Hiroo Nasu

Development of sedentary communities in the Maya lowlands: coexisting mobile groups and public ceremonies at Ceibal, Guatemala.

Significance The results of our research at the lowland Maya site of Ceibal add to the growing archaeological understanding that the transition to sedentism did not necessarily occur simultaneously across different social groups within a region and that monumental constructions did not always postdate fully established sedentism. Whereas sedentary and mobile populations are, in many cases, interpreted to have maintained separate communities, our study suggests that groups with different levels of mobility gathered and collaborated for constructions and public ceremonies. These data indicate that the development of sedentism was a complex process involving interactions among diverse groups, and that collaborative construction projects and communal gatherings played a critical role in this social transformation by facilitating social integration among different groups. Our archaeological investigations at Ceibal, a lowland Maya site located in the Pasión region, documented that a formal ceremonial complex was built around 950 B.C. at the onset of the Middle Preclassic period, when ceramics began to be used in the Maya lowlands. Our refined chronology allowed us to trace the subsequent social changes in a resolution that had not been possible before. Many residents of Ceibal appear to have remained relatively mobile during the following centuries, living in ephemeral post-in-ground structures and frequently changing their residential localities. In other parts of the Pasión region, there may have existed more mobile populations who maintained the traditional lifestyle of the preceramic period. Although the emerging elite of Ceibal began to live in a substantial residential complex by 700 B.C., advanced sedentism with durable residences rebuilt in the same locations and burials placed under house floors was not adopted in most residential areas until 500 B.C., and did not become common until 300 B.C. or the Late Preclassic period. During the Middle Preclassic period, substantial formal ceremonial complexes appear to have been built only at a small number of important communities in the Maya lowlands, and groups with different levels of sedentism probably gathered for their constructions and for public rituals held in them. These collaborative activities likely played a central role in socially integrating diverse groups with different lifestyles and, eventually, in developing fully established sedentary communities.

High-precision radiocarbon dating of political collapse and dynastic origins at the Maya site of Ceibal, Guatemala

Significance Tracing political change through refined chronologies is a critical step for the study of social dynamics. Whereas coarse chronologies can give an impression of gradual change, better temporal control may reveal multiple episodes of rapid disruption comprised in that span. Precise dating through radiocarbon determinations and ceramic studies is particularly important for the study of the Preclassic collapse, which lacks calendrical dates recorded in texts. The high-precision chronology of Ceibal revealed waves of decline over the course of the Preclassic and Classic collapses in a temporal resolution that was not possible before. The emerging understanding of similarities and differences in the two cases of collapse provides an important basis for evaluating the vulnerability and resilience of Maya political systems. The lowland Maya site of Ceibal, Guatemala, had a long history of occupation, spanning from the Middle Preclassic Period through the Terminal Classic (1000 BC to AD 950). The Ceibal-Petexbatun Archaeological Project has been conducting archaeological investigations at this site since 2005 and has obtained 154 radiocarbon dates, which represent the largest collection of radiocarbon assays from a single Maya site. The Bayesian analysis of these dates, combined with a detailed study of ceramics, allowed us to develop a high-precision chronology for Ceibal. Through this chronology, we traced the trajectories of the Preclassic collapse around AD 150–300 and the Classic collapse around AD 800–950, revealing similar patterns in the two cases. Social instability started with the intensification of warfare around 75 BC and AD 735, respectively, followed by the fall of multiple centers across the Maya lowlands around AD 150 and 810. The population of Ceibal persisted for some time in both cases, but the center eventually experienced major decline around AD 300 and 900. Despite these similarities in their diachronic trajectories, the outcomes of these collapses were different, with the former associated with the development of dynasties centered on divine rulership and the latter leading to their downfalls. The Ceibal dynasty emerged during the period of low population after the Preclassic collapse, suggesting that this dynasty was placed under the influence from, or by the direct intervention of, an external power.