Past Human Populations Research Articles

Late-Holocene hydroclimatic change and its effect on human activity at Xiada Co on the western Tibetan Plateau

The scarcity of paleoclimate records in the western Tibetan Plateau (TP) hinders our understanding of how environmental evolution affects past human population, agriculture, and animal husbandry. Here, we utilized a range of materials to investigate the impact of climate change on human activities in the Xiada Co basin on the western TP during the Late-Holocene. We presented a continuous compound-specific hydrogen isotope record of sedimentary leaf waxes (δ2Hwax) from a sediment core of Xiada Co, and compared it to XRF core-scanning elements, brGDGT-based mean annual air temperature (MAAT) record, and fecal stanol-based human population proxy record from the same sediment core, as well as archeological evidence from the TP. The δ2Hwax exhibited a sustained increasing trend during the period from 4700 to 900 cal yr BP, followed by a generalized decrease in δ2Hwax values during 900–0 cal yr BP. The multi-proxy analysis of Xiada Co sediments revealed that the δ2Hwax values mainly reflect changes in the ISM precipitation, and are also influenced to some extent by glacier meltwater. Furthermore, a warm and humid climate condition was conducive to human habitation. Appropriate adaptation strategies, such as the herding of cold-tolerant and dry-tolerant sheep and the cultivation of barley in the western TP, led to a surge in population density during 3400–2900 cal yr BP, despite the slightly deteriorated climate background. This study confirmed the importance of choosing the right adaptive strategies to cope with climate change for human survival and development on the Tibetan Plateau.

Technological and Dietary Responses to Holocene Climate Events in the Northern Great Basin

ABSTRACT Environmental instability caused by extended periods of drought no doubt impacted past human populations by limiting economic options and driving changes in social and technological organization. Here we examine two sets of Great Basin sites with occupations spanning the middle and late Holocene droughts: one associated with lowland springs and another with upland springs. We use dietary markers retrieved via starch granule analysis to evaluate whether artifact form relates to resources processed, how changes in tool form might be related to past changes in climate, environment, and social organization, and what, if any, differences mark upland vs. lowland resource use. Our data suggest that changes in tool form track with environmental fluctuations and that in both upland and lowland settings diets focused primarily on tubers and high-return seeds and that these profitable and stable food sources likely anchored populations during periods of drought.

Do counts of radiocarbon-dated archaeological sites reflect human population density? A preliminary empirical validation examining spatial variation across late Holocene California

AbstractResearchers increasingly rely on aggregations of radiocarbon dates from archaeological sites as proxies for past human populations. This approach has been critiqued on several grounds, including the assumptions that material is deposited, preserved, and sampled in proportion to past population size. However, various attempts to quantitatively assess the approach suggest there may be some validity in assuming date counts reflect relative population size. To add to this conversation, here we conduct a preliminary analysis coupling estimates of ethnographic population density with late Holocene radiocarbon dates across all counties in California. Results show that counts of late Holocene radiocarbon-dated archaeological sites increase significantly as a function of ethnographic population density. This trend is robust across varying sampling windows over the last 5000 BP. Though the majority of variation in dated-site counts remains unexplained by population density. Outliers reveal how departures from the central trend may be influenced by regional differences in research traditions, development-driven contract work, organic preservation, and landscape taphonomy. Overall, this exercise provides some support for the “dates-as-data” approach and offers insights into the conditions where the underlying assumptions may or may not hold.

Investigating food production-associated DNA methylation changes in paleogenomes: Lack of consistent signals beyond technical noise.

