Linear Enamel Hypoplasia Prevalence Research Articles

Tracing early life histories from Roman times to the Medieval era: weaning practices and physiological stress

In humans, breastfeeding and weaning depend on the infant’s needs and physiology but are also influenced by environmental and cultural factors. While infant feeding strategies vary across different regions and historical eras, the associated transition from breastmilk to solid foods is universally thought to be stressful. However, still little is known about infant feeding practices and possibly associated stress in former times. This also applies to the period of transition from classical antiquity to medieval times, which shaped modern Western civilization. To enhance the understanding of childhood nutrition and stress during this period, we first analyzed stable carbon and nitrogen isotopes in serial dentine samples from the first molars of 38 individuals buried in the region once known as the Roman frontier province of Raetia secunda, now encompassing Southern Bavaria. In addition, we investigated the presence of linear enamel hypoplasia (LEH), known to be a marker of unspecific physiological stress, within their dentition. We used this data to create isotope profiles that display dietary changes in comparison with the occurrence of LEH. We found highly variable δ15N and δ13C values and different shapes of isotope profiles which indicate different nutrition of breastfeeding individuals, complementary foods and post-weaning diets, and individual weaning patterns. For most individuals, the weaning process was completed between the ages of two and three. Interestingly, some females of non-local origin show longer weaning periods, likely displaying the influence of different cultural practices in other communities. We also found that LEH most frequently occurred in the post-weaning phase, which supports the assumption that children were at increased risk once breastfeeding had ceased completely. Furthermore, a change in the post-weaning diet in the seventh century coincided with an increased prevalence of LEH, indicating that the foods chosen or available during this time affected the susceptibility of children to stress. In conclusion, our study unveiled diverse infant feeding strategies practiced across various communities, both in different historical eras and geographical locations.

Oral Health of Sambaqui Groups in Saquarema, Brazil

This article presents differences and similarities in dietary practices of fisher-gatherer groups excavated from two sambaquis (shell-mound archaeological sites) in Saquarema, Rio de Janeiro state, Brazil. We analyzed the buccal apparatus of 35 individuals excavated from Sambaqui da Beirada, dated from 5437 to 3440 years cal BP, and Sambaqui do Moa, dated from 4770 to 3199 years cal BP. Our oral health analysis of 852 alveoli and 704 teeth assessed the frequency and degree of teeth wear and the prevalence and frequency of caries, linear enamel hypoplasia, calculus, periapical cavities, and antemortem teeth loss. We applied the chi-square test and Fisher exact test to test statistical significance. Severe tooth wear, the absence of caries, a high frequency and prevalence of dental calculus, and a low prevalence of linear enamel hypoplasia were found in both sites, although periapical cavities and antemortem teeth loss indexes varied greatly. Despite a superficial homogeneity, the results point to variation in the physiopathological processes that occurred at both sites, including differences related to age and sex. These oral health-related results, together with other archaeological data from both sambaquis, showcase the expected cultural differences stemming from dietary practices.

Chronology, duration, and periodicity of linear enamel hypoplasia at the late Iron Age site Non Ban Jak, Thailand: A quantitative microscopic analysis

We provide the first application of a quantitative microscopic approach that does not rely on the presence of perikymata for the identification and comprehensive analysis of linear enamel hypoplasia (LEH) to a large archaeological sample from Southeast Asia. Additionally, we introduce MicroPolySharp, a new computer program that automates the assessment of these stress episodes, and we present new dental crown width/height ratios for the region.Enamel surface depth profiles were measured from epoxy dental replicas generated from 48 individuals using a confocal microscope. The identification and analysis of LEH episodes was undertaken using MicroPolySharp, which combines three recently published methods specifically suited to worn archaeological samples. Ten parameters were examined: frequency, prevalence, episode duration, stress duration, recovery duration, age at first onset, age at last onset, total growth disruption, proportion of available enamel affected, and periodicity.Results revealed a high prevalence of LEH: 97.92 % (47/48) individuals affected. LEH frequency averaged 2.5 episodes per individual (range = 1 to 4 episodes). The chronology of episodes averaged 3.66 years (range = 1.4 to 5.5 years). The age of earliest episode occurrence averaged 3.1 years (range = 1.4 to 4.2 years). While the age of last episode averaged 4.3 years (range = 2.9 to 5.5 years). Duration of growth disruptions (stress + recovery) averaged 103 days (range = 27 to 269 days). Consistent with other studies, the average duration of the stress portion of episodes was 56 days (range = 9 days to 6.4 months) while the duration of the recovery portion averaged 47 days (range = 8 days to 5 months). The total amount of growth disruption for individuals averaged 263 days (range = 87 to 543 days). The proportion of available crown height affected by growth disruption averaged 21 % (range = 6 % to 42 %), while LEH periodicity for the sample averaged 8.6 months (range = 2.4–23 months). Stress and recovery durations, along with age at first episode, were the most sensitive and useful parameters for discerning differences between the subgroups of interest. Finally, the effects of any amount of variable crown height wear within the study group was found to have a significant confounding effect on all aspects of LEH results and interpretation if not properly controlled. Given the high prevalence, all individuals were, for the most part, equally affected. Future analysis of samples from the periods prior to and leading up to the Late Iron Age from nearby sites will be required to provide much needed context to the high levels of systemic stress observed at Non Ban Jak.

