Past Human Populations Research Articles

Beyond diet reconstruction: Stable isotope applications to human physiology, health, and nutrition

ABSTRACTAnalysis of stable carbon and nitrogen isotopes from soft or mineralized tissues is a direct and widely‐used technique for modeling diets. In addition to its continued role in paleodiet analysis, stable isotope analysis is now contributing to studies of physiology, disease, and nutrition in archaeological and living human populations. In humans and other animals, dietary uptake and distribution of carbon and nitrogen among mineralized and soft tissue is carried out with varying efficiency due to factors of internal biology. Human pathophysiologies may lead to pathology‐influenced isotopic fractionation that can be exploited to understand not just skeletal health and diet, but physiological health and nutrition. This study reviews examples from human biology, non‐human animal ecology, biomedicine, and bioarchaeology demonstrating how stable isotope analyses are usefully applied to the study of physiological adaptation and adaptability. Suggestions are made for future directions in applying stable isotope analysis to the study of nutritional stress, disease, and growth and development in living and past human populations. Am. J. Hum. Biol. 25:445–456, 2013. © 2013 Wiley Periodicals, Inc.

Fibrous dysplasia in a 120,000+ year old Neandertal from Krapina, Croatia.

We describe the first definitive case of a fibrous dysplastic neoplasm in a Neandertal rib (120.71) from the site of Krapina in present-day Croatia. The tumor predates other evidence for these kinds of tumor by well over 100,000 years. Tumors of any sort are a rare occurrence in recent archaeological periods or in living primates, but especially in the human fossil record. Several studies have surveyed bone diseases in past human populations and living primates and fibrous dysplasias occur in a low incidence. Within the class of bone tumors of the rib, fibrous dysplasia is present in living humans at a higher frequency than other bone tumors. The bony features leading to our diagnosis are described in detail. In living humans effects of the neoplasm present a broad spectrum of symptoms, from asymptomatic to debilitating. Given the incomplete nature of this rib and the lack of associated skeletal elements, we resist commenting on the health effects the tumor had on the individual. Yet, the occurrence of this neoplasm shows that at least one Neandertal suffered a common bone tumor found in modern humans.

Carles Lalueza-Fox

Carles Lalueza-Fox

The Archaeology of Cosmic Impact: Lessons from Two Mid-Holocene Argentine Case Studies

Cosmic impact is a category of natural catastrophe neglected or misunderstood by most archaeologists in reconstructions of past human population dynamics. We discuss the nature of impact by asteroids and comets and what is known and theorized about the Quaternary Period impact record. As case studies for our exploration of how archaeological method and theory can be productively applied to the study of cosmic impact, we focus on two confirmed Holocene asteroid impacts in central and northeastern Argentina, Rio Cuarto and Campo del Cielo, both likely dating between 6 and 3 cal ky BP. We model and assess the potential destructive effects of these impacts on contemporary hunting and gathering populations using several lines of evidence. The search for Quaternary Period cosmic impacts, along with the documentation of the effects of confirmed cosmic impacts on human populations, particularly of those organized in small-scale social groups, represents a challenge and key opportunity for future archaeological research.

DNA FROM HUMAN ANCIENT BACTERIA: A NOVEL SOURCE OF GENETIC EVIDENCE FROM ARCHAEOLOGICAL DENTAL CALCULUS

We report a molecular methodology to obtain and analyse ancient bacterial DNA from archaeological dental calculus. Recent and archaeological DNA samples, as old as 4000 bp, were successfully extracted and amplified with species-specific PCR primers. We propose this approach in order to: detect the presence of specific bacterial species infecting past human populations; compare the composition of ancient oral microbiomes among human populations; and analyse the genetic variability and covariation of bacteria and human host populations. Genomic analysis of bacteria from dental calculus is a promising source of evidence for palaeopathological and micro-evolutionary studies, focused either on micro-organisms or their human hosts.

Understanding Entheses: Bridging the Gap Between Clinical and Anthropological Perspectives

An enthesis is the interface where tendon meets bone, providing both muscle anchorage and stress dissipation. Previous anthropological research suggests size and complexity of entheses observable in osteological material, are indicative of the strain magnitude resulting from repetitive muscle contractions during the performance of daily routines. These proposed "musculoskeletal stress markers" are routinely incorporated into bioarcheological studies as evidence of general activity patterns past human populations participated in. However, much of how this complex osteotendinous interface develops and responds to mechanical strains is poorly understood. The following review seeks to shed light on this structural enigma by synthesizing current findings in both the clinical and anthropological literature, in the interest of generating new conversations in how entheses respond to contractual forces and the systemic influences (i.e., genetics, hormones), that surround their morphological development. Only once we truly understand the etiology of tendon insertion sites, will the value of enthesial research in reconstructing human behavior be determined.