The Neolithic transition introduced major diet and lifestyle changes to human populations across continents. Beyond well-documented bioarcheological and genetic effects, whether these changes also had molecular-level epigenetic repercussions in past human populations has been an open question. In fact, methylation signatures can be inferred from UDG-treated ancient DNA through postmortem damage patterns, but with low signal-to-noise ratios; it is thus unclear whether published paleogenomes would provide the necessary resolution to discover systematic effects of lifestyle and diet shifts. To address this we compiled UDG-treated shotgun genomes of 13 pre-Neolithic hunter-gatherers (HGs) and 21 Neolithic farmers (NFs) individuals from West and North Eurasia, published by six different laboratories and with coverage c.1×-58× (median = 9×). We used epiPALEOMIX and a Monte Carlo normalization scheme to estimate methylation levels per genome. Our paleomethylome dataset showed expected genome-wide methylation patterns such as CpG island hypomethylation. However, analyzing the data using various approaches did not yield any systematic signals for subsistence type, genetic sex, or tissue effects. Comparing the HG-NF methylation differences in our dataset with methylation differences between hunter-gatherers versus farmers in modern-day Central Africa also did not yield consistent results. Meanwhile, paleomethylome profiles did cluster strongly by their laboratories of origin. Using larger data volumes, minimizing technical noise and/or using alternative protocols may be necessary for capturing subtle environment-related biological signals from paleomethylomes.

Archaeology meets environmental genomics: implementing sedaDNA in the study of the human past

Sedimentary ancient DNA (sedaDNA) has become one of the standard applications in the field of paleogenomics in recent years. It has been used for paleoenvironmental reconstructions, detecting the presence of prehistoric species in the absence of macro remains and even investigating the evolutionary history of a few species. However, its application in archaeology has been limited and primarily focused on humans. This article argues that sedaDNA holds significant potential in addressing key archaeological questions concerning the origins, lifestyles, and environments of past human populations. Our aim is to facilitate the integration of sedaDNA into the standard workflows in archaeology as a transformative tool, thereby unleashing its full potential for studying the human past. Ultimately, we not only underscore the challenges inherent in the sedaDNA field but also provide a research agenda for essential enhancements needed for implementing sedaDNA into the archaeological workflow.

Frequent disturbances enhanced the resilience of past human populations.

The record of past human adaptations provides crucial lessons for guiding responses to crises in the future1-3. To date, there have been no systematic global comparisons of humans' ability to absorb and recover from disturbances through time4,5. Here we synthesized resilience across a broad sample of prehistoric population time-frequency data, spanning 30,000 years of human history. Cross-sectional and longitudinal analyses of population decline show that frequent disturbances enhance a population's capacity to resist and recover from later downturns. Land-use patterns are important mediators of the strength of this positive association: farming and herding societies are more vulnerable but also more resilient overall. The results show that important trade-offs exist when adopting new or alternative land-use strategies.

Masticatory habits of the adult Neanderthal individual BD 1 from La Chaise-de-Vouthon (France).

The analysis of dental wear provides a useful approach for dietary and cultural habit reconstructions of past human populations. The analysis of macrowear patterns can also be used to better understand the individual chewing behavior and to investigate the biomechanical responses during different biting scenarios. The aim of this study is to evaluate the diet and chewing performance of the adult Neanderthal Bourgeois-Delaunay 1 (BD 1) and to investigate the relationship between wear and cementum deposition under mechanical demands. The macrowear pattern of BD 1 was analyzed using the occlusal fingerprint analysis method. We propose a new method for the bilateral measurement of the cementum volume along both buccal and lingual sides of the molar root. BD 1's anterior dentition is more affected by wear compared to the posterior one. The macrowear pattern suggest a normal chewing behavior and a mixed-diet coming from temperate environments. The teeth on the left side of the mandible display greater levels of wear, as well as the buccal side of the molar crowns. The cementum analysis shows higher buccal volume along the molar roots. BD1 could have been preferably chewing on the left side of the mandible. The exploitation of various food resources suggested by the macrowear analysis is compatible with the environmental reconstructions. Finally, the greater wear on the buccal side of the molar occlusal surface and the greater volume of cementum in that side of the molar roots offers a preliminary understanding about the potential correlation between dental wear and cementum deposition.

