Jason E. Laffoon

Mapping multiple source effects on the strontium isotopic signatures of ecosystems from the circum-Caribbean region

A method for mapping strontium isotope ratio (87Sr/86Sr) variations in bedrock and water has been recently developed for use in the interpretation of 87Sr/86Sr datasets for provenance studies. The mapping process adopted the simplifying assumption that strontium (Sr) comes exclusively from weathering of the underlying bedrock. The scope of this bedrock-only mapping method is thus limited to systems where the contributions of other sources of Sr are minimal. In this paper, we build on this 87Sr/86Sr mapping method by developing a mixing model of Sr fluxes from multiple sources to the bioavailable Sr pool. The new multiple source model includes: (1) quantitative calculations of Sr fluxes from bedrock weathering using an empirical rock weathering model; and (2) addition of sub-models calculating the contribution of Sr fluxes from atmospheric aerosols based on outputs from global climate model simulations. We compared the performance of the new multiple source model and the bedrock-only mapping method in predicting observed values from two datasets of bioavailable 87Sr/86Sr from the circum-Caribbean region (Antilles and Mesoamerica). Although the bedrock-only method performs relatively well in Mesoamerica (n = 99, MAE = 0.00011, RMSE = 0.00073), its prediction accuracy is lower for the Antillean dataset (n = 287, MAE = 0.0021, RMSE = 0.0027). In comparison, the new multiple source model, which accounts for the deposition of sea salt and mineral dust aerosols, performs comparably well in predicting the observed 87Sr/86Sr values in both datasets (MAE = 0.00040, RMSE = 0.00087 and MAE = 0.00014, RMSE = 0.0010). This study underscores the potential of using process-oriented spatial modeling to improve the predictive power of Sr isoscapes over large spatial scales and to refine sampling strategies and bioavailable Sr dataset interpretations for provenance studies.

Investigating human geographic origins using dual-isotope (87Sr/86Sr, δ18O) assignment approaches.

Substantial progress in the application of multiple isotope analyses has greatly improved the ability to identify nonlocal individuals amongst archaeological populations over the past decades. More recently the development of large scale models of spatial isotopic variation (isoscapes) has contributed to improved geographic assignments of human and animal origins. Persistent challenges remain, however, in the accurate identification of individual geographic origins from skeletal isotope data in studies of human (and animal) migration and provenance. In an attempt to develop and test more standardized and quantitative approaches to geographic assignment of individual origins using isotopic data two methods, combining 87Sr/86Sr and δ18O isoscapes, are examined for the Circum-Caribbean region: 1) an Interval approach using a defined range of fixed isotopic variation per location; and 2) a Likelihood assignment approach using univariate and bivariate probability density functions. These two methods are tested with enamel isotope data from a modern sample of known origin from Caracas, Venezuela and further explored with two archaeological samples of unknown origin recovered from Cuba and Trinidad. The results emphasize both the potential and limitation of the different approaches. Validation tests on the known origin sample exclude most areas of the Circum-Caribbean region and correctly highlight Caracas as a possible place of origin with both approaches. The positive validation results clearly demonstrate the overall efficacy of a dual-isotope approach to geoprovenance. The accuracy and precision of geographic assignments may be further improved by better understanding of the relationships between environmental and biological isotope variation; continued development and refinement of relevant isoscapes; and the eventual incorporation of a broader array of isotope proxy data.

Life and death at precolumbian Lavoutte, Saint Lucia, Lesser Antilles

Abstract The Caribbean archaeological record requires immediate attention and protection. Development and natural forces have impacted archaeological sites, destroying or severely damaging them. The precolumbian site of Lavoutte, located in northern Saint Lucia, has been known as a major Late Ceramic Age (a.d. 1000–1500) settlement since the 1960s, but it has been damaged over the past decades by both natural and human processes. Multidisciplinary field and laboratory methodologies were implemented during a rescue project at the site from 2009 to 2010. This paper presents the results of collaborative efforts between local and international organizations. The first goal was to demonstrate the importance of protection and rescue of endangered archaeological sites. Secondly, we aimed to show that by adopting a multidisciplinary approach including artifact analysis, bioarchaeology, paleoenvironmental reconstruction, and geochemistry, severely damaged sites can be of significant informational value.