Landscape‐ and small‐scale determinants of grassland species diversity: direct and indirect influences

Species richness is influenced both by mechanisms occurring at landscape scales, such as habitat availability, and local‐scale processes, that are related to abiotic conditions and plant–plant interactions. However, it is rarely tested to what extent local species richness can be explained by the combined effect of factors measured at multiple spatial scales. In this study, we quantified the simultaneous influence of historical landscape‐scale factors (past human population density, and past habitat availability – an index combining area and connectivity) and small‐scale environmental conditions (shrub cover, and heterogeneity of light, soil depth, and other soil environmental variables) on plant species richness in dry calcareous grasslands (alvars). By applying structural equation modelling (SEM) we found that both landscape conditions and local environmental factors had significant direct and indirect (i.e. through the modification of another factor), effects on species richness. At the landscape scale, we found a direct positive influence of historical habitat availability on species richness, and indirect positive influence of past human population (via its effects on historical habitat availability). At small scales, we found a positive direct influence of light heterogeneity and shrub cover on species richness. Conversely, we found that small‐scale soil environmental heterogeneity, which was mainly determined by soil depth heterogeneity, had a negative effect on species richness. Our study indicates that patterns of species richness in alvar grasslands are positively influenced by the anthropogenic management regime that maintained the landscape habitat conditions in the past. However, the abandonment of management, leading to shrub invasion and increased competition for light resources also influenced species richness. In contrast to the positive heterogeneity–diversity relationship we found that soil heterogeneity reduced species richness. Environmental heterogeneity, occurring at the plant neighbourhood scale (i.e. centimetres), can increase the isolation among suitable soil patches and thus hinder the normal functioning of populations. The combination of previous knowledge of the system with new ecological theories facilitates disentangling how species richness responds to complex relationships among factors operating at multiple scales.

Variability and standardization: The early Gravettian lithic complex of Grotta Paglicci, Southern Italy

Lithic assemblages contribute to gather insights into past human populations, their technical know-how and behaviour. The present research focuses on the period of the first Gravettian, dated between 29,000 and 27,000 BP, by analysing the technological aspects of the lithic industry recovered from layer 23 of Grotta Paglicci at Rignano Garganico (Apulia, Southern Italy). Stone tool production is characterized by the twofold concept of variability and standardization: blade débitage, one the one hand, is finalized at the manufacture of a differentiated set of tools for domestic activities, whose variability is determined by size, shape and edges, and sometimes by retouch and functional fractures, whilst bladelet production, on the other hand, aims at obtaining standardized backed tools referable to armatures hafted onto throwing weapons. Standardization of the backed points is determined both by débitage and by intensive modification. Different modalities for bladelet production are documented, among which prevails the exploitation of burin cores on thick blades. The flintknappers’ technical choices show several similarities to contemporaneous industries of Central and Western Europe. The evident change in armature manufacture which took place after 30,000 BP, represented throughout Europe by the diffusion of straight and pointed backed armatures, was most likely related to the development of new hunting technologies.

Estimation of skeletal adult age distribution of Okhotsk people in northern Japan

The demographic structure of prehistoric hunter-gatherer societies has contributed to our understanding of the life history patterns of past human populations. The purposes of this study are to examine the human skeletal remains associated with the Okhotsk culture, to estimate age-at-death distribution using the Buckberry–Chamberlain system of auricular surface aging and the Bayesian approach, and to discuss whether paleodemographic estimates can yield an appropriate mortality profile of prehistoric hunter-gatherers in Japan. The application of the Bayesian theorem to the age-at-death estimation was based on the modern Japanese and Spitalfields known-age collections, assuming uniform, reference, and model prior probabilities. The age distributions of the Okhotsk had low proportions of young adults and high proportions of elderly adults. The results indicated that 24.4–51.3% of individuals were above the age of 55 years. The newly employed technique of the Bayesian estimation yielded the age distributions with significant numbers of elderly individuals, which are contrary to usual paleodemographic estimates. The results of this study suggest direct and plausible evidence of demographic traits in the Okhotsk people and allow us to reveal the mortality schedules of the prehistoric hunter-gatherers that otherwise could not be reconstructed from historical or ethnological records.