Non-ingested vertebrate prey remains accumulated by the Chaco eagle (Buteogallus coronatus): neo-taphonomy to evaluate open-air faunal records in central western Argentina

The Chaco eagle (Buteogallus coronatus) is a large, endangered, and little-known bird of prey distributed throughout southern South America. This bird of prey accumulates large amounts of prey remains around its nests in open landscapes. To present a reliable pattern to distinguish the action of the Chaco Eagle as a potential accumulator of faunal remains in open-air archaeological contexts, we conducted a neo-taphonomic study in an area of the eastern plains of the CWA, analyzing modern remains accumulated around a nest of the Chaco eagle. Our taxonomic analysis allowed us to identify the presence of different taxa belonging to two classes: mammals and reptiles. Most of the specimens identified were non-ingested remains. The armadillo Zaedyus pichiy was the most conspicuous prey species, represented by osteoderms and skulls. We registered several endoskeletal remains and osteoderms of the Chaco tortoise (Chelonoidis chilensis), as well as bone and tooth remains of two little-known and reported species in the study area: the red tegu (Salvator rufescens) and the Patagonian weasel (Lyncodon patagonicus). In addition, we found remains corresponding to two species of small-sized rodents. We also discovered strongly digested vertebrae of an indeterminate small Ophidia preserved in the only recovered pellet. The proportion of weathering was high, with stages 1 and 2 identified as the most dominant degrees. Notably, specimens with two stages of weathering were detected based on the side grounded to the floor. The proportions of breakage, on the other hand, were low. We hope this work contributes to the distinction of accumulating agents in the region's archaeological sites, especially considering the high importance that armadillos have had for the past human populations of the area.

Patterns of infectious disease in ancient Brazilian groups: The role of different environments and demographic parameters

In the last 200ka, humans have explored and adapted to a changing world. Environmental challenges faced by humans today, like emergent pathogens and overpopulation, are not that different from the ones in the past. This article aims to discuss the patterns of disease observed in ancient human populations from southeastern and southern Brazil (hunter-gatherer groups associated to riverine and coastal shellmounds and agriculturalists associated to the Tupiguarani archaeological Tradition). The role of new pathogens and high demographic density will be discussed, as well as the interpretations regarding the frequencies of chronic infectious diseases that affect bones. We will also present the importance of understanding patterns of health and disease in past human populations in order to address present day scenarios related to climate change, vulnerable populations, and disease. Warning: This article discusses and presents images of ancient human remains. While we acknowledge that this can be a sensitive topic, we would like to stress the importance of studying and generating knowledge about past human populations which otherwise would be completely unknown and forgotten.

Landscapes of Movement Along the (Pre)Historical Libyan Sea: Keys for a Socio-Ecological History

Abstract This study examines the influence of Human Ecodynamics and Historical Ecology to understand the complexities of historical mobility. Based on Landscape Archaeology, this study considers some of these theoretical principles for studying and reconstructing the movements of past human populations. This discussion is grounded on the example of a research project focused on modelling movement and interaction patterns between the Aegean area (Crete) and northeastern African region (Marmarica) from the Late Bronze to Roman times. The project works with multivariate data representative of the routes and non-human factors that may interplay in biocultural processes. Three key aspects structure this article: (1) the emergence of Human Ecodynamics and Historical Ecology in archaeology, (2) their impact on the theoretical evolution of Landscape Archaeology, and (3) the methodological implementation of these principles through a case study. We specifically discuss the strengths of Human Ecodynamics and Historical Ecology to enhance the conceptualisation of mobility by considering the heterarchical interrelationships between human and non-human agents. Our methodological implementations showcase this by using computational approaches to model human pathways influenced by and in constant relationship with their environment. This research thus highlights the importance of transdisciplinary approaches to studying historical mobility from an archaeological and complex systems perspective.

Past human expansions shaped the spatial pattern of Neanderthal ancestry.

The worldwide expansion of modern humans (Homo sapiens) started before the extinction of Neanderthals (Homo neanderthalensis). Both species coexisted and interbred, leading to slightly higher introgression in East Asians than in Europeans. This distinct ancestry level has been argued to result from selection, but range expansions of modern humans could provide an alternative explanation. This hypothesis would lead to spatial introgression gradients, increasing with distance from the expansion source. We investigate the presence of Neanderthal introgression gradients after past human expansions by analyzing Eurasian paleogenomes. We show that the out-of-Africa expansion resulted in spatial gradients of Neanderthal ancestry that persisted through time. While keeping the same gradient orientation, the expansion of early Neolithic farmers contributed decisively to reducing the Neanderthal introgression in European populations compared to Asian populations. This is because Neolithic farmers carried less Neanderthal DNA than preceding Paleolithic hunter-gatherers. This study shows that inferences about past human population dynamics can be made from the spatiotemporal variation in archaic introgression.

