Research Objectives
Culture change in the ancient Andes has all too often been imputed to catastrophic climatic perturbations such as droughts and El Ni帽o floods, according to a model of 鈥榩unctuated equilibrium鈥� (Shimada et al. 1991; Moseley et al. 1981). While recognising their importance, we seek to develop our previous research, which distinguishes also the impacts of more gradual, human-induced change (Beresford-Jones et al. 2009 a, b, in press; French 2010a & b; Lane 2006, 2009).
We start by tracking the long-term shifts in settlement along the course of the R铆o Ica, from headwaters to mouth, as societies have mitigated, mediated and provoked environmental change through changing practices of land and water management.听 For settlement dynamics are of course a reflex of the various political, social, economic and ecological factors that underlie the flowering, decline (or collapse), and regeneration of societies (Schwartz & Nichols 2006). We aim, thereby, to answer three research questions:
- How and when did settlement change along the drainage?
- How does that relate to changes in water and land management?
- Why did these changes occur?
The viability of this broad task is assured by the wide range of existing (if rather piecemeal) research already available for us to draw upon 鈥� our own included.听 We shall now bring this together and supplement it by new, targeted studies on those areas for which few or no data yet exist, to produce an integrated model of settlement and land and water management along the entire course of the R铆o Ica.听 The answers to our first two research questions, then, will unfold from testing the following hypotheses:
补.听听听That vast, largely unexplored shell middens up to 150 m deep at the mouth of the R铆o Ica are the vestiges of the earliest settlement of semi-sedentary societies exploiting a rich marine resource, and date to the early Holocene (Engel 1957).
产.听听听That floodplain agriculture began on the coast during the early Ocucaje phases c. 750 bc, when settlement seems to have been concentrated in the lower Ica Valley (Massey 1991, Cook 1999).听 Thereafter, interactions between highlands and coast intensified during the so-called Early Horizon.
c.听听 That settlement and irrigation agriculture expanded in the late Ocucaje (or 鈥楶aracas鈥�) phases, and in due course evolved over the subsequent Early Intermediate Period (c. 0-500 ad) into the flourishing Early Nasca society (or societies) 鈥� any distinction between them being 鈥渆ssentially arbitrary鈥� (Menzel et al. 1964: 2).
诲.听听听That Late Nasca subsequently collapsed into internecine warfare. Settlements were dislocated and fewer. Canal systems were abandoned in the lower Ica Valley (Beresford-Jones et al. 2009b).听 Hypotheses proposed to explain Nasca鈥檚 demise include:听 El Ni帽o/La Ni帽a climatic perturbations (Silverman & Proulx 2002); underlying, gradual processes of human-induced deforestation exacerbating the former (Beresford-Jones et al. 2009a and b); and increasing aridity in the highlands (Eitel & M盲chtle 2009).
别.听听听That critical also to Nasca鈥檚 鈥榗ollapse鈥� is a political dimension. For it coincides with the recently revised time depth of the Middle Horizon (ad 550鈥�1000), when the huge urban centre of Wari in the Ayacucho highlands rose to dominate the coast (Menzel 1967, Schreiber 1999). This Middle Horizon 鈥渁pparently marks the virtual replacement of one culture by a radically different one on the south coast鈥� (Rowe 1956: 148).
f.听听 That by around ad 1000 Wari itself, and thereby its influence on the Ica Valley, collapsed.听 Hypotheses for why this occurred include climate change and environmental degradation in Wari鈥檚 own urban core (Isbell et al. 1991).听 At this time too the lower Ica Valley was abandoned to significant settlement (Beresford-Jones 2009a).
