Better research and citations The article is working it seems from some rather dated material on Beringia In Bonatto SL Salzano FM 1997 A single and early migration for the peopling of the Americas supported by mitochondrial DNA sequence data Proc Nat Acad Sci 94 5 1866 1871 They indicate that migration could have been occuring as early as 55 000 ybp In addition differing information has come from the comparison of mtDNA haplotypes and Y chromosomal haplotypes Compare Silva Jr W Bonatto S Holanda A Ribeiro dos Santos A Paix o B Goldman G Abe Sandes K Rodriguez Delfin L Barbosa M Pa Larson M Petzl Erler M Valente V Santos S Zago M 2002 Mitochondrial Genome Diversity of Native Americans Supports a Single Early Entry of Founder Populations into America Am J Hum Genet 71 1 187 192 and Lell J Sukernik R Starikovskaya Y Su B Jin L Schurr T Underhill P Wallace D 2002 The Dual Origin and Siberian Affinities of Native American Y Chromosomes Am J Hum Genet 70 1 192 206