Close encounters vs. missed connections? A critical review of the evidence for Late Pleistocene hominin interactions in western Eurasia

Recent advances in the study of ancient DNA recovered from fossils and cave sediments have profoundly changed our views on the biological and cultural interactions between populations and lineages of fossil Homo in the Later Pleistocene of Eurasia. A spatiotemporally complex picture emerges, with multiple population admixture and replacement events. Focusing on the evidence from Western Eurasia, we consider here how the mapping out of between-species interactions based on fossil and material cultural evidence is being replaced by a broader approach. Traditional narratives about human migrations and the biological and/or cultural advantages of our own species over the Neanderthals are now giving way to the study of the biological and cultural dynamics of past human populations and the nature of their interactions in time and space.

Muscle activity during crouched walking.

Muscle activity during crouched walking has been previously studied in the context of the evolution of hominin bipedalism and human movement disorders. However, crouched walking could also be used in approach hunting where postural height (actual height of the body from the ground to the top of the head during locomotion) is the limiting factor. Here, we aim to analyze the relationship between relative postural height (%stature), kinematics, and muscle activity during crouched walking. Adult males (n = 19) walked with extended limbs and at three degrees of crouch while their 3D motion capture kinematics and lower limb muscle electromyography were recorded. We measured activation of tibialis anterior, soleus, gastrocnemius medialis, gastrocnemius lateralis, vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus. We analyzed the effects of postural height on kinematics and muscle activation using linear mixed effects model. Flexion angles, individual muscle activation (except for medial gastrocnemius), and total muscle activation were negatively related to relative postural height, that is, were greater at more crouched postures. Relative postural height had a stronger effect on the activation of the thigh and gluteal muscles compared to shank muscles. General increase in lower limb muscle activation at lower postural heights suggests a negative relationship between relative postural height and fatigue, and may indicate a possible mechanism by which short stature could benefit the hunter in approach hunting. Greater activation of thigh and gluteal muscles relative to shank muscles may help to identify crouched walking in past human populations.

Poirier's facet in past human populations from Radom (14th-17th and 18th-19th centuries).

Femoral head-neck defects are commonly reported in the anatomical and anthropological literature. The best-known types are Poirier's facet and Allen's fossa; however, their aetiology and definition are still debated. The aim of this study was to analyse the frequency of Poirier's facet in the skeletal population from Radom (Poland, 14th-19th century). Additionally, a comparison of Poirier's facet prevalence in two chronological periods (the populations from Radom during the 14th-17th century and the 18th-19th century) was done. The femora of 367 adult individuals (184 males, 140 females, 43 unknown sex) from the osteological collections from Radom (14th-19th century) (Poland) were analysed according to the frequency of Poirier's facet. In the Late Medieval population from Radom (14th-17th century), Poirier's facet was noted in 33% of individuals, while in Radom individuals from 18th-19th century, Poirier's facet was observed in 34%. In the analysed skeletal group, Poirier's facet was usually observed on both femoral bones. Males from 18th-19th century had more occasions of Poirier's facet observed compared to the 14th-17th century males, while in females, Poirier's facet was slightly more frequently observed in 14th-17th century Radom individuals. There were not statistically significant differences in the Poirier's facet frequencies between males and females in Radom from the 14th-17th century (38% in males, 29% in females). In the Medieval and Modern skeletal series from Radom (18th-19th), males had significantly higher frequencies (44%) of this skeletal trait compared to females (18%). It could be hypothesised that 18th-19th century Radom males engaged in more demanding physical activity than females. Poor knowledge about Poirier's facet aetiology, insufficient archaeological and historical knowledge about the Radom individuals' lifestyle, and a small sample size from the 14th-17th Radom sample do not allow for drawing such unambiguous conclusions, and further analyses are needed.

Eye and hair color prediction of an early medieval adult and subadult skeleton using massive parallel sequencing technology.

