Seriation and Joint Probability: Unifying Archaeological Dates in the Central Mediterranean, ca. 4th-1st c. BCE

Probability theory has been applied to archaeological chronology since the advent of radiocarbon dating, but key chronological indicators, such as artifact typologies, continue to be dated in descriptive terms (e.g., "in the later 3rd c. BCE"). Moreover, the informational inter-dependency for how contexts and assemblages affect others’ dating can become opaque. This paper illustrates the use of two new R packages, lakhesis and eratosthenes, to construct a wholly formal method for archaeological dating, focusing on the central Mediterranean in the last four centuries BCE. Contextual seriation is used to compare and sequence disparate contexts alongside stratigraphic relationships, to define a joint probability density function. A case study of tombs, stratigraphic units, shipwrecks, and other depositional events is then implemented for the last four centuries BCE, illustrating how the formal estimation of events is be achieved. The resulting marginal densities can then be checked against conventional dates, not just to revise typological distinctions and revisit comparisons where discrepancies emerge, but above all to obtain a precise, probabilistic estimation of the occurrence of all archaeological events.