Pergamon Quaternary International, Vol. 43144, pp. 153-159,1997. Copyright 0 1997 INQUA! Elsevier Science Ltd PII: S1040-6182(!+7)00031-1 Printed in Great Britain. All rights reserved. 104&6182/97 $32.00 THE IMPACT OF CLIMATIC CHANGE ON PAST CIVILIZATIONS. A REVISIONIST AGENDA FOR FURTHER INVESTIGATION Linda Manzanilla Institute de Investigaciones Antropolo’gicas, UNAM-Cd. Universitaria, Circuito Exterior, 04.510 Mkxico D.F., MLxico This article outlines some of the current discussions regarding climatic change and civilization responses. Recent data from the Near East and Northern Africa on one hand, and from Mesoamerica and the Andean Region on the other, are reviewed and discussed in order to obtain a general picture of issues currently open for debate. 0 1997 INQUA/ Elsevier Science Ltd INTRODUCTION In this paper, some personal and undoubtedly con- troversial ideas will be put forward on the relationship between climate change and early civilization collapses, using some recent research examples(Tainter, 1990). The International Geosphere-BiosphereProgramme has pro- posedthe PAGES project for past global changesas one of its core projects (IGBP, 1992). Its goals are the reconstruction of a climatic and environmental history during the glacial cycles of the Pleistocene-Holocene, the assessment of the natural processes associated with climatic change, as well as a detailed climatic history for the last 2000 years. Archaeology, working with close ties to palaeoenvironmental studies (particularly pollen, phytolith, botanical and fauna1 macrofossils), allows an understanding of those millennia when human societies were affected by climatic, marine, and solar variations, or in those cases where they acted as prime movers in altering their environments. The study of past global changes (Bradley, 1989; Moss, 1992) is particularly relevant during the last 15 millennia, when Pleistocene human groups underwent significant transformation in their hunting-gathering modes of subsistence, during the passage to the Holocene. From predatory hunting of relatively large herbivorous herds, humansdepended on the gathering and hunting of small animals; a phenomenon that modified band size and social organization. Variations in sea-level during glacial and interglacial periods also affected the settlement pattern of coastal groups primarily dedicated to the consumption of marine molluscs. The so-called ‘Neolithic Revolution’, in which domes- tication of plants and animals began, permitted the general sedentarization of groups which had formerly been semi-nomadic. In the Near East, the diffusion of sedentary lifestyles promoted an expansionof settlements in the Negev and Jordanian regions. Many ninth millennium BP village sites, still with complex coopera- tive systems related to stone, bone, and antler crafts, have been detected and studied in this region. Nevertheless,the most fundamental human transforma- tion of the environment was the so-called ‘Urban Revolution’ (Childe, 1973). The growth of great urban developments, one of which covered the central Basin of Mexico, is the hallmark of this type of civilization. These were not however new phenomena. Someancient cases of early urban developments, their impact on environmental change, and also their fragility with respect to climatic change will be reviewed (Manzanilla, 1993). MESOPOTAMIA Mesopotamia lacked rocks, metals and minerals, and from very early periods, the Neolithic societies of these great deltaic and alluvial plains had to participate in extensive long-distance exchange networks to obtain raw materials ranging from the roughest basalt, for grinding tools, to the gold used in elite art objects for the rulers (Manzanilla, 1986b). The first proto-Sumerian cities of the Lower Mesopotamian plain grew on ancient settle- ments near the great rivers, elevating their living sites more and more to protect them from floods. The Tigris and Euphrates regimes are erratic; changes in their courses provoked massive abandonment of settlements; catastrophic floods - one of which ravaged Baghdad in 1954 (Buringh, 1957) - destroyed demographic clusters constructed with mudbricks. Flood strata observed in Kish, Shurrupak, and Ur (Raikes, 1966) can be explained by meteorological and hydrological factors, as well as tectonics. Changes in exchange routes, so vital for Mesopotamia with respectto the supply of raw materials, also causedsite abandonment. These factors strongly affected the mentality of the inhabitants of Mesopotamia who, unlike the Egyptians, saw nature as a domain of constant and menacing changes, so that humans were always subject to the whims of the gods. Furthermore the inhabitants of Mesopotamia could only occupy this portion of Iraq thanks to the use of irrigation techniques. The cultivated areas were located in the flood basins on both sides of the 153