Origins and genetic legacies of the Caribbean Taino

Significance Ancient DNA has revolutionized the field of archaeology, but in the Caribbean and other tropical regions of the world, the work has been hampered by poor DNA preservation. We present an ancient human genome from the Caribbean and use it to shed light on the early peopling of the islands. We demonstrate that the ancestors of the so-called “Taino” who inhabited large parts of the Caribbean in pre-Columbian times originated in northern South America, and we find evidence that they had a comparatively large effective population size. We also show that the native components in some modern Caribbean genomes are closely related to the ancient Taino, suggesting that indigenous ancestry in the region has survived through the present day. The Caribbean was one of the last parts of the Americas to be settled by humans, but how and when the islands were first occupied remains a matter of debate. Ancient DNA can help answering these questions, but the work has been hampered by poor DNA preservation. We report the genome sequence of a 1,000-year-old Lucayan Taino individual recovered from the site of Preacher’s Cave in the Bahamas. We sequenced her genome to 12.4-fold coverage and show that she is genetically most closely related to present-day Arawakan speakers from northern South America, suggesting that the ancestors of the Lucayans originated there. Further, we find no evidence for recent inbreeding or isolation in the ancient genome, suggesting that the Lucayans had a relatively large effective population size. Finally, we show that the native American components in some present-day Caribbean genomes are closely related to the ancient Taino, demonstrating an element of continuity between precontact populations and present-day Latino populations in the Caribbean.

Sourcing nonnative mammal remains from Dos Mosquises Island, Venezuela : new multiple isotope evidence

Archeological excavations of Amerindian sites on Dos Mosquises Island, Los Roques Archipelago, Venezuela, uncovered a wide range of evidence reflecting seasonal exploitation of local resources and multiple ritual depositions of large quantities of ceramic figurines, lithics, and faunal remains. Zooarchaeological analysis revealed the presence of modified and unmodified bones and teeth from numerous imported mammal species. Local geographic and environmental conditions preclude permanent establishment of terrestrial mammal populations and as such, there are no native mammalian taxa on the island itself or the surrounding oceanic archipelago. The presence of these faunal remains on Dos Mosquises can be attributed to the intentional movement of animal resources from the mainland to Los Roques by indigenous groups in the Late Ceramic Age (~AD 1200–1500). Despite attributions to a mainland source region, little else is known about the origins of these unique specimens. Here, we apply strontium (87Sr/86Sr), oxygen (δ18O), and carbon (δ13C) isotope analyses of tooth enamel from various archeologically recovered taxa including deer, peccary, tapir, ocelot, margay, opossum, fox, and weasel to investigate their geographic origins via comparisons with macro-regional models of precipitation δ18O and bioavailable 87Sr/86Sr. The 87Sr/86Sr results are highly variable both for the overall assemblage and between specimens within the same taxa, indicating origins from different geochemical environments of mainland South America. The combined archeological and isotopic evidence are consistent with origins within the late pre-colonial Valencioid Sphere of Interaction which encompassed the Lake Valencia Basin, surrounding regions, and several offshore island groups including Los Roques archipelago.

A Multi-Isotope Investigation of Human and Dog Mobility and Diet in the Pre-Colonial Antilles

ABSTRACT The complex relationships between humans and dogs (Canis lupus familiaris) have a very deep and unique history. Dogs have accompanied humans as they colonised much of the world, and were introduced via human agency into the insular Caribbean where they became widespread throughout the Ceramic Age. It is likely that the dynamic interactions between humans, dogs, and their environments in the Caribbean were spatially, chronologically, and socially variable. However, almost no research has specifically addressed the nature, or potential variability, of human/dog interactions in this region. This study presents isotopic (strontium and carbon) evidence bearing on human and dog paleomobility and paleodietary patterns in the pre-colonial Caribbean. The isotope results illustrate a generally high degree of correspondence between human and dog dietary practices at all analysed sites but also slight differences in the relative importance of different dietary inputs. Striking parallels are also observed between the human and dog mobility patterns and shed light on broader networks of social interaction and exchange. Lastly, the paper addresses the possible utility and relevance of canine isotope data as proxies for inferring past human behaviours.

