This question has popped up a few times, but I can point you to this discussion I participated in a few years ago which might interest you. You'll see there that it all depends on which definition of Capitalism you are using (Marxian, Schumpeterian, or something else entirely). If Capitalism is the mere existence of private enterprise, then we have to look no further than the collapse of the Mycenaean "Palace Economy" and trace the seafaring routes of ancient merchants as early as the Bronze and Iron ages. If we are instead discussing a political and social system constructed by and for owners of capital (with that capital, in turn, operated by a wage-laborers) the system probably first emerged in Mediterranean Europe sometime in the 12th or 13th centuries (principally Italy — Incidentally my own area of interest).

When all's been said and done, I would pose a conceptual question: why is there a need for "a safe consensus-driven answer" to exist? Any Social Science theory will naturally be constrained by whatever definitions you are applying, and what underlying assumptions you are starting from. There is always room for more discussion and interpretations, and the very underlying assumptions of what defines Social Science labels is no exception.