Steven Hackenberger

Patterns of mtDNA Diversity in Northwestern North America

The mitochondrial DNA (mtDNA) haplogroups of 54 full-blooded modern and 64 ancient Native Americans from northwestern North America were determined. The control regions of 10 modern and 30 ancient individuals were sequenced and compared. Within the Northwest, the frequency distribution for haplogroup A is geographically structured, with haplogroup A decreasing with distance from the Pacific Coast. The haplogroup A distribution suggests that a prehistoric population intrusion from the subarctic and coastal region occurred on the Columbia Plateau in prehistoric times. Overall, the mtDNA pattern in the Northwest suggests significant amounts of gene flow among Northwest Coast, Columbia Plateau, and Great Basin populations.

Three-dimensional GPR study of a prehistoric site in Barbados, West Indies

Abstract Prior results of surface artifact collecting, test excavations, and auger sampling on an archaeological site in Barbados suggested that we experiment with ground-penetrating radar (GPR) as a method to target areas for future study. The site is associated with village occupations of Amerindians that are dated to between ∼2000 and 500 years ago. Archaeological features include burials, hearths, ceramic lined wells and postholes. Artifact middens contain pottery sherds, conch shells, and other marine resource debris. The site selected was located at the southern tip of Barbados and is situated on a deep stabilized surface behind a large active dune system. The soil layer consists of dry, clean quartz sand. We obtained limited ground truth at the site by hand auguring in areas of field-identified anomalies, and by auguring control holes away from anomalies. Anomalies were usually large diffractors such as conch shells and rocks. We used 3D visualisation software to perform standard processing enhancements and to assemble the parallel lines into three-dimensional volumes. The dimensions, distribution, and shapes of time-sliced amplitude anomalies were consistent with those of previously excavated burials, poles, and pit structures. In particular, we interpret the data as indicating the presence of a circular house structure with four center posts; this structure was previously unknown at this site. The work presented here builds upon and extends earlier excavation-based findings at this site, and will allow for better-focused excavations in the future.

Preliminary results of three-dimensional GPR-based study of a prehistoric site in Barbados, West Indies

Prior results of surface artifact collecting, test excavations, and auger sampling on an archaeological site in Barbados suggested that we experiment with GPR as a method to target areas for future study. The site is associated with village occupations of Amerindians that are dated to between approximately 2000 and 500 years ago. Archaeological features include burials, hearths, ceramic lined wells and post holes. Artifact middens contain pottery sherds, conch shells, and other marine resource debris. The site selected was located at the southern tip of Barbados and is situated on a deep stabilized surface behind a large active dune system. The soil layer consists of dry, clean quartz sand. We obtained limited ground truth at the site by hand-auguring in areas of field- identified anomalies, and by auguring control holes away from anomalies. Anomalies were almost always large diffractors such as conch shells and rocks. We used 3D software to perform standard processing enhancements and to assemble the parallel lines into three-dimensional volumes. The dimensions, distribution, and shapes of time-sliced amplitude anomalies were consistent with those of previously excavated burials, poles, and pit structures. These features would not have been obvious using conventional a profile-based GPR survey.

CALCINED BONE AS A RELIABLE MEDIUM FOR RADIOCARBON DATING: A TEST USING PAIRED NORTH AMERICAN SAMPLES

Radiocarbon dating using charcoal and bone collagen, two standards of archaeological chronology, can be difficult to impossible in environments where natural burning is common and bone does not preserve well. In such settings, charcoal ages cannot always be trusted and collagen is unavailable. Calcined bone can be a viable alternative medium in these situations but it has rarely been exploited in the Americas. One area that could benefit from its use is the forested Pacific Northwest. We compare calcined bone ages with charcoal and/or collagen dates from individual features or discrete cultural strata in 10 Washington, Oregon, Idaho, and British Columbia sites dating between 9000 and 100 B.P. Resulting radiocarbon age estimates based on calcined bone closely match those based on charcoal and/or collagen in nearly all cases. We obtained calcined bone dates from three additional Holocene-aged sites that had not previously produced accurate results, obtaining findings consistent with estimates based on cross dating. Preserving well where all other organic media of cultural origin are lost or unreliable, calcined bone holds promise for dating sites in conifer forests and other acidic soil settings, and can allow researchers to refine archaeological sequences that have long defied accurate chronometric analysis. La datación por radiocarbono usando carbón y colágeno óseo, dos estándares para la cronología arqueológica, puede ser difícil o imposible en ambientes donde los incendios naturales son comunes y el material óseo no se conserva bien. En tales condiciones los resultados del fechamiento por carbón no siempre son confiables y el colágeno no puede ser recuperado. La datación de hueso calcinado puede ser una técnica alternativa viable en estas situaciones, pero rara vez se ha explotado en América. Un área que podría beneficiarse de su uso es el boscoso Noroeste del Pacífico de Norteamérica. Se compararon las edades de fragmentos de hueso calcinado con aquellas de muestras de carbón o colágeno desde fogatas, estructuras individuales o estratos culturales discretos en 10 sitios de Washington, Oregón, Idaho y Columbia Británica que datan entre 9000 y 100 a.P. Las estimaciones resultantes de la edad de radiocarbono sobre hueso calcinado coinciden con aquellas procedentes de carbón o colágeno en casi todos los casos. Se obtuvieron fechas sobre hueso calcinado para tres sitios adicionales que previamente no habían producido resultados precisos, obteniendo fechas coherentes con las estimaciones basadas solamente en estilo cultural. Dado que se conserva bien en contextos donde se pierden o no son confiables todos los demás medios orgánicos de origen cultural, el hueso calcinado representa una promesa para la datación de sitios en bosques de coníferas y otros ambientes con suelos ácidos, permitiendo refinar las secuencias arqueológicas que previamente habían desafiado un análisis cronométrico preciso.