Proto-Indo-European and Indo-Anatolian

[Kale]

So now that it seems like the mainstream is on board with a Steppe origin of PIE, what does linguistics have to say about PPIE?
For example are there any hints of language contacts which could point to which component of 'CLV' ancestry is more likely to have conveyed PPIE?

[Jaska]

So now that it seems like the mainstream is on board with a Steppe origin of PIE, what does linguistics have to say about PPIE?
For example are there any hints of language contacts which could point to which component of 'CLV' ancestry is more likely to have conveyed PPIE?

Ancient contacts or distant relatedness for Indo-European has been proposed at least with Uralic and some Caucasian language families. In the "Nostratic" or "Trans-Eurasian" frameworks many Eurasian language families are bundled as relatives, some models including also Indo-European. However, in such comparisons the criteria are so loose that different results become mutually contradictory. Critical linguists are skeptic if we can ever prove any such distant relatedness between language families beyond doubt.

[Kale]

Does that include loanwords also (at or before the PIE stage)?

[Jaska]

Does that include loanwords also (at or before the PIE stage)?

Well, some loanwords are more convincing than others. Many Proto-Uralic words formerly considered borrowings from Proto-Indo-European like *nimi 'name' and *weti 'water' are difficult, because either there is no clear donor language/stage or there must be assumed unexpected sound substitutions or borrowing from some peculiar stem variant. Such words are so few in number that there probably will never appear several examples of the same developments. This leaves room for chance resemblance: even if the meaning is the same, there are only few matching sounds per word.

[Ebizur]

There are some eerie similarities among the personal pronouns of many languages of northern Eurasia (Indo-European, Uralic, Turkic, Mongolic, Tungusic, Yukaghir). However, for the first-person singular personal pronouns, the similarity only holds for the oblique cases; I do not recall finding anything like Indo-European "I" (German ich, Latin ego, etc.) in those other language families of northern Eurasia. The "I" words rather resemble Austronesian first-person singular personal pronouns.

[Kale]

Does that include loanwords also (at or before the PIE stage)?

Well, some loanwords are more convincing than others. Many Proto-Uralic words formerly considered borrowings from Proto-Indo-European like *nimi 'name' and *weti 'water' are difficult, because either there is no clear donor language/stage or there must be assumed unexpected sound substitutions or borrowing from some peculiar stem variant. Such words are so few in number that there probably will never appear several examples of the same developments. This leaves room for chance resemblance: even if the meaning is the same, there are only few matching sounds per word.

What are some loanwords that seem convincing, and from what languages do they derive?

[Jaska]

What are some loanwords that seem convincing, and from what languages do they derive?

According to Zsolt Simon 2020, *meti 'honey' and *wetä- 'to pull, lead' are phonologically and semantically straightforward and without problems. There are several other words with some semantic distance or slight phonological aberration, usually also considered plausible loanwords.

The Proto-Indo-European reconstructions of these two words are according to him *u̯edʰ- and *medʰu-. The problem is that rather similar-looking words were known in many branches in their early stages (and in some even later). These two lack cognates in Samoyedic, which could either point to (1) a post-Proto-Uralic borrowing or (2) these words disappearing later in Samoyedic. Therefore there are many possible donor language stages: Late Proto-Indo-European (into Pre-Proto-Uralic, if it was spoken in Europe), Archaic Indo-European (post-PIE), Northwest Indo-European, Early or Middle Proto-Indo-Iranian, possibly also Proto-Balto-Slavic or even early stages of Germanic (although regionally improbable).