In 1998 Dr. Michael Brown and colleagues found European/Caucasoid mitochondrial DNA markers in Indian tribes, mainly concentrated in the Great Lakes region of North America. Mitochondrial DNA allows researchers to determine dates that the groups mixed with each other. What they found was that European/Caucasoid DNA made it to the Americas between 12,000 and 36,000 years ago.Additionally, researchers investigating Human Lymphocyte Antigen (HLA’s) have found these markers in Peruvian Paracas Mummies, and American Indians in Northeastern America. These markers are now understrood to have arrived in the Americas "in antiquity." See here for HLA literature review.
4. Genetic Findings - Halogroup X DNA and HLA Markers from Trevor T. on Vimeo.