Mothers and Infants in the Prehistoric Santa Clara Valley: What Stable Isotopes Tell Us about Ancestral Ohlone Weaning Practices

Breast-feeding and weaning are a part of childhood in all human populations, but the exact timing of these milestones varies between groups. As infants incorporate the nutrients from breast milk into their growing bones, chemical evidence is captured in the form of higher stable nitrogen (δ15N) isotope values. This study interprets δ15N values in the bone collagen of children (n = 24) buried at the Yukisma Mound (CA-SCL-38), in Santa Clara County, California. Radiocarbon dates for this site span 2200-250 B.P., but primarily fall during the Late period (740-230 B.P.). In the one probable mother-infant pair available for study, a 2.9 per mil enrichment of δ15N values was observed, consistent with the expected trophic level enrichment of breast-feeding infants. δ15N values of children under seven years old suggest the introduction of weaning foods between 1.5 and 2 years of age, and cessation of breast-feeding by 3 to 3.5 years of age. These results differ from the practices reported in the ethnohistoric literature. This paper includes photos of human remains, taken during excavation at CA-SCL-38 by Ohlone Family Consulting Services, the CRM arm of the Muwekma Ohlone Tribe (which also served as the Most Likely Descendant tribal group for this project). The images were provided to the authors by the tribe, and specific permission was granted to include them in this publication

Evolutionary ecology, resource depression, and niche construction theory: applications to central California hunter–gatherers and Mimbres-Mogollon Agriculturalists

Abstract Evolutionary ecology is a theoretical framework that has been widely applied to problems in human evolution and prehistory. Because the approach often focuses on how behavioral adjustments to changing socio-ecological conditions create novel selective pressures that in turn drive other changes in morphology and behavior, it draws on the same evolutionary logic that underlies niche construction theory. We illustrate here the important role that niche construction has played in archaeological applications of evolutionary ecology with two detailed case studies: one from Late Holocene hunter-gatherer populations in Central California and one from Mimbres-Mogollon agriculturalists in New Mexico. These examples illustrate that evolutionary ecology-based approaches, with an emphasis on formal predictive modeling, allow for the incorporation of niche construction as it affects model parameters with reference to specific problems involving past behavior. Further modeling and empirical applications will expand the synergies between these complementary approaches and advance our understanding of the human past

Comparison of strontium isotope ratios in Mexican human hair and tap water as provenance indicators

Deceased undocumented border crossers are some of the most difficult individuals to identify due to the inability to narrow down the region of origin and therefore to obtain family reference samples for DNA comparison. The isotopic compositions of various body tissues have been demonstrated to be useful biomarkers for tracking locations and movements to aid in the identification of human remains. This study closes the large spatial gap of available 87Sr/86Sr ratios from North America in tap water and presents the first 87Sr/86Sr human tissue-based ratios from Mexico. The 101 hair samples from 32 locations in Mexico range in 87Sr/86Sr ratios from 0.70424 to 0.71613 (ΔSrmax–min = 0.01189). Furthermore, 151 tap water samples from 51 locations range between 0.70404 to 0.71385 (ΔSrmax–min = 0.00981). Overall, small variations in the hair and tap water samples collected from individual locations were recorded (ΔSrmax–min = 0.00041 and 0.00034 respectively). Despite the fact that Mexico is one of the largest bottled water consumers in the world, the 87Sr/86Sr ratios of human hair and tap water correlated strongly (R2 = 0.87 for location averages and R2 = 0.80 when using individual data points). These data represent a valuable resource for identifying the provenance of human remains

Contrasting Male and Female Dietary Life Histories: A Case Study at an Ancestral Muwekma Ohlone Heritage Site in San Jose, California

Stable carbon and nitrogen isotope analyses of bones and teeth at the ancestral heritage Muwekma Ohlone site of Yakmuy ‘Ooyákma-tka (“Place of the East Ridge Site”; CA-SCL-215) reveal significant differences in the dietary life history of males and females. Overall, isotope data indicate that site inhabitants were primarily dependent on low trophic-level foods, likely plants, and minor amounts of marine food for their main source of dietary protein. From tooth dentin serial samples, we found that males were elevated by 0.6-1.0‰ in δ15N in early childhood (age 1-9 years) relative to females, while δ13C values were similar by sex, indicating boys were accessing slightly greater amounts of higher trophic-level foods, such as meat from game. The sex-biased difference in δ15N diminishes during the second decade of life, as female δ15N values increase and become equal to males. However, a difference in δ13C emerges during the second decade where female δ13C values are elevated relative to males. This could indicate that teenage females consumed higher amounts of low trophic-level, marine-derived protein, such as shellfish. During later adult years, the difference in δ13C disappears, while males again show an increase in δ15N relative to females. Although these differences are small, they reveal important sex-biased life history patterns during childhood and adulthood in this ancient community

