Which claim? Are you referring to the claim that Lithuanian is the closest language to Proto-Indo-European? I’m no expert on this. All present-day Indo-European languages are equally far in time from Proto-Indo-European. I don’t know what the evidence is for Lithuanian being close in form to Proto-Indo-European.
Lithuanian has many conservative grammatical features which make it closer to Indo-European than most other IE languages. But it’s sort of like saying “Fred looks more like his grandmother than his twin sister Ethel does, so Fred is older.”
A speaker of modern Lithuanian would not be able to understand Proto-Indo-European. He or she would, however, have a slightly easier time learning it than a speaker of Modern English. Almost any IE language is going to have some archaic features. Lithuanian just happens to have a lot.
It seems to me, and again it is a very subjective judgement by a non-linguist, that Lithuanian is comparable in development with the Latin or Greek of 2000 years ago. The parent language had 8 noun cases - Latin has 6, modern Lithuanian has 7 (and some more). Lithuanian only recently and incompletely lost the dual number, and still has traces of the optative mood.
Yes, the claim I referenced up thread in my first post. (Is there any other claim about Lithuanian and PIE in this thread?) For some reason, I thought you were a linguist or something of the sort and would be able to address the question.
Anyhow, this is the sort of reference I was asking about:
Anyhow, I think Dr. Drake covered it.
I have a master’s degree in linguistics, but I’ve been out of the field since 1977.
OK. So I’m not going completely crazy. Well, not based on that fact at any rate. 
Yeah, you’ve got to be careful with wild claims like that.
It’s quite possible. I’m sure an old edit (a year old, for example) will have it. I have browsed some other unfamiliar passages of the New Testament in Scots (they’re not hard to find, and this site has prose and poetry in Scots too) and have been unable to decipher them. Granted, it’s a lot easier than, say, German (which I also don’t speak), but that’s the nature of the game: a Swede can understand a Norwegian text better than he can a Dutch text. In fact, with a tip of the hat to Wendell Wagner, we would be remiss to ignore the example of Swedish and Norwegian: apparently, a Swede and a Norwegian who meet for the first time and have no common language can understand each other just fine. Scots is much further from English than Swedish seems to be from Norwegian, so why wouldn’t it be a language?
The other classic example of how arbitrary the language/dialect thing can be is Chinese: Mandarin and Cantonese are different enough to be separate languages, but they’re considered dialects of the same language because (among other reasons) neither one has its own army or navy.
Also, see the signature.
Most linguists would say that Chinese consists of something like fourteen different languages, not fourteen different dialects:
http://www.ethnologue.com/show_family.asp?subid=90150
There are people around who still call them dialects, but those are people who don’t know much about linguistics. They are mutually unintelligible. Also, I have the impression that Swedish and Norwegian are just barely mutually intelligible. A Swede and a Norwegian could understand each other but only with difficulty.
I had a pair of students once, one from Sweden and one from Norway, who communicated just fine by each using her native language. Of course, they knew each other, and I don’t know what region each was from within the countries, but when I asked them about it they said once they got used to each other’s way of speaking there were rarely any problems.