The long term response of ancient societies to climate change has been a matter of global debate. Until recently, the lack of integrative studies between archaeological, palaeoecological, and palaeoclimatological data had prevented an evaluation of the relationship between climate change, distinct subsistence strategies, and cultural transformations across the largest rainforest of the world, Amazonia. Here, we review the most relevant cultural changes seen in the archaeological record of six different regions within Greater Amazonia during late pre-Columbian times. We compare the chronology of those cultural transitions with high-resolution regional palaeoclimate proxies, showing that, while some societies faced major reorganisation during periods of climate change, others were unaffected and even flourished. We propose that societies with intensive, specialised land-use systems were vulnerable to transient climate change. In contrast, land-use systems that relied primarily on polyculture agroforestry, resulting in the formation of enriched forests and fertile Amazonian Dark Earths in the long term, were more resilient to climate change.

Chichén Itzá dominated the political landscape of the northern Yucatán during the Terminal Classic Period (AD 800-1000). Chronological details of the rise and fall of this important polity are obscure because of the limited corpus of dated hieroglyphic records and by a restricted set of radiocarbon dates for the site. Here we compile these and review data and evaluate them within the context of political and climatic change in northern Yucatán at the end of the Classic period. The available data point to the end of elite activity at Chichén Itzá around AD 1000, a century after the collapse of Puuc Maya cities and other interior centers. Evidence supports a population shift in the eleventh century towards some coastal locations during a time associated with the end of monumental construction and art at Chichén Itzá. Our results suggest that regional political disintegration came in two waves. The first was the asynchronous collapse of multiple polities between AD 850 and 925 associated with a regional drying trend and punctuated by a series of multi-decadal droughts in the ninth and tenth centuries. The second wave was the political collapse at Chichén Itzá that coincides with the longest and most severe drought recorded in regional climate records between AD 1000 and 1100. This is a time that some scholars have characterized as a "dark age" across the northern Maya lowlands. Political developments during the Postclassic period (AD 1000-1517) correspond with a return to higher rainfall. These patterns support a strong relationship between political disintegration and climatic stress in the Maya lowlands. This research employs Bayesian radiocarbon models in conjunction with calendar dates on carved monuments and climate proxies to evaluate the rise and fall of Maya political centers and serves as an example of the impact of climate change on rainfall-dependent societies in Mesoamerica.

No abstract

Accurate and high-resolution airborne light detection and ranging (lidar) data have become increasingly important for the discovery and visualization of complete archaeological settlement systems in the Maya Lowlands. We present the results of systematic quantitative analysis of lidar data and ground verification for the major centers of Cahal Pech, Baking Pot, and Lower Dover in the Belize Valley. The Belize Valley is characterized by high density populations living in growing modern towns and villages, and by large-scale agricultural production. This urban environment presents a challenge to reconnaissance efforts since modern construction and agricultural activities have destroyed ancient ruins and created new vegetation patterns. Lidar data was analyzed within a GIS using the Topographic Position Index (TPI) to identify the location of possible archaeological remains. Small-scale, site-level TPI analysis helped identify more detailed archaeological features including small house mounds, terraces, and ditches. Results indicate that lidar data recorded for areas with dense vegetation (e.g., low brush and secondary regrowth) may be less reliable for identification of archaeological remains. The quantitative and qualitative differences between spatial analyses and pedestrian survey results among land cover types indicate that traditional settlement pattern study methods, including pedestrian survey, remain vital to ground-truthing all types of spatial data.

No abstract