A geometric morphometric relationship predicts stone flake shape and size variability

The archaeological record represents a window onto the complex relationship between stone artefact variance and hominin behaviour. Differences in the shapes and sizes of stone flakes—the most abundant remains of past behaviours for much of human evolutionary history—may be underpinned by variation in a range of different environmental and behavioural factors. Controlled flake production experiments have drawn inferences between flake platform preparation behaviours, which have thus far been approximated by linear measurements, and different aspects of overall stone flake variability (Dibble and Rezek J Archaeol Sci 36:1945–1954, 2009; Lin et al. Am Antiq 724–745, 2013; Magnani et al. J Archaeol Sci 46:37–49, 2014; Rezek et al. J Archaeol Sci 38:1346–1359, 2011). However, when the results are applied to archaeological assemblages, there remains a substantial amount of unexplained variability. It is unclear whether this disparity between explanatory models and archaeological data is a result of measurement error on certain key variables, whether traditional analyses are somehow a general limiting factor, or whether there are additional flake shape and size drivers that remain unaccounted for. To try and circumvent these issues, here, we describe a shape analysis approach to assessing stone flake variability including a newly developed three-dimensional geometric morphometric method (‘3DGM’). We use 3DGM to demonstrate that a relationship between platform and flake body governs flake shape and size variability. Contingently, we show that by using this 3DGM approach, we can use flake platform attributes to both (1) make fairly accurate stone flake size predictions and (2) make relatively detailed predictions of stone flake shape. Whether conscious or instinctive, an understanding of this geometric relationship would have been critical to past knappers effectively controlling the production of desired stone flakes. However, despite being able to holistically and accurately incorporate three-dimensional flake variance into our analyses, the behavioural drivers of this variance remain elusive.     

The evolution of strength,elasticity and rupture behaviour of birch tar made with ‘double-pot’ techniques during tar cooking

Birch tar was the first adhesive produced by humans. Its study has consequences for our understanding of human evolution and the development of specialised craftsmanship. One of the better-documented birch tar making methods is the ‘double-pot’ technique, where two containers are used, one containing bark, the other collecting the tar. Birch tar made with double-pots has low viscosity and bad adhesive properties. To obtain a usable adhesive, it must be reduced in volume by cooking. We investigate the evolution of tar’s mechanical properties during cooking. We use lap-shear tests to investigate strength, stiffness and failure behaviour. We found that tar must be cooked for 90 min to acquire adhesive properties. When cooked for longer, strength and stiffness increase over a 30 min lasting time span. Cooking for even longer, beyond this 30 min window, produced a substance that could no longer be used as an adhesive. The implications are that tar cooking requires a high level of skill because specific signs indicating the desired properties must be recognised during the process. Tar cooking constitutes a supplementary investment in time and resources and appears to be associated with a certain degree of risk.     

Simulating Lithic Raw Material Variability in Archaeological Contexts: A Re-evaluation and Revision of Brantingham’s Neutral Model

This paper presents a systematic re-evaluation of Brantingham’s (American Antiquity, 68(3), 487-509, 2003) neutral model of raw material procurement. I demonstrate that, in its original form, the model is ill-suited to the identification of archaeologically visible patterns, as it can only simulate processes governing the composition of toolkits and these differ substantially from those influencing the composition of discard records. I discuss and implement a series of modifications, and provide a detailed analysis of discard records produced under revised model definitions. On this basis, I argue that qualitative similarities in patterns generated by the neutral model and those evidenced in archaeological contexts cannot be used to prove, or disprove, the adaptive or functional significance of raw material variability (cf. Brantingham 2003). However, I show that the revised model can be used to detect deviations from neutral expectations quantitatively and within well-defined error ranges. I outline a new set of predictions for what archaeological variability should look like under the simplest procurement, transport, and discard behaviors, and argue that deviations from each of these may be traceable to specific behavioral domains (e.g., biased mobility, raw material selectivity). I also demonstrate that (a) archaeological sites or assemblages do not offer an adequate proxy for the average composition of ancient forager toolkits; (b) assemblage richness is, by itself, a very poor predictor of occupational histories; and (c) that the common practice of calculating expected frequencies from distances to sources is flawed, regardless of how such distances are measured.     

Matters of Sex and Gender in F. J. Gall’s Organology: A Primary Approach

The originator of phrenology, F. J. Gall (1758–1828), saw himself as a natural scientist and physiologist. His approach consisted of brain anatomy but also of palpating skulls and inferring mental faculties. Unlike some of the philosophical principles underlying Gall’s work, his conception of sex/gender has not yet been examined in detail. In this article, I will focus on Gall’s treatment of men and women, his idea of sex differences, and how far an assumed existence of dichotomous sexes influenced his work. In examining his primary writings, I will argue that Gall held some contradictory views concerning the origin and manifestation of sex/gender characteristics, which were caused by the collision of his naturalistic ideas and internalized gender stereotypes. I will conclude that Gall did not aim at deducing or legitimizing sex/gender relations scientifically, but that he tried to express metaphysical reasons for a given social order in terms of functional brain mechanisms.