In 1996, two college students in Kennewick, Washington, stumbled on 9400 year old human bones, eroding out of the banks of the Columbia river. Denmark scientists were able to extract DNA from the skeleton. They found it was more common to “native North Americans”, than any of the other populations worldwide.
Beringia theory purposed people migrated from Siberia to Alaska across land bridge that spawned the currently Bering straight. It is believed they did so tracking large animals and game heards.
Bibliography: Adovasio, J. M., & Pedler, D. (2016a). Strangers in a New Land: What Archaeology Reveals about the First Americans. Firefly Books.
Rasmussen, Morten; Sikora, Martin; Albrechtsen, Anders; Korneliussen, Thorfinn Sand; Moreno-Mayar, J. Víctor; Poznik, G. David; Zollikofer, Christoph P. E.; Ponce de León, Marcia S.; Allentoft, Morten E.; Moltke, Ida; Jónsson, Hákon; Valdiosera, Cristina; Malhi, Ripan S.; Orlando, Ludovic; Bustamante, Carlos D.; Stafford Jr, Thomas W.; Meltzer, David J.; Nielsen, Rasmus; Willerslev, Eske (June 18, 2015). “The ancestry and affiliations of Kennewick Man”. Nature. 523 (7561): 455–458. Bibcode:2015Natur.523..455R. doi:10.1038/nature14625.
kennewick Man, The Scientific Investigation of an Ancient American Skeleton, edited by Douglas W. Owsley and Richard L. Jantz. College Station: Texas A&M University Press, 2014. ISBN 978-1623492007.