Variation in fibular robusticity reflects variation in mobility patterns

During hominin plantigrade locomotion, the weight-bearing function of the fibula has been considered negligible. Nevertheless, studies conducted on human samples have demonstrated that, even if less than that of the tibia, the load-bearing function of the fibula still represents a considerable portion of the entire load borne by the leg. The present study assesses whether variation in habitual lower limb loading influences fibular morphology in a predictable manner. To achieve this, both fibular and tibial morphology were compared amongst modern human athletes (field hockey players and cross-country runners) and matched sedentary controls. Peripheral quantitative computed tomography was used to capture two-dimensional, cross-sectional bone images. Geometric properties were measured at the midshaft for each bone. Results show a trend of increased fibular rigidity from control to runners through to field hockey players. Moreover, relative fibular robusticity (fibula/tibia) is significantly greater in hockey players compared with runners. These results are likely the consequence of habitual loading patterns performed by these athletes. Specifically, the repeated directional changes associated with field hockey increase the mediolateral loading on the lower leg in a manner that would not necessarily be expected during cross-country running. The present study validates the use of the fibula in association with the tibia as a mean to provide a more complete picture of leg bone functional adaptations. Therefore, the fibula can be added to the list of bones generally used (tibia and femur) to assess the correspondence between mobility patterns and skeletal morphology for past human populations.

Brief communication: Oxygen isotopes as a biomarker for sickle‐cell disease? Results from transgenic mice expressing human hemoglobin S genes

The origins of sickle-cell disease (SCD) are well understood, as are its evolutionary pressures on humans and pathological presentation. However, because it has not been possible to identify SCD in archaeological contexts, its biocultural effects on past populations are unknown. Previous research investigating oxygen isotope fractionation during respiration among anemics suggests that oxygen isotopes in bone apatite may provide a biological marker for SCD in skeletal remains. This pilot study reports δ(18) O ratios in bone apatite of transgenic laboratory mice expressing human SCD globins and compares them to healthy control mice. The δ(18) O ratios of sick mice are significantly lower than those of healthy mice (-5.6‰ vs. -4.5‰; P = 0.002), and the sickest mice exhibit the lowest ratios of all (mean δ(18) O = -5.8‰). These preliminary results suggest that this method may be usefully applied to skeletal materials of past human populations whose diets and water sources do not differ substantially.

Using the life history model to set the stage(s) of growth and senescence in bioarchaeology and paleodemography

Paleodemography, the study of demographic parameters of past human populations, relies on assumptions including biological uniformitarianism, stationary populations, and the ability to determine point age estimates from skeletal material. These assumptions have been widely criticized in the literature and various solutions have been proposed. The majority of these solutions rely on statistical modeling, and have not seen widespread application. Most bioarchaeologists recognize that our ability to assess chronological age is inherently limited, and have instead resorted to large, qualitative, age categories. However, there has been little attempt in the literature to systematize and define the stages of development and ageing used in bioarchaeology. We propose that stages should be based in the human life history pattern, and their skeletal markers should have easily defined and clear endpoints. In addition to a standard five-stage developmental model based on the human life history pattern, current among human biologists, we suggest divisions within the adult stage that recognize the specific nature of skeletal samples. We therefore propose the following eight stages recognizable in human skeletal development and senescence: infancy, early childhood, late childhood, adolescence, young adulthood, full adulthood, mature adulthood, and senile adulthood. Striving toward a better prediction of chronological ages will remain important and could eventually help us understand to what extent past societies differed in the timing of these life stages. Furthermore, paleodemographers should try to develop methods that rely on the type of age information accessible from the skeletal material, which uses life stages, rather than point age estimates.

Trace-element evidence for foreigners at a Maya port in Northern Yucatan

The present paper explores the potentials of trace elements in human dental enamel to indicate mobility and to detect the presence of individuals who had migrated into a community after childhood. Three Pre-Hispanic samples of infants from the Yucatán peninsula were chosen, one from the northern coast (Xcambó), one from the coast of the Gulf of Mexico (Campeche) and the last one from the tropical inland rain forest (Calakmul). Infants’ first permanent molars are the term of reference because infants were very likely born in the same place where they died and therefore are supposed to represent the local geo-chemical environment. Their chemical signature was then compared to the one of the adults from the site of Xcambó. The elemental composition was recorded by means of laser ablation-time of flight-ICP-MS. Sr and Ba (and secondly Mg and I) discriminate well the three infant samples. All the Early Classic adults from Xcambó fall within the range of variation of the site’s infants, while 25% of the Late Classic adults fall outside the range in agreement with archaeological, bioarcheological, and isotopic evidence. LA-ICP-Ms analyses of trace elements in archaeological samples can be an important analytical tool to detect foreigners in local populations. The selection of infants as reference values helps reduce the limits faced by trace element analyses in past human populations studies.

