Socio-environmental dynamics in the Central Atacama Desert (22°S) during the Late Holocene

In the Central Atacama Desert (22°-24°S; henceforth CAD), around 3700 cal yrs BP,

human economies begin to transition from relying mostly on hunting and gathering to

increasingly incorporating horticulture and pastoralism became more intensive during

the Late Intermediate Period (LIP; beginning at ca. 1050 cal yrs BP /900 AD). In this

extreme environment, the well-being of past and present farming and herding

communities is directly tied to water availability. The lack of proper paleoclimatic/environmental records in terms of their temporal/spatial resolution

impeded evaluation whether sedentarization was synchronous, in some degree, with

the amelioration of dry conditions recorded during the Late Holocene at millennial

timescales. The present paper thus aims (1) to reconstruct the past environmental and

climatic dynamics in the CAD (22°S) during the late Holocene at millennial to subcentennial scales based on the pollen record of fossil rodent middens of Cuesta Chita site and; (2) to discuss their possible relationship to changes in cultivation and water management as seen at the archaeological sites of Topaín, Paniri and Turi, located in the Salado River basin. The CCH rodent midden pollen record reflects wetter (drier) than present phases around 4400, 3650, 3000, 2200-2100, 1600, 855-840, 520-450 and 100 cal yrs BP (980, 450-115 cal yrs BP). By the time that wetter-than-present conditions occurred in the CAD (Formative Period, 3500-1050 cal yrs BP), local

communities had already developed small-scale horticultural practices, yet they did not

develop extensive or intensive agricultural practices. Indeed, historical processes

leading to economic transformations and the rapid adoption of intensive agriculture

throughout the CAD after 1000 cal yrs BP occurred and were probably favored by

wetter than present conditions, suggesting positive correlations between climatic and

cultural change. However, these correlations are complex and non-deterministic. In

fact, decreased moisture between 650-600 cal yrs BP in the Turi Basin was met by

agropastoralists at Topaín with complex local strategies that included changing water

management practices and significantly extending farmed lands. Similarly, the Topaín

fields were abandoned during a period of much-wetter-than-present conditions. The

chronologically fine-grained comparison of the CCH and archaeological records

reveals that the relationship between climate and culture is complex, non-deterministic, and historically contingent, with examples of agricultural expansion during a time of water stress, and the abandonment of fields during a time of abundance.

Paleoenvironment. Prehispanic farming. Climate and culture. Atacama Desert. Late. Holocene.