THE RELEVANCE OF BODY LANGUAGE TO EVOLUTION OF LANGUAGE RESEARCH SŁAWOMIR WACEWICZ & PRZEMYSŁAW ŻYWICZYŃSKI Department of English, Nicolaus Copernicus University, Fosa Staromiejska 3 Toruń, 87-100, Poland The heterogeneous category of phenomena covered by the term body language (roughly equivalent to nonverbal communication, NVC), although essential to human day-to-day communication, is also largely dissociable from human verbal behaviour. As such, it has received little attention in the area of evolution of language research. In this paper we point to an important factor – signal reliability (honesty) as an elementary constraint on communication as an evolutionarily stable strategy (ESS) – which shows promise of restoring the relevance of broadly construed body language to the evolution of language. Contemporary research on the emergence of language-like communication has tended to target the language-related cognitive capacities, with relatively less focus on the fundamental game-theoretic constraints as dictated by evolutionary logic. Communication, in order to remain an ESS, must be honest, i.e. signals must be reliably correlated with those aspects of the environment for which they are shorthand 1 . Despite suggestions at possible mechanisms (e.g. Scott-Phillips 2008), the origin of honest, cooperative signalling in human phylogeny remains among the least understood aspects of the evolution of language. It has been compellingly argued that the evolution of communication in nonhuman animals is reception-driven, i.e. it is the receivers that are selected to “acquire information from signalers who do not, in the human sense, intend to provide it” (Seyfarth & Cheney 2003: 168). Body language is characterised by similar properties, that is the transfer of information not intentionally provided by the signaller. Crucially, it is this last property that makes body language resistant to manipulation, and thus endows it with relatively high signal reliability (honesty). At the same time, in mimetic (Donald 1991) creatures, body 1 The full argument, principally an extension of the reasoning already extremely well established in evolutionary literature, is made in Wacewicz & Żywiczyński (2008), section 2.