An analysis of modern pollen rain from the Maya lowlands of northern Belize

In the lowland Maya area, pollen records provide important insights into the impact of past human populations and climate change on tropical ecosystems. Despite a long history of regional paleoecological research, few studies have characterized the palynological signatures of lowland ecosystems, a fact which lowers confidence in ecological inferences made from palynological data. We sought to verify whether we could use pollen spectra to reliably distinguish modern ecosystem types in the Maya lowlands of Central America. We collected 23 soil and sediment samples from eight ecosystem types, including upland, riparian, secondary, and swamp ( bajo) forests; pine savanna; and three distinct wetland communities. We analyzed pollen spectra with non-metric multidimensional scaling (NMDS), and found significant compositional differences in ecosystem types' pollen spectra. Forested sites had spectra dominated by Moraceae/Urticaceae pollen, while non-forested sites had significant portions of Poaceae, Asteraceae, and Amaranthaceae pollen. Upland, bajo, and riparian forest differed in representation of Cyperaceae, Bactris-type, and Combretaceae/Melastomataceae pollen. High percentages of pine ( Pinus), oak ( Quercus), and the presence of Byrsonima characterized pine savanna. Despite its limited sample size, this study provides one of the first statistical analyses of modern pollen rain in the Maya lowlands. Our results show that pollen assemblages can accurately reflect differences between ecosystem types, which may help refine interpretations of pollen records from the Maya area.

Adolescent health in medieval Serbia: signs of infectious diseases and risk of trauma

Although pattern of health in adults has been frequently assessed in past human populations, health status of adolescents as a distinct life stage has usually been overlooked. Inconsistency in number and meaning of recognised age categories in anthropological literature, as well as chronological age ranges used to define them, further complicate the interpretation of adolescent health. In this study, we analysed signs of pathological conditions on skeletal remains of 81 adolescents from a medieval site of Stara Torina (northern Serbia). Diagnostic palaeopathological procedures comprised gross examination, digital radiography, and histological analysis. Skeletal signs of anaemia such as cribra orbitalia and other porotic phenomena as well as signs of non-specific bone infection were observed frequently, while evidence of bone trauma was recorded in a very low percentage of individuals. In addition, we recorded two conditions relatively rarely observed in palaeopathological contexts: a case of skull and vertebral asymmetry indicative of congenital muscular torticollis, and a case of a fibrous cortical defect on distal femur. Comparison with available information from other medieval adolescent samples from Serbia demonstrated that while mortality was relatively constant throughout the sample, Stara Torina showed a much higher occurrence of bone disease. Characteristics of observed skeletal conditions, supported by available historical reports, suggest that the health of medieval adolescents in the examined population was most significantly affected by infectious processes.

Life-history theory, past human populations and climatic perturbations

A sensitivity and elasticity analysis is performed on historical life-tables, that of Swedish females from 1751-1755 and 1966-1970, i.e. during and after the Little Ice Age. Coupled with life-history theory, this approach supplies us with some ideas on how stature can be understood as a proxy for conditions during the intrauterine growth, important if we aspire to calibrate proposed climatic perturbations and their effect on past societies. Matrix population models represent a versatile tool that has been used extensively in conservation biology, ecology, primatology and evolutionary demography. As of yet, applications in bioarchaeology/human osteology have been restricted to population forecasting. The following paper introduces matrix population models and discusses their use in bioarchaeology. Copyright (C) 2010 John Wiley & Sons, Ltd. (Less)

Seasonal modulation of reproductive effort during early pregnancy in humans

Life history theory predicts that early pregnancy presents a relatively low cost, uncontested opportunity for a woman to terminate investment in a current reproductive opportunity if a conceptus is of poor quality and/or maternal status or environmental conditions are not propitious for a successful birth. We tested this hypothesis in rural Bolivian women experiencing substantial seasonal variation in workload and food resources. Significant risk factors for early pregnancy loss (EPL) included agropastoralism versus other economic strategies, conception during the most arduous seasons versus other seasons, and increasing maternal age. Anovulation rate (AR) was higher during the most arduous seasons and in older women. Breastfeeding and indicators of social status and living conditions did not significantly influence either risk of EPL or AR. Averaged over the year, anovulation occurred in about 1/4 of the cycles and EPL occurred in about 1/3 of the conceptions. This is the first evidence of seasonality of EPL in a non-industrialized population, and the first to demonstrate a relationship between economic activities and EPL. These findings suggest that both anovulation and EPL are potential mechanisms for modulating reproductive effort; such "failures" may also be nonadaptive consequences of conditions hostile to a successful pregnancy. In either case, variation in EPL risk associated with different subsistence activities can be expected to influence fertility levels and birth seasonality in both contemporary and past human populations. These consequences of variability in the risk of EPL can impact efforts to understand the sources of variation in reproductive success.

