I like the ideas behind studying human migration using genetics as a tool to prove (or disprove) certain theories. I find it a bit too heavy for my liking but I am all for the technology that makes understanding the mystery just that little bit easier. Mistanthable's explanations in points 2 and 4 are intriguing. The gene flow would have be maintained from its original source for the markers to stand out more, otherwise as mentioned, it becomes swamped out and probably disappears althogether. Using this model there is no way of proving that there was an invasion. If there was already some form of minor cultural contact between the different peoples before the invasion (or mass migration if some prefer using this term instead), how could we tell for sure who was who if we can't identify one group of peoples from another if we are fundamentally the same at a genetic level? This is really cool stuff.Do you see this technology developing to the point we can definitely use it to prove or disprove and invasion theory?