Recent applications of isotope analysis to forensic anthropology

Isotope analysis has become an increasingly valuable tool in forensic anthropology casework over the past decade. Modern-day isotopic investigations on human remains have integrated the use of multi-isotope profiles (e.g. C, N, O, H, S, Sr, and Pb) as well as isotopic landscapes (“isoscapes”) from multiple body tissues (e.g. teeth, bone, hair, and nails) to predict possible region-of-origin of unidentified human remains. Together, data from various isotope analyses provide additional lines of evidence for human identification, including a decedent’s possible region-of-birth, long-term adult residence, recent travel history, and dietary choices. Here, we present the basic principles of isotope analysis and provide a brief overview of instrumentation, analytical standards, sample selection, and sample quality measures. Finally, we present case studies that reflect the diverse applications of isotope analysis to the medicolegal system before describing some future research directions. As shown herein, isotope analysis is a flexible and powerful geolocation tool that can provide new investigative leads for unidentified human remains cases

Intra- And Inter-Individual Variation In Δ\u3csup\u3e13\u3c/sup\u3eC And Δ\u3csup\u3e15\u3c/sup\u3eN In Human Dental Calculus And Comparison To Bone Collagen And Apatite Isotopes

There are mixed opinions on the suitability of dental calculus for paleodietary reconstruction using stable isotope analysis. We examine δ13C and δ15N values of calculus samples from two regions, central California in the USA and Sai Island in the Sudan. When atomic C/N ratios are less than 12 in calculus, results show positive correlations at both the regional and individual level between stable isotopes of bone collagen and calculus, suggesting these materials track similar dietary behaviors. Correlations are still positive but lower between δ13C values of calculus and bone apatite. Stable isotope ratios of calculus show between 30% and 50% greater variation than bone, are typically enriched in 15N (mean = 2.1‰ higher), and are depleted in 13C relative to bone collagen (mean = 0.8‰ lower) and apatite (mean = 6.4‰ lower). Calculus from multiple teeth was analyzed separately for seven individuals to examine intra-individual variation. Results show that within an individual δ13C varies up to 1.8‰, and δ15N up to 2.1‰, which may explain some of the weak bone-calculus correlations previously reported in the literature. When atomic C/N ratios are greater than 12, calculus correlates more poorly with bone collagen, suggesting these samples should be treated with caution

Trophy Heads or Ancestor Veneration? A Stable Isotope Perspective on Disassociated and Modified Crania in Precontact Central California

Few items in the archaeological record capture the imagination more than human heads separated from their bodies. Such items are sometimes assumed to indicate warfare practices, where "trophy heads" display power and fighting prowess. Other times, they are interpreted as representing ancestor veneration. Isolated crania are not uncommon in the Early period (ca. 4500-2500 B.P.) in Central California. Some anthropologists interpret them as trophy heads, but isotopic analyses at CA-CCO-548 suggest an alternative interpretation. Strontium isotope analyses on one modified cranium produced values consistent with local individuals, and both headless burials and people buried with extra skulls overlap in carbon and nitrogen isotopes. Further, teeth from two individuals who were buried with extra skulls suggest both were weaned at early ages (before age 2), much earlier than other individuals at the site. Together with contextual information, we argue that the isotopic data are more consistent with the hypothesis that extra skulls and headless burials represent ancestor veneration rather than trophies, shedding new light on Early-period societies in Central California

Isotopic and genetic analyses of a mass grave in central California: Implications for precontact hunter-gatherer warfare.

Analysis of a mass burial of seven males at CA-ALA-554, a prehistoric site in the Amador Valley, CA, was undertaken to determine if the individuals were "locals" or "non-locals," and how they were genetically related to one another.The study includes osteological, genetic (mtDNA), and stable (C, N, O, S) and radiogenic (Sr) isotope analyses of bone and tooth (first and third molars) samples.Isotopes in first molars, third molars, and bone show they spent the majority of their lives living together. They are not locals to the Amador Valley, but were recently living to the east in the San Joaquin Valley, suggesting intergroup warfare as the cause of death. The men were not maternally related, but represent at least four different matrilines. The men also changed residence as a group between age 16 and adult years.Isotope data suggest intergroup warfare accounts for the mass burial. Genetic data suggest the raiding party included sets of unrelated men, perhaps from different households. Generalizing from this case and others like it, we hypothesize that competition over territory was a major factor behind ancient warfare in Central California. We present a testable model of demographic expansion, wherein villages in high-population-density areas frequently fissioned, with groups of individuals moving to lower-population-density areas to establish new villages. This model is consistent with previous models of linguistic expansion