The impact of early childhood stressors on later growth in medieval and postmedieval London

AbstractThis research examined the relationship between linear enamel hypoplasia (LEH) and stature in medieval and postmedieval London cemeteries to determine whether individuals with LEH in their permanent dentition also exhibited shorter stature. Pathological and metric data for 87 adult individuals from the medieval East Smithfield Black Death cemetery and 136 adult individuals from the postmedieval St. Bride's Lower Churchyard Cemetery were used in this study. A two‐way ANOVA, a component of the general linear model (GLM), was run to compare LEH prevalence to maximum femoral length, while accounting for time period and sex. The results showed a significant association in both samples between presence of LEH and femur length in males. The association did not differ between cemeteries, indicating no temporal change in the relationship. Examination of the distribution suggests the association was stronger in males than in females, a possible indication of superior female buffering in these samples. This research provides a look at how environmental stressors in childhood may have permanent effects on growth in past populations while also attempting to better understand how males and females may differ in buffering against episodes of stress.

Sex differences in linear enamel hypoplasia prevalence and frailty in Ancestral Puebloans

ObjectivesWe consider sex-biased effects of mortality and frailty patterns and how they may be influenced by early life stress using linear enamel hypoplasia (LEH). MethodsLEH was recorded as present/absent on the canines of 192 Ancestral Puebloans from what is now New Mexico. We use Kaplan-Meier survival analyses and Usher’s multi-state model of morbidity and mortality to estimate survival probability and relative risk of death. ResultsWe find no difference in survival probability between males and females with LEH, although individuals without LEH live longer, regardless of their sex. Males with LEH are frailer than their age-matched peers without LEH. Females follow a similar trend, although this result is not significant. ConclusionsLEH presence does not have a consistent relationship with mortality or probability of survival, indicating that early-life stress conveys different biological impacts across the lifespan and across individuals. Equivalent survival probability between the sexes could reflect cultural and/or biological consequences including equivalent buffering capabilities, lack of preferential treatment, or hidden effects of social status. When stress indicators such as LEH are observed in adults, they represent a stressor survived by a child. Some children exposed to the stressor likely died prior to lesion formation, while some potentially survived the stress event without developing a lesion. Sex differences in stress indicators that form during childhood are likely best understood when examined in children (of known sex) at risk of developing them. They could also be addressed through the comparison of LEH age at formation in adults of known sex.

Heterogeneous frailty and the expression of linear enamel hypoplasia in a genealogical population.

Linear enamel hypoplasia (LEH) is a common skeletal marker of physiological stress (e.g., malnutrition or illness) that is studied within and across populations, without reference to familial risk. We examine LEH prevalence in a population with known genealogical relationships to determine the potential influence of genetic heritability and shared environment. LEH data of 239 individuals from a single population were recorded from the Ohio State University Menegaz-Bock collection dental casts. All individuals were of known age, sex, and genealogy. Narrow-sense heritability estimates were obtained for LEH presence and count data from all unworn, fully erupted teeth (excluding third molars) using SOLAR (v.8.1.1). Age, sex, and age-sex interaction were included as covariates. Models were re-run with a household effect variable. LEH persists across generations in this study population with moderate, significant heritability estimates for presence in four teeth, and count in four teeth (three teeth were significant for both). When a household effect variable was added, no residual heritability remained for LEH count on any tooth. There was no significant household effect for three of the four teeth that had significant heritability estimates for LEH presence. Age was a significant covariate. Further analyses with birth year data revealed a secular trend toward less LEH. This study provides evidence for familial risk of LEH (genetic and environmental) that has consequences for the broad use of this skeletal marker of stress. These results have repercussions for archaeological assemblages, or population health studies, where genetic relatives and household groups might be heavily represented.

