Chapter 38 describes the DNA evidence which ties the story together. The widespread Bering Straits theory that the first Amerindians originally came from East Asia is brought into question. Could the Americas have been populated solely by migrations across the Bering Land bridge? An intriguing DNA haplogroup has recently been found in several Native American populations – haplogroup X. The X group is the only Amerindian haplogroup that does not show a strong connection to East Asia. What is interesting is that although haplogroup X is itself rare, it has a perplexingly wide geographic range: despite its relative scarcity the group is found throughout Europe and the Middle East. In North America this haplogroup is found particularly among Native Americans, especially tribes living in and around the Great Lakes area.
Further reading:
Distribution of Haplotype X2 map: 
Jeff Lindsay – Enter Haplogroup X: http://www.jefflindsay.com/LDSFAQ/DNA.shtml#x
Reidla et al: Origin and Diffusion of mtDNA Haplogroup X:
