Migration and maize in the Virú Valley: Understanding life histories through multi-tissue carbon, nitrogen, sulfur, and strontium isotope analyses.

OBJECTIVES: Stable isotope analysis can provide crucial insight into the function and development of early state-level societies on the north coast of Peru. MATERIALS AND METHODS: Multi-tissue (bone collagen, tooth enamel, hair, nail, skin, and tendon) stable isotope analyses (carbon, nitrogen, sulfur, and strontium) were conducted for 13 individuals from the lower Virú Valley. RESULTS: Non-seasonal changes in a predominantly C4 -based terrestrial diet, with minimal inputs of marine foods were identified. One individual (Burial 5), however, had a stable isotope signature unlike any previously found on the north coast of Peru, indicating both a large contribution of C3 -terrestrial resources to their diet and an 87 Sr/86 Sr value suggestive of highland residence during childhood. DISCUSSION: This research provides the first strong stable isotope evidence of a highland individual within a coastal burial in northern Peru, new insight into the ritual killing event at Huaca Santa Clara during the late middle horizon and supporting evidence of the importance of C4 terrestrial resources to the developing Virú polity during the early intermediate period.

Statecraft and expansionary dynamics: A Virú outpost at Huaca Prieta, Chicama Valley, Peru.

Interpolity interaction and regional control were central features of all early state societies, taking the form of trade-embedded in political processes to varying degrees-or interregional conquest strategies meant to expand the polity's control or influence over neighboring territories. Cross-cultural analyses of early statecraft suggest that territorial expansion was an integral part of the process of primary state formation, closely associated with the delegation of authority to subordinate administrators and the construction of core outposts of the state in foreign territories. We report here on a potential case of a core outpost, associated with the early Virú state, at the site of Huaca Prieta in the Chicama Valley, located 75 km north of the Virú state heartland on the north coast of Peru. This site is discussed in the context of other possible Virú outposts in the Moche Valley, Pampa La Cruz, and Huaca Las Estrellas, and as part of a broader reflection on expansionary dynamics and statecraft.

Primary state formation in the Viru Valley, north coast of Peru.

The origins of urban life and functioning states are two of the most fascinating research problems in anthropological archeology and a topic that has intrigued generations of scholars working on the Peruvian north coast. In this region, Andeanists have documented the rise of Moche as a dominant culture during the first millennium A.D., and the emergence of urban life and stately institutions at this society's principal center. Although there is a broad consensus that Moche represents an archaic state, it is still unclear whether it is an example of primary state formation or a case of a second-generation state. To document this question, archaeological excavations were recently carried out at the Gallinazo Group site in the Virú Valley. Results from a radiocarbon dating program indicate that a functioning state probably emerged in this valley during the second century B.C., possibly preceding Moche by a few centuries. These results necessarily raise question regarding the nature of state development on the north coast of Peru and, in particular, whether there was a single center of state development in this region or multiple sites where similar conditions and processes led to the parallel emergence of functioning states.

Building Mexican isoscapes: Oxygen and hydrogen isotope data of meteoric water sampled across Mexico.

Oxygen and hydrogen isotope data of meteoric water samples are compiled from several States across Mexico. This dataset includes 287 oxygen and hydrogen (and deuterium excess) isotope data corresponding to meteoric water collected from the surface, groundwater wells, irrigation and observation wells, and water supply boreholes. These data facilitate the development of maps to determine the spatial distribution of water stable isotopes, also known as "isoscapes", of the Mexican territory. As such, this dataset (and the isoscapes built from it) is useful in geographic mobility studies that aim to evaluate geographic origins and residency of particular human and/or non-human individuals in antiquity and in contemporary times. Further discussion about the data and an example of an isoscape of Mexico using the meteoric water oxygen isotope data are provided in "Residential Patterns of Mexica Human Sacrifices at Mexico-Tenochtitlan and Mexico-Tlatelolco: Evidence from Phosphate Oxygen Isotopes" (Moreiras Reynaga et al., 2021). Overall, the dataset is useful in developing interpolated maps of water stable isotopes for relevant archeological, bioarchaeological, forensic, hydrogeological, and ecological research.

Carbon and nitrogen isotopic survey of northern peruvian plants: baselines for paleodietary and paleoecological studies.

The development of isotopic baselines for comparison with paleodietary data is crucial, but often overlooked. We review the factors affecting the carbon (δ(13)C) and nitrogen (δ(15)N) isotopic compositions of plants, with a special focus on the carbon and nitrogen isotopic compositions of twelve different species of cultivated plants (n = 91) and 139 wild plant species collected in northern Peru. The cultivated plants were collected from nineteen local markets. The mean δ(13)C value for maize (grain) was -11.8±0.4 ‰ (n = 27). Leguminous cultigens (beans, Andean lupin) were characterized by significantly lower δ(15)N values and significantly higher %N than non-leguminous cultigens. Wild plants from thirteen sites were collected in the Moche River Valley area between sea level and ∼4,000 meters above sea level (masl). These sites were associated with mean annual precipitation ranging from 0 to 710 mm. Plants growing at low altitude sites receiving low amounts of precipitation were characterized by higher δ(15)N values than plants growing at higher altitudes and receiving higher amounts of precipitation, although this trend dissipated when altitude was >2,000 masl and MAP was >400 mm. For C(3) plants, foliar δ(13)C was positively correlated with altitude and precipitation. This suggests that the influence of altitude may overshadow the influence of water availability on foliar δ(13)C values at this scale.

Stable isotope biogeochemistry of seabird guano fertilization: results from growth chamber studies with maize (Zea mays).

BACKGROUND: Stable isotope analysis is being utilized with increasing regularity to examine a wide range of issues (diet, habitat use, migration) in ecology, geology, archaeology, and related disciplines. A crucial component to these studies is a thorough understanding of the range and causes of baseline isotopic variation, which is relatively poorly understood for nitrogen (δ(15)N). Animal excrement is known to impact plant δ(15)N values, but the effects of seabird guano have not been systematically studied from an agricultural or horticultural standpoint. METHODOLOGY/PRINCIPAL FINDINGS: This paper presents isotopic (δ(13)C and δ(15)N) and vital data for maize (Zea mays) fertilized with Peruvian seabird guano under controlled conditions. The level of (15)N enrichment in fertilized plants is very large, with δ(15)N values ranging between 25.5 and 44.7‰ depending on the tissue and amount of fertilizer applied; comparatively, control plant δ(15)N values ranged between -0.3 and 5.7‰. Intraplant and temporal variability in δ(15)N values were large, particularly for the guano-fertilized plants, which can be attributed to changes in the availability of guano-derived N over time, and the reliance of stored vs. absorbed N. Plant δ(13)C values were not significantly impacted by guano fertilization. High concentrations of seabird guano inhibited maize germination and maize growth. Moreover, high levels of seabird guano greatly impacted the N metabolism of the plants, resulting in significantly higher tissue N content, particularly in the stalk. CONCLUSIONS/SIGNIFICANCE: The results presented in this study demonstrate the very large impact of seabird guano on maize δ(15)N values. The use of seabird guano as a fertilizer can thus be traced using stable isotope analysis in food chemistry applications (certification of organic inputs). Furthermore, the fertilization of maize with seabird guano creates an isotopic signature very similar to a high-trophic level marine resource, which must be considered when interpreting isotopic data from archaeological material.