Leroi-Gourhan's investigation of human prehistory in Le Geste et la parole questions the boundaries, or limits, that more traditional kinds of humanism have assigned to the human, pushing back the origins of the human to include hominid forms that might previously have been regarded as 'prehuman', and widening our definition of the human by considering the diverse 'externalizations' of mind and body in different forms of technical behaviour. This article examines the different models of interpretation informing the narrative of human evolution proposed in Le Geste et la parolefor example, the pervasive but never explicitly marked concept of equilibrium, and modes of conceptualization (e.g. control, feedback) and technical practice (e.g. electronics) drawn from cybernetics. The article argues that, while Leroi-Gourhan's theory of the technical origins of language is a compelling one, as his exposition moves from the prehistorical homme fossile to l'homme actuel and finally to the hypothetical homme du futur, he appears to delineate another limit to the human: a point in human/technological evolution at which humanity becomes not more but less human than its historical and prehistorical ancestors. The article concludes by asking to what extent Leroi-Gourhan's semi-indictment of modern technology is consistent with the more fundamental philosophy of technology that one finds in his work.