A bioavailable strontium isoscape for Western Europe: A machine learning approach

Strontium isotope ratios (87Sr/86Sr) are gaining considerable interest as a geolocation tool and are now widely applied in archaeology, ecology, and forensic research. However, their application for provenance requires the development of baseline models predicting surficial 87Sr/86Sr variations (“isoscapes”). A variety of empirically-based and process-based models have been proposed to build terrestrial 87Sr/86Sr isoscapes but, in their current forms, those models are not mature enough to be integrated with continuous-probability surface models used in geographic assignment. In this study, we aim to overcome those limitations and to predict 87Sr/86Sr variations across Western Europe by combining process-based models and a series of remote-sensing geospatial products into a regression framework. We find that random forest regression significantly outperforms other commonly used regression and interpolation methods, and efficiently predicts the multi-scale patterning of 87Sr/86Sr variations by accounting for geological, geomorphological and atmospheric controls. Random forest regression also provides an easily interpretable and flexible framework to integrate different types of environmental auxiliary variables required to model the multi-scale patterning of 87Sr/86Sr variability. The method is transferable to different scales and resolutions and can be applied to the large collection of geospatial data available at local and global levels. The isoscape generated in this study provides the most accurate 87Sr/86Sr predictions in bioavailable strontium for Western Europe (R2 = 0.58 and RMSE = 0.0023) to date, as well as a conservative estimate of spatial uncertainty by applying quantile regression forest. We anticipate that the method presented in this study combined with the growing numbers of bioavailable 87Sr/86Sr data and satellite geospatial products will extend the applicability of the 87Sr/86Sr geo-profiling tool in provenance applications.

Advancing the Study of Amerindian Ecodynamics in the Caribbean: Current Perspectives

Perspectives Michelle J. LeFebvre , Christina M. Giovas b,c and Jason E. Laffoon d,e Department of Natural History, Florida Museum of Natural History, Gainesville, FL, USA; Department of Archaeology, Simon Fraser University, Burnaby, Canada; Department of Anthropology, University of Oregon, Eugene, OR, USA; Faculty of Archaeology, Leiden University, Leiden, Netherlands; Faculty of Science, Vrije Universiteit, Amsterdam, Netherlands

87Sr/86Sr data indicate human post-juvenile residence mobility decreases over time-elapsed since initial Holocene island colonization in the Pacific and Caribbean

During the Holocene colonization of islands in the Pacific and Caribbean by agropastoral and horticulturalist communities, a variety of proxies (material, genetic, zoogeographic etc.) indicate substantial inter-island and inter-community contact. It has been suggested that this contact represents an adaptive response to mitigate intrinsic demographic fragility during the initial phases of island colonization, and that this exogamous imperative faded in the aftermath of initial dispersal as overall population density increased. Here, we evaluate this model by synthesizing and comparing increasingly available 87Sr/86Sr data from funerary populations in the Pacific and Caribbean. After performing basic hygienic discrimination, we conclude that the Caribbean data—both from across the region, and on an intra-site/island basis—lend support to this model, with high early in-migration succeeded by comparatively low in-migration in a relationship which, based on chi-square tests, is statistically significant (1, N = 290) = 4.046, p = 0.044). The Pacific situation is more complex, with data from the Bismarck Archipelago and northern Solomon Islands skewing the analysis. However, in considering these data in detail, we demonstrate that there are reasons to suppose that the Pacific data may also tentatively support a model of high rates of in-migration being replaced later in settlement histories by comparatively low rates. We conclude by highlighting future directions for this incipient research program.

Jette Arneborg, Jan Heinemeier & Niels Lynnerup. Greenland Isotope Project: diet in Norse Greenland AD 1000–AD 1450 (JONA Special Volume 3). 2012. Steuben (ME): Journal of the North Atlantic; ISSN 1935-1984 ebook.

His defence of the ‘chiefdom’ as an appropriate conceptualisation of early political-territorial social coherence is very strong; Irish readers should not dismiss this as an Americanism—I am anticipating a reaction, perhaps unfairly!—but engage with what he is attempting to do, and recognise its roots in Colin Renfrew’s important work of the 1970s. Much less strong is his suggested chronology of settlement contemporary with his purported chiefdoms (Chapter 5). Fabric analysis of unmortared stone forts may tell us more about the predilection of individual builders (and the quality of limestone they could prise from the karst pavements) than it does about the passage of time. Moreover, the suite of radiocarbon dates is too few in number and comes from too limited a series of sites. In fairness, Gibson sets out his arguments carefully, so others with a liking for regression analysis and seriation may be convinced, but my ‘I-doubt-this’ needle shot straight into the red zone long before I reached Table 5.6, his tabulated summary of the early medieval chronology.