THINK OF A BLIND MAN WITH A STICK. Where does the blind man’s self end and the rest of the world begin? Where do we draw, and on what basis can we draw, as Gregory Bateson asks, a delimiting line across the extended cognitive system which determines the blind man’s locomotion? At the tip of the stick? At the handle of the stick? Or at some point halfway up the stick? (Bateson 1973, 318). More than four decades after Merleau-Ponty (1962), Polanyi (1966) and Bateson (1973) fi rst raised these questions they are still with us, maybe more timely than ever if one considers the radical innovations that are taking place in the area of neuroprosthetics. For instance, Brain-Machine Interfaces (BMIs) now make it possible for a monkey or human to operate remote devices directly via neural activity (see Nicolelis 2001; 2003; Donoghue 2002).Of course, impressive as the ability to control a robotic hand by ‘thought’ alone might seem, it is, nonetheless, simply the most recent chapter of an old story, which archaeology knows well, and of which the fi rst chapter was probably already written some 2.6 mya [million years ago; ed. note] with the manufacture of the fi rst stone tools. Indeed, from an archaeological perspective the challenge that the BMS question, or in fact any other Brain-Artefact Interface, poses is even greater. One needs simply to replace the stick with any of the numerous artefacts that constitute the diverse archaeological inventory of prehistoric material culture, from the tools and marked objects of the Stone Age to the more recent symbolic or ‘exographic’ (Donald 1991) technologies, in order to realize that there is more to the BMS question than a mere philosophical puzzle. The problem is further complicated if one considers that for archaeology the stick is not simply a ‘pathway along which differences are transmitted under transformation’ (Bateson 1973, 318), but instead a difference in itself. The stick, to use McLuhan’s formulation, is very often not the medium but the message (1964).