Using a multimethod life history approach to navigate the osteological paradox: A case study from Prehispanic Nasca, Peru.

OBJECTIVES: We leverage recent bioarchaeological approaches and life history theory to address the implications of the osteological paradox in a study population. The goal of this article is to evaluate morbidity and mortality patterns as well as variability in the risk of disease and death during the Late Intermediate period (LIP; 950-1450 C.E.) in the Nasca highlands of Peru. We demonstrate how the concurrent use of multiple analytical techniques and life history theory can engage the osteological paradox and provide salient insights into the study of stress, frailty, and resilience in past populations. MATERIALS AND METHODS: Crania from LIP burial contexts in the Nasca highlands were examined for cribra orbitalia (n = 325) and porotic hyperostosis (n = 270). All age groups and both sexes are represented in the sample. Survivor/nonsurvivor analysis assessed demographic differences in lesion frequency and severity. Hazard models were generated to assess differences in survivorship. The relationship between dietary diversity and heterogeneity in morbidity was assessed using stable δ15 N and δ13 C isotope values for bone collagen and carbonate. One hundred and twenty-four crania were directly AMS radiocarbon dated, allowing for a diachronic analysis of morbidity and mortality. RESULTS: The frequency and expression of both orbital and vault lesions increases significantly during the LIP. Survivor/nonsurvivor analysis indicates cranial lesions co-vary with frailty rather than robusticity or longevity. Hazard models show (1) decreasing survivorship with the transition into the LIP, (2) significantly lower adult life expectancy for females compared to males, and (3) individuals with cranial lesions have lower survivorship across the life course. Stable isotope results show very little dietary diversity. Mortality risk and frequency of pathological skeletal lesions were highest during Phase III (1300-1450 C.E.) of the LIP. CONCLUSION: Results provide compelling evidence of increasing physiological stress and mortality in the Nasca highlands during the LIP, but also reveal substantial heterogeneity in frailty and the risk of death. Certain members of society experienced a heavier disease burden and higher mortality compared to their contemporaries. Elevated levels of disease and lethal trauma among females account for some of the sex differences in survivorship but cannot explain the large degree of female-biased mortality. We hypothesize that parental investment in males or increased female fertility rates may explain these differences.

Increased dental fluctuating asymmetry is associated with active skeletal lesions, but not mortality hazards in the precontact Southwest United States.

OBJECTIVE: This study examines whether individuals with higher dental fluctuating asymmetry (DFA) are frailer than those with lower DFA, by examining whether increased DFA is associated with skeletal lesion formation. SUBJECTS AND METHODS: 150 individuals with permanent teeth and 64 individuals with deciduous teeth. All individuals are Ancestral Puebloans from archaeological sites in modern-day New Mexico. We estimate DFA in three ways: (a) deciduous DFA only, (b) permanent DFA only, and (c) a composite of permanent and deciduous DFA. We analyzed DFA alongside lesion status for cribra orbitalia (CO) and porotic hyperostosis (PH), as well as the presence/absence of enamel hypoplasia (EH). All stress indicators were further analyzed for their impact on mortality hazards. RESULTS: We find that individuals with active CO and PH lesions have increased DFA, while those with healed lesions have lower DFA. We found no relationship between EH and DFA. Further, DFA alone does not predict individual mortality but CO does. CONCLUSIONS: Individuals with increased DFA are frailer and therefore, less capable of buffering themselves against perturbations to their health than those with lower DFA. All results indicate that individuals in this study with lower DFA were more successful in buffering themselves against random environmental impacts during childhood. While DFA alone does not predict mortality hazard, its relationship to lesion status (lower DFA in individuals with healed lesions) indicates that it would be a valuable addition to studies of health and stress.

Lack of biological mortality bias in the timing of dental formation in contemporary children: Implications for the study of past populations.

OBJECTIVES: Biological mortality bias is the idea that individuals who perish (non-survivors) are biologically distinct from those who survive (survivors). If biological mortality bias is large enough, bioarchaeological studies of nonsurvivors (skeletal samples) cannot accurately represent the experiences of the survivors of that population. This effect is particularly problematic for the study of juvenile individuals, as growth is particularly sensitive to environmental insults. In this study, we test whether biological mortality bias exists in one dimension of growth, namely dental development. MATERIALS AND METHODS: Postmortem computed tomography scans of 206 children aged 12 years and younger at death were collected from two institutions in the United States and Australia. The sample was separated into children dying from natural causes as proxies for non-survivors and from accidental causes as proxies for survivors. Differences in the timing of dental development were assessed using sequential logistic regressions between dental formation stages and residual analysis of dental minus chronological age. RESULTS: No consistent delay in age of attainment of dental stages was documented between survivors and non-survivors. Delays between survivors and non-survivors in dental relative to chronological age were greatest for infants, and were greater for females than for males. DISCUSSION: Lack of biological mortality bias in dental development reinforces confidence in juvenile age estimates and therefore in skeletal growth profiles and growth studies. As dental development is known to be less environmentally sensitive than skeletal growth and development, further studies should examine biological mortality bias in long bone length.

A paleoepidemiological approach to the osteological paradox: Investigating stress, frailty and resilience through cribra orbitalia.

