 SD, and those with a height-for-age < -3.00, respectively. Short stature at grade 1 could be a marker of future dental caries in the permanent teeth at grade 6.

Assessing the association of skeletal indicators of stress with mean age-at-death in sub-adults

OBJECTIVES

The present study investigated the association of skeletal indicator of stress presence with mean age-at-death as a means of understanding whether commonly studied indicators are indeed indicative of increased frailty.

MATERIALS AND METHODS

Using a medieval Gaelic population from Ballyhanna (Co. Donegal), the present study assessed the association between skeletal indicators of stress and mean age-at-death using the Kaplan-Meier survival function with log rank test to determine whether these indicators were associated with younger age-at-death, and therefore increased frailty, in sub-adults only (0 to 18 years, N = 139) and through comparison to an all-ages cohort (N = 318).

RESULTS

Only linear enamel hypoplasia was found to be associated with significantly decreased survivorship across the all-ages cohort but, conversely, was associated with increased survivorship when analysis was restricted to sub-adults. All other indicators assessed were associated with increased age-at-death for both all-age cohorts and sub-adult cohorts (cribra orbitalia), increased age-at-death when assessing all ages only (porotic hyperostosis and healed periosteal lesions); or were sufficiently rare in adults to prevent comparative analysis (stunting and micronutrient deficiency). Increased survivorship in individuals with higher numbers of co-morbid skeletal indicators was observed for both sub-adults alone and all age cohort.

DISCUSSION

These findings suggest that these commonly recorded skeletal indicators may be more accurately viewed simply as records of stressor exposure and subsequent survival only, rather than providing evidence that these sub-adults are frailer than their similarly aged-at-death peers. Thus, the demographic and sociocultural context is essential to the interpretation of observed skeletal indicators of stress.

Skeletal evidence of structural violence among undocumented migrants from Mexico and Central America

OBJECTIVES

We examine the prevalence and sociodemographic risk factors of skeletal indicators of stress in forensic samples of undocumented migrants from Mexico and Central America.

MATERIALS AND METHODS

Cranial and dental remains of 319 migrants recovered in the Arizona and Texas borderlands were assessed for porotic hyperostosis (PH), cribra orbitalia (CO), and linear enamel hypoplasias (LEH). Logistic regression models for each condition were estimated to test for associations with biological sex, age, recovery location, and whether individuals were identified. Additional models estimated for a subsample of identified migrants included region of origin, residential context, and community indigeneity.

RESULTS

The full sample shows moderate crude prevalence of CO (9.6%) and LEH (34.1%), and a high prevalence of PH (49.6%). Significantly higher odds of PH are associated with being male (2.16 times higher), unidentified (1.89 times higher), and recovered in Arizona (3.76 times higher). Among identified migrants, we fail to find associations significant at the p < 0.05 level between skeletal stress and all sociodemographic variables except age.

DISCUSSION

The factors associated with PH may be related to influences on decisions to migrate and diversity among migrant sending regions. The skeletal evidence for early life stress is generally consistent with common public health concerns among impoverished communities in the region. The lesions themselves are viewed as embodied risk of physiological disturbance when resource access is structured by higher-level social, economic, and political forces. Forensic anthropologists would benefit from increased sensitivity to embodied structural violence among the vulnerable individuals and communities they serve.

Does age estimated from teeth forming in different early life periods show differential discrepancy with known age?

OBJECTIVES

The aim of this study is to explore growth discrepancies in the dentition of impoverished children and examine how dental development is impacted by environmental influences throughout childhood, thereby identifying which teeth are more sensitive to the effects of biocultural factors and are consequently less useful to predict age.

METHODS

Length measurements of developing teeth (deciduous and permanent) were taken from individuals of known age and sex (n = 61) from the Certosa collection, a 19th century skeletal assemblage representing Italian children of low socioeconomic status. Discrepancies between age estimates based on tooth length and chronological age were calculated, and the accuracy and precision of age prediction between earlier forming teeth and later forming teeth were compared.

RESULTS

Deciduous teeth produced more precise dental age estimates (mean age discrepancy -0.092 years), while discrepancies between chronological age and age based on developing permanent dentition were larger (-0.628 years). The difference between these discrepancies in age estimates for deciduous and permanent teeth was significant (p < 0.001), indicating that age prediction from deciduous tooth length is more accurate than age predicted using permanent tooth length.

CONCLUSION

An increasing variation and delay in tooth length for age reflects increasing susceptibility to biocultural factors, which impacts tooth growth during the course of childhood. Teeth whose development occurs earlier in life are less variable in their growth and provide more accurate estimations of age as a result.

Metabolic diseases in Andean paleopathology: Retrospect and prospect

John Verano's 1997 synthesis of Andean paleopathology guided two decades of research and was instrumental in establishing modern Andean paleopathology. This paper reviews the current state and new directions in the study of skeletal metabolic disorders in the Central Andean archaeological record. Key historical, ecological, methodological, and contextual issues intersect with the study of metabolic bone diseases in Andean paleopathology. This paper further examines known temporal and spatial distribution of these disorders, as well as the strengths and weaknesses of the record of linear enamel hypoplasias, cribra orbitalia, porotic hyperostosis, scurvy, and rickets. Many other metabolic bone diseases have yet to be documented such as pellagra, hypophosphatasia, osteomalacia, and mucopolysaccharidosis among others. This work closes with considerations in the search for these undocumented diseases, but such an effort is only one part of new wave of advancements just on the horizon. The study of metabolic diseases in Andean paleopathology can lead the development of more sophisticated approaches to data collection, analysis, and interpretation - especially regarding theoretical interpretations from various bodies of social theory to the Developmental Origins of Health and Disease hypothesis, life history approaches, and phenotypic adaptive plasticity and constraint.

Insights on patterns of developmental disturbances from the analysis of linear enamel hypoplasia in a Neolithic sample from Liguria (northwestern Italy)

OBJECTIVE

To assess developmental disturbances through the analysis of linear enamel hypoplasia (LEH) frequency and to infer environmental stress and life history within Neolithic communities from Liguria (Italy).

