It has long been thought that Native Americans came from Siberia via the land bridge that was created during the ice age. An alternate hypothesis holds that some or all immigrants arrived by boat. The map above shows the way that MtDNA Haplogroups which pass from mother to daughter have distributed throughout the world. There are five major Haplogroups in America.  Haplogroups A through D clearly came to America from Asia.

But the origin of Haplogroup X is not so clear. It is largely absent from Siberia and West Asia but is found in Europe and West Asia. The map below shows an alternate theory about how X may have reached America. For some time scientists have thought that X and other European MtDNA Haplogroups found in America were from recent European interactions. But X is very old and distant from old world Haplogroups.


"The Solutrean hypothesis is an alternative theory about the Settlement of the Americas and was first proposed in 1998. Its key proponents include Dennis Stanford, of the Smithsonian Institution, and Bruce Bradley, of the University of Exeter.

According to the Solutrean hypothesis, people associated with the Solutrean culture migrated from Ice Age Europe to North America, bringing their methods of making stone tools with them and providing the basis for the later Clovis technology found throughout North America. The hypothesis rests upon proposed similarities between European Solutrean and Early American Clovis technology. 

They think that these early immigrants could have used technology similar to current arctic natives, using small boats to follow the ice sheet from Europe to America. This theory has little acceptance from scientists who continue to believe that all native Americans originated in Asia."



I am certainly no expert in this field - my background is human ecology and city planning - but there are a number of recent DNA developments that support a possible early migration from Europe to America. The map below shows current concentrations of MtDNA Haplogroup X passed from mother to child. Note that it is concentrated in Europe and west Asia. It is a long trip through Asia and Siberia to America. Not impossible, but it looks less likely since their is virtually no trace in west Asia or far northwest America.


http://en.wikipedia.org/wiki/Haplogroup_X_(mtDNA)

The maps below show the distribution of the Male "Y" DNA which is passed from father to son with little change. It is also interesting. The map shows the path of "Y" DNA from Asia to America.  There are two major lines, Q3 and C which clearly originated in Asia.


The map below shows concentration of  male Haplogroup "Q". It clearly originated in Asia.



But there is a third major Male Haplogroup among Native Americans, R-1. As you can see from the map, it is concentrated in Europe and Central Asia and in America. The strongest concentrations are in northeast North America. It is possible that it arrived from Asia, but why would it be so strongly concentrated in northeast America?  The map supports the theory that the initial immigration was from Europe or west Asia.

http://en.wikipedia.org/wiki/Haplogroup_R-M173


Bryan Sykes has written a number of excellent books about genetics. He recently wrote a book entitled "DNA America". One of the findings that surprised him was that there was very minimal MtDNA Native American genetic heritage among New Englanders, even among those who believed that they had a Native American maternal ancestor. 


Professor Gates of the PBS series "Finding Your Roots with Henry Louis Gates, Jr" was surprised to find that most of the African Americans who believed that they had a maternal Native American ancestor found out from DNA testing that they did not have a Native American ancestor. Gates was also surprised that his Maternal MtDNA line originated in Europe, not as he thought in Africa. 

I have a good paper trail to a Native American maternal ancestor. But the DNA test indicated that our maternal ancestor was European.

It seems very unlikely that Native Americans left so little genetic imprint on Americans who have roots back to precolonial America. 

I think that it is much more likely that northeast America did have substantial ancient European immigration. You can see it on the maps for Haplogroups X and R1.  










Members of the Creek (Muscogee) Nation in Oklahoma around 1877. Note the evidence of mixed European and African ancestry. L to R, Lochar Harjo, unidentified man, John McGilvry, Silas Jefferson or Hotulko miko (Chief of the Whirlwind).

More on intermarriage among Native Americans and European Immigrants at: