Reconstructing the technical and cognitive abilities of past hominins requires an understanding of how skills like stone toolmaking were learned and transmitted. We ask how much of the variability in the uptake of knapping skill is due to the characteristics of the knapping sequences themselves? Fundamental to skill acquisition is proceduralization, the process whereby skilful tasks are converted from declarative memories (consciously memorized facts and events) into procedural memories (sub-consciously memorized actions) via repetitive practice. From knapping footage, we time and encode each action involved in discoidal, handaxe, Levallois and prismatic blade production. The structure and complexity of these reduction sequences were quantified using k-mer analysis and Markov chains. The amount of time spent on tasks and the pattern of core rotations revealed portions of these reduction sequences that are predisposed to being converted into procedural memories. We observed two major pathways to achieve this proceduralization: either a repetitive or a predictable sequence of core rotations. Later Acheulean handaxes and Levallois knapping involved a predictable platform selection sequence, while prismatic blade knapping involved a repetitive exploitation of platforms. Technologies and the portions of their reduction sequence that lend themselves to proceduralization probably facilitated the more rapid uptake of stone toolmaking skill.

Acheulean bifaces dominate the archaeological record for 1.5 million years. The meaning behind the often symmetrical forms of these tools is the topic of considerable debate, with explanations ranging from effectiveness as a cutting tool to sexual display. Some, however, question whether the symmetry seen in many Acheulean bifaces is intentional at all, with suggestions that it is merely the result of a bias in hominin perception or an inevitable consequence of bifacial flaking. In this paper we address the issue of intention in biface symmetry. First, we use transmission chain experiments designed to track symmetry trends in the replication of biface outlines. Secondly, we use archaeological data to assess the symmetry of Acheulean bifaces from British, East African and Indian assemblages in relation to reduction intensity; the degree of bifaciality; and the symmetry of four Middle Palaeolithic bifacial core assemblages. Thirdly, we look at specific examples of the reduction sequences that produced symmetrical Acheulean cleavers at the sites of Olorgesailie CL1-1, Isinya, Chirki, Morgaon and Bhimbetka. All three lines of evidence support the notion that symmetry was a deliberately imposed property of Acheulean bifaces and not an epiphenomenon of hominin visual perception or bifacial technology.

A new non-parametric method based on Gaussian Processes (GP) was proposed recently to measure the Hubble constant H0. The freedom in this approach comes in the chosen covariance function, which determines how smooth the process is and how nearby points are correlated. We perform coverage tests with a thousand mock samples within the ΛCDM model in order to determine what covariance function provides the least biased results. The function Matérn(5/2) is the best with sligthly higher errors than other covariance functions, although much more stable when compared to standard parametric analyses.

The Jwalapuram Locality 9 rockshelter in southern India dates back to 35 000 years ago and it is emerging as one of the key sites for documenting human activity and behaviour in South Asia. The excavated assemblage includes a proliferation of lithic artefacts, beads, worked bone and fragments of a human cranium. The industry is microlithic in character, establishing Jwalapuram 9 as one of the oldest and most important sites of its kind in South Asia.

A detailed attribute analysis of notched flakes from upper layers of Combe Grenal, a key site in the debates about the nature of Middle Paleolithic assemblage variation in France, is used to evaluate the applicability to Combe Grenal of the reduction model offered by Holdaway, McPherron, and Roth as an explanation for morphological and size variation within notched specimens. We conclude that traditional implement types can be viewed as arbitrary divisions in a continuum of size and notch abundance, which can be explained by reference to a model of differential reduction. Specimens with greater numbers of notches are inferred to have been more reduced than specimens with fewer notches. Notch dimensions did not change as more notches were added, but complex notches were more commonly constructed in the middle of the reduction process rather than at the beginning or end. The location and abundance of notches were probably constrained by the size and shape of the flake blank: more notches were added to long flakes and to their distal end, indicating regular patterns of blank selection and treatment. These inferences can be used to suggest that flake blanks may have been an important factor in constraining the position, frequency, and perhaps even kind of notches that were placed on retouched flakes. We discuss implications of this proposition.