MATERIALS

43 unworn/minimally worn permanent anterior teeth of 13 individuals recovered from nearby caves and dated to c. 4800-4400 cal. BCE.

METHODS

LEH defects were identified with high-resolution macrophotos of dental replicas, age at LEH was calculated via perikymata counts. LEH defects matched between two or more teeth were considered as systemic disturbances. LEH frequency by age classes was analyzed via GLZ and Friedman ANOVA.

RESULTS

Number of matched defects per individual range between 2-12. The mean LEH per individual was highest in the 2.5-2.99 age category, with a significant increase relative to earlier growth stages, followed by a decline.

CONCLUSION

LEH may reflect life-history in the local ecology of Neolithic Liguria, where several individuals with osteoarticular tuberculosis have been recorded. Disease burden may have triggered developmental disturbances around the time of weaning. Age at first defect was negatively correlated with age at death and positively with the total number of defects, suggesting that early stress may have affected survivorship.

SIGNIFICANCE

The study contributes to the reconstruction of ecological pressures among Neolithic people of Liguria, and informs on environmental challenges during the Neolithic adaptive expansion.

LIMITATIONS

The visual examination of macrophotos is prone to observer error; mid-crown tends to display more visible LEH due to tooth architecture.

SUGGESTIONS FOR FURTHER RESEARCH

Apply different quantitative methods to examine severity and duration of disturbances.

Enamel neonatal line thickness in deciduous teeth of Australian children from known maternal health and pregnancy conditions

BACKGROUND

Physiological disruptions to early human development have implications for health and disease in later life. Limited research has explored how prenatal factors influence dental development in children of mothers with known pregnancy conditions. Enamel in human deciduous teeth begins forming in utero and is highly susceptible to physiological upsets experienced perinatally. The moment of birth itself is marked in deciduous enamel by the Neonatal Line (NNL) as a baby transitions from the uterine to external environment. This study evaluates the effect of maternal health factors that include stress and alcohol consumption on NNL in teeth from Australian children.

STUDY DESIGN AND SUBJECTS

Mothers (n = 53) were interviewed about their health during pregnancy and experience of birth. Sixty-five deciduous teeth (incisors, molars, one canine) from their children were donated for histological examination. Neonatal line thickness was measured from thin sections and evaluated against maternal and neonatal factors using statistical analyses, controlling for tooth type and birth number.

RESULTS AND CONCLUSIONS

The only maternal factor of a statistically significant effect on NNL thickness was alcohol consumption. Children of mothers who drank occasionally during pregnancy had a thicker NNL when compared to children of mothers who abstained. These results suggest that maternal lifestyle factors influence NNL formation possibly due to physiological changes that disrupt calcium homeostasis during enamel deposition. We highlight large intra-specific variation in human NNL expression. The potential of dental sampling in identifying children with prenatal exposure to alcohol is suggested.

Patterns of funerary variability, diet, and developmental stress in a Celtic population from NE Italy (3rd-1st c BC)

Little is known about the types of social organization characterizing the pre-Roman Celtic populations of Italy. Here, we explore the funerary variability characterizing the late Iron Age site of Seminario Vescovile (SV: Verona, Italy, 3rd-1st c. BC), and test its possible correlation to diet and relative exposure to developmental stressors. Patterns on funerary treatment (N = 125), δ13C and δ15N (N = 90), and linear enamel hypoplasia (N = 47) from SV are compared, and their possible association with sex and age-at-death further discussed. Results point to the presence at SV of variable funerary customs while at the same time demonstrating a rather homogenous diet and exposure to developmental stressors: funerary treatment is mainly correlated to age-at-death but do not appear to be associated to either isotopic patterns or hypoplasia frequencies. Accordingly, even if some weak social differentiation may have characterized the individuals buried at SV, this was not reflected in markedly differing living conditions. Our study is the first to attempt an exploration of the links between age, sex, funerary variability, and diet in a pre-Roman Celtic community from Italy. While highlighting the potential of a multifaceted approach in bioarcheology, it also points to a series of analytical and theoretical issues relevant when trying to disentangle the cultural and biological dimensions of social differentiation in the past.

Bioarchaeological profile of stress and dental disease among ancient high altitude Himalayan communities of Nepal

OBJECTIVES

This study examines biological indicators of dental disease and nonspecific stress in human remains of three high altitude Himalayan archaeological sites to test whether shared ecological constraints led to similar bioarchaeological profiles in these markers.

METHODS

Samples (n = 170) derive from three sites in Nepal dating to two periods (400-50 BCE and c. 400-650 CE). Dental diseases (caries, antemortem tooth loss, and abscesses) were assessed by both the number of individuals and the number of elements observed, while childhood stress markers included observation of growth disruptions (enamel hypoplasia and adult femur length/stature) and cranial porosities. Statistical analysis included chi-square and Fisher's exact tests for categorical data and ANOVA and t-tests for metric data.

RESULTS

There are significant differences between the sites and sexes in frequencies of dental diseases in the adult samples. There are low frequencies of childhood stress markers overall and the femur length data show no significant differences across sites, but significant sexual dimorphism within each site. Females have reduced stature compared to contemporary Tibetan samples residing at a similar elevation.

CONCLUSIONS

Variations in dental disease frequencies between the sites may be due to local variations in microenvironment, cultural, and/or temporal differences in resource availability, food consumption and preparation, as well as the age structure of the samples. The low frequencies of markers for nonspecific stress may be indicative of the ability of these ancient Himalayan groups to successfully meet the challenges posed by the extreme conditions of high altitude living through biocultural adaptations.