Social Status and Its Relationship to Non-specific Stress at Late Iron Age Non Ban Jak, Northeast Thailand

The rise of social inequality is a key development in human history and is linked to deteriorating health. These associated health impacts are poorly understood for Iron Age (420 B.C.–A.D. 500) northeast Thailand. To clarify this issue we investigate whether social status differences influence non-specific stress at the site of Non Ban Jak (A.D. 300–800), which comprises two separate burial mounds. These mounds are thought to represent the neighborhoods of two distinct social groups at the site. Quantitative analyses were used to explore differences in grave goods among the adults of Non Ban Jak (N = 47). Long bone lengths, ages at death, and linear enamel hypoplasia (LEH) were examined to explore differences in non-specific stress on the basis of age, sex, burial mound, and mortuary phase. Results demonstrated that older adults of both sexes, males of all ages, and west mound individuals received greater grave good quantities and may therefore have been of higher social status. West mound individuals were taller and had a lower prevalence of LEH compared to those from the east mound. Although female LEH prevalence and mortality were reduced relative to males, decreasing stature over time and high neonatal mortality indicated greater female stress. Lower-status individuals may therefore have suffered increased stress relative to those of higher status. Artifactual and epigraphic evidence supports the suggestion of sex- and class-based status differences at Non Ban Jak, legitimized and perpetuated through the adoption of residential burial and new religious ideologies. การปรากฎขึ้นของความไม่เท่าเทียมทางสังคมเป็นพัฒนาการสำคัญอย่างหนึ่งในประวัติศาสตร์มนุษยชาติและเชื่อมโยงกับสุขภาพที่เสื่อมลง ความรู้ความเข้าใจเกี่ยวกับสุขภาวะที่เกี่ยวเนื่องกับความไม่เท่าเทียมทางสังคมในสมัยเหล็ก (ประมาณ ๒,๔๐๐ – ๑,๕๐๐ ปีมาแล้ว) ในภาคตะวันออกเฉียงเหนือนี้ยังมีน้อย ดังนั้น เพื่อสร้างความเข้าใจให้ชัดเจนในเรื่องนี้ เราจึงได้ศึกษาตรวจสอบว่าความแตกต่างด้านสถานะทางสังคมมีอิทธิพลต่อความตึงเครียดหรือไม่ ทั้งนี้ เราใช้หลักฐานทางโบราณคดีจากแหล่งโบราณคดีโนนบ้านจาก (กำหนดอายุระหว่าง ๒,๓๐๐ – ๑,๒๐๐ ปีมาแล้ว) ซึ่งมีเนินหลุมฝังศพ ๒ เนิน เราเชื่อว่าเนินดินหลุมฝังศพทั้งสองเนินนี้เป็นแหล่งฝังศพของกลุ่มคน ๒ กลุ่มที่เป็นเพื่อนบ้านกันหรือมีความใกล้ชิดทางสังคม เราใช้วิธีการวิเคราะห์เชิงปริมาณในการศึกษาตรวจสอบความแตกต่างของวัตถุอุทิศที่พบร่วมกับหลุมฝังศพของคนในวัยที่เป็นผู้ใหญ่ นอกจากนี้ เรายังวิเคราะห์ความยาวของกระดูกแขน-ขา อายุเมื่อตาย และการเสื่อมผุของเคลือบฟัน เพื่อตรวจสอบระดับความแตกต่างของความตึงเครียดตามเพศ อายุ/วัย กลุ่มสังคม และช่วงเวลา ผลการศึกษาพบว่าผู้ใหญ่วัยสูงอายุทั้งเพศหญิงและชาย ผู้ชายทุกวัย และกลุ่มคนจากเนินฝังศพด้านตะวันตกมีจำนวนวัตถุอุทิศมากกว่ากลุ่มคนจากเนินฝังศพทางตะวันออก และดังนั้นคนที่ถูกฝังในเนินดินฝังสพทางตะวันตกอาจจะมีสถานภาพสูงกว่าคนที่ถูกฝังในเนินดินหลุมฝังศพทางตะวันออก คนที่ถูกฝังในเนินดินหลุมฝังศพทางตะวันตกมีร่างกายที่สูงกว่าและมีการเสื่อมผุของเคลือบฟันน้อยกว่าคนที่ฝังที่เนินดินทางตะวันออก และแม้ว่าการเสื่อมผุของเคลือบฟันและอัตราการเสียชีวิตของผู้หญิงลดลงเมื่อเปรียบเทียบกับผู้ชาย แต่ผู้หญิงก็มีส่วนสูงเฉลี่ยลดลง และมีอัตราการเสียชีวิตของทารกในครรภ์สูงขึ้นตามช่วงเวลาซึ่งอาจจะแสดงว่าผู้หญิงมีชีวิตความตึงเครียด และคนที่มีสถานภาพทางสังคมต่ำก็มีความตึงเครียดมากกว่าคนที่มีสภาพทางสังคมที่สูงด้วย หลักฐานประเภทโบราณวัตถุและจารึกโบราณสนับสนุนว่าความแตกต่างทางสถานภาพทางสังคมและเพศที่แหล่งโบราณคดีโนนบ้านจากเกิดขึ้นและดำรงอยู่ดังจะสะท้อนให้เห็นจากการฝังศพในที่อยู่อาศัยและการเข้ามาของระบบความเชื่อทางศาสนาอันใหม่

