Integration of Archaeological Phase Information and Radiocarbon Results from the Jama River Valley, Ecuador: A Bayesian Approach

Archaeological syntheses of western Ecuadorian prehistory have been hampered by a lack of reliable absolute chronologies and detailed cultural sequences for many key areas, one of which is northern Manabí Province, known principally as the territory of the Jama-Coaque cultural tradition. This study presents a seven-phase cultural sequence for the Jama River valley of northern Manabí that spans over 3,600 calendar years. A statistical model relating the successive archaeological phases is established, based on prior knowledge of the stratigraphy and ceramic seriation from key archaeological sites throughout the valley. A Bayesian statistical approach is then employed to calibrate 37 radiocarbon determinations for the purpose of estimating calendar dates for the limits of these phases. Apart from its contribution to the prehistory of a poorly studied area, the analysis illustrates the value of a probabilistic Bayesian approach to radiocarbon calibration, especially when the determinations relate to archaeologically predefined phases. It also demonstrates the dangers of uncritically applying generalized periodization schemes to specific sequences of historical development and highlights the need for reassessing Ecuadorian chronology through more precise interregional correlations.