Enamel biorhythms of humans and great apes: the Havers-Halberg Oscillation hypothesis reconsidered

The Havers-Halberg Oscillation (HHO) hypothesis links evidence for the timing of a biorhythm retained in permanent tooth enamel (Retzius periodicity) to adult body mass and life history traits across mammals. Potentially, these links provide a way to access life history of fossil species from teeth. Recently we assessed intra-specific predictions of the HHO on human children. We reported Retzius periodicity (RP) corresponded with enamel thickness, and cusp formation time, when calculated from isolated deciduous teeth. We proposed the biorhythm might not remain constant within an individual. Here, we test our findings. RP is compared between deciduous second and permanent first molars within the maxillae of four human children. Following this, we report the first RPs for deciduous teeth from modern great apes (n = 4), and compare these with new data for permanent teeth (n = 18) from these species, as well as with previously published values. We also explore RP in teeth that retain hypoplastic defects. Results show RP changed within the maxilla of each child, from thinner to thicker enameled molars, and from one side of a hypoplastic defect to the other. When considered alongside correlations between RP and cusp formation time, these observations provide further evidence that RP is associated with enamel growth processes and does not always remain constant within an individual. RP of 5 days for great ape deciduous teeth lay below the lowermost range of those from permanent teeth of modern orangutan and gorilla, and within the lowermost range of RPs from chimpanzee permanent teeth. Our data suggest associations between RP and enamel growth processes of humans might extend to great apes. These findings provide a new framework from which to develop the HHO hypothesis, which can incorporate enamel growth along with other physiological systems. Applications of the HHO to fossil teeth should avoid transferring RP between deciduous and permanent enamel, or including hypoplastic teeth.

The magnitude of changes in linear growth within Taiwanese families: intrinsic sex-associated biology, socially mediated behaviors, or both?

OBJECTIVE

This study evaluates competing hypotheses about implications of greater female growth canalization for differences in male and female growth as developmental settings improve.

PARTICIPANTS AND METHODS

Intergenerational declines in gender bias and rapid economic growth in Taiwan permit assessment of the two hypotheses using anthropometric and background information from 107 Taiwanese parents and their young adult offspring. Differences in parents' values were first evaluated across grandfathers' occupational status categories reflecting good to relatively poor early circumstances in the parental generation. The extent of intergenerational change in heights or knee heights within 56 father-son pairs were then compared with those in 51 statistically independent mother-daughter pairs across the same occupational categories using repeated measures analyses.

RESULTS

Change in mean heights and knee heights across grandfathers' occupational categories were noticeably greater for fathers than mothers. Overall, intergenerational gains within families in height and knee height were statistically significant (p < 0.0005) in father-son (3.89 cm; 1.85 cm) and mother-daughter pairs (4.14 cm; 1.67 cm). However, among families where grandfather's occupations were "privileged," father-son pairs are similar in average height (Δ = -0.36 cm) and knee height (Δ = 0.53 cm) while mothers were significantly shorter (Δ = 3.88 cm) with shorter knee heights (Δ = 1.74 cm) than their daughters.

DISCUSSION

The hypothesis that females are inherently less capable of responding to growth promoting characteristics of early environments is not supported. Intergenerational declines in male preference combined with rapid but equitable economic growth better account for intergenerational changes reported.

Calcaneal Quantitative Ultrasound Indicates Reduced Bone Status Among Physically Active Adult Forager-Horticulturalists

Sedentary lifestyle contributes to osteoporosis and fragility fracture risks among modern humans, but whether such risks are prevalent in physically active preindustrial societies with lower life expectancies is unclear. Osteoporosis should be readily observable in preindustrial societies if it was regularly experienced over human history. In this study of 142 older adult Tsimane forager-horticulturalists (mean age ± SD, 62.1 ± 8.6 years; range, 50 to 85 years; 51% female) we used calcaneal quantitative ultrasonography (qUS) to assess bone status, document prevalence of adults with reduced bone status, and identify factors (demographic, anthropometric, immunological, kinesthetic) associated with reduced bone status. Men (23%) are as likely as women (25%) to have reduced bone status, although age-related decline in qUS parameters is attenuated for men. Adiposity and fat-free mass positively co-vary with qUS parameters for women but not men. Leukocyte count is inversely associated with qUS parameters controlling for potential confounders; leukocyte count is positively correlated within adults over time, and adults with persistently low counts have higher adjusted qUS parameters (6% to 8%) than adults with a high count. Reduced bone status characteristic of osteoporosis is common among active Tsimane with minimal exposure to osteoporosis risk factors found in industrialized societies, but with energetic constraints and high pathogen burden.

Low mineral density of a weight-bearing bone among adult women in a high fertility population

Evolutionary theories of aging posit that greater reproductive effort causes somatic decline given a fundamental trade-off between investing energy in reproduction and repair. Few studies in high fertility human populations support this hypothesis, and problems of phenotypic correlation can obscure the expected trade-off between reproduction and somatic condition. This cross-sectional study investigates whether greater reproductive effort is associated with reduced calcaneal bone mineral density (BMD) among female Tsimane forager-farmers of lowland Bolivia. We also investigate whether female Tsimane BMD values are lower than sex- and age-matched US reference values, despite the fact that Tsimane engage in higher physical activity levels that can increase mechanical loading. To measure calcaneal BMD, quantitative ultrasonography was performed on 130 women (mean ± SD age = 36.6 ± 15.7, range = 15-75) that were recruited regardless of past or current reproductive status. Anthropometric and demographic data were collected during routine medical exams. As predicted, higher parity, short inter-birth interval, and earlier age at first birth are associated with reduced BMD among Tsimane women after adjusting for potential confounders. Population-level differences are apparent prior to the onset of reproduction, and age-related decline in BMD is greater among Tsimane compared with American women. Greater cumulative reproductive burden may lower calcaneal BMD individually and jointly with other lifestyle and heritable factors. Fitness impacts of kin transfers in adulthood may determine the value of investments in bone remodeling, and thus affect selection on age-profiles of bone mineral loss.

