I get it that few or none of you are all that interested in this, but I ran across this interesting historical linguistic theory from 20 years ago by Johanna Nichols and thought I would put it forward. Nichols suggests connections among languages in the Old World and the New World on the basis of deep structure. She examines families of languages for how they mark possessives, their typical word-order (SVO, VSO, etc), and the initial consonants for pronouns. She sees a Pacific Rim Necklace of language relationships, which is quite different than what most linguists see. The standard explanation is that there is no demonstrable connection between the two sides of the Pacific, other than Eskimo-Aleuts, the last arrivals. I understand that there is some minority acceptance for a connection between Ket in Siberia and Na-Dene (Navajo, Hopi) languages in the Americas.
Nichols also believes there has not been enough time for a single language to differentiate enough to create all the remaining New World languages, and believes that humans must have arrived much earlier than Clovis*, or that there were multiple waves of settlement of peoples already speaking different languages. The possibilities keep narrowing because of the periods of glaciation. There are eras when movement is much less possible.
Both of these are intriguing because of the genetic connections we can now trace. There is an "impossible" genetic pattern deep in the Amazon. There is only an overlap of a few percent, but some Amazonian groups have a connection to genetic patterns in the Andaman Islands, which are between India and Burma, to save you looking it up. Tribes moving from island to island is not unknown, especially if the next island is actually visible at times. Yet in the case of moving east from South Asia, you can only get as far as the Solomon Islands that way, even allowing for the ocean being 300 feet lower. If you know the islands are there out as far at Pitcairn, skilled navigators, such as those who peopled the Pacific thousands of years later, can make it. That still leaves over a thousand miles of open ocean before you land on what is now Chile. (At least South America is hard to miss at that point.) Plus, it's not good enough to just wash up on shore after a freak storm. To start a colony you need at least a dozen people, and fifty is a better low estimate. So that's not really possible. OTOH, leaving no trace in North America on your way to the Amazon by curling up along the Aleutian glacial coasts doesn't work either. Not to mention why a seafaring people would take it into their heads to cross the Andes. No sensible explanation is available, and yet there it is.
I do have a possible explanation for that linguistic clock in the New World, however. Nichols's estimate is based on language differentiation in populated areas. In Eurasia and Africa, if you were moving, you kept bumping up against other people. That would keep groups of similar language together longer. Yes, things can get pretty diverse over time in mountainous areas such as the Caucasus, where everyone settles in a different upper valley. Yet the connections can still be discovered by linguists. But in the New World, people could spread out quickly and lose contact with each other. Isolated languages change more rapidly. I think Nichols's clock runs too slowly for that reason.
*I think there is growing support for pre-Clovis, though not at the depth she describes. Monte Verde seems to have earned support from even hardcore Clovis believers, but that is only a couple of thousand years earlier. There is even a hint that discovered human fires and tools date back 32,000 years ago. A lot can go wrong in that sort of isolated find, but at least it's out there.
Update: Better analogy. It is as if a few pieces of broken bottle were unearthed far up the Amazon, and were found to be not only of a type of bottle from the Andaman Islands, but a matched fit for shards of a bottle that was broken there. People would not only wonder at the impossibility, they would wonder where the other pieces of the bottle might be found.