INTRODUCTION

The earth's climate changed significantly between 1 Ma and 500 ka, most notably in the frequency, amplitude, and duration of cold, arid periods. Compared with the Early Pleistocene (Chapter 3), these occurred less frequently but lasted longer, and the volume of global ice (as indicated by the marine isotope record) was much greater. In Europe and North America, these cold periods were characterised by extensive ice sheets, the earliest of which in Europe occurred in Marine Isotope Stage (MIS) 16, ca. 650–620 ka (Head and Gibbard 2005:13). Many of these cold periods began gradually but ended abruptly. These cold conditions have dominated the last 600,000 years, and were interrupted by relatively short periods of higher temperatures, precipitation, and sea levels, with the partial exception of the unusually long interglacial MIS 11 (423–362 ka). Depending upon whether the duration of these warm, moist (= interglacial) periods was as little as only ca. 11,000 years (as indicated by the warmest part of the last interglacial, MIS 5e), or as long as 61,000 years, as in MIS 11, conditions across Eurasia would have been colder and drier than today for most of the last 600,000–800,000 years. A final important detail is that both glaciations and interglacials during the Middle Pleistocene experienced numerous short-term (submillennial or even decadal) climatic oscillations, the effects of which on hominins might have been major (see, e.g., McNabb 2005) but cannot be evaluated for Asia without major improvements in the quality of archaeological data.