A comparative study of stress episode prevalence and duration among Jomon period foragers from Hokkaido

This study reconstructs linear enamel hypoplasia (LEH) prevalence and stress episode duration among Jomon period foragers from Hokkaido, Japan (HKJ). Results are compared to Jomon period samples from coastal Honshu, Japan (HSJ) and Tigara Inupiat from Point Hope, Alaska (PHT) to provide a more comprehensive perspective on the manifestation of stress among circum-Pacific foragers. LEH were identified macro- and microscopically by enamel surface depressions and increased perikymata spacing within defects. Individuals with more than one anterior tooth affected by LEH were labeled as LEH positive. Stress episode durations were estimated by counting the number of perikymata within the occlusal wall of each LEH and multiplying that number by constants reflecting modal periodicities for modern human teeth. LEH prevalence and stress episode duration did not differ significantly between the two Jomon samples. Significantly greater frequencies of LEH were found in HKJ as compared to PHT foragers. However, HKJ foragers had significantly shorter stress episode durations as compared to PHT. This suggests that a greater proportion of HKJ individuals experienced stress episodes than did PHT individuals, but these stress events ended sooner. Similarity in stress experiences between the two Jomon samples and differences between the HKJ and PHT are found. These findings are important for two reasons. First, stress experiences of foraging populations differ markedly and cannot be generalized by subsistence strategy alone. Second, due to significant differences in episode duration, stress experiences cannot be understood using prevalence comparisons alone.

Linear enamel hypoplasia and growth in an Australian Aboriginal community: Not so small, but not so healthy either

BACKGROUND

While much is strongly suspected about synergisms linking courses of growth and development with nutrient intakes, immune function, disease exposures, and energy expenditures, debates remain regarding the probability of permanent impairments to growth and function under various circumstances.

AIM

This study tests a series of related hypotheses in an attempt to reconcile evidence of increasing physiological stress among Warlpiri and Pintubi infants and young children following settlement in the 1940s with their frequently rapid and undelayed longitudinal growth in stature during adolescence.

SUBJECTS AND METHODS

The study used archived cross-sectional and longitudinal records of stature, weight, and dental casts collected by the Dental School at the University of Adelaide beginning in 1951 at the then recently settled community of Yuendumu. Longitudinal modelling of height data and all statistical tests were accomplished using SYSTAT 10. Height, weight, and BMI (kg m-2) for age z-scores were calculated using NCHS reference data. Dental casts were scored for linear enamel hypoplasia (LEH) with each defect assigned to an enamel developmental unit. The extent of height catch-up was estimated using conditional height gain.

RESULTS

Cross-sectional analyses indicate significant associations between birth year and women's heights (n = 105, p = 0.02) or height for age z-scores (p = 0.003), but no similar associations among men. Final height for age z-score was significantly associated with sex (p < 0.0005), onset (p = 0.031), and an onset by number of enamel defects interaction (p = 0.033). Late adolescent height z-scores were only significantly negatively associated with increasing numbers of defects among individuals with enamel defects appearing prior to about 18 months of age (n = 60, p = 0.019). With longitudinally estimated age at peak height velocity (APHV) statistically controlled, peak height velocity (PHV) was similarly significantly positively associated with conditional height gain in males (n = 50, p = 0.01) and females (n = 31, p = 0.05). Exploratory analyses suggest that with timing and intensity of PHV controlled, childhood body mass was only significantly positively associated with catch-up in height among those who experienced defect onset relatively early (n = 80, p = 0.005).

CONCLUSION

Results help explain previously documented, and apparently contradictory, outcomes of settlement processes. Rapid and relatively undelayed late childhood and adolescent growth associated with catch-up in height occurred through a confluence of increasing early childhood systemic stress followed by increases in net energy consumption that probably increased as children aged.

Markers of physiological stress in juvenile bonobos (Pan paniscus): are enamel hypoplasia, skeletal development and tooth size interrelated?

A reduction in enamel thickness due to disrupted amelogenesis is referred to as enamel hypoplasia (EH). Linear EH in permanent teeth is a widely accepted marker of systemic physiological stress. An enigmatic, nonlinear form of EH commonly manifest in great ape and human deciduous canines (dc) is known as localized hypoplasia of primary canines (LHPC). The etiology of LHPC and what it signifies-localized traumatic or systemic physiological stress-remains unclear. This report presents frequency data on LHPC, hypostotic cranial traits, and tooth size in a sample of juvenile bonobos, then tests hypotheses of intertrait association that improve knowledge of the etiology and meaning of LHPC. The fenestration hypothesis is tested using hypostotic cranial traits as a proxy for membrane bone ossification, and the relationship between tooth size, LHPC, and hypostosis is investigated. Macroscopic observations of EH, hypostotic traits, and measurements of buccolingual tooth size were conducted according to established standards. LHPC was found in 51.2% of bonobos (n = 86) and in 26% of dc teeth (n = 269). Hypostotic traits were observed in 55.2% of bonobos (n = 96). A test of the association between LHPC and hypostosis yielded nonsignificant results (chi(2) = 2.935; P = 0.0867). Primary canines were larger in specimens with LHPC than in unaffected specimens (paired samples t test; udc, P = 0.011; ldc, P = 0.018), a result consistent with the fenestration hypothesis of LHPC pathogenesis. Hypostosis was not associated with differences in tooth size (P > 0.05). LHPC may be an indirect indicator of physiological stress, resulting from large, buccally displaced primary canines.

Patterns in dental enamel hypoplasia by sex and age at death in two archaeological populations

AIMS

Levels of enamel hypoplasia in past populations are frequently used to study health. However, few studies have looked at patterning in the occurrence of different types of hypoplasia. In this pilot study, skeletal remains from an Iron Age tomb at Pella in Jordan were analysed for the presence of linear and pit enamel hypoplasia, to investigate enamel hypoplasia aetiology by comparison of the results obtained for adults and juveniles, and females and males.

METHODS AND RESULTS

The proportion of individuals with enamel hypoplasia was determined for males and females and for adults and juveniles using the F.D.I. Developmental Defects of Enamel (DDE) Index. Although males and females had a similar percentage of individuals affected, females had a higher prevalence of enamel hypoplasia per tooth than males. Adults had a higher prevalence of enamel hypoplasia than juveniles. In particular, adults had a higher prevalence of linear enamel hypoplasias and pit enamel hypoplasia arrays, but a similar prevalence of single pit enamel hypoplasia when both the permanent and deciduous dentitions were considered. These differences were largely due to different patterns and frequencies of enamel hypoplasia in deciduous teeth compared to permanent teeth.

