I've been interested in Historical Linguistics (as a hobby) for quite a while and one of the recent topics that caught my attention was the hypothesis of Kortlandt, Bomhard, and others that Indo-European languages originated through an amalgamation of a pre-Uralic phylum under Ponto-Caucasian influence.
I have been able to get to some free resources about this theory, but unfortunately they were not thorough. For this reason, I would like to ask, if somebody knows any, to direct me to an article /pdf, online-book/ that descibes how Indo-Uralists explain the fundamental differences between IE and Uralic phonology?
More precisely, how come (according to their theory) pIE had 3 series of plosives with free (probably pitch) accent, while pUralic is much more conservative with only one series of stops and a fixed stress on the root? I know some Uralic languages exhibit consonant graduation, however it is not semantic, so definitely cannot explain the difference between pIE *bʰendʰ- /bend, bond/ and *pent- ~ *pont- /pass, path/