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.
Bibliographical noteFunding Information:
This research has been supported by many institutions and people. We would like to thank the Instituto N acional de Cultura for granting the necessary permits to complete the archaeological and agricultural field work. Ramiro Ma-tos, Jorge Silva, and Miguel Martinez provided assistance in both Lima and Jauja, Peru, to get the various projects underway. Our colleagues of the Upper Mantaro Archaeological Research Project collaborated on many aspects of the research; they include Timothy Earle, Cathy Scott, Terry D'Altroy, Andy Christenson, Manuel Es·cobedo, Ruben Garcia Soto, Cathy Costin, Glenn Russell, Elsie Sandefur, Lisa LeCount, and Heidi Lennstrom. The geological field work was carried out under the direction of H. E. Wright, Jr., with additional help from Carrie Pat-terson. Andres Moya Castro of Ataura, Peru, provided invaluable assistance in all aspects of the fieldwork. We also wish to thank the people of Jauja, Peru, and the surrounding communities, especially Hacienda Acopalca, who kindly allowed us to interview them and conduct our field research on their land. The initial archaeological and agricultural studies were funded by a Fulbright-Hayes Doctoral Dissertation Grant, with further excavations and laboratory analyses funded by National Science Foundation grants BNS-8203723 and BNS-8451369. The geological field work was funded by the National Geographic Society. This paper is contribution 406 of the Limnological Research Center. This research is dedicated to the people of this region who are going through yet another period of political upheaval.
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