Increasing behavioral flexibility? An integrative approach to understanding the Middle Stone Age of southern Africa

Michael Bolus1, Angela A. Bruch2, Miriam N. Haidle2, Christine Hertler2, Andrew W. Kandel1, Michael Märker1
1 Heidelberger Akademie der Wissenschaften, ROCEEH Tübingen
2 Heidelberger Akademie der Wissenschaften, ROCEEH Frankfurt/Main

V 4.2 in Steinzeitlicher Mensch und Umweltwandel - zur Archäologie von Umweltrisiken

18.09.2012, 08:50-09:10, H8

The Middle Stone Age (MSA) of Africa represents a period of cultural innovation adopted by modern humans between roughly 200 and 30 ka. While researchers generally attribute behavioral variability during the MSA to social and environmental causes, neither provides a complete explanation. As patterns at the site level come into focus, large-scale trends explaining cultural expansions remain uncertain.

The Still Bay (SB) from 77-70 ka and the Howieson’s Poort (HP) from 65-59 ka represent the two most studied phases of the MSA of southern Africa. The most notable artifacts of the SB include bifacial leaf points, bone tools, shell beads, and engraved ocher, while the HP is noted for backed segments and engraved ostrich eggshells. For the purpose of our analyses we grouped the phases before the SB into an entity that we refer to as Pre-SB. For the same reason we grouped the phases after the HP into a single Post-HP unit. The Pre-SB and the Post-HP incorporate some elements of the SB and HP, but are not as easy to define based on their lithic technology. The reasons for the appearance and the demise of all of these phases remain unclear.

To test the hypotheses of cultural and environmental causality and examine potential routes of expansion, we devised new ways to view diachronic datasets from localities in southern Africa. The research team queried the ROCEEH Out-of-Africa Database for known MSA sites. We used a specialization index and developed a tool group index to assess variability in tool types; assessed transport distances of raw materials to examine patterns of movement across the landscape; reviewed the complexity of the cognition necessary to manufacture simple, composite and complementary tools; applied stochastic models such as boosted regression trees and statistical mechanics to explain the geographic distribution of sites in relation to specific combinations of environmental factors; and reconstructed classes of biomes and climatic constraints associated with the MSA.

These varied techniques allowed the ROCEEH team to integrate and process information with the surprising result that we observed little diachronic change in the MSA despite the increasing cultural flexibility observed through the HP. During the Post-HP cultural performance appears to decrease, but this may be an artifact of the lack of data. More importantly, we observed that climate was not the most significant factor driving human activities during the MSA. These results concur with new publications and help us examine changes in the behavioral flexibility of the inhabitants of southern Africa during the MSA.

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Letzte Änderung 20.05.2012