Style, Function and Cultural Transmission

Recent evolutionary approaches to the understanding of lithic variability take us back to long-standing issues in lithic studies to do with the claimed contrast between style and function and the Binford-Bordes debate of the 1960s concerning the factors that affect inter-assemblage variation. In fact, the style and function contrast is an unhelpful one, not least when considering the question of convergence. Taking the definition of style as ‘a way of doing’, all functions are carried out in locally specific ways that have a transmission history, although the extent to which the history of the attributes relevant to the function have been subject to random drift and innovation patterns, as opposed to selection, will vary. Moreover, in a subtractive technology like lithics the extent to which a transmission signal will be visible in an attribute like the angle of a cutting edge is unclear. The contrasting view is that, in the case of lithics, functional requirements will always call into existence the technical innovations to satisfy them, which in any case are not that difficult to find. The paper addresses these and related issues with reference to previous work by Shennan and colleagues on the use of material culture to identify within and between group variation, the extent to which isolation-by-distance in space and time can account for the similarities and differences between assemblages, and the role of phylogenetic methods

Glint tracking using adaptive optical techniques

Adaptive optical techniques have been employed to track target glint returns using two-axis steering and focus correction. Measurements were made on laboratory apparatus, operating at 10.6 µm. The apparatus consists of a low power CO2 laser, a 300-Hz bandwidth wavefront manipulator, focusing optics to form a far-field beam pattern, a moving glint (a small polished sphere), and an on-axis receiver that views target return. Adaptive control is implemented by tagging each correction mode with a high-frequency low-amplitude dither which is a small fraction of the available mode range. Classical hill-climbing servos are used to maximize glint return by nulling the dither component of each correction at a zero slope point corresponding to maximum target power.</jats:p