In any case, I expounded on an alternative, out of-America, view of ancient human dispersals in The Genius of Kinship: The Phenomenon of Human Kinship and the Global Diversity of Kinship Terminologies (Cambria Press, 2007) as well as here (http://anthropology.net/2008/05/12/the-genius-of-kinship-human-kinship-systems-and-the-search-for-human-origins/).

The Amos and Hoffman paper offered some evidence that is consistent with out-of-America and contradicts out-of-Africa.

From a personal point of view, I’d prefer people who clearly have a great deal to say on whatever topic, to write their own blog posts/articles in which all their thoughts are laid out clearly and coherently, rather than engage in the kinds of diatribe that all too often end up with insults traded and credibility questioned – a zero sum game that is of benefit to few, if anyone at all.

Alternatively, where instances of extended threads that depart from the original post become too commonplace, I’d suggest that there are innumerable fora elsewhere online which might be more suitable venues for such discussions to take place.

It is evidence that Native Americans had not enough evolutive time to develope anything of the sort, because they arrived only in “recently”, maybe some 15,000 years ago. Instead elsewhere they had plenty of time, maybe two million years or more if we count from H. erectus.

I thought we’ve already discussed this issue at some point: the skin color of the Khoisans, which both Y chromosome and mtDNA studies nominated to be the oldest human population, is controlled by a derived allele. It’s lighter than that of other blacks and is often likened to the skin color of Mongoloids. E.g., “The lightly pigmented hunter–gatherer San population of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations” (Norton et al. 2007, 719).

So, we don’t really know what skin color the earliest humans had. Maybe it was intermediate exactly like that of American Indians. Your theory of American Indians losing tropical pigmentation is contradicted by the Amos and Hofman paper under discussion, which, as you yourself pointed out, demonstrated that Amerindians are the least bottlenecked among the human populations in their sample.

The only way to control for subjective biases is to painstakingly weigh different options and to take all disciplines and all data into consideration. We’re in the business of human origins. Since when have “humanistic” and “anthropological” become curse words?

Enough. I know also, that like other “humanistic” disciplines (linguistics, anthropology in general) is prone to subjective interpretation. Slippery, largely speculative, science that must be taken with great caution, where most of what is written (apart of the field data) is just educated opinions.

I will also tell you another thing (and please Tim or Kambiz, feel free to cut this rather off topic discussion whenever you think convenient): American Natives are the only continental population worldwide where tropical peoples are not black (dark brown to black skin color). This is a well known fact and is because they lost their tropical pigmentation when migrating to Siberia and Beringia and have not got evolutionary time to regain it. This alone is enough evidence to discard your hypothesis, though of course there is much more.