Previous to writing this book, Goldman had also written ANCIENT POLYNESIAN SOCIETY, a study of Polynesian traditions. This gives him a very special and unique perspective. This is why his comments should carry an additional weight.
This is what he writes on p. 1,
"For reasons that remain to be discovered, the Indian tribes of this area [NW Coast] share formal principles of rank, lineage, and kinship with Pacific islanders."
What a strange way to put it... "For reasons that remain to be discovered?" Perhaps the reasons are the easiest in the world to discover -- for those, that is, who will take into consideration the most basic and logical principles of maritime migrations. The reason may be that the Hawaiian Islands are _downwind_ from NW Coast, generally speaking, and so they can be considered as the most natural recipient of NW Coast migrations.
And Goldman writes further,
"The Kwakiutl, especially, seem very close to what I have designated as the "traditional" Polynesian society. They share with Polynesians a status system of graded hereditary ranking of individuals and of lineages; a social class system of chiefs ("nobles"), commoners, and slaves; concepts of primogeniture and seniority of descent lines; a concept of abstract supernatural powers as special attributes of chiefs; and a lineage system that leans toward patriliny, but acknowledges the maternal lines as well. Finally, Kwakiutl and eastern Polynesians, especially, associate ambiguity of lineage membership with "Hawaiian" type kinship, a fully classificatory system that does not distinguish between maternal and paternal sides, or between siblings and cousins."
This is quite a list of very specific anthropological similarities. All this can be explained very parsimoniously by the derivation of the Hawaiians from the NW Coast.
And he adds this,
"Like the Polynesian, the Kwakiutl family histories are regarded by the Indians as authentic genealogical records." 
Those Eurocentric scholars who have the habit of dismissing aboriginal histories as of little value should take note of this item.
Also, Goldman notes this about the early impressions of Captain Cook,
"Captain James Cook, fresh from Oceania, was struck by resemblances to NZ garments, houses, and woodcrafts. Resemblances in formal systems of descent and rank with Oceania are also striking." 
Goldman writes about these revealing parallels,
"The Kwakiutl do in fact reveal specific Polynesian traits in respect to rank and kinship. The title ate, translated as "lord" seems cognate with Polynesian ati with a similar meaning; Kwakiutl have a talking chief (elk) who corresponds in function to the Polynesian counterpart. Kwakiutl kinship has the common Polynesian usages of a single term for siblings of opposite sex, and of differentiating by relative seniority siblings of same sex but not those of opposite sex. Also, with respect to kinship, Kwakiutl and Polynesian societies have similar terms (-tsaya, -taina) for younger siblings of the same sex."
So these, of course, are very specific linguistic parallels.
This is what Goldman suggests as a way to explain such close cultural similarities,
"There's reason enough to suspect complex origins for Northwest Coast cultures. It is even feasible to imagine the possibility of Kwakiutl as a fusion of Polynesian and North American Indian." [18-19]
But could Kwakiutl have been the _middle term_ between North American Indian and Polynesian? Goldman has never considered this possibility.
He seems to have a curious blind spot here in his vision. Indeed, why such a facile assumption that the direction of influence must have come _to_ America, as opposed to _from_ America? I'm afraid that here, as in so many similar cases with anthropologists, the automatic assumption seems to be that Native Americans were not creative enough to develop these cultural traits independently.
And also he writes,
"Now that culture historians are more respectful of Oceanic maritime skills, the possibility of early overseas influences need not be considered remote". 
Yes, perhaps culture historians are indeed more respectful of Oceanic maritime skills nowadays. A good thing too. But it remains to be regretted that they are still not in the least respectful of the maritime skills of the ancient Native Americans. So, unfortunately, it seems like there's still an awful lot of ignorance in this area among academic professionals.
All of the above seems to provide additional support for the theory that NW Coast Indians came to Hawaii starting ca 400 CE and gradually became Polynesians.
One further note from Goldman's book. Under the influence of Boas, who spent a great deal of his professional life studying Kwakiutl culture, the word potlatch became a big fixture in anthropological literature. But, according to Goldman, the whole thing may have been a misinterpretation of some Kwakiutl ritual celebrations the real nature of which was rather different. Goldman criticises Boas for putting too much stress on the term potlatch. According to him, the whole concept was a misunderstanding, but it then acquired a life of its own in anthropological literature.
"Strictly speaking, the term "potlatch" has no valid place in the vocabulary of professional writing on Kwakiutl simply because it is local jargon and not a Kwakiutl word. ... There never were, at least in precontact days, such events as "potlatches". 
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