Those findings from the Uni of Vienna (UW) conflict with some insights from the Max Planck Society (MPS), based on their Bayesian phylogenetic analysis, and agree with others:
- the MPS study dates Early PIE to be 8100 years old; the new UW one dates it as two millenniums younger, 6000~5500 years old.
- MPS puts the Urheimat (original homeland) in the south of the Caucasus, UW to the north.
- Both studies would place the Early PIE Urheimat somewhere around the Caucasus (the CLV speakers), and the Late PIE in the Pontic-Caspian steppe (the Yamnaya culture)
Personally I'm not surprised. The further someone tries to fix the oddities of Proto-Indo-European, the closer its phonology resembles the Northwestern Caucasian languages, and to a smaller degree the Northeast and Kartvelian ones. Almost like they were sharing areal features:
- The odd two-vowels system can be better explained if it was initially vertical instead of horizontal;
- lots and lots of consonants, including secondary articulations that colour the nearby vowels;
- glottalised consonants (it's currently seen as a fringe hypothesis, but perhaps it should be reviewed); etc.
And while I'm going to say is just conjecture from my part, it's possible that the vertical vowel system had three vowels, and one of those either merged with *e or got deleted depending on the environment. That would make it even more similar to NW Caucasian languages like Adyghe and Ubyx.