By definitive answer, I meant to point at a single factor as the “cause” for the success of Indo-European languages. Which I would argue is not possible because ther isn’t one cause.
I do believe we can tease out contributing factors, and be certain of them based on logic and praxeology.
Think of the paintings at Peche Merle: one of the things they express is the idea that “horses have spots”, but that type of relationship is not the same kind as what we’re talking about. And yet that kind of ownership, the expression of sort of mechanical relationships between certain things, is a fundamental property of the world that language must express just in order to be useful.
In English we use “to have” and “to own” in different senses. Especially re: the libertarian concept of property. So the question is, does a language exist where “to have” exists but not “to own”? And don’t forget that usage changes over time, and I don’t know of a single culture that exists today that doesn’t have a concept of personal property. So even languages that evolved without it, would have been adapted to that idea, right?
Indeed.