Two millennia of changes in human ecology: archaeobotanical and invertebrate records from the lower Ica valley, south coast Peru

Abstract

This paper presents archaeobotanical and invertebrate evidence from the flotation and analyses of 46 archaeological contexts from six middens from the Samaca and Ullujaya basins, lower Ica Valley, south coast of Peru. This is part of one of the world’s driest deserts and organic remains can enjoy extraordinary preservation in its hyperarid climate. Each of these contexts represents snapshots with which to piece together a picture of changing human ecology in the lower Ica Valley over nearly two millennia, from Ocucaje Phases 3/4 of the Early Horizon (c. 750 b.c.); through to Early Nasca Phases 2/3 (c. a.d. 100–450); Late Nasca Phases 6/7 (c. a.d. 450–600) and Middle Horizon Epoch 2 (c. a.d. 900). They also offer proxy evidence of wider ecological changes in these basins. Read together with geoarchaeological and pollen data, the archaeobotanical data we present show a gradual intensification of agriculture from small-scale Early Ocucaje societies subsisting mainly on gathered marine and terrestrial resources, through to sophisticated irrigation agriculture by Nasca times, but culminating in a collapse of agricultural production and a return to the gathering of wild marine and plant resources much later, during the Middle Horizon. This trajectory of human ecology is consistent with the model presented elsewhere of a gradual removal of Prosopis dominated riparian woodland for the purpose of increasing agricultural production, which in time exposed the landscape of the lower Ica Valley to high-energy, episodic flood events and of one of the world’s strongest and most persistent wind regimes.