Multiproxy isotopic analyses of human skeletal material from Rapa Nui: Evaluating the evidence from carbonates, bulk collagen, and amino acids.

OBJECTIVES: Stable isotope ratio analysis of bulk bone collagen dominates research into past diet; however, bone carbonate and compound specific isotope analyses (CSIA) of amino acids provide alternative, yet complementary, lines of evidence toward that same research goal. Together they inform on different aspects of diet, allowing greater certainty in reconstructions. Here we present new data on carbonate isotopes for Rapa Nui and reevaluate prehistoric diet in the context of these new and previously published bulk collagen and CSIA data. MATERIALS AND METHODS: We analyzed carbon isotopes in bone carbonate from 28 prehistoric human teeth from Rapa Nui. These represent a subset of material examined previously for carbon and nitrogen isotope ratios in bulk collagen. We then reevaluate prehistoric diet in light of these and other published data. In addition, we analyzed carbon and nitrogen isotope ratios in 28 modern plant specimens from Rapa Nui to better approximate the isotopic value of the terrestrial endmember. RESULTS: Bulk data suggest a predominantly terrestrial diet, with the amount of marine sources incorporated varying though time. While previously argued to reveal greater amounts of marine consumption, reanalysis of recently published CSIA data suggests this result may relate to the proportion of carbon assimilated rather than consumed. Utilizing models incorporating concentration dependence for estimating dietary proportions results in much lower estimates of marine consumption, in line with findings of the bulk data. DISCUSSION: While these data indicate a larger focus on terrestrial resources, limitations in all forms of analysis make it difficult to determine exact dietary contributions in this mixed system. Better understanding of the complex physiological processes governing isotopic routing and fractionation, and knowledge of appropriate isotopic endmember values are needed to advance this research.

Oxygen isotope analysis of human bone phosphate evidences weaning age in archaeological populations.

Here we report bone phosphate oxygen (δ(18)Op) values from perinates/neonates and infants (<3.5 years; n = 32); children (4-12 years; n = 12); unsexed juveniles (16-18 years; n = 2); and adult bones (n = 17) from Wharram Percy, North Yorkshire, England, in order to explore the potential of this method to investigate patterns of past breastfeeding and weaning. In prior studies, δ(15)N and δ(13)C analyses of bone collagen have been utilized to explore weaning age in this large and well-studied assemblage, rendering this material highly appropriate for the testing and development of this alternative method targeting the inorganic phase of bone. Data produced reveal (18)O-enrichment in the youngest perinatal/neonatal and infant samples, and an association between age and bone δ(18)Op (and previously-published δ(15)N values), with high values in both these isotope systems likely due to breastfeeding. After the age of 2-3 years, δ(18)Op values are lower, and all children between the ages of 4 and 12, along with the vast majority of sub-adults and adults sampled (aged 16 to >50 years), have δ(18)Op values consistent with the consumption of local modern drinking water. The implications of this study for the reconstruction of weaning practices in archaeological populations are discussed, including variations observed with bone δ(15)Ncoll and δ(18)Op co-analysis and the influence of culturally-modified drinking water and seasonality. The use of this method to explore human mobility and palaeoclimatic conditions are also discussed with reference to the data presented.

Stable nitrogen isotope analysis of dentine serial sections elucidate sex differences in weaning patterns of wild chimpanzees (Pan troglodytes).

