Murray Gell-Mann: Do all languages have a common ancestor?

[Update: My educated guess is that Gell-Mann is talking about nostratic languages, or maybe a larger "macrofamily".  Here's a post from Paleogot on long-range theories of language (for Aditya, especially):

I'm sure I must have hinted before that I hate when some treat long-range theories (like Nostratic, North Caucasian, Dene-Caucasian, or whatever far-away proto-language) as if they're written in stone. A person with a level head recognizes these ideas for what they are, idle conjectures requiring many ammendments before something more substantial can be made of them. However, I'm not against conjecture as long as it's fully differentiated from facts or well-substantiated theories. I also think there is an important difference between sharing conjectures for discussion on a blog or in a forum versus wasting trees to write a manifesto of your pseudolinguistic doctrine for you to enforce on disbelievers.

As much as I sound like a conservative fart for downplaying long-range comparison, I'm actually quite interested in it. It's just that I haven't read anything serious enough for me to go "wow!" yet and as I learn more, the errors in books start to become more apparent. Overall, I'm the most impressed (in a very moderate sense) by the Nostratic hypothesis as presented by Allan Bomhard who proposes that Indo-European, Uralic-Yukaghir, Altaic, Eskimo-Aleut, Elamite, Dravidian, Sumerian, Kartvelian and Afro-Asiatic language families come from a parent language dated to about 15 000 BCE in a period following the last ice age. He wasn't the first to come up with this century-old theory but he had a few different takes on it. For now, Nostratic is not an established theory because it doesn't present enough evidence to prove its claims, but it doesn't hurt to suggest further improvements that may help to inspire discussion and, just maybe, progress.

When looking through Allan Bomhard's Indo-European and the Nostratic Hypothesis (1996) or The Nostratic Macrofamily: A Study in Distant Linguistic Relationship (1994) co-authored by Allan Bomhard and John Kerns, one thing that I noticed was how many pronouns are being reconstructed without a clear structure. This is but one of a number of serious gaps in this theory just waiting to be resolved.

A similar post from Language Log.  But I also invite readers to link to arguments in favor of the hypotheses as well.]