Africa from MIS 6–2: Population Dynamics and Paleoenvironments

T volume includes papers from a conference held at the McDonald Institute for Archaeological Research in 2010. The aim of the conference was to examine the histories of populations on the African continent through the use of a variety of data sets—archaeology, genetics, paleoenvironments, and paleontology—to reach a more nuanced understanding of hominin skeletal and behavioral evolution, how populations were spatially distributed across Africa, and the impact of climatic factors on group size and movement. The conference participants sought to position data from Africa to aid in the construction of theoretical frameworks and to benefit from frameworks developed elsewhere. In addition to a preface and introductory chapter, the volume is divided into four parts, three of which organize the papers into broad ecological zones. Part I includes four chapters dealing with coastal areas of Africa, primarily southern Africa where extensive research has been conducted, and one contribution for northwest Africa. Part II features the deserts, with three papers on the Sahara and four papers on desert biomes in southern Africa. Part III focuses on grasslands, woodlands, and rainforests, with two papers on East Africa, one on southern Africa, and two on central Africa. Finally, Part IV presents several overviews—skeletal evidence, African genetics, and an assessment of future directions for research in Africa. Chapter 1, by B.A. Steward and S.C. Jones, introduces the volume and the rationale for its organization into biomes, as well as the advantages and the data sets still lacking. They are careful to note that each of these general biomes actually contains considerable diversity (topography, sediments, vegetation, water availability, and so forth). In the coastal biome, for example, they observe that there is high vegetation diversity between coastal regions, ranging from areas characterized by tropical forests to those with deserts. Moreover, most research has occurred in South Africa or the Maghreb, yet Africa is a continent with abundant coastlines elsewhere still to be investigated. And, there also is the issue of data now submerged on the continental shelves. Deserts in Africa, on the other hand, offer highly visible archaeology, but do not necessarily lead to good organic preservation, particularly for surface finds which also can suffer from surface deflation and erosion. River systems that once ran through parts of deserts could have been occasional corridors for movement through otherwise arid regions and may have influenced population density and group size. For grasslands, woodlands, and rainforests, they ask if such contexts were biogeographical corridors or instead might have operated as barriers to movement. In particular, rainforests were patchy spots across the landscape during arid periods, and likely not refugia, partly due to significant deficiencies in food resources for hominins. Part I: The first three chapters in Part I (Coasts) are studies from the coastlines of southern Africa. Chapter 2, by A.S. Carr, B.M. Chase, and A. Mackay, focuses on the Middle Stone Age (MSA) in the southern part of South Africa. It is an overview of the archaeology in the period from 170–55 kya, which is derived primarily from cave and rockshelter contexts. They discuss present-day landscape, coastal geomorphology, and climate, and then examine these aspects during the Quaternary, during which lower sea level added up to 50,000km2 of land (Agulhas Bank) to current coastlines. During periods of higher sea level, aridification is marked by the formation of sand dunes in some areas. By using data from the transition between the Pleistocene and the Holocene, the authors offer modeling of climate changes occurring during the MSA and the potential influences on hominin populations. They observe that it was local resources that were most critical to site placement and the use of various parts of the landscape rather than fluctuations in the size and density of populations. In Chapter 3, by A. Mackay, the main focus is the technological flexibility inherent in the MSA lithic assemblages from the southern African sites of Diepkloof, Hollow Rock Shelter, Klein Kliphuis, and Klipfonteinrand, and how the use of these technologies was a strategy for responding to changes induced by climatic variation through time, rather than lithics used as markers in a culture history approach. Although the notion of flexibility is set within a technological framework, the actual lithics used in the analysis are retouched tools, particularly backed pieces, and unifacial and bifacial points. Technology is thus defined somewhat differently than it is in other literature, where technology refers to how the lithic pieces are manufactured. Here, technology has more to do with the form and choice of stone raw material of the pieces, and thus perhaps by implication, how they may have been hafted and used. Mackay notes that only bifacial points do not reoccur through the stratigraphies of the four sites, as these are confined to assemblages classified as Still Bay. The fact that the other types (backed elements, unifacial points) do reoccur through time is the basis for arguing for flexibility in choosing between various options available in order to meet particular challenges, a