We now return to the three basic questions addressed in our experiments.
1. Can substantial relative and absolute agreement be demonstrated at Copan between two independent methods of dating site occupations?
The answer to this question is a resounding “yes.” Thirteen of the fourteen relevant radiocarbon dates (93 percent of the cases) fit their associated occupation spans at an acceptable level or better. The strong inference is that the larger hydration array for Copan, which dates 230 additional sites (some with occupations later than those included here), is generally trustworthy. Disregarding the not relevant experiments, both methods retain independently the same general occupation order among sites, with Experiment F departing most from expectations. Taken as independent sets and as absolute dates, both methods yield similar conclusions.
2. Do radiocarbon dates independently corroborate the late presence of people and Coner or Coner-like ceramics in the Copan Valley (i. e., long after a. d. 850-950) as indicated by the hydration dates?
The radiocarbon dates in Experiment A-D by themselves demonstrate extended occupation of a site with an overwhelmingly Coner assemblage. The 1 range of pilot date 2 (a. d. 985-1029) falls entirely after a. d. 950, by which time, according to the revised ceramic sequence, no more Coner ceramics were used at Copan. Radiocarbon dates from Experiment E and their wider archaeological associations strongly support Viel’s reconstruction of the Acbi/Coner transition at A. D. 600-650, and thus exhibit good absolute as well as relative implications. Radiocarbon dates from Experiment A-D show that it is highly likely that this Coner-phase site was occupied until at least a. d. 985-1029. A minimal duration of roughly 400 years for Coner-like ceramics is thus indicated independently by the radiocarbon dates at these two sites.
The late burial event at site 99A-18-2 (Experiment B) might indicate an even longer duration of Coner types. If it represents a late occupation undetected by our hydration dates, then Coner-like ceramics were still being used in the late thirteenth, or the fourteenth, century. If this burial was post-occupation, then people were probably living somewhere else in the valley, and as yet we have no indications of late, full household assemblages lacking Coner or Coner-like types. In either case the conclusion is the same—ceramic types and assemblages that would be labeled Coner, given current definitions of the phase, were probably still being used 600-700 years after the Acbi/Coner transition.
Disregarding any hydration dates at all, one could argue that the presence of a late and reasonably numerous agricultural population in the Copan Valley is independently indicated by the radiocarbon record. This conclusion also squares with the archaeomagnetic and palynological evidence cited earlier. In particular, the latest calibrated date from Rue’s sediment sequence accords extremely well with Experiment B. The infant death event captured by this experiment might fall right into the 1 span (a. d. 1301-1413) of Rue’s latest calibrated radiocarbon date, which suggests that significant numbers of farmers were still clearing land.
3. If radiocarbon dates suggest adjustments should be made to hydration spans, what sorts of adjustments are appropriate?
Divergence is shown at the early ends of occupation spans in Experiments N, K, F, L, G, and I (although both of the latter show overlap at the Is level with their hydration spans and so are not very conclusive on this point). Experiments N, K, and L suggest that their occupation spans might begin somewhat earlier than predicted, or that extraneous old skeletal material was introduced. On the other hand. Experiments H and M show radiocarbon dates slightly later than the occupation spans. Given these findings, and the generally excellent agreement between the two dating methods, it does not appear that any adjustment to the hydration rate curve used for Copan is currently warranted.
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