CONCLUSIONS

The different patterns of occurrence of the various forms of hypoplasia observed in this study imply that single pits may have a different aetiology to linear enamel hypoplasias and pit arrays. By investigating similar patterns in other archaeological populations, we may develop a better understanding of the specific causes of particular types of enamel hypoplasia, and may be able to more meaningfully interpret enamel hypoplasia data from past populations.

Dietary variation and stress among prehistoric Jomon foragers from Japan

Current archaeological evidence indicates that greater dietary reliance on marine resources is recorded among the eastern Jomon, while plant dependence prevailed in western/inland Japan. The hypothesis that the dietary choices of the western/inland Jomon will be associated with greater systemic stress is tested by comparing carious tooth and enamel hypoplasia frequencies between the eastern and western/inland Jomon. Demographic collapse coincides with climate change during the Middle to Late Jomon period, suggesting dwindling resource availability. It is hypothesized that this change was associated with greater systemic stress and/or dietary change among the Middle to Late Jomon. This hypothesis is tested by comparing enamel hypoplasia and carious tooth frequencies between Middle to Late and Late to Final Jomon foragers. Enamel hypoplasia was significantly more prevalent among the western/inland Jomon. Such findings are consistent with archaeological studies that argue for greater plant consumption and stresses associated with seasonal resource depletion among the western/inland Jomon. Approximately equivalent enamel hypoplasia frequencies between Middle to Late and Late to Final Jomon foragers argues against a demographic collapse in association with diminished nutritional returns. Significant differences in carious tooth frequencies are, however, observed between Middle to Late and Late to Final Jomon foragers. These results suggest a subsistence shift during the Middle to Late Jomon period, perhaps in response to a changed climate. The overall patterns of stress documented by this study indicate wide-spread environmentally directed biological variation among the prehistoric Jomon.

Dental enamel hypoplasias and health changes in the Middle Bronze Age – Early Iron Age transition at Pella in Jordan

Dental enamel hypoplasias are increasingly being used in epidemiological studies as indicators of health within both modern and prehistoric populations. This symptom of growth disruption is used here to examine possible changes in health occurring at the transition between the Bronze Age and Iron Age in Jordan, through examination of enamel hypoplasias in skeletal remains from two tombs at the archaeological site of Pella. A small but not statistically significant difference in the prevalence and frequency of hypoplastic defects was found between the two time periods. These results suggest that the political and economic changes occurring at this time were not sufficiently stressful to cause a dramatic deterioration in health at the onset of the Early Iron Age.

Focused life history data and linear enamel hypoplasia to help explain intergenerational variation in relative leg length within Taiwanese families

This study first examines the hypothesis that significant intergeneration increases in stature within 85 Taiwanese families in two study locations were primarily the result of increases in subischial leg length. It then evaluates a second hypothesis that independent assessments of the extent of intergenerational change in childhood environments within these families helped account for parent-offspring differences in relative leg length. Childhood environments were assessed using two criteria: developmental environment scores derived from life history data and evidence of linear enamel hypoplasia (LEH). Relative leg length was represented in two ways, as either the difference between internally estimated sex-specific z-scores of sitting height and subischial leg length (z(D) = z(SH) - z(LL)) or as relative sitting height (RSH; sitting height/height x 100). Paired Student t tests indicated intergenerational increases in relative leg length were significantly greater than zero in both study locations (P < or = 0.012). The second hypothesis, tested using a hierarchical model with maximum likelihood estimation that allowed for nesting of more than one offspring per family, received support as midparent-offspring differences in composite scores were significantly positively associated with midparent-offspring differences in relative leg length. This was true alone (P = 0.018), and when significant associations with LEH prevalence among mothers and offspring were statistically controlled for (P = 0.010). Evidence also indicated that while the large majority of offspring were taller than their midparental average height (84.3%; 91/108), offspring who were taller were also more likely to have relatively longer legs than by chance alone (Fishers exact, P = 0.027).

Environmental effects on skeletal versus dental development: Using a documented subadult skeletal sample to test a basic assumption in human osteological research

This study examines the relationship between measures of skeletal and dental development and socioeconomic factors in a 20th century documented skeletal sample of children from Portugal. The skeletons are of known sex and chronological age, and include other biographic data, such as cause of death. Growth in the length of the long bone is used as a measure of skeletal growth, and schedules of tooth formation are used as a measure of dental development. These two measures of physiological age were compared to chronological age, to assess growth and developmental status. Socioeconomic indicators were obtained from the supporting documentation, and include the occupation of the father and the place of residence, which were used to build a socioeconomic classification based on two groups, one of low and the other of high socioeconomic status. Growth and development status was then compared in these two groups. Results show that socioeconomic differences are much more pronounced in skeletal growth than in dental development. This largely supports the assertion that dental development is buffered against environmental factors relative to skeletal development. However, in this study, skeletal maturation could not be assessed, and findings indicate that dental development can show significant delays at the lower end of the socioeconomic gradient.

Brief Communication: Linear enamel hypoplasia and the shift from irregular to regular provisioning in Cayo Santiago rhesus monkeys (Macaca mulatta)

This study investigates changes in the prevalence of linear enamel hypoplasia (LEH) before and after the shift from irregular to regular provisioning in the Cayo Santiago rhesus monkey population. Prior to 1956, monkeys on this island colony did not receive consistent provisions, and were reported to be in poor health (Rawlins and Kessler [1986] The Cayo Santiago Macaques; Albany: State University of New York Press). A regular provisioning program, instituted in August 1956, resulted in the improved health of individuals and the growth of the population (Rawlins and Kessler [1986] The Cayo Santiago Macaques; Albany: State University of New York Press). LEH, a developmental defect of enamel, is a sensitive indicator of systemic physiological stress (Goodman and Rose [1990] Yrbk. Phys. Anthropol. 33:59-110). It was therefore hypothesized that the prevalence of LEH would be higher in monkeys who were irregularly provisioned than in monkeys who experienced regular provisioning. To test this hypothesis, teeth were examined for LEH in a sample of 181 female rhesus monkeys. The results support the hypothesis: the mean number of defects was statistically significantly higher in the preprovisioned group than it was in the postprovisioned one. When LEH prevalence was assessed using only defects occurring on antimeric pairs, the preprovisioned group again had a higher prevalence than the postprovisioned one, although the difference was not statistically significant, most likely because of the reduced sample size. The results of this study indicate that changes in LEH prevalence, at least in this population of rhesus monkeys, are associated with changes in nutritional status.

