Noburu Adachi et al.
Abstract
Ancient DNA recovered from 16 Jomon skeletons excavated from Funadomari site, Hokkaido, Japan was analyzed to elucidate the genealogy of the early settlers of the Japanese archipelago. Both the control and coding regions of their mitochondrial DNA were analyzed in detail, and we could securely assign 14 mtDNAs to relevant haplogroups. Haplogroups D1a, M7a, and N9b were observed in these individuals, and N9b was by far the most predominant. The fact that haplogroups N9b and M7a were observed in Hokkaido Jomons bore out the hypothesis that these haplogroups are the (pre-) Jomon contribution to the modern Japanese mtDNA pool. Moreover, the fact that Hokkaido Jomons shared haplogroup D1 with Native Americans validates the hypothesized genetic affinity of the Jomon people to Native Americans, providing direct evidence for the genetic relationships between these populations. However, probably due to the small sample size or close consanguinity among the members of the site, the frequencies of the haplogroups in Funadomari skeletons were quite different from any modern populations, including Hokkaido Ainu, who have been regarded as the direct descendant of the Hokkaido Jomon people. It appears that the genetic study of ancient populations in northern part of Japan brings important information to the understanding of human migration in northeast Asia and America.
That ‘single American entry’ theory is so dead in the water.
Mathilda's Anthropology Blog. 
This is very interesting because previously – possibly as much as 12-14 years ago, I attended a conference in which someone described blood type occurrences in the New World, and there was an island of Japanese-type blood types in Central America. The interesting thing about this is that if one looks at the pattern of ocean currents and wind directions, one could say that there is an oceanic highway from the area east of Japan to Central America. It is quite possible to hypothesize that fishermen or coastal traders from East Asia were blown by a monsoon into the eastward currents of the Central Pacific and carried ultimately to the West Coast of the Americas. This must have happened more than once. Several years ago, an excavation for a building in Portland, Oregon, uncovered a Japanese style ceramic fragment, except that the clay was definitely from the Willamette River basin. The date of the layer was about 600 years, if I remember correctly. It suggested that a potter or someone with pottery skills had somehow been transported to the West Coast of North America. Given the way storm tracks blow across the Pacific, this was probably not a rare event.
I shall have to google that pottery story.
They’ve found type M, probably from the Asutraloid colonisation on the West coast too.The Americas have always been home a immigrants from every continent.
Interesting, I’ll have to read the entire article. This does not necessarily kill the single-entry theory, although I agree that it is no longer viable. The Jomon could have gotten the DNA from a shared ancestral relationship when both Native Americans and the Jomon were in central Asia. Genetics tells one about genes, not how those genes got there or where they came from.