Phenotypic trait prediction in ancient DNA analysis can provide information about the external appearance of individuals from past human populations. Some studies predicting eye and hair color in ancient adult skeletons have been published, but not for ancient subadult skeletons, which are more prone to decay. In this study, eye and hair color were predicted for an early medieval adult skeleton and a subadult skeleton that was anthropologically characterized as a middle-aged man and a subadult of unknown sex about 6years old. When processing the petrous bones, precautions were taken to prevent contamination with modern DNA. The MillMix tissue homogenizer was used for grinding, 0.5g of bone powder was decalcified, and DNA was purified in Biorobot EZ1. The PowerQuant System was used for quantification and a customized version of the HIrisPlex panel for massive parallel sequencing (MPS) analysis. Library preparation and templating were performed on the HID Ion Chef Instrument and sequencing on the Ion GeneStudio S5 System. Up to 21ng DNA/g of powder was obtained from ancient petrous bones. Clean negative controls and no matches with elimination database profiles confirmed no contamination issue. Brown eyes and dark brown or black hair were predicted for the adult skeleton and blue eyes and brown or dark brown hair for the subadult skeleton. The MPS analysis results obtained proved that it is possible to predict hair and eye color not only for an adult from the Early Middle Ages, but also for a subadult skeleton dating to this period.

Exploring prenatal and neonatal life history through dental histology in infants from the Phoenician necropolis of Motya (7th–6th century BCE)

The biological life history of infants from archaeological contexts can provide a unique insight into past human populations. Dental mineralized tissues contain a permanent record of their growth that can provide access to the prenatal and early infant life, and mortality, of human skeletons. This study focuses on the histomorphometric analysis of deciduous teeth from the ‘Archaic Necropolis’ of Motya (7th–6th century BCE, Sicily–Italy). The histomorphometric analysis is conducted on prenatal and postnatal enamel of eight anterior deciduous teeth from seven individuals from this Phoenician population to estimate their chronological age-at-death, health, and enamel growth parameters. Proteomic analysis has been used to determine the sex of the infants.The presence of the Neonatal Line in all specimens indicates that the seven individuals survived birth. The occurrence of at least one Accentuated Line in prenatal enamel in four out of seven individuals suggests the foetuses and/or their mothers experienced a stress-related event during pregnancy. As expected, there was limited variation in Daily Secretion Rates near the Enamel Dentine Junction. These rates increase toward the outer enamel surface and decrease toward the cervix.Our findings illustrate the importance of dental histology for reconstructing perinatal and early infancy mortality and morbidity patterns at Motya, which sheds light on the socio-cultural perception of new-borns and infants in an ancient Phoenician community.

Multiproxy paleodietary reconstruction using stable isotopes and starch analysis: The case of the archaeological site of Playa del Mango, Granma, Cuba

Paleoethnobotanical and stable isotope studies have demonstrated that the indigenous groups that populated the Antilles, traditionally understood as dependent exclusively on wild resources, cultivated and consumed both C3 and C4 plants even before the arrival of the ceramic-bearing Arawak groups. However, the relative importance of cultigens and the differential use of plants, especially maize, between populations and individuals remains unknown. In this paper we combined the analysis of stable isotopes (δ15N, δ13Cco, δ13Cen, δ13Cap, δ34S) of 27 individuals from the archaeological site of Playa del Mango, Cuba with the identification of starch grains in dental calculus. The stable isotope results indicate that the sampled population had a 70:30 C3/C4 diet, where at least 65 % was based on C3 protein. Starches from C3 (e.g., Marantaceae, Ipomoea batatas) and C4 plants (Zea mays) were found in similar proportions (50:50). These results support that the lack or abundance of starch grains cannot be used to infer directly the frequency at which C3 and C4 plants were consumed within a small population. Statistically significant differences between females and males in the carbon isotope composition of diet, and its energy portion, suggests a differential consumption of plants by sex. Playa del Mango individual diets were statistically different from those of coeval sites, supporting our previous findings that groups with different dietary traditions concurrently inhabited Cuba in precolonial times. The study demonstrates the power of combined use of stable isotope models, and starch analysis, to provide a more nuanced reconstruction of dietary practices in past human populations.

The petrous bone contains high concentrations of osteocytes: One possible reason why ancient DNA is better preserved in this bone.