驳.听听听That in the highlands the subsequent Late Intermediate Period saw a fragmentation of power as acephalous societies engaged in more sophisticated systems of hydraulic management, underpinning a complex, mixed agro-pastoralist economy (Lane 2009). On the coast, meanwhile, new canal systems opened up, for the first time, the middle Ica Valley to agriculture and substantial occupation (Massey 1991). One of the centres of the Late Intermediate was Ica-Chincha, ultimately to become among the most powerful polities under the Inca Late Horizon (Menzel 1976; Rostworowski 1989).
h.听听 That the settlement patterns encountered by the Spanish when the City of Ica was founded in the middle Ica Valley in 1563 (Rossel Castro 1968), are, more or less, still those of today.听 Yet the Spanish conquest brought population collapse of up to 94% by some estimates (Cook 1981), followed by resettlements (reducciones), especially in the highlands.听 In due course, a rigid new social stratification emerged, reflected not least in the control of water resources.听 This persisted for centuries in the middle Ica Valley, where the population remains concentrated today (Or茅 2005). Only in recent decades has that social order fractured, partly as a consequence of increasing 鈥� and clearly unsustainable 鈥� borehole exploitation of deep fossil groundwater (The Guardian 2010).
Having established a platform of data to answer our first two research questions, we shall then be able to turn to the third and much more contentious one of why change occurred. In previous research we have adopted the perspective of historical ecology (Bal茅e 1998) to show how various land use and water management strategies, adopted at different times by different societies in the lower Ica Valley, impacted upon the landscape.听 We aim now to expand the scale of that analysis to produce a picture, integrated along the whole R铆o Ica drainage, for how watershed management and land-use have both shaped and been shaped by the florescence and decline of cultures through time.听 As the above hypotheses suggest, naturally, this will include the impacts of climatic perturbations, but we expect it to go far beyond traditional models in requiring a much greater role also for human agency 鈥� in creating, managing, and sometimes provoking detrimental landscape change.
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Significance of the Research
This study of the Ica Valley will provide a concrete case-study charting how water management and land-use strategies have impacted upon human settlement and intra-site dynamics along the course of one river through prehistory and, indeed recorded times through to the present.听 By taking 鈥� for the first time 鈥� an entire single watershed as its focus, it will provide a more nuanced study that does not just theorise on but describes how highland and lowland strategies of land use and water management were inter-related.听 Regionally, the R铆o Ica case-study provides an excellent local proxy for understanding the changes in water management across the Andes.听 More widely, it offers a framework by which to map the differences and relationships through time between human ecologies and social organisations in the highlands and on the coast.
Moreover, the answers to our archaeological research questions have powerful contemporary resonance. For today a new 鈥楬orizon鈥� is unfolding. The Ica coast has seen a population explosion through massive economic migration down from the Ayacucho highlands. The consequences of this are the abandonment of highland hydraulic systems, falling water tables on the coast and tremendous pressure upon fragile natural and agricultural biomes, all of which increase vulnerability to extreme climatic perturbations. By understanding similar processes in the past, we may hope to contribute to planning properly for the future.听 Our case-study models water management as the reflex of human agency and concomitant political ecology over deep archaeological time-scales, through to the present day. Its relevance is obvious in a world where captive water resources are relentlessly in decline along the tropical belt, and water conflicts ever more likely in the twenty-first century (Gleick et al. 2009).
Methodology
To answer the research questions defined above, we seek to combine archaeological field methods with the GIS mapping, geoarchaeological and archaeobotanical techniques.
Last year we excavated a Preceramic shell midden 'L-颅1' (c. 5000 BC ) at the river estuary, alongside a detailed survey of the river mouth and adjoining shoreline and lomas fog meadows, each of which provided specific resources for its ancient fisher-颅hunter-颅gatherer inhabitants. This work suggests great shifts in the local estuarine ecology as a consequence of marine transgression and changes in shoreline morphology, which may have driven a move towards greater sedentism, agriculture and settlement further inland.
By the Late Intermediate Period (AD 1200鈥�1450) this process had culminated in extensive irrigation on the coast, and vast terracing systems in the highlands. Concurrent excavations at 'H-颅8' Samaca (at 250 m asl) and Sangayaico (at 3,800 m asl) are revealing the gradual accumulation of that hydraulic landscape. The wealth of material culture recovered in stratigraphic association at these sites will allow us to explore coast-颅 highland interactions through GIS work.
Meanwhile, on-颅going geomorphological and archaeobotanical analyses of highland moors, terraces and coastal middens, together with a GIS data base of all extant archaeology and hydraulic modelling will help us track the development of cultural adaptations along the R铆o Ica and understand concomitant environmental and climate change.
