GSA QUATERNARY GEOLOGY AND GEOMORPHOLOGY DIVISION FAROUK EL-BAZ AWARD FOR DESERT RESEARCH: DESERT-MARGIN AREAS: HOT SPOTS OF EARLY CULTURAL DEVELOPMENT

Why is cultural development accelerating since approximately 15 ka ago? The hypothesis is: The triggers for these significant processes are climatic (hydrological) fluctuations in (sub-) tropical desert-margin areas.

Concerning the Old World, studies show that Holocene climate changes caused dryland aridization leading to the present deserts and triggered the concentration of people at favorable places like groundwater-lakes or river oases. As a result marginalization/regionalization and fragmentation of human groups and different adaptation processes to the changing environments caused different `cultures´ about 6 ka ago after the Holocene Altithermal.

In order to test the hypothesis independently, that means in the New World, we studied over c. 10 years the environments in the western Andes and in the coastal desert of southern Peru (Ica-Nazca region). We combined information from archaeological findings with own data sets from geo-archives, in particular from spectacular Holocene desert-loess landscapes (loess deposition: c. 11 ka until c. 4 ka) and river deposits.

The temporal coincidence of hydrological changes with pulses of cultural development reveal similar processes as found in the Old World. Aridization and population concentration coincide with the onset of sedentism at least since the 4^thmillennium B.C.E. along river oases, followed by the invention of ceramics), the specification of cultural characteristics and settlement shifts in accordance with significant hydrological fluctuations at c. 1.8 ka B.C.E., between 200 and 700 A.D., at c. 1200 A.D. and finally around 1600 A.D. (OSL-data by Dr. Kadereit; radiocarbon data by Dr. Kromer, both Heidelberg University).

The similarity of the processes supports the idea that (sub-)tropical desert-margin areas due to the sensitivity to hydrological changes were the hot spots of early cultural development in the Old as well as in the New World.