Paleoclimate during Neandertal and early modern human occupation in Israel: Tooth enamel stable isotope evidence.

摘要

Much debate in paleoanthropology has focused on the complex pattern of human evolution in Israel during the Late Pleistocene under the premise that climate change was a primary determinant for observed changes in human migration events. A paramount question is whether Neandertal and early modern human occupations in Israel alternated as environmental conditions fluctuated. Bar-Yosef and others propose that early modern humans occupied Israel during a warm, dry period of the Emian Interglacial, Oxygen Isotope Stage 5 (OIS 5), approximately 110 kyr. Neandertals, on the other hand, inhabited the region between 70 and 50 kyr as a result of European climate degeneration at the onset of the WUrm glaciation (OIS 4).; The above hypothesis was tested through stable oxygen and carbon isotope analyses of fossil herbivore enamel carbonate from the sites of Amud, Tabun, Skhul, and Qafzeh to reconstruct paleoclimatic conditions during the Late Pleistocene. A baseline comparative sample, established from the teeth of modern and Early Holocene analogues across Israel, represents present-day climatic conditions---a long, dry summer and a rainy winter.; Through sequential analyses of goat and gazelle teeth from Amud and Tabun layers B and C, a seasonal amplitude of 6‰ in enamel delta 18O was observed, indicating seasonal changes in delta18 O of body water. The modern and Early Holocene teeth, on the other hand, show little seasonal change. Thus, it is inferred that rain fell throughout the year during the time of occupation by Neandertals. Periods of summer rains were also associated with higher humidity and denser forest cover. Neandertals, therefore, occupied Israel under cooler and wetter conditions than today with more closed woodland.; Data obtained from Qafzeh, Skhul, and Tabun D show a trend in d 18O and d13C that is similar to the modern proxy data. That is, drier conditions with rainfall occurring only in the winter. In contrast to present-day conditions, however, enamel d13C values from Qafzeh demonstrate the presence of C4 vegetation, indicating a drier, more open environment near the cave. It appears thus far that early modern humans and Neandertals did live under different climatic conditions in Israel during the Late Pleistocene.