I did a little research...
The bitch was finding out what question to ask. The secret words are "haplogroup X."
From this article:
But the surprise was that about 3 percent of the Native Americans tested had mtDNA from a different haplogroup, called X. Some populations, such as the Ojibwa from the Great Lakes region, have a high concentration of X - 25 percent.
There's more in the article.
Another source places this genetic pattern not only in Northern Indians, but in the Navajo(!)
And of course, Wikipedia fills in a lot of the details.
Now THAT'S "walking!"