I'm not sure if this type of thread is allowed, but I've been pondering the possibility that language began as commands rather than expression of arbitrary thoughts. This is based on the observation that in a majority of world languages the imperative form of the verb is a "root" or "defective" form, lacking in inflections or affixes present in non-imperative conjugations.
From this, I suppose that commands could have been the proto-form of language due to the fact that primitive commands need at most a single verb and a single noun - the object of the sentence; as its the only one, this argument would need no marking for case, and no morphosyntactic alignment. As the ability to add an actor to the sentence, the means by which this is accomplished gave rise to the different alignments as well as topic-prominent structure.
Has this idea been explored before? What evidence is there for and against this idea?