Updated on 23 March 2014, then 16 March 2015
A theory is presented according to which "languages" with structural variability and compositional semantics evolved in several species for *internal* use (e.g. in perception, planning, learning, forming goals, deciding, etc.) before *external* languages evolved for communication. The theory implies that such internal languages develop in young humans before a language for communication.
It is is also noted that the standard notion of 'compositional semantics' has to allow for the propagation of semantic content from parts to wholes to be potentially context sensitive at every stage: i.e. current context, speaker intentions, user knowledge, shared goals, can all affect how semantics of larger parts are derived from semantics of smaller parts+syntactic structure. This applies as much to non-verbal languages as to verbal ones.
This theory of how human languages evolved from earlier 'internal languages' (GLs) is inconsistent with the best known published theories of evolution or development of language.
But that does not make it wrong. Moreover, this theory is supported by empirical evidence including the example of deaf children in Nicaragua: http://en.wikipedia.org/wiki/Nicaraguan_Sign_Language