A new paper recently released discusses the origins of Native American populations. Diekenes Anthropology Blog has been a great source for years now, and it looks like he may have obtained an advance copy of the paper. He does a good job of taking a look at it, so please visit his link at http://dienekes.blogspot.com/2012/07/reconstructing-origin-of-native.html
There has been a lot of discussion over the years about whether the Native people came in one group or in different groups, characterized as waves. This paper says three groups. In the past, other researchers have reached other conclusions.
It’s also quiet interesting that it doesn’t seem to be a one way street – that some Native genes are found in the Chukchi people in Russia. Since we know that the Chukchi people are the closest matches to the Native people in Alaska and western Canada, and we’ve known that for a long time, I wonder how they are measuring the backflow to Russia, and how they know it’s backflow from Native people here. I think that differentiation would be exceedingly difficult because that is the originating population.
Academic researchers and papers don’t always agree, but they are all cogs in the wheel of learning and always interesting.
Native Heritage Project 
Great article Roberta. Keep us posted on any updates.
I’m not an expert in DNA evaluation, but it would seem that the migration of Q1a3 etc. Haplogroups may have taken place over a long period of time and it did not all happen at once. It is my opinion that possibly there were many migrations from Asia to North America and possibly back to Asia. Additionally, these people probably didn’t arrive in the same way, some may have walked other may have come down the coast by small boats etc., both of course following the food chain.
When these groups arrived, some comingled, other didn’t or were isolated, this could explain the difference in Q1a3 and Q1a3a groups. We have just skimmed the surface of DNA genealogical research. As the DNA pool expands a clearer picture of all the groups that came to the Americas by way of Asia will become more settled. We must think outside of the box on such issues and not be predisposed to any one scenario.