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There is a general awareness amongst archaeologists that the intensity of a sampling program, i.e. the number of pits, their size and their spacing, has a strong bearing on discovery rates. However, rarely is the effect of this relationship on specific sampling strategies explicitly assessed due to the difficulty of running the required mathematical models. This paper presents a new simulation tool Dig It, Check It, which allows the archaeologist to easily determine the effectiveness of a sampling program against a variety of artefact site types. This is the first model to be presented which employs simulation to assess the effectiveness of irregular, real-world subsurface sampling programs through the importation of an ArcGis file. This means that a sampling strategy which includes test-pits of varying sizes and intervals can be assessed, as can survey areas of non-rectangular shape. Small artefact concentrations are particularly vulnerable to detection failure, and this model allows the archaeologist to determine whether their absence reflects reality or is a product of the sampling program.

This paper presents a new simulation tool, Dig It, Design It, which allows the archaeologist to easily design an optimal subsurface sampling program for the detection of buried artefacts. The design of such a program rests upon the relationship between the sampling methodology and the characteristics of the artefact concentrations under study, principally their size, density and density distribution. While the need to consider this relationship has been previously established, a model which automatically performs these calculations had not yet been designed. Dig It, Design It is the first model to be presented which considers artefact site properties and detection probabilities to produce an optimal sampling strategy for the archaeologist, and to provide the detection probabilities for artefact sites with different properties. The model is available online, is very easy to use, and no mathematical knowledge is required. Dig It, Design It thus has the potential to dramatically increase the use of statistically defensible sampling programs within the archaeological community.

In the southern African archaeological sequence, the Levallois method of core reduction is considered to be a distinctive technological feature of the Middle Stone Age (MSA). Similarly, the transition from MSA to Later Stone Age (LSA) has been defined by a decline in the prevalence of Levallois and an increase in prismatic blade production and the use of bipolar percussion to reduce cores. Reanalysis of material recovered from Howiesons Poort Shelter - the eponymous site for the Howiesons Poort phase of the southern African MSA - has revealed that most of the Levallois cores from the site were knapped using a combination of freehand and bipolar percussive techniques. In these cases, freehand percussion was used to prepare and re-shape the cores, while bipolar percussion was used as a targeted strategy for detaching Levallois flakes. The discovery of this combination is significant because the accepted definition of the Levallois method prescribes the use of freehand, hard-hammer percussion only. This paper describes the trends in core morphology and reduction processes associated with this bipolar Levallois strategy and evaluates some possible motivations for using bipolar percussion to detach Levallois flakes. Analysis of core dimensions and reduction sequences suggests a gradual strategic transition between freehand Levallois and bipolar bidirectional-opposing reduction strategies as cores become smaller. Contrary to traditional depictions of the technique, bipolar percussion was used by knappers at Howiesons Poort Shelter on cores of a wide range of sizes regardless of material, particularly in situations where control over the force and location of flake removing blows was critical. As well as adding to a growing image of the technological and behavioural complexity of Howiesons Poort (and indeed MSA) hominins, these discoveries have important implications for our understanding of both the Levallois reduction method and the bipolar percussive technique.

Today studies of lithic technology almost invariably employ models of the reduction process, and often models of the extent of reduction that specimens and classes of tools have undergone. Debates about the explanation of lithic assemblage variability are based upon methods for inferring the nature and extent of reduction. In this paper, we construct a conceptual framework for evaluating the competing reduction indices for estimating the extent of flake retouching. With this framework we offer a new synthesis of reduction indices and the debates that have surrounded their use.