Ceramic Seriation, Sites Chronology, and Old Oyo Factor in Northcentral Yorubaland, Nigeria

This study is an attempt to provide a chronological seriation of pottery from Igbomina in northcentral Yorubaland. The ceramic sequence is developed using multivariate statistical analysis. From the K-means cluster analysis, ceramic collections that are roughly contemporaneous were grouped together; next the collections were seriated with multidimensional scaling to reveal whether they form a pattern that may be chronologically significant. Evaluation of the results of the pottery analysis from the Igbomina sites was based on the chronological division of Old Oyo pottery as well as on radiocarbon dating of associated material from excavated sites in the region. Pottery types from Old Oyo became known in Igbomina probably as early as the thirteenth century AD, and continued to occur in some areas until the late eighteenth century. The presence of Oyo pottery in Igbomina has important implications for the understanding of Oyo's relations with the northern Yoruba group and the frontier position of Igbomina during the Old Oyo Empire.Cette étude cherche à fournir une sériation chronologique de la céramique provenant de Igbomina situé dans la partie centrale du nord de Yorubaland. La séquene de céramique a été élaborée en utilisant une analyse statistique multidimensionnelle. Les collections de céramique plus ou moins contemporaines ont été groupées en se servant de la moyenne du facteur K de la classification ascendante hiérarchique, elles ont ensuite été ordonnées au moyen d'une analyse des proximités pour voir si elles formaient un schéma chronologique significatif. L'évaluation des résultats de l'analyse céramique des sites Iglomina est fondée sur les divisions chronologiques de la céramique Oyo ancienne ainsi que sur des dates radiocarbones obtenues sur du matériel en association provenant de sites fouillés dans la région. Les types de céramique de l'Oyo ancien sont probablement arrivés à Igbomina dès le 13ème siècle et ont continué à apparaître dans certains endroits jusqu'à la fin du 18ème siècle. La présence de la céramique Oyo à Igbomina comporte des implications importantes pour nos connaissances sur les relations des Oyo avec les groupes Yoruba du nord et sur la position de la frontière de Igbomina pendant l'empire Oyo ancien.     

Stylistic variability of stemmed obsidian tools (mata’a), frequency seriation,and the scale of social interaction on Rapa Nui (Easter Island)

Easter Island, or Rapa Nui, has been the focus of much research and speculation, particularly with reference to the island’s hundreds of giant, enigmatic statues and the set of conditions that supported their construction and transportation. In this paper, we analyze an abundant class of lithic artifacts, mata’a, to study of patterns of cultural transmission with implications for the evolution of groups, competition, and scale of socio-political organization among this island population. While these kinds of studies often draw upon assemblages of decorated ceramics, here we show how analysis of variability unconstrained by performance allows us to measure aspects of inheritance related to the manufacture of these artifacts. In the case of mata’a from Rapa Nui, we demonstrate that it is possible to reach falsifiable conclusions about the evolutionary dynamics that shaped the remarkable archaeological record on Rapa Nui.     

Aurignacian ethno-linguistic geography of Europe revealed by personal ornaments

Our knowledge of the migration routes of the first anatomically modern populations colonising the European territory at the beginning of the Upper Palaeolithic, of their degree of biological, linguistic, and cultural diversity, and of the nature of their contacts with local Neanderthals, is still vague. Ethnographic studies indicate that of the different components of the material culture that survive in the archaeological record, personal ornaments are among those that best reflect the ethno-linguistic diversity of human groups. The ethnic dimension of beadwork is conveyed through the use of distinct bead types as well as by particular combinations and arrangements on the body of bead types shared with one or more neighbouring groups. One would expect these variants to leave detectable traces in the archaeological record. To explore the potential of this approach, we recorded the occurrence of 157 bead types at 98 European Aurignacian sites. Seriation, correspondence, and GIS analyses of this database identify a definite cline sweeping counter-clockwise from the Northern Plains to the Eastern Alps via Western and Southern Europe through fourteen geographically cohesive sets of sites. The sets most distant from each other include Aurignacian sites from the Rhône valley, Italy, Greece and Austria on the one hand, and sites from Northern Europe, on the other. These two macro-sets do not share any bead types. Both are characterised by particular bead types and share personal ornaments with the intermediate macro-set, composed of sites from Western France, Spain, and Southern France. We argue that this pattern, which is not explained by chronological differences between sites or by differences in raw material availability, reflects the ethnolinguistic diversity of the earliest Upper Palaeolithic populations of Europe.     

Refining correspondence analysis-based ceramic seriation of regional data sets

Ceramic seriation is one of the primary tools used by archaeologists to create chronologies, especially for surface survey data. In this article, we outline a bootstrapped approach to correspondence analysis-based seriation designed to help assess and improve the stability of relative orderings produced through such analyses. This procedure systematically identifies and removes small samples and sites with unusual samples, such as those with multiple components, which are not handled well by seriation and require secondary interpretation. Our approach combines data from multiple projects in the Zuni region of the American Southwest in order to gauge the effects of intraregional variation in ceramic distributions and reexamine prior interpretations of demographic change based on individual projects. This analysis highlights two previously unknown regional trends, including variation in the distribution of multicomponent sites and potential short-term depopulation of a significant part of the region. Based on this example, we further suggest that our method may be particularly useful in situations where little prior chronological information is available.     

The goodness of fit and statistical significance of seriation solutions

This paper presents a method for determining the statistical significance and goodness of fit of seriation solutions based on correspondence analysis. The basic assumption is that seriation solutions corresponding to relative chronological sequences should have unimodal distributions of types across assemblages in a sequence. In order to evaluate significance of chronological signal in data, the observed number of modes of a seriation solution based on correspondence analysis is compared to a distribution of number of modes generated by randomization of the original data table. A quantitative measure of the goodness of fit is presented. The method is tested on two data sets: 1) archaeological data with a known chronological ordering 2) non-archaeological data without a chronological patterning. The method successfully detected a significant chronological signal in the former, and failed to detect it in the latter.