Faster growth corresponds with shallower linear hypoplastic defects in great ape canines

Deeper or more ‘severe’ linear enamel hypoplasia (LEH) defects are hypothesized to reflect more severe stress during development, but it is not yet clear how depth is influenced by intrinsic enamel growth patterns. Recent work documented inter- and intraspecific differences in LEH defect depth in extant great apes, with mountain gorillas having shallower defects than other taxa, and females having deeper defects than males. Here, we assess the correspondence of inter- and intraspecific defect depth and intrinsic aspects of enamel growth: enamel extension rates, outer enamel striae of Retzius angles, and linear enamel thickness. Thin sections of great ape canines (n = 40) from Gorilla beringei beringei, Gorilla gorilla gorilla, Pan troglodytes, and Pongo spp. were analyzed. Enamel extension rates were calculated within deciles of enamel-dentine junction length. Linear enamel thickness and the angle of intersection between striae of Retzius and the outer enamel surface were measured in the imbricational enamel. Mountain gorillas have faster enamel extension rates and shallower striae angles than the other taxa examined. Mountain gorillas have thinner imbricational enamel than western lowland gorillas and orangutans, but not chimpanzees. In the combined-taxon sample, females exhibit larger striae angles and thicker imbricational enamel than males. Enamel extension rates are highly negatively correlated with striae angles and LEH defect depth. Enamel growth variation corresponds with documented inter- and intraspecific differences in LEH defect depth in great ape canines. Mountain gorillas have shallower striae angles and faster extension rates than other taxa, which might explain their shallow LEH defect morphology and the underestimation of their LEH prevalence in previous studies. These results suggest that stressors of similar magnitude and timing might produce defects of different depths in one species or sex vs. another, which has implications for interpretations of stress histories in hominins with variable enamel growth patterns.

Is There a Link Between Matriline Dominance Rank and Linear Enamel Hypoplasia? An Assessment of Defect Prevalence and Count in Cayo Santiago Rhesus Macaques (Macaca mulatta)

Linear enamel hypoplasias are developmental defects ranging in appearance from microscopic to macroscopic furrows in enamel that encircle the tooth crown. Environmental stressors, including lack of food and infectious diseases during early periods of development, are known to induce hypoplasias in human and nonhuman primates. Social correlates of hypoplasias have not been extensively studied, however. Here, we examined the relationship between matriline dominance rank and linear enamel hypoplasia prevalence (i.e., absence or presence) and count (the total number of hypoplasias observed) in free-ranging rhesus monkeys (Macacca mulatta) in Cayo Santiago, Puerto Rico. We sampled 86 female offspring from low-, mid-, and high-ranking matrilines. Our results show that although hypoplasia prevalence and count were numerically higher in the combined group of low-and mid-ranking matrilines than in high-ranking matrilines, this effect was not statistically significant. There was, however, a significant negative relationship between age and hypoplasia prevalence, as well as between age and mean number of enamel defects, likely due to the attrition and abrasion of enamel that wear away shallow defects as individuals age. Future studies would benefit from using large sample sizes and collecting detailed behavioral data to determine if and when social status mediates enamel defect formation.

