Mitochondrial DNA is passed exclusively through the maternal line. I think that it has very little effect on the hereditary process. That may be why it's proven useful over a longer timescale. Mutation of the DNA occurs at a fairly predictable rate, or so current thinking goes. That allows us to trace the branching of different population groups based on the divergence of mitochondrial DNA. As I understand it, most biologists believe that the mitochondrium was once a separate organism that migrated into the cell. That would be a fascinating process in itself. So any paternal Native American DNA won't show up in your mitochondrium, although it wouldn't be surprising to find markers in your regular DNA. There was an interesting article a few months ago--I think it was in Scientific American--about some Navajo women who were allowing sequencing of their DNA to help scientists find such markers. But the article went on to say that most Indians were still quite distrustful of supporting such a process. Given the last 500 years of history, it's sort of hard to blame them.

OK. I still am not totally sure how that works. I wondered about the mitochondrial DNA since the supposed Native American blood >goes through me, my mom, her dad, then his mom. For some reason I got the impression that the mitochondrial stuff might trace

Experts think the American continents were first populated around 14,000 years ago. But who did it? And, how many of them were >there? Using DNA samples from modern Native Americans and Asians, a new computer model suggests a founding group as small as >210 people with only 70 breeding individuals. These numbers make many researchers skeptical, because such a small group would >have been in danger of extinction. Also, studies based on blood markers suggest a breeding population of 100 to 1,000 individuals in >the founding group. There may be a bit more to the story. There is an increasing amount of evidence that there may have been earlier migration events--some of the dating of various sites point to more ancient timelines. Your surmise of small breeding populations still holds true, I think, but there may have been a few different clusters. The old Bering land bridge theory has not been undermined, but there's a small prejudice built into that that holds that older populations wouldn't have been capable of travel by boat. We've now got very strong indications that the aboriginal population of Australia reached there 50,000 years ago by sea, so it's pretty clear our ancient ancestors could build a decent boat when they had to. There's no reason to believe that small boats couldn't stay close to shore and find their way to the Americas. The Inuit got pretty good in their little skin boats.

Interesting little sub-topic. Boy does this group wander into the weeds sometimes.