This is nonsense. Nobody really knows how any particular language developed before it was written down. In particular we do not know the unrecorded languages th

This is nonsense. Nobody really knows how any particular language developed before it was written down. In particular we do not know the unrecorded languages that were spoken in the vicinity at the same time. Most of linguistics is a mental parlor game that says, if all languages always evolved by differentiating according to abstract transformations like Medieval German and Latin did, then this is what people spoke 6,000 years ago. If people want to play that kind of combinatoric game, then fine, but don't claim that it reflects reality. It could just as well be that all languages start by being creoles and then settling into a steady state as economic ties and trade encourage people to remove unneeded variations. You could build up a whole theory of linguistics based on that, and come up with different results. For instance, German would likely be recognized as originating from Ancient Turkic languages in creole with ancient Iranian. Until somebody takes the time to try out one or more different linguistic base theories, all we have is this pseudo-science of creating artificial proto-language and people claiming that word x could not come from older word y because sound s never changes into sound r. Even in the face of evidence to the contrary in modern languages in near historic times. Quite frankly it is hard to learn enough languages really well to properly study them. I only know 7 and like most people, most are close to my native language because that makes it easier to learn. And if you don't study the prehistory and mythology and archaeology of a region, how can you hope to make sense of language groupings and divisions. Language is inherently a cultural thing.