Dental health status of skeletal remains excavated from an abandoned well at Ajnala, India: a bioarchaeological study

Present study was conducted to assess dental health status of the mid-19th century skeletal remains excavated from an abandoned ancient well and to scrutinize the demographic affiliations of the remains. Thousands of bones, teeth and contextual items were excavated non-scientifically from an abandoned well situated underneath a religious structure at Ajnala (Amritsar, India). Four thousands four hundred and seventy five teeth of each type were examined for presence of dental pathologies of caries, wear and linear enamel hypoplasia (LEH). The frequency distribution of each pathological state was calculated for each tooth type using international dental standards available in the literature. The overall dental status was characteristic of young individuals having low prevalence of dental caries and enamel hypoplasiac lesions.
 Very few teeth had seriously exposed dentine and pulp cavity; indicating consumption of some cariogenic food items. The maxillary and posterior teeth were more affected with dental caries than the mandibular and anterior teeth. LEH defects were found more commonly distributed in the lower canines (44.9%) and upper incisors (34.8%) than their corresponding counterparts and statistically significant differences were noticed in LEH prevalence between anterior and, posterior dentition. The overall percentage of LEH has been found as 15.8%; with 15.4% maxillary and 16.2% mandibular teeth being affected with LEH. The paleodontogical examinations, contextual items and the preliminary molecular findings supported the written versions that victims of Ajnala skeletal remains had sound dental health status and probably belonged to adult males who were killed in 1857 as per written versions.

Examining the osteological paradox: Skeletal stress in mass graves versus civilians at the Greek colony of Himera (Sicily).

Bioarchaeologists interpret skeletal stress as evidence of resilience or frailty, where absence of lesions might result from lack of exposure to pathogens (i.e., good health) or extreme vulnerability (i.e., selection). We examine physiological stress in two skeletal series from Greek Himera: (1) nine mass graves from the battles of Himera (480 and 409 BCE) and (2) Himeran civilians (648-409 BCE). Civilians are assumed to have died from multiple causes, including ill health leading to their deaths. Individuals from the battles presumably died while in relatively good health, in battle. More skeletal stress among civilians than battle casualties would support the idea that skeletal stress is a sign of frailty at Himera. We compare variation in skeletal stress between and among civilians and battle casualties. Cribra orbitalia, porotic hyperostosis, linear enamel hypoplasia (LEH), and sub-periosteal new bone formation, were examined in 474 individuals (mass graves n = 64; civilians n = 410). Chi-square tests showed significantly higher prevalence of LEH (p = 0.04) and sub-periosteal new bone formation (p = 0.05) among young and mid-aged adult male civilians than mass grave casualties. Skeletal stress was also lower in the earlier battle, and varied among civilians with burial style. Our findings generally support the hypothesis that skeletal stress is evidence of frailty (i.e., leading to greater risk of mortality). However, the relationship between stress and frailty is complicated by social factors, when considering historical context. In particular, a possible "soldier-class" may have experienced less stress than the overall civilian population.

Quantifying linear enamel hypoplasia in Virunga Mountain gorillas and other great apes.

