The Howiesons Poort lithic sequence of Klipdrift Shelter, southern Cape, South Africa

The driving force behind tool-stone selection in the African Middle Stone Age

In the Stone Age, the collection of specific rocks was the first step in tool making. Very little is known about the choices made during tool-stone acquisition. Were choices governed by the knowledge of, and need for, specific properties of stones? Or were the collected raw materials a mere by-product of the way people moved through the landscape? We investigate these questions in the Middle Stone Age (MSA) of southern Africa, analyzing the mechanical properties of tool-stones used at the site Diepkloof Rock Shelter. To understand knapping quality, we measure flaking predictability and introduce a physical model that allows calculating the relative force necessary to produce flakes from different rocks. To evaluate their quality as finished tools, we investigate their resistance during repeated use activities (scraping or cutting) and their strength during projectile impacts. Our findings explain tool-stone selection in two emblematic periods of the MSA, the Still Bay and Howiesons Poort, as being the result of a deep understanding of these mechanical properties. In both cases, people chose those rocks, among many others, that allowed the most advantageous trade-off between anticipated properties of finished tools and the ease of acquiring rocks and producing tools. The implications are an understanding of African MSA toolmakers as engineers who carefully weighed their choices taking into account workability and the quality of the tools they made.

Evidence for Earlier Stone Age 'coastal use': The site of Dungo IV, Benguela Province, Angola

The relationship between Earlier Stone Age (ESA) hominins and the southern African coastal environment has been poorly investigated, despite the high concentration of open-air sites in marine and fluvial terraces of the coastal plain from c. 1Ma onward during the Mid-Pleistocene Transition. Southern Africa provides some of the earliest evidence of coastal subsistence strategies since the end of the Middle Pleistocene, during the Middle Stone Age (MSA). These coastal MSA sites showcase the role of coastal environments in the emergence and development of modern human behaviors. Given the high prevalence of coastal ESA sites throughout the region, we seek to question the relationship between hominins and coastal landscapes much earlier in time. In this regard, the +100 m raised beaches of the Benguela Province, Angola, are key areas as they are well-preserved and contain a dense record of prehistoric occupation from the beginning of the Middle Pleistocene, including sites like Dungo, Mormolo, Sombreiro, Macaca and Punta das Vacas. Accordingly, this paper provides a critical review of the coastal ESA record of southern Africa and a detailed presentation of the Dungo IV site, through a qualitative technological analysis coupled with a quantitative inter-site comparison with contemporary southern African coastal plain sites. Through our detailed technological analyses, we highlight the influence of coastal lithological resources on the technical behaviors of hominin groups, and we propose the existence of a "regional adaptive strategy" in a coastal landscape more than 600 000 years ago. Finally, we argue for the integration of coastal landscapes into hominins' territories, suggesting that adaptation to coastal environments is actually a slower process which begins with "territorialization" well before the emergence and development of Homo sapiens.

Howiesons Poort backed artifacts provide evidence for social connectivity across southern Africa during the Final Pleistocene

Examining why human populations used specific technologies in the Final Pleistocene is critical to understanding our evolutionary path. A key Final Pleistocene techno-tradition is the Howiesons Poort, which is marked by an increase in behavioral complexity and technological innovation. Central to this techno-tradition is the production of backed artifacts-small, sharp blades likely used as insets in composite tools. Although backed artifacts were manufactured for thousands of years before the Howiesons Poort, this period is marked by a phenomenal increase in their production. In this paper we test both social and environmental hypotheses to explain this phenomenon. We correlate environmental data with changing frequencies of backed artifact production at Sibudu and assess morphological similarity across seven sites in southern Africa. We find that these artifacts are made to a similar template across different regions and that their increased production correlates with multiple paleo-environmental proxies. When compared to an Australian outgroup, the backed artifacts from the seven southern African sites cluster within the larger shape space described by the Australian group. This leads us to argue that the observed standardized across southern Africa is related to cultural similarities and marks a strengthening of long-distance social ties during the MIS4.

Regional patterns of diachronic technological change in the Howiesons Poort of southern Africa

The Howiesons Poort (HP) of southern Africa plays an important role in models on the early behavioral evolution of Homo sapiens. The HP is often portrayed as a coherent MSA industry characterized by early complex material culture. Recent work has emphasized parallel technological change through time across southern Africa potentially driven by ecological adaptations or demographic change. Here we examine patterns of diachronic variation within the HP and evaluate potential causal factors behind these changes. We test previous temporal assessments of the technocomplex at the local and regional level based on high-resolution quantitative data on HP lithic assemblages from Sibudu (KwaZulu-Natal) and comparisons with other southern African sites. At Sibudu, consistent unidirectional change in lithic technology characterizes the HP sequence. The results show a gradual reduction in typical HP markers such as the proportion of blades, backed pieces, and HP cores, as well as declining size of blades and backed artifacts. Quantitative comparisons with seven HP sites in South Africa suggest that lithic technology varies between regions over time instead of following similar changes. Concerning hypotheses of causal drivers, directional changes in lithic technology at Sibudu covary with shifting hunting patterns towards larger-sized bovids and a gradual opening of the vegetation. In contrast, variation in lithic technology shows little association with site use, mobility patterns or demographic expansions. Unlike at Sibudu, diachronic changes at other HP sites such as Diepkloof, Klasies River and Klipdrift appear to be associated with aspects of mobility, technological organization and site use. The regional diachronic patterns in the HP partly follow paleoclimatic zones, which could imply different ecological adaptations and distinct connection networks over time. Divergent and at times decoupled changes in lithic traits across sites precludes monocausal explanations for the entire HP, supporting more complex models for the observed technological trajectories.