Offspring provisioning is one of the most energetically demanding aspects of reproduction for female mammals. Variation in lactation length and weaning strategies between chimpanzees (Pan troglodytes), our closest living relative, and modern human societies have been reported. When and why these changes occurred is frequently debated. Our study used stable nitrogen isotope data of tooth root dentine from wild Western chimpanzees (Pan troglodytes verus) in Taï National Park, Côte d'Ivoire, to quantify weaning in these chimpanzees and explore if infant sex plays a role in maternal investment. We analyzed serial sections of deciduous lateral incisor root dentine from four Taï chimpanzees to establish the δ(15) N signal of nursing infants; we then analyzed serial sections of first permanent mandibular molar root dentine from 12 Taï chimpanzees to provide quantitative δ(15) N data on weaning in this population. Up to 2 years of age both sexes exhibited dentine δ(15) N values ≈2-3‰ higher than adult female Taï chimpanzees, consistent with a nursing signal. Thereafter a steady decrease in δ(15) N values consistent with the onset, and progression, of weaning, was visible. Sex differences were also evident, where male δ(15) N values decreased at a significantly slower rate compared to females. Confirmation of sex differences in maternal investment among Taï chimpanzees, demonstrates the viability of using isotope analysis to investigate weaning in non-human primates. Additionally, assuming that behaviors observed in the Taï chimpanzees are illustrative of the ancestral pattern, our results provide a platform to enable the trajectory of weaning in human evolution to be further explored.

Isotopic evidence of high reliance on plant food among Later Stone Age hunter-gatherers at Taforalt, Morocco.

The transition from hunting-gathering to agriculture stands as one of the most important dietary revolutions in human history. Yet, due to a scarcity of well-preserved human remains from Pleistocene sites, little is known about the dietary practices of pre-agricultural human groups. Here we present the isotopic evidence of pronounced plant reliance among Late Stone Age hunter-gatherers from North Africa (15,000-13,000 cal BP), predating the advent of agriculture by several millennia. Employing a comprehensive multi-isotopic approach, we conducted zinc (δ66Zn) and strontium (87Sr/86Sr) analysis on dental enamel, bulk carbon (δ13C) and nitrogen (δ15N) and sulfur (δ34S) isotope analysis on dentin and bone collagen, and single amino acid analysis on human and faunal remains from Taforalt (Morocco). Our results unequivocally demonstrate a substantial plant-based component in the diets of these hunter-gatherers. This distinct dietary pattern challenges the prevailing notion of high reliance on animal proteins among pre-agricultural human groups. It also raises intriguing questions surrounding the absence of agricultural development in North Africa during the early Holocene. This study underscores the importance of investigating dietary practices during the transition to agriculture and provides insights into the complexities of human subsistence strategies across different regions.

A stable isotope (δ13C and δ15N) perspective on human diet on Rapa Nui (Easter Island) ca. AD 1400-1900.

Ecological and environmental evidence suggests that Rapa Nui was among the most marginally habitable islands in Eastern Polynesia, with only a fraction of the biotic diversity found on archipelagos to the west, and capable of sustaining many fewer cultigens traditionally transported by Polynesian colonizers. However, archaeological evidence for human dietary adaptations under such restrictions is limited. Little is known about the particulars of the subsistence base and dietary changes on Rapa Nui that may be associated with a hypothesized late prehistoric decline in the quality and diversity of food sources. To better understand prehistoric Rapa Nui diet we examined stable carbon and nitrogen isotope compositions of human teeth along with archaeological faunal material thought to comprise the Rapa Nui food web. Our results indicate that contrary to previous zooarchaeological studies diet was predominantly terrestrial throughout the entire sequence of occupation, with reliance on rats, chickens and C3 plants. While a few individuals may have had access to higher trophic level marine resources, this is evident only later in time (generally post-AD 1600). A decline in (15)N through time was observed, and may be attributed to declines in available terrestrial proteins; however, presently we cannot rule out the effect of changing soil and plant baseline δ(15)N. Our results also suggest differential access to higher trophic level marine resources among contemporaneous populations, but more research is required to clarify this observation.

Using SXRF and LA-ICP-TOFMS to Explore Evidence of Treatment and Physiological Responses to Leprosy in Medieval Denmark.

