Zebu: Harbingers of Doom in Bronze Age Western Asia?
Matthews, Roger, Antiquity
Collapse and climate in the Bronze Age
A major area of study in recent years has been that of the collapse of complex human societies (Tainter 1988). In parallel with issues of the rise of civilization and the growth of complex states, there has been a developing interest in their decline and fall, especially as correlated against episodes of climatic change (Butzer 1995). Few areas of the world offer such rich, varied and chronologically deep material on this topic as western Asia.
Throughout the late prehistory and early history of western Asia long periods of relative stability, in gross terms, were punctuated by short, sharp episodes of disruption and change. Three major phases of massive and widespread cultural disruption appear to have occurred. These episodes took place at the start, in the middle and at the close of the Bronze Age, that is at approximately 3000, 2200 and 1200 BC. In each case there is persuasive, although not universally accepted, evidence for the collapse of Bronze Age societies. The first of these punctuations is attested in the collapse of the `Uruk world system' at the very transition of the Chalcolithic and Bronze Ages (Algaze 1993). At this time, the end of the 4th millennium, there is evidence for a sharp curtailment of the previously broad spread of south Mesopotamian cultural influence and for substantial social and political upheaval across vast areas.
At the end of the Early Bronze Age, in the late 3rd millennium, well-established empires and civilizations fell apart and died. In Mesopotamia, the empire of Akkad shrank rapidy from its greatest spread to an embattled and short-lived core in the south. Large-scale settlement upheavals and social collapse are attested by archaeological evidence from much of the Mediterranean world and beyond, including the Iberian Peninsula, Greece and the Aegean, the Levant, Egypt, Anatolia, Mesopotamia, Iran and the Indus Valley (Peltenburg 2000; Weiss 2000; Weiss & Bradley 2001). Effects of this dramatic episode appear to linger on for a period of a millennium or more in marginal regions most sensitive to climatic fluctuations, such as the western Habur River area of north Syria, completely abandoned by permanent settlement through the later 3rd and all of the 2nd millennia BC (Hole 1997).
A thousand years later, at the end of the Late Bronze Age around 1200 BC, a comparable scale of social and state collapse is attested by archaeological and historical evidence from an equally broad geographical range (Neumann & Parpola 1987; Ward & Joukowsky 1992). In Anatolia the Hittite empire came to a sudden end, and there is convincing evidence for widespread disruption across much of the Mediterranean world.
Many scholars believe that climatic factors were heavily implicated in the timing and nature of these vast and complex processes. Based on examination of climatic evidence from a range of sources, Butzer has underlined the importance of three `incisive episodes of major ecological significance, perceptible to some degree or other throughout the Near East', occurring at approximately 3000, 2200 and 1300 BC (Butzer 1995: 136-8). In environmental terms, the single major element of these devastating episodes, called `dry shifts' by Butzer, is a substantial decrease in precipitation, as attested by fluctuations in the water levels of Lake Van (east Anatolia) and Lake Zeribar (west Iran), and in oak-pollen records obtained from sediment sequences from these two lakes (Butzer 1995: figure 2). In addition, evidence from deep-sea sediments from such widely separated locations as the North Atlantic (deMenocal 2001) and the Gulf of Oman (Cullen et al. 2000) reinforces the picture of regular and protracted episodes of excessively cool and dry climate in the Bronze Age, putatively caused by fluctuations in solar irradiance and volcanism (deMenocal 2001: 668). The Gulf of Oman evidence, in particular, shows an abrupt increase in wind-borne dust of Mesopotamian origin lasting for a period of 300 years from about 2300 BC (Cullen et al. …