The aim of the present text is to consider 18th century language genealogies, as proposed by Rousseau and Condillac, in relation to the question of gesture and affectivity. For it seems that a certain form of affect - need in Condillac, passion in Rousseau - comes to play a central role in the speculations concerning the possible origin of human communication whose nature is invariably considered to be gestural as well as vocal. Our aim will be to show that the insights both thinkers present on the subject corresponds, quite remarkably, with certain findings of modern linguistics and psychology. It is, of course, impossible to treat the issue in all its complexity; all that we will attempt to do is concentrate on certain significant passages and pinpoint what we consider to be the most remarkable arguments., Josef Fulka., and Obsahuje bibliografické odkazy