Leprosy can lead to blood depletion in Zn, Ca, Mg, and Fe and blood enrichment in Cu. In late medieval Europe, minerals were used to treat leprosy. Here, physiological responses to leprosy and possible evidence of treatment are investigated in enamel, dentine, and cementum of leprosy sufferers from medieval Denmark (n = 12) and early 20th century Romania (n = 2). Using SXRF and LA-ICP-TOFMS, 12 elements were mapped in 15 tooth thin sections, and the statistical covariation of paired elements was computed to assess their biological relevance. The results show marked covariations in the Zn, Ca, and Mg distributions, which are compatible with clinical studies but cannot be directly attributed to leprosy. Minerals used historically as a treatment for leprosy show no detectable intake (As, Hg) or a diffuse distribution (Pb) related to daily ingestion. Intense Pb enrichments indicate acute incorporations of Pb, potentially through the administration of Pb-enriched medication or the mobilization of Pb from bone stores to the bloodstream during intense physiological stress related to leprosy. However, comparisons with a healthy control group are needed to ascertain these interpretations. The positive correlations and the patterns observed between Pb and essential elements may indicate underlying pathophysiological conditions, demonstrating the potential of SXRF and LA-ICP-TOFMS for paleopathological investigations.

Infancy, childhood, and puberty on the Silk Road revealed with isotopic analysis of incremental dentine.

Childhood is a unique phase in human life history, in which newborns are breastfed and weaned, and are progressively familiarized to adult diets. By investigating dietary changes from infancy to adolescence, valuable information regarding past cultural behaviors and aspects of human lives can be explored and elucidated. Here, in conjunction with published isotopic results of serial dentine (n = 21) from Yingpan Man, new δ13C and δ15N results are obtained from 172 samples of incremental dentine from 8 teeth of 8 individuals of the Yingpan cemetery, located in Xinjiang, China. The δ13C values range from - 18.2 to - 14.6‰ with a mean ± SD value of - 16.3 ± 0.9‰, and the δ15N results range between 13.4 and 19.9‰ with a mean ± SD value of 16.0 ± 1.4‰. This indicates that the childhood diets were mixtures of C3 and C4 dietary resources and were clearly influenced by breastfeeding and weaning practices. In particular, the findings indicate that there were significant inter-individual differences in terms of the timing and duration of breastfeeding and weaning practices as well as childhood dietary practices at Yingpan. For instance, three individuals were exclusively breastfed after birth, while, two individuals and Yingpan Man were not. In addition, the post-weaning diets of most Yingpan individuals were relatively stable, but one individual and Yingpan Man displayed clear evidence of increased consumption of C4 foods, likely millet, during late and post-weaning periods. Further, 7 individuals had unique dietary changes between 9 to 14 years old. Potential factors related to this are presented from the perspective of changes in social roles that might be caused by their early participation in the social division of labor or puberty and marriage.

Revealing lost secrets about Yingpan Man and the Silk Road.

Yingpan Man, is one of the most exquisitely preserved mummies found in the Xinjiang Uyghur Autonomous Region of China. Here links between Yingpan Man and the Silk Road are explored through a detailed isotopic and bioarchaeological investigation of his life history. Analytical techniques of carbon, nitrogen, and sulfur stable isotope ratio analysis on hair, teeth, muscle and bones as well as associated animal and plant remains, radiocarbon dating and starch grain analysis of dental calculus are presented to visualize never before seen aspects of Yingpan Man's life, including: environment, breastfeeding and weaning practices, adolescent and adult diet, disease and nutritional status as well as season of death. Furthermore, in combination with a detailed review of his associated grave goods, this research examines the social status and identity of Yingpan Man, and demonstrates the profound impact and cultural fusion that the Silk Road had upon the peoples of Xinjiang and Eurasia.

The genetic prehistory of the New World Arctic.

The New World Arctic, the last region of the Americas to be populated by humans, has a relatively well-researched archaeology, but an understanding of its genetic history is lacking. We present genome-wide sequence data from ancient and present-day humans from Greenland, Arctic Canada, Alaska, Aleutian Islands, and Siberia. We show that Paleo-Eskimos (~3000 BCE to 1300 CE) represent a migration pulse into the Americas independent of both Native American and Inuit expansions. Furthermore, the genetic continuity characterizing the Paleo-Eskimo period was interrupted by the arrival of a new population, representing the ancestors of present-day Inuit, with evidence of past gene flow between these lineages. Despite periodic abandonment of major Arctic regions, a single Paleo-Eskimo metapopulation likely survived in near-isolation for more than 4000 years, only to vanish around 700 years ago.