" if racial IQ does vary"
It does (psychology.uwo.ca/faculty/rushtonpdfs/race_evolution_behavior.pdf).
It would be an extraordinary coincidence if it did not. We would require a theory to explain to us why this trait in particular was unaffected, while so many others were affected, by natural selection.
Let's look at the evidence: Black countries are crap and uncivilized apart from where the whites, Jews, Arabs or Chinese went there to exploit the resources and incidentally created some form of civilisation. Blacks were roaming around Africa for hundreds of thousands of years yet they developed nothing. The same can be said for the so-called Aborigines in Australia, they did precisely nothing. When whites came across blacks in Africa they were not confronted by a group of people who had developed technology and civilisation and education systems and healthcare systems and military systems and appropriate clothing, they were met by groups of savages, many of them naked but all at least half-naked, living day to day, no agriculture, nothing. Zilch. Zip. The same goes for the whites who arrived in Australia.
Now it is true, it is my point after all, that their environment was "harder" than ours and less conducive to developing high IQ. That is my point.
According to the theory of evolution and natural selection we were all the same people at one time (I don't believe that, but this is the current accepted dogma and I assume you subscribe to it, apologies if you do not but the debate can be held with others who do) all living in the same area. All drawn from the same colour and IQ population.
At some point a group relocated to some other area where the environment was different. Some people argue that the ones who left had changed and then relocated due to new differences, or were not sampled equally from the population, some say they were the same people when they left. Who knows! Either way, the theory goes that some of them got relocated.
In their now different environments, natural selection favoured some traits over others. The most obvious is the skin colour. Less obvious is testosterone levels, which appear to be higher in blacks than in whites (www.ncbi.nlm.nih.gov/pubmed/3455741) - indicating that the differing environments did affect testosterone levels. There are many other physical and biological differences between the races related to susceptibility to certain diseases and illnesses.
A recent study suggests that high testosterone stands in the way of creating a civilised society (http://science.slashdot.org/story/14/08/03/1543210/ancient-skulls-show-civilization-rose-as-testosterone-fell)
Well, put the two studies together and join the dots.
The fact is that black neighbourhoods in white countries are crap and less civilised even decades after their emancipation and access to education and affirmative action programs, and the same "starting conditions" as whites. Can it all be due to white oppression given that blacks in Africa and Australia were in a similar state before they ever saw a white man?
What about those studies?
Every time I mention them my posts are instantly marked "troll" or "flamebait". People are keen to mark it down, but clearly from my writing you can see that I am not a troll or a flamer. Nobody wants to discuss the implications of a study that suggests that blacks have higher testosterone and another study that suggests that higher testosterone stifles the development of civilisation and link it to the fact that blacks failed to create a civilisation in their own lands despite there being no white people stopping them for hundreds of thousands of years.
Perhaps it is not so implausible to suggest that blacks, on average and all other statistical disclaimers given, might have higher testosterone and lower IQ than whites, which leads to lower likelihood of developing a civilization and might even hinder ability to behave in a civilised manner? It seems consistent with the evidence.