Linear enamel hypoplasias as indicators of systemic physiological stress: evidence from two known age-at-death and sex populations from postmedieval London

Enamel hypoplasias are useful indicators of systemic growth disturbances during childhood, and are routinely used to investigate patterns of morbidity and mortality in past populations. This study examined the pattern of linear enamel hypoplasias in two different burial populations from 18th and 19th Century church crypts in London. Linear enamel hypoplasias on the permanent dentitions of individuals from the crypt of Christ Church, Spitalfields, were compared to enamel defects on the teeth of individuals from St. Bride's. The method used involves the identification of enamel defects at a microscopic level, and systemic perturbations are detected by matching hypoplasias among different tooth classes within each individual. The pattern of linear enamel hypoplasias was contrasted between individuals from the burial sites of Spitalfields and St. Bride's, between males and females, and between those aged less than 20 years of age and those aged over 20 years at death. Six different parameters were examined: frequency of linear enamel hypoplasias, interval between defects, duration of hypoplasias, age at first occurrence of hypoplasia, age at last occurrence of hypoplasia, and the percentage of enamel formation time taken up by growth disturbances. All individuals in the study displayed linear enamel hypoplasias, with up to 33% of total visible enamel formation time affected by growth disruptions. Multiple regression analysis indicated a number of significant differences in the pattern of enamel hypoplasias. Individuals from Spitalfields had shorter intervals between defects and greater percentages of enamel formation time affected by growth disturbances than did individuals from St. Bride's. Females had greater numbers of linear enamel hypoplasias, shorter intervals between defects, and greater percentages of enamel formation time affected by growth disturbances than males. There were also differences in the pattern of enamel hypoplasias and age at death in this study. Individuals who died younger in life had an earlier age at first occurrence of enamel hypoplasia than those who survived to an older age. The pattern of enamel hypoplasias detected in this study was influenced by tooth crown geometry and tooth wear such that most defects were found in the midcrown and cervical regions of the teeth, and greater numbers of defects were identified on the anterior teeth. Differences in sensitivity of the parameters used for the detection of enamel hypoplasias were found in this study. The percentage of visible enamel formation time affected by growth disturbances was the parameter that identified the greatest number of significant differences among the subgroups examined.

Malnutrition and dental caries: a review of the literature

Protein-energy malnutrition occurs when there are deficiencies in protein, energy foods or both, relative to a body's needs. This paper reviews the association of early childhood malnutrition with: (1) dental caries, (2) enamel hypoplasia, (3) salivary gland hypofunction, and (4) delayed eruption. Studies suggest that caries of the primary dentition is associated with early childhood malnutrition, though the effect on caries of the permanent dentition has essentially not been studied. Enamel hypoplasia, salivary glandular hypofunction and saliva compositional changes may be mechanisms through which malnutrition is associated with caries, while altered eruption timing may create a challenge in the analysis of age-specific caries rates.

Association of diet with dental caries in preschool children

This article updates the evidence linking dietary factors to dental caries in preschool children and recommends dietary approaches to reduce caries risk. Along with nutritional factors, a comprehensive approach to preventing dental caries in preschool children must include good oral hygiene, appropriate use of fluorides, and access to preventive and restorative dental care.

Rapid morphological change in living humans: implications for modern human origins

Human body size and body proportions are interpreted as markers of ethnicity, 'race,' adaptation to temperature, nutritional history and socioeconomic status. Some studies emphasize only one of these indicators and other studies consider combinations of indicators. To better understand the biocultural nature of human size and proportions a new study of the growth of Maya-American youngsters was undertaken in 1999 and 2000. One purpose of this research is to assess changes in body proportion between Maya growing up in the US and Maya growing up in Guatemala. Height and sitting height of 6-12-year-old boys and girls (n=360) were measured and the sitting height ratio [sitting height/height]x100, a measure of proportion, was calculated. These data are compared with a sample of Maya of the same ages living in Guatemala and measured in 1998 (n=1297). Maya-American children are currently 10.24 cm taller, on average, and have a significantly lower sitting height ratio, (i.e. relatively longer legs, averaging 7.02 cm longer) than the Guatemala Maya. Maya-American children have body proportions more like those of white children in the US than like Maya children in Guatemala. Improvements in the environment for growth, in terms of nutrition and health, seem to explain both the trends in greater stature and relatively longer legs for the Maya-Americans. These findings are applied to the problem of modern human origins as assessed from fossil skeletons. It has been proposed that heat adapted, relatively long-legged Homo sapiens from Africa replaced the cold adapted, relatively short-legged Homo neandertalensis of the Levant and Europe [J Hum Evol 32 (1997a) 423]. Skeletal samples of Maya adults from rural Guatemala have body proportions similar to adult Neandertals and to skeletal samples from Europe with evidence of nutritional and disease stress. Just as nutrition and health status explains the differences in the body proportions of living Maya children, these factors, along with adaptation to climate, may also explain much of the differences between the Neandertal and African hominid samples.

Caries and micronutrient intake among urban South African children: a cohort study

OBJECTIVE

To report on associations between caries and micronutrient intake among a 'true cohort' group of 5-year-old urban black South African children.

METHODS

The study sample was a true cohort that had nutrition as well as dental information for 1991 and 1995 (n = 259). Micronutrient intake and dental caries associations were examined with SAS using the linear logistic analysis and a critical level of statistical significance of P < 0.05.

RESULTS

Of the 21 micronutrients investigated, vitamin B12, riboflavin, magnesium and biotin were individually significantly associated with caries incidence, but taken together only magnesium was significant.

