International audienceThree levels of intelligibility ought to be taken into account when one considers the origin and evolution of language: the level of the individual (as biological or psychological entity), the level of (proto-)linguistic forms and semiotic practices, and the level of social structures. In the present talk we shall be specifically concerned with the latter two dimensions of the evolution of language and symbolic activities. We contend that: (i) the psychological domain (beliefs, desires, abilities, dispositions) is inconceivable in the absence of a constitutive relation to social stakes and practices (especially various public semiotic practices); (ii) linguistic structures and functions cannot be understood in the abse...