We have questioned the assumption that SV (agent-action) structures are basic and primary and have shown that thetic VS unaccusative structures, involving an event+theme unit, are better candidates for simple, primary proto-syntactic “fossils.” We have shown that thetic unaccusative structures are simpler syntactically, prosodically, semantically and informationally, and have suggested that this is due to the fact that syntactic evolution progressed from a stage with thetic statements (with no arguments, such as It is cold, or with only (...) one argument, typically unaccusative, such as Spanish Ha llegado Juan (has arrived Juan) or Serbian Pao sneg (fallen.PP snow)), to more complex categorical assertions, involving agents and a syntactic and intonational separation between the subject and the predicate. Obviously, this raises many questions. How did thetic statements intergrade into categorical statements, and what were the evolutionary factors that facilitated this transition? Did both of the informational dichotomies (Topic-Comment and Focus-Background) develop from thetic statements or are F-B structures simpler than T-C? We leave these questions for future research. (shrink)