CONCLUSIONS

The association of micronutrient intake with caries was weak, isolated and not clinically relevant. Micronutrient intake was not an indicator of the presence or absence of caries among the children studied.

Macroscopic and microscopic analyses of linear enamel hypoplasia in Plio-Pleistocene South African hominins with respect to aspects of enamel development and morphology

This study uses macroscopic and microscopic methods to analyze the expression of linear enamel hypoplasia (LEH) in Plio-Pleistocene South African hominins. LEH is a developmental defect of enamel that is used in many anthropological contexts as a physiological stress indicator. Previous research has not settled the question as to whether differences in LEH expression exist between Paranthropus and Australopithecus and if they exist, to what extent these differences might be explained simply by taxonomic differences in enamel development and morphology rather than by differential stress experience. In this study, the analysis of LEH is conducted with respect to differences between Paranthropus and Australopithecus in aspects of enamel development and morphology that are thought to influence LEH expression. Two factors impacting LEH expression are considered: the duration of enamel formation, and the spacing of perikymata. It is predicted that if the first factor strongly influences the expression of LEH, then there should be fewer defects per tooth in Paranthropus because of its abbreviated crown formation spans (and fast extension rates) relative to Australopithecus. It is also predicted that because Australopithecus has more densely packed perikymata in comparable regions of the crown than Paranthropus, this taxon should, on average, have narrower defects than Paranthropus. To address these questions, 200 Australopithecus and 137 Paranthropus teeth were examined for LEH, and the analysis of defect width with respect to perikymata spacing was conducted on tooth impressions examined under a scanning electron microscope using INCA (Oxford Instruments) measurement software. Data support the first prediction: Australopithecus does have significantly more defects per canine tooth than Paranthropus. Data do not support the second prediction in large part because several Australopithecus specimens have wide groove defects in which perikymata are not visible and enamel is irregular. Such wide grooves are not predicted by perikymata spacing such that alternative explanations, including taxonomic differences in ameloblast sensitivity and the duration/severity of disruptions to enamel growth, must be considered.

Enamel hypoplasia in a Canadian historic sample

Analyses of historical skeletal samples provide useful comparisons of the prevalence of skeletal indicators of stress to documentary information on health, diet, and socioeconomic status. A sample of the permanent dentitions of 253 adults from the St. Thomas' Anglican Church 19th-century skeletal sample in Belleville, Ontario, was examined macroscopically for the prevalence of enamel defects on the six anterior maxillary and mandibular teeth. The maximum frequency of hypoplasias on the left mandibular canine is 36.1%. The prevalence of enamel defects is low to moderate compared to almost all other reported frequencies in historical samples, which is consistent with historical descriptions of this developing community of middle to high socioeconomic status Canadians. Hypoplasias are significantly more frequent in males but there are no significant differences in the mean age at death between individuals with hypoplasia and those without. Calculations of the peak ages of occurrence of hypoplasias fall within the commonly observed 2-4-year range. This is not consistent with separate studies, demographic, isotopic and historical, of the introduction of complementary foods to 19th-century Belleville infants and of the weaning process. These results do not support the view that peak ages of occurrence of hypoplastic defects are associated with the cessation of breast-feeding or the weaning process in general. Am. J. Hum. Biol. 11:513-524, 1999. Copyright 1999 Wiley-Liss, Inc.

Well-being changes in response to 30 years of regional integration in Maya populations from Yucatan, Mexico

Infant mortality rate (IMR), overall frequency of linear enamel hypoplasia (LEH), sexual dimorphism in LEH, age of onset of LEH, and age at menarche were used as indicators to test the hypothesis that the origin and development of the tourist industry and increased state participation on Maya subsistence agriculturists in the early 1970s had improved the well-being of the Maya. Two historical moments where inferred from the data. The first was derived from cheap and effective immunization and sanitation campaigns that reduced IMR from 143.4/1,000 live births in the early 1960s to 97.4 in the early 1970s. State participation broke the undernutrition-disease cycle enough to reduce LEH frequencies significantly (from 71.9% in individuals born before 1971 to 51.5% in those born in 1971 or after, chi(2) = 55.72; 1 df; alpha = 0.00001) and to eliminate the sex difference in LEH expression (from a 14.8% LEH difference between men and women before 1971 [Male/Female Odds Radio = 0.45, alpha significant at 0.05] to a nonsignificant 2% difference). Improvement in overall living conditions reflected in a "modern stage" infant mortality regime and an almost disappearance of LEHs, resulted from gradual improvements in living conditions that did not become apparent until the 1980s. Trends in the age at menarche are not statistically significant, probably due to methodological limitations. However, if overall living conditions continue to improve or stay as they are today, accelerations in maturation should become noticeable.

Dietary determinants of dental caries and dietary recommendations for preschool children

OBJECTIVES

The purpose of this review, commissioned by the Administration for Children and Families, the Health Resources and Services Administration, the Health Care Financing Administration, and the Department of Agriculture's Food and Nutrition Service, was to update the evidence of the dietary factors that affect dental caries, and subsequently formulate dietary recommendations for preschool children based on principles of cariology.

METHODS

Literature on the dental caries process, dietary factors affecting dental caries initiation and progression, and nutrition education and counseling were reviewed and synthesized. Dietary guidelines for children at various ages were then constructed based on the review.

RESULTS

Dental caries in preschool children is due to a combination of factors, including colonization of teeth with cariogenic bacteria, type of foods and frequency of exposure of these foods to the cariogenic bacteria, and susceptible teeth. Caries risk is greatest if sugars are consumed at high frequency and are in a form that is retained in the mouth for long periods. Sucrose is the most cariogenic sugar because it can form glucan that enables firm bacterial adhesion to teeth and limits diffusion of acid and buffers in the plaque. There is emerging interest in the effects of tooth development and its role in the future dental caries risk of the child.

