The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. 2) Does handaxe symmetry increase through time, perhaps demonstrating evolving cognitive structures and social intelligence in archaic Homo?We present data addressing the first of these questions and offer a novel explanation for both symmetry and the apparent 'tyranny of the handaxe' in the Lower Palaeolithic world.
Explaining handaxe symmetrySensitivity to symmetry is a fundamental element of mammalian visual perception, hardwired and controlled by an automatically functioning brain network residing in the medial occipital gyrus (Hodgson 2009). In humans, it forms part of a package of core geometrical concepts that emerges at the age of about four months. From an evolutionary perspective, this may reflect that biologically important objects (such as people, predators and prey) are symmetrical, making symmetry perception a key discriminatory tool for processing visual information and, thus, vital for survival (Wynn 2002;Hodgson 2009).Yet, while symmetry may be evident in the pattern recognition mechanisms of animals in general (and ubiquitous in the natural world), it was only with the emergence of hominins of the Homo erectus grade and the Acheulean techno-complex (~1.75ma) that humans began to artificially impose symmetry (and shape) onto stone tools, in the form of handaxes. It is the imposition of form onto the world, rather than simply perceiving it in the world; that act constitutes for Wynn (1995, 2002) a cognitive leap, especially in shape recognition (symmetry, mirroring) and spatial thinking (the knapping process). The putative increased levels of symmetry after 500ka, when it is found not only in plan-view but also more commonly in side-and end-views, marks another cognitive milestone that saw the development of modern Euclidian understandings and manipulations of shape and space (Wynn 2002: 402). By this point, hominins were also able to intentionally manipulate symmetry in other ways, sometimes deliberately violating it by creating twisted edges-as
Materials and methodsTwenty-two British Lower Palaeolithic assemblages were analysed, ranging in age from MIS13 to MIS8 (~520-300ka) and comprising 1405 handaxes. These were selected because they represent stratigraphically secure groups recovered from excavations, or by unbiased collectors (Roe 1968; White 1998a). The assemblages are listed in Hardaker and Dunn (2005) divided handaxes into six handaxe symmetry classes (HSC) and provided a description for each class (Table 2); a graphical key to understanding these values is p...