An approach to interpreting possible steps in language evolution is offered here from systemic functional linguistic (SFL) theory. SFL models language at three levels from sounds to wordings to complex patterns of social discourse. Typological studies in this framework have shown striking commonalities at each level across languages, that are not yet adequately accounted for by existing models of language phylogenesis. Four conditions are suggested for developing explanatory models that may account for these linguistic phenomena. These include (a) a mechanism for reproducing complex cultural behaviours intergenerationally over extended time, (b) a sequence by which articulated wordings could evolve from non-linguistic primate communication, (c) extension of the functions of wording from enacting interpersonal interactions to representing speakers' experience, and (d) the emergence of complex patterns of discourse for delicately negotiating social relations, and for construing experience in genres such as narrative. These conditions are explored, and some possible steps in language evolution are suggested, that may be correlated with both linguistic research and archaeological models of cultural phases in human evolution. The aims of the article are to offer some useful tools to the field of language evolution, at the same time as indicating potential interpretations of existing work, using insights from SFL research.