CONCLUSIONS

Nutrition education and counseling for the purposes of reducing caries in children is aimed at teaching parents the importance of reducing high frequency exposures to obvious and hidden sugars. Guidelines include: avoiding frequent consumption of juice or other sugar-containing drinks in the bottle or sippy cup, discouraging the behavior of a child sleeping with a bottle, promoting noncariogenic foods for snacks, fostering eating patterns consistent with the Food Guide Pyramid, limiting cariogenic foods to mealtimes, rapidly clearing cariogenic foods from the child's oral cavity either by toothbrushing or by consumption of protective foods, and restricting sugar-containing snacks that are slowly eaten (e.g., candy, cough drops, lollipops, suckers). Along with nutritional factors, a comprehensive approach to preventing dental caries in preschool children must include improved general dietary habits, good oral hygiene, appropriate use of fluorides, and access to preventive and restorative dental care.

Interpreting sex differences in enamel hypoplasia in human and non-human primates: Developmental, environmental, and cultural considerations

The purpose of this review is to provide a synoptic, critical evaluation of the evidence of, and potential etiological factors contributing to, sex differences in the expression of enamel hypoplasia (EH). Specifically, this review considers theoretical expectations and empirical evidence bearing on two central issues. The first of these is the impact of a theorized inherent male vulnerability to physiological stress on sex differences in EH. The second issue is the potential contribution to sex differences in EH of intrinsic differences in male and female enamel composition and development. To address this first issue, EH frequencies by sex are examined in samples subject to a high degree of physiological stress. Based on the concept of inherent male vulnerability (or female buffering), males in stressful environments would be expected to exhibit higher EH frequencies than females. This expectation is evaluated in light of cultural practices of sex-biased investment that mediate the relationship between environmental stress and EH expression. Defects forming prenatally afford an opportunity to study this relationship without the confounding effects of sex-biased postnatal investment. Data bearing on this issue derive from previously conducted studies of EH in permanent and deciduous teeth in both modern and archaeological samples as well as from new data on Indian schoolchildren. To address the second issue, fundamental male-female enamel differences are evaluated for their potential impact on EH expression. A large sex difference in the duration of canine crown formation in non-human primates suggests that male canines may have greater opportunity to record stress events than those of females. This expectation is examined in great apes, whose canines often record multiple episodes of stress and are sexually dimorphic in crown formation times. With respect to the first issue, in most studies, sex differences in EH prevalence are statistically nonsignificant. However, when sex differences are significant, there is a slight trend for them to be greater in males than in females, suggesting a weak influence of greater male vulnerability. Cultural practices of sex-biased investment in children appear to have greater impact on EH expression than does male vulnerability/female buffering. With respect to the second issue, sex differences in the composition and development of enamel were reviewed and determined to have limited or unknown impact on EH expression. Of these factors, only the duration of crown formation was expected to affect EH expression by sex within the great apes. The data support an association between higher defect counts in the canines of great ape males relative to those of females that may be the result of longer crown formation times in the canines of great ape males. This review concludes with an assessment of the nature of the evidence currently available to examine these issues and suggests future avenues for research focused on elucidating them.

Patterns of dental enamel defects at ancient Mendes, Egypt

The dental remains of 88 individuals from Old Kingdom, First Intermediate, and Greco-Roman periods at the ancient Egyptian site of Mendes (Tell er-Rub(c)a) were examined for dental enamel hypoplasia, and the results reported here provide some of the first comparative data on enamel defects in ancient Egypt. Overall, 48% of the individuals in the sample have one or more teeth with hypoplasia, with 17% of permanent teeth and 8% of deciduous teeth affected. The permanent teeth account for 87% of the total number of affected teeth, a prevalence over deciduous teeth that is significant at alpha = 0.05. Permanent and deciduous teeth display different patterns of hypoplasia, with the former exhibiting both discrete pitting and linear furrowing, and the latter exhibiting only pits. Teeth with linear defects significantly outnumber those with pits by a factor of more than three to one. Only permanent canines display more than one lesion on a tooth, with a mean of 1.4 defects per affected tooth. Although calculation of the age of insult from lesion position is imprecise, it appears that stress episodes occurred most commonly between approximately 3-5 years of age. The presence of pits in the deciduous dentition, however, suggests that physiological stresses began in utero. There is no statistically significant difference in the frequency of enamel defects between males and females. An observed decrease in the frequency of defects from the Old Kingdom period to the subsequent First Intermediate and Greco-Roman periods is not significant at alpha = 0.05, although such a decrease is expected given epigraphic and other data that refer to prolonged drought and malnutrition in the late Old Kingdom. The calculated chi(2) value of 3.83 is significant at the 0.10 level, however, and since our sample is rather small and the magnitude of the chi-square statistic is a function of sample size, we recommend that future research investigate further the relationship between the frequency of enamel defects and the time period in which they occur.

Hardships of contact: enamel hypoplasias in Tupí-Mondé Amerindians from the Brazilian Amazonia

This paper presents an assessment of enamel defects (hypoplasias) in the permanent anterior teeth of three Tupí-Mondé-speaking groups from the Brazilian Amazonia: the Gavião, Suruí, and Zoró. These are native societies that experienced the onset of permanent contact with Brazilian national society in different periods of the 20th century. Tupí-Mondé dentition is highly hypoplastic, which is possibly related to exposure to adverse health and nutritional conditions. Data for the Gavião, Suruí, and Zoró are in agreement with results from other populations that show that certain teeth, the maxillary central incisors and the mandibular canines in particular, tend to be more hypoplastic. Although all types of teeth show hypoplasia concentrations at some enamel zones, there is substantial intertooth variation in the age at which peaks occur. It is argued that hypoplasia concentrations at certain ages are unlikely to be related to postweaning stresses for the Tupí-Mondé. Statistically significant associations between presence of enamel defects and deficits in physical growth (height-for-age) were detected in children 7-11 years of age. Diachronic assessment of enamel defects, which rested upon the potential of enamel as "memory" of past periods of systemic physiological perturbation, allowed us to unravel aspects related to the dynamics of Tupí-Mondé life during the 20th century. Frequencies of enamel zones with defects peaked during the contact years of each of the Tupí-Mondé groups, attesting to the extreme social and biological hardships that characterized the contact experiences of these native societies with Brazilian national society.