The chronology of occupation at Teouma, Vanuatu: Use of a modified chronometric hygiene protocol and Bayesian modeling to evaluate midden remains

A number of radiocarbon dates, both published and unpublished have been obtained from archaeological deposits across the Teouma site on the island of Efate in Vanuatu. These are on a range of materials from the midden and associated cemetery including charcoal (13) and shell (7) as well as a number of less commonly dated 14C sample types including bone from 2 terrestrial giant tortoises (?Meiolania damelipi), 8 pigs (Sus scrofa) and 2 chickens (Gallus gallus). Thirty-six human bone collagen dates and 5 Conus sp. shell ring artifacts from the cemetery context have been discussed in detail elsewhere (Petchey et al., 2014). In this paper, we evaluate the radiocarbon data according to observed contextual associations and established understandings of 14C offsets, and collate all available information in a Bayesian framework to establish the age and duration of the settlement at Teouma. This analysis provides a maximum age range for the Lapita deposits of between 3000 and 2560 cal BP and a most likely start date of 2920-2870 cal BP and end date of 2870-2750 cal BP (68.2% prob.). This is slightly younger age for the deposits than previously reported, but is in keeping with evaluation of the burials themselves, the majority of which are dated to between 2940 and 2720 cal BP. This age range indicates that the site was in use at the same time as colonization events in Tonga (2850-2830 cal BP) and Fiji (3020-2860 cal BP), and supports the hypothesis that Vanuatu was at the center of a region-wide interaction sphere for several generations after initial settlement.