Muslims have been reproducing at a very high rate for the last 30 years or so. What racial theory explains that?
Religion is now heavily influencing the birth-rate due to focus on family, in the absence of tribal cultures such as found in palaeo times. Not all religions, of course, mainly those which are anti-Liberal in tone. Of course, a higher fertility-rate can be racial in origin(for example, Negroes are more likely to give birth to twins).
GS, I would not harp on too much on the theme of superiority of any kind, if I were you, especially as intelligence is not really testable as yet(only IQ tests, not intelligence). Let me give you a few examples to prove my point:-
1) The Cro-Magnon hunter-gatherers were far more intelligent than modern humans, with c.11+% larger average brain-size and were also built far better on the physical front given better genetics due to natural selection over the countless millenia. The settled communities were way dumber by comparison with smaller average brains and with physically weaker bodies due to poorer diets and which were far more prone to disease within crowded communities of the time- but, because of greater social cooperation, they still managed to defeat the hunter-gatherers over time.
2)The Sassanid Persians had a vastly complicated culture and society, one of the finest of the Ancient World. Yet, they were easily beaten by a bunch of worthless, uncultured, inbred desert bandits from the Arabian Peninsula.
3) I am also not exactly convinced of the so-called "intelligence" of any ethnic group on this planet. Take the current Brexit crisis here in Europe, for example. I have recently had several Liberals, two of whom(worryingly!) are relatives, talking to me hysterically over the phone etc. about how terrible it is that Britain has turned against the EU because, now,they say it will be more difficult to invite in the millions more "refugees" into Europe. Now, since Saudi Arabia and Qatar, both instigators of the current Middle-Eastern crisis in Syria et al, have had the intelligence to refuse to invite these fellow-ethnic refugees/rapefugees/dregs of society into their own countries with the obvious claim that they are all wannabe terrorists or criminals etc., it has come to my mind that such Liberals, if they had been present in a more enlightened/less decadent society from hundreds or thousands of years ago , would simply have been put into a home for "special" people.
Assad is being very clever indeed in shoving all the dregs of Syrian society into Europe(and Putin is gloating too). Assad seems to be copying Castro who emptied the Cuban prisons and lunatic asylums and sent them onto the US.
GS, it might be wiser not to sidetrack the Neanderthal threads with more modern references in future. All I want to show is that the previous dubious Out of Africa notions that Neanderthals were somehow dumber than modern humans or that they were a wholly separate species were simply not true. That seemed clear even in the 1970s to me already, despite Neanderthals being unfairly portrayed then as being apelike.