Andreas Johansson scripsit:

> Now, you don't need to be a linguist to note that there's nothing to say that
> there weren't several groups of early immigrants, who may've spoken languages
> which separated long before their speakers crossed to the Americas.

Even the most aggressive lumpers don't think that Eskimo-Aleut (which
still has relatives in Asia), Na-Dene (basically Haida, Tlingit, and
Athapaskan), and the remaining languages are related below the level
(if there is such a level) of Proto-World.

> But what does people think of thirty thousand years as an
> estimate of the time it takes from one language splitting in two and the
> relationship between the respective descendants getting totally obscured?

The time-depth of Indo-European is only 6000 years, and Austronesian
perhaps 10,000.  Most mainstream linguists don't think that relationships
are even determinable when the time-depth gets greater than that.

First known example of political correctness:   John Cowan
"After Nurhachi had united all the other
Jurchen tribes under the leadership of the
Manchus, his successor Abahai (1592-1643)       [log in to unmask]
issued an order that the name Jurchen should       --S. Robert Ramsey,
be banned, and from then on, they were all         _The Languages of China_
to be called Manchus."