Speaking of Debates
Arun and I have a sort of debate going on regarding languages and origins. Now I live on a continent where almost everybody arrived from somewhere else pretty recently and have never known any other, so it doesn't seem very important to me whether Indian civilization is wholly autochthonous or influenced by others, but it is interesting historically.
There are two lines of evidence that have a lot of power here, one linguistic and the other genetic. It has long been argued that the linguistic evidence (the existence and structure of the Indo-European language group) favors an invasion and conquest of much of the Eurasian world by horse domesticating agricultural "Aryans" from somewhere. Genetic evidence is much more recent, and, at least according that adduced by Arun, seems to argue for something different.
One approach to resolving the contradiction, if contradiction there be, is to devalue the linguistic evidence. If I understand correctly, that's what a couple of recent posts by Arun argue. I don't find the arguments convincing.
There are at least two themes here: 1)Maybe the linguistic movement was much earlier than currently hypothesized, or 2)The linguistic structure inferred is a mirage. I'm not too impressed by 1) and I think 2) is quite wrong.