Rousseau is known for saying that words are necessary in order to establish the use of words. Condillac, it seems,was the first to see that language origin involves a similar paradox. Faced with this situation, I have expounded and elucidated Popper's hypothesis of a two-step origin of human language — which appears to meet this paradox very well — using evidence from ethological and psychological research. A situational analysis suggests that, on the one hand, spoken language originally resulted from playful improvisation or invention, based upon certain pre-adaptations for communication (proto-language codes) which early man shared in part with other higher primates. Human language, on the other hand, probably evolved further under the influence of a combined selection pressure deriving from certain interacting exosomatic (external) factors. This evolution may have been a consequence of the way in which Homo sapiens" use of language changed the impact of these factors.