Stature estimation in an early medieval (XI‐XII c.) Polish population: Testing the accuracy of regression equations in a bioarcheological sample

Accurate stature estimation from skeletal remains can foster useful information on health and microevolutionary trends in past human populations. Stature can be estimated through the anatomical method and regression equations. The anatomical method (Fully: Ann Med Leg 36 [1956] 266-273; Raxter et al.: Am J Phys Anthropol 130 [2006] 374-384) is preferable because it takes into account total skeletal height and thus provides more accurate estimates, but it cannot be applied to incomplete remains. In such circumstances, regression equations allow estimates of living stature from the length of one or few skeletal elements. However, the accuracy of stature estimates from regression equations depends on similarity in body proportions between the population under examination and those used to calibrate the equations. Since genetic affinity and body proportions similarity are not always clearly known in bioarcheological populations, the criteria for selection of appropriate formulae are not always straightforward. This may lead to inaccurate stature estimates and imprecise accounts of past life conditions. Prompted by such practical and theoretical concerns this study aimed at (1) estimating living stature in an early medieval (XI-XII c.) Polish sample (40 male; 20 female) through the anatomical method and developing population-specific regression formulae; and (2) evaluating the accuracy of estimates obtained with regression methods commonly employed in European populations. Results indicate that when applied to the skeletal remains from Giecz, our formulae provide accurate estimates, with non-age-corrected formulae performing better than age-corrected ones. Our formulae provide better estimates than those calibrated on recent populations and their use in medieval Polish populations is preferable.

Archaeological Demography

Archaeological demography investigates the structure and dynamics of past human populations using evidence from traces of human activities and remnants of material culture in the archaeological record. Research in this field is interdisciplinary, incorporating findings from anthropology, paleogenetics, and human ecology but with a remit that extends beyond the primarily biological focus of paleodemography. Important questions addressed by archaeological demography include the establishment of methods for inferring past population structure, the timing of the emergence of modern human demographic systems, the relative importance of attritional and catastrophic patterns of mortality, and the search for adaptive explanations for demographic transitions, colonization events, and population extinctions. Archaeological evidence, including the extent of settlements and site catchment areas as well as measures of the exploitation, consumption, and discard of materials and artifacts, have traditionally been used as proxies for estimating past population size and density. In recent years this evidence has been supplemented by increasingly large data sets compiled from radiocarbon dating programs. These data sets have been used to investigate demographic waves of advance during continental-scale periods of colonization and cultural change and to detect episodes of population decline, extinction, and hiatuses in settlement history. By considering studies of human genetic diversity that indicate temporary but drastic reductions in effective population size, I hypothesize that catastrophic mortality may have had an important role in long-term population processes and may have limited long-term rates of growth, particularly in prehistoric populations.

Archaeological Demography

Archaeological demography investigates the structure and dynamics of past human populations using evidence from traces of human activities and remnants of material culture in the archaeological record. Research in this field is interdisciplinary, incorporating findings from anthropology, paleogenetics, and human ecology but with a remit that extends beyond the primarily biological focus of paleodemography. Important questions addressed by archaeological demography include the establishment of methods for inferring past population structure, the timing of the emergence of modern human demographic systems, the relative importance of attritional and catastrophic patterns of mortality, and the search for adaptive explanations for demographic transitions, colonization events, and population extinctions. Archaeological evidence, including the extent of settlements and site catchment areas as well as measures of the exploitation, consumption, and discard of materials and artifacts, have traditionally been used as proxies for estimating past population size and density. In recent years this evidence has been supplemented by increasingly large data sets compiled from radiocarbon dating programs. These data sets have been used to investigate demographic waves of advance during continental-scale periods of colonization and cultural change and to detect episodes of population decline, extinction, and hiatuses in settlement history. By considering studies of human genetic diversity that indicate temporary but drastic reductions in effective population size, I hypothesize that catastrophic mortality may have had an important role in long-term population processes and may have limited long-term rates of growth, particularly in prehistoric populations.