Linear enamel hypoplasia (LEH) is a condition marked by localized reductions in enamel thickness, resulting from growth disruptions during dental development. We use quantitative criteria to characterize the depth of LEH defects and "normal" perikymata in great apes. We test the hypothesis that mountain gorillas have shallow defects compared to other taxa, which may have led to their underestimation in previous studies. Previous attempts to characterize LEH morphology quantitatively have been limited in sample size and scope. We generated digital elevation models using optical profilometry (Sensofar PLu Neox) and extracted 2D coordinates using ImageJ to quantify depths in canines from three great ape genera (N = 75 perikymata; 255 defects). All defect depths fall outside the distribution of perikymata depths. Mountain gorilla defects are significantly shallower than those of other great ape taxa examined, including western lowland gorillas. Females have significantly deeper defects than males in all taxa. The deepest defect belongs to a wild-captured zoo gorilla. Virunga mountain gorilla specimens collected by Dian Fossey exhibit deeper defects than those collected recently. Shallow defect morphology in mountain gorillas may have led to an underestimation of LEH prevalence in past studies. Defect depth is used as a proxy for insult severity, but depth might be influenced by inter- and intra-specific variation in enamel growth. Future studies should test whether severe insults are associated with deeper defects, as might be the case with Haloko, a wild-captured gorilla. Ongoing histologic studies incorporating associated behavioral records will test possible factors that underlie differences in defect morphology.

Child Health in Five Early Medieval Irish Sites: A Multidisciplinary Approach

AbstractWith the aim to reconstruct child health in five early medieval (5th–12th c. CE) Irish sites, an osteoarchaeological study of three biological stress indicators – cribra orbitalia, linear enamel hypoplasia (LEH) and periostitis – has been conducted on 229 skeletons. In addition, Irish early medieval written sources testifying on child health during this period were consulted. These data were furthermore combined with the results of stable isotope analyses (nitrogen and carbon) conducted on subadult bone specimens. Cribra orbitalia was found in 27.5% of the studied individuals (48.6% of subadults were affected), with only two cases active at the time of death. The prevalence of LEH per individual is 63.5% (78.9% in subadults and 59.7% in adults). The age ranges of LEH formation vary between 1.9 and 4.8 years for the maxillary teeth and between 1.8 and 6.2 years for the mandibular teeth. Periosteal inflammations were recorded in over one third of the studied subadults (36.2%) with six cases active at the time of death. The stable isotope results suggest a diet based on terrestrial food sources, with little or no marine input. The presented data strongly suggest that most of the individuals were exposed to a high level of physiological stress during their childhood, and as such does not support the so called ‘osteological paradox’ hypothesis. The observed disturbances were probably caused by a synergistic effect of various biological and socio‐cultural factors. Although the historical records indicate certain differences in diet and lifestyle between social classes and the sexes, this study showed that the children of all ages had poor health in all social classes across a wide geographical location for the full time period of the early medieval. Copyright © 2016 John Wiley & Sons, Ltd.

Aspects of health in prehistoric mainland Southeast Asia: Indicators of stress in response to the intensification of rice agriculture

Numerous bioarcheological investigations have suggested that as agriculture intensifies, levels of physiological stress and poor health increase. However, previous research in Southeast Asia suggests that a decline in health was not universal. This study aimed to provide the first investigation of human health during the intensification of rice agriculture in the large skeletal sample from the prehistoric site of Ban Non Wat, Northeast Thailand (1750-420 b.c.). Health was analysed using two indicators of childhood stress, the prevalence of linear enamel hypoplasia (LEH), a measure of early childhood stress, and stature, as a measure of late childhood stress, were collated for 190 adults. Sex-specific diachronic relationships between the prevalence of LEH and stature were explored. For both sexes, initially the prevalence of LEH was found to decrease and then increase over time. Stature remained constant over time for males, although for females stature increased initially, then decreased. Early childhood stress was not significantly correlated with stature in females (P = 0.185), but high levels of LEH were unexpectedly correlated with taller male stature (P = 0.017). Our findings suggest an initial improvement in health during agricultural intensification at this site, likely related to a reduction in physiological perturbations and maintenance of a nutritious diet during this time. The subsequent deterioration in health may reflect geomorphologically and archaeologically indicated variation in environmental conditions and consequential sociocultural changes. We suggest that the sex-differences in the relationship between stature and LEH may relate to the timing of stress and/or catch-up growth.

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.