The characterization of ancient DNA in fossil bones is providing invaluable information on the genetics of past human and other animal populations. These studies have been aided enormously by the discovery that ancient DNA is relatively well preserved in the petrous bone compared to most other bones. The reasons for this better preservation are however not well understood. Here we examine the hypothesis that one reason for better DNA preservation in the petrous bone is that fresh petrous bone contains more DNA than other bones. We therefore determined the concentrations of osteocyte cells occluded inside lacunae within the petrous bone and compared these concentrations to other bones from the domestic pig using high resolution microCT. We show that the concentrations of osteocyte lacunae in the inner layer of the pig petrous bone adjacent to the otic chamber are about three times higher (around 95,000 lacunae per mm3) than in the mastoid of the temporal bone (around 28,000 lacunae per mm3), as well as the cortical bone of the femur (around 27,000 lacunae per mm3). The sizes and shapes of the lacuna in the inner layer of the petrous bone are similar to those in the femur. We also show that the pig petrous bone lacunae do contain osteocytes using a histological stain for DNA. We therefore confirm and significantly expand upon previous observations of osteocytic lacuna concentrations in the petrous bone, supporting the notion that one possible reason for better preservation of ancient DNA in the petrous bone is that this bone initially contains at least three times more DNA than other bones. Thus during diagenesis more DNA is likely to be preserved in the petrous bone compared to other bones.

Osteoarthritis in past human populations from Radom (14th-17th and 18th-19th century).

Osteoarthritis (OA) is a widespread skeletal condition in the historical population, but it still raises many methodological and interpretative problems. The present study aimed to examine the osteoarthritic changes (osteophytes, porosity, eburnation) in the skeletal material from Radom (14th-19th century) (Poland), enriching knowledge about osteoarthritis and its prevalence in the past. Additionally, a comparison of OA changes prevalence in two chronological periods (the population from Radom during the 14th-17th century versus the 18th-19th century) was done. In the Late Medieval (14th-17th century) population from Radom, osteoarthritic changes were observed in 22% of individuals (males, 18%; females, 29%) and in the Modern Period Radom (18th-19th century) in 25% individuals (males, 25.7%; females, 26.5%). In both skeletal samples, the greatest number of OA changes was recorded in the hip and elbow. Knee and ankle were the least affected joints. Osteophytes were the most frequently observed type of lesions, while eburnation was the least frequent. Although the higher prevalence of osteoarthritis in the Modern Period in Radom is noted, the differences are not statistically significant. Taking the multifactorial etiology of osteoarthritic changes, and the fact that osteoarthritis, as a single indicator of health, could not tell much about the overall lifestyle of past human populations, one must be caution when drawing unambiguous conclusions according to the simple, linear effect of environmental changes on osteoarthritic changes formation.

Dimension variability of the M2 human molar teeth: comparisons between prehistoric and medieval samples

Teeth are a valuable source of information for studies regarding past human populations in archaeological and forensic contexts. In dental anthropology, the linear measurements of tooth crowns are used for assessing morphological variability and sexual dimorphism in both modern and past human populations. The aim of this research is to evaluate the M2 molar crown variability in archaeological human populations from Prehistory (Chalcolithic and Bronze Age, ~ 5000-1150 BCE) and Middle Ages (13th-17th centuries) discovered in sites from North-Eastern Romania. The objectives of this study emphasize on the diachronic comparison of the M2 molar crown variables between prehistoric and medieval samples (1), and the assessment of sexual dimorphism expression (2). The two crown measurements, mesio-distal (MD) and bucco-lingual (BL) diameters, were performed using ImageJ software on occlusal digital images acquired stereo-microscopically. The crown index (CI), crown area (CA) and the sexual dimorphism index (SDI), along with the two linear measurements, were subjected to univariate and multivariate statistical analysis. Our results show that the variation coefficient (CV) differs for the MD variable in the female upper M2 molars, being higher in the medieval sample than the prehistoric one; also, a higher variability is remarked for the mandibular molar in the medieval sample than in prehistoric one. In females, the MD and CA variables for mandibular M2 molars and the BL and CA for maxillary molars showed significant statistical differences between the medieval and prehistoric mandibular teeth, with higher values for the exemplar from Middle Ages. Similar result was obtained in males, for the CA variable in the upper M2 molars. In our study, the sexual dimorphism manifested at the M2 crown molar was highlighted in the prehistoric sample, though less in the medieval one.