The contribution of formal syntactic theories to modern linguistics is still widely regarded as focused on synchronic generalizations rather than on clas- sical evolutionary problems. This chapter sums up the results of an ongoing research project, which suggest that theoretical syntax may provide unex- pected evidence for phylogenetic issues typical of the historical–comparative paradigm. The level of analysis tentatively used in the research is not that of surface patterns, but that of the more abstract grammatical parameters investigated since Chomsky (). On these grounds, we will contend that formal grammar, along the model of molecular genetics, can be construed as a potential contribution to the study of the human past; and that, in turn, the reality of parameter systems, as cognitive theories of grammatical variation and its implicational structure, receives radically new support precisely from their success with historical issues.