OBJECTIVES: The Osteological Paradox posits that skeletal lesions may differentially be interpreted as representing resilience or frailty. However, specific consideration of the etiologies and demographic distributions of individual skeletal indicators can inform the criteria on which to differentiate stress, frailty, and resilience. Adopting a life history approach and adaptive plasticity model, this study proposes a framework for the analysis and interpretation of a commonly reported skeletal lesion, cribra orbitalia, which considers the underlying mechanisms of the condition, the clinical and epidemiological literature relating to anemia and malnutrition, and the bioarcheological evidence. MATERIALS AND METHODS: Data were extracted from the European (n = 33 populations) and American (n = 19 populations) modules of the Global History of Health Project. Kaplan-Meier and Cox regression analyses were applied, where time was the age-at-death, and the factor or covariate was presence or absence of cribra orbitalia. RESULTS: Of 37 samples that produced significant results, 21 demonstrated a change in relationship when the subadults were excluded from analysis. When subadults were included, individuals with cribra orbitalia present had statistically significant lower survival time. With subadults excluded, the relationship either became nonsignificant or was reversed. DISCUSSION: We demonstrate that in many cases the inclusion of subadults in analysis impacts upon the apparent mortality associated with cribra orbitalia. Examining cribra orbitalia in children and adults has two separate goals: in children, to determine the prevalence and risk of death associated with active lesions and stress; and in adults, to determine whether childhood health assaults that cause cribra orbitalia are associated with frailty or resilience.

Growth response of dental tissues to developmental stress in the domestic pig (Sus scrofa).

OBJECTIVES: To compare relative response of enamel, dentin and bone to developmental stressors between attritional and catastrophic mortality assemblages of pigs. MATERIALS AND METHODS: Heads from 70 Sus scrofa of known sex, weight and age comprising an attritional sample of 50 sick pen (SP) pigs that died prematurely versus 20 control pigs slaughtered at 6 months (Catastrophic assemblage). Hard tissue changes (alveolar bone thinning), abnormal bone formation (Harris lines) and re-modeling (auditory bullae) were recorded. Areas and volumes of coronal enamel and dentin were recorded from microCT scans with Avizo 6.3 and Geomagic Wrap. RESULTS: Attritional and catastrophic assemblages are metrically indistinguishable. Ages at death and tissue measures in the SP pigs are differentially distributed, necessitating partition into developmental outcome cohorts. SP "late death" pigs are of lesser physiological maturity than expected, free of disease, with large dental tissue dimensions, comparable to "Controls". SP "early death" pigs have 5% less dentin and enamel and chronic bone infection. Older cohorts of the SP "early deaths" mortality assemblage show progressively reduced enamel. SP pigs show dental evidence of reduced bone mass in the maxilla. DISCUSSION: Bone, dentin and enamel tissues, each, respond distinctively to developmental stressors. Bone mass evinces malnutrition not disease. Both dental tissue reduction and abnormal bone formation link to chronic infection. Paradoxically, reduced dentin mass signals lower survivorship while reduced enamel signals enhanced survivorship. Meaningful comparison of Attritional and Catastrophic assemblages necessitates recognition of developmental outcome cohorts, stratified by age at death and physiological maturity, to reveal heterogeneity of survivorship, tissue measures and lesions.

High prevalence of adult and nonadult scurvy in an early agricultural transition site from Mainland Southeast Asia was associated with decreased survivorship.

OBJECTIVES: The osteological paradox recognizes that the presence of lesions is not always directly related with increased mortality. When combined with the clinical, historical, and epidemiological literature on scurvy, survivorship analysis, a form of statistical analysis to assess the relationship between the presence of diseases in the archeological record and survival, helps determine the overall burden of the disease both in terms of morbidity and mortality. This article explores the relationship between scurvy and survivorship in 26 adults from Man Bac, a Neolithic site from northern Vietnam together with prepublished evidence of scurvy in the nonadult population (n = 44). METHODS: Diagnosis of scurvy included differential diagnosis combined with the Snoddy, A. M. E., Buckley, H. R., Elliott, G. E., Standen, V. G., Arriaza, B. T., & Halcrow, S. E. (2018). Macroscopic features of scurvy in human skeletal remains: A literature synthesis and diagnostic guide. American Journal of Physical Anthropology, 167(4), 876-895. https://doi.org/10.1002/ajpa.23699 threshold criteria and the Brickley, M. B., & Morgan, B. (2023). Assessing diagnostic certainty for scurvy and rickets in human skeletal remains. American Journal of Biological Anthropology, 181, 637-645 diagnostic certainty approaches. Kaplan-Meier survival curves were produced to assess the relationship between the presence of probable scurvy and age-at-death. RESULTS: The prevalence of probable scurvy in adults (35%) was considerably lower than reported for the nonadults (80%). Almost all lesions observed in the adults were in a mixed stage of healing. Kaplan-Meier analysis demonstrated no difference in survivorship between infants and children (<15 years) with or without probable scurvy, whereas a meaningful difference was observed for the adults and adolescents (15+ years). CONCLUSIONS: The findings demonstrate that scurvy considerably decreased survivorship to older age categories. The degree of lesion remodeling, however, indicates that scurvy was not necessarily the direct cause of death but contributed to an overall disease burden that was ultimately fatal.