Contact in the Andes: Bioarchaeology of systemic stress in colonial Mórrope, Peru

The biocultural interchange between the Eastern and Western Hemispheres beginning in the late fifteenth century initiated an unprecedented adaptive transition for Native Americans. This article presents findings from the initial population biological study of contact in the Central Andes of Peru using human skeletal remains. We test the hypothesis that as a consequence of Spanish colonization, the indigenous Mochica population of Mórrope on the north coast of Peru experienced elevated systemic biological stress. Using multivariate statistical methods, we examine childhood stress reflected in the prevalence of linear enamel hypoplasias and porotic hyperostosis, femoral growth velocity, and terminal adult stature. Nonspecific periosteal infection prevalence and D(30+)/D(5+) ratio estimations of female fertility characterized adult systemic stress. Compared to the late pre-Hispanic population, statistically significant patterns of increased porotic hyperostosis and periosteal inflammation, subadult growth faltering, and depressed female fertility indicate elevated postcontact stress among both children and adults in Mórrope. Terminal adult stature was unchanged. A significant decrease in linear enamel hypoplasia prevalence may not indicate improved health, but reflect effects of high-mortality epidemic disease. Various lines of physiological, archaeological, and ethnohistoric evidence point to specific socioeconomic and microenvironmental factors that shaped these outcomes, but the effects of postcontact population aggregation in this colonial town likely played a fundamental role in increased morbidity. These results inform a model of postcontact coastal Andean health outcomes on local and regional scales and contribute to expanding understandings of the diversity of indigenous biological variation in the postcontact Western Hemisphere.

Dental indicators of health and stress in early Egyptian and Nubian agriculturalists: A difficult transition and gradual recovery

Although agriculture is now the globally predominant mode of food production, studies of the skeletal remains of early agriculturalists have indicated high levels of physiological stress and poor health relative to hunter-gatherers in similar environments. Previous studies identifying this trend in different regions prompt further research of the causes and effects of subsistence transitions in human societies. Here, 242 dentitions from five ancient Egyptian and Nubian populations are examined: 38 individuals from Jebel Sahaba (Upper Paleolithic), 56 from Badari (Predynastic), 54 from Naqada (Predynastic), 47 from Tarkhan (Dynastic), and 47 from Kerma (Dynastic). These populations span the early period of agricultural intensification along the Nile valley. Skeletal remains were scored for the presence of linear enamel hypoplasia (LEH) of the dentition, an established indicator of physiological stress and growth interruption. The prevalence of LEH was highest in the "proto-agricultural" (pastoralist) Badari population, with a gradual decline throughout the late Predynastic and early Dynastic periods of state formation. This suggests that the period surrounding the emergence of early agriculture in the Nile valley was associated with high stress and poor health, but that the health of agriculturalists improved substantially with the increasing urbanization and trade that accompanied the formation of the Egyptian state. This evidence for poor health among proto- and early agriculturalists in the Nile valley supports theories that agricultural intensification occurred as a response to ecological or demographic pressure rather than simply as an innovation over an existing stable subsistence strategy.

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).

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 hypoplasia in gibbons (Hylobates lar carpenteri).

This study describes the expression of linear enamel hypoplasia (LEH), a sensitive dental indicator of physiological stress, in Thailand gibbons (Hylobates lar carpenteri). Previous studies of enamel hypoplasia in hominoids have focused on great apes, with little attention given to the expression of this stress indicator in gibbons. In that gibbons differ from both monkeys and great apes in numerous life history features, LEH expression in gibbons might be expected to show significant differences from both. In this study, 92 gibbon specimens from two sites in Thailand were compared with several samples of monkeys and great apes in their expression of LEH. The intertooth distribution of LEH in gibbons was compared to that of chimpanzees and rhesus monkeys. Gibbon populations from both sites exhibit LEH frequencies intermediate between those of the monkey samples, in which LEH prevalence is usually low, and those of the great ape samples, in which LEH prevalence is high. Gibbons differ significantly from monkeys, but not great apes, in the number of individuals whose teeth record multiple stress events. Multiple episodes of stress are rarely recorded in the teeth of monkeys, while multiple stress events occur with higher frequency in gibbons and great apes. Taxonomic variation in the duration of crown formation, the prominence and spacing of perikymata on dental crowns, life history features, and/or experience of physiological stress may explain these patterns. The intertooth distribution of LEH in gibbons is, for different reasons, unlike that of either chimpanzees or rhesus monkeys. The mandibular canines of gibbons have significantly more LEH than any of their other teeth. Aspects of crown morphology, perikymata prominence/spacing, enamel thickness, and crown formation spans are potential causes of taxonomic variation in the intertooth distribution of LEH.