By way of Beringia
Jennifer Raff and Deborah Bolnick have written a paper on native American genetics, arguing that the haplogroups that some have viewed as evidence for migration across the Atlantic is instead best explained as Beringia migration as with the rest of the native American genome. Thus giving a kick in the shins to the Solutrean hypothesis. The argument turns on the fact that European haplogroups are not what they once were. PDF available here.