[blam]

"However, they are probably mostly descended from them."

Nah. Read this:

Vintage Skulls

"The oldest human remains found in the Americas were recently "discovered" in the storeroom of Mexico's National Museum of Anthropology. Found in central Mexico in 1959, the five skulls were radiocarbon dated by a team of researchers from the United Kingdom and Mexico and found to be 13,000 years old. They pre-date the Clovis culture by a couple thousand years, adding to the growing evidence against the Clovis-first model for the first peopling of the Americas.

"Of additional significance is the shape of the skulls, which are described as long and narrow, very unlike those of modern Native Americans."

[Sherman Logan]

The people who were here 8,000 to 10,000 years ago, which were referenced in your first post, are not necessarily descended from those here 13,000 years ago, referenced in your second post. There is lots of evidence that the ancestors of today's Indians arrived about 11,000 years ago from Siberia, constituting the "Clovis culture."

Where those who may have been in North America before that came from is a lot more obscure at this point.