No, actually if you watched any documentaries, they all say that as soon as humans invented agriculture and began to live in sedentary communities, social stratification quickly occurred.
Well, yes, I know; what did you think I meant by "sufficient material surplus"?
Only in our hunter-gather days did we resemble any kind of egalitarian society. Even then, there was strict social hierarchy. There was nothing to accumulate but the strongest members of a clan got first picking during harvest and when an animal was butched. Basically what rankings they could produce they did.
That is not universally true. There is not, as you seem to assume, a "basic" model for human society, and there is great variety between primitive societies. Most, in fact, tend to distribute goods on an as-need basis, rather than in accordance with status; essentially a form of communism. High social status tends to take the form of prestige and influence, rather than the formalised hierarchy you suggest. Those groups in which hierarchy does begin to emerge are typically those who have been able to adopt a more sedentary lifestyle, and so allow a material surplus to develop,
Social stratification is inherently in our biology and in the biology of most other great apes(with Bonobos being the one sole exception I can think of), and thats because out of all the great Ape societies, Bonobo society is female dominated and not male-dominated.
Bonobos are, however, our closest relatives, so that rather suggests that referencing Great Apes may be a rather fruitless task.
OK. So if we're talking "cladistic signficance" why are Polar Bears classified as a different species from Kodiaks? If there is a "cladistic significance" there then why wouldn't there be a "cladistic significance" between an Eskimo and an African?
http://en.wikipedia.org/wiki/Polar_bear
http://en.wikipedia.org/wiki/Kodiak_bear
http://en.wikipedia.org/wiki/Eskimo
http://en.wikipedia.org/wiki/African
Because the Polar and Kodiak bears are distinct species, which is to say that they have undergone
speciation. Eskimos and "Africans" have not, and not least because the latter does not refer to any one ethnic group or "race". (In fact, even if we are to take it as a reference to Sub-Saharan or "Black" Africans, they still represent a great many ethnic groups; there is more genetic diversity, in fact, in Sub-Saharan African than in the rest of the human species put together. If your Racialism was accurate, most humans would be a sub-set of a sub-set of African, rather than a set of equal level.)