¹⁴C and Maya Long Count Dates: Using Bayesian Modelling to Develop Robust Site Chronologies

Abstract

Bayesian statistics has now demonstrated its strong utility in archaeology, specifically through software that conditions radiocarbon data. Only recently has this technology been applied within Maya archaeology, however, in part because the Maya calendar provides a much greater resolution in dating archaeological events than is possible with radiocarbon data. The Long Count in particular allows for the assignment of some events relative to each other, accurate to the day. In this paper, a new approach is presented to incorporate robust records of both in the same Bayesian analysis through the OxCal software. The results do call for a reconsideration of the earliest radiocarbon studies in the Maya area from the 1960s, as well as the latest attempts to corroborate the currently popular calendar correlation known as the GMT. This new study demonstrates the value of the approach and corroborates the 1σ accuracy of the GMT, while at the same time opening up the possibility of revision by 20 or more years.

Radiocarbon Data, Bayesian Modeling, and Alternative Historical Frameworks

“…Arguably the strongest prior information we have as archaeologists are the stratigraphic, depositional environments from which radiocarbon data are recovered (e.g., Aldana 2015; Bachand 2008; Bronk Ramsey 2000, 2009a; Kennett et al 2014; Krus 2016; Monaghan et al 2013; Overholtzer 2015; Pluckhahn et al 2015; Schilling 2013; Steier and Rom 2000; Thompson et al 2016; Whittle and Bayliss 2007). More general priors, including culture-historic frameworks, ceramic sequences, and settlement patterns among many others, can also be employed as prior beliefs (e.g., Alberti 2013; Boaretto et al 2005; Buck et al 1996; Greco and Otero 2015; Greco and Palamarczuk 2014; Manning et al 2006; Mazar and Bronk Ramsey 2008; Needham et al 1998; Raczky and Siklósi 2013; Regev et al 2012; Turck and Thompson 2016).…”

The Role of Solar Observations in Developing the Preclassic Maya Calendar

“…The 584,285 correlation, originally proposed by Eric Thompson in 1972 and revived by Floyd Lounsbury (1982, 1983), is generally referred to as the GMT correlation. Although Gerardo Aldana (2011, 2015:12–17) has questioned the GMT correlation and disputes supporting evidence from the Tikal lintels, Douglas Kennett and colleagues (2013:4) conclude that the Tikal lintels were probably carved by removing the exterior wood (the more recent wood), so the radiocarbon dates assessed with Bayesian modelling help confirm the GMT correlation. Of course, this evidence cannot be used to distinguish between variants of the GMT that adjust dates by only a few days or weeks.…”

Progression and Issues in the Mesoamerican Geospatial Revolution

“…The interpretation of radiocarbon dates has proved to be crucial for positioning the beginning and end of the Maya "collapse," as well for positioning the Maya Classic period calendar in terms of our own time scales. Each new advance in radiocarbon methodology brings forward new considerations of dating factors (see Satterthwaite andRalph 1960 andRalph 1965 for an earlier interpretation of the correlation and, then, Aldana 2015 andKennett et al 2013 for recent arguments).…”