Climatic Change and its Effect on Prehispanic Agriculture in the Central Peruvian Andes

Abstract

The effect of climatic change on human and natural populations is most readily discernible in geographic locations where climate is a significant factor in limiting the range of activities. Today, as in the past, severe minimum temperatures at high altitudes limit the range of production of various crops in the Peruvian Andes. Periodic climatic cooling, as evidenced by the deposits from two recent glaciations, lowered the upper elevation limit of maize and significantly reduced the area available for its cultivation in the northern Mantaro River Valley. Paleoethnobotanical data from the same area suggest that during the most recent period of climatic cooling, less maize was produced compared to the warmer time periods that bracket this event. During the cooler phase, climatic constraints on maize production could have exacerbated already existing social tensions, perhaps leading to an increased establishment of more defensive settlements. This study shows how climate can affect human actions. This does not mean that climate dictated the major social and political changes seen in the archaeological record; but including environmental constraints and climatic change in discussions about the past can, given appropriate data, provide a more complete picture of cultural change.