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Research seminar 12 November 2020: Dates and Dispersals: spatio-temporal resolution and pre-Columbian cultural expansions in South America with Dr Phil Riris (Bournemouth University)

Inferring episodes of population expansion, admixture, diffusion, and/or migration in prehistory is undergoing a resurgence in macro-scale archaeological interpretation. In parallel to this renewed popularity, expanding access to computational tools and datasets has seen the use of aggregated radiocarbon datasets for the study of dispersals also increasing.

This talk critically assesses the application of radiocarbon dates for the study of prehistoric dispersals, by reflecting on the qualities of the underlying data, particularly chronometric uncertainty, which, it is argued, has been systematically downplayed in dispersals studies. It will frame dispersals explicitly in terms of hypothesis
testing and advocates for developing reflexive practice in the application of radiocarbon dates to prehistoric dispersals.

The talk outlines an analytical solution that not only incorporates chronometric uncertainty but, importantly, tests whether the datasets provide statistically significant evidence for a dispersal process. It draws on recent results on cultural expansions within South America, employing two emblematic examples, the Arauquinoid
series (Venezuela and Guianas) and Tupiguarani tradition (Brazil and Argentina). The analysis identifies fundamental issues with resolution that complicate identification of pre-Columbian cultural dispersals through straightforward spatial gradients of radiocarbon data.

Beyond simply improving on method, the results identify an issue at the heart of archaeological inquiry, demonstrating that theoretical frameworks for the study of dispersals should be evaluated with rigour by: 1) constructing more critical statistical null models and 2) evaluating alternative mechanisms of cultural expansion.

The recording can be found here.

Date: 12 November 2020

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