All of this has been proven wrong, again and again.
An Irish genetics professor argues:
The idea that intelligence can differ between populations has made headlines again, but the rules of evolution make it implausible ...Humans have several advantages over the animals. Being social, vocal cords for speech, opposable thumbs to use tools, walking erect so hands can carry objects, low body hair to allow long-distance running without overheating, digesting milk as adults, and intelligence. Being social may be the biggest, as it allows building large cooperative societies. No animals can do this, except certain insects like ants and bees who form kin-based groups. I think that humans are the only ones to form non-kin-based large social groups.
The balance between these variants has been maintained by natural selection to keep average height “just right”. Intelligence is not like that. Unlike height, where being ever taller had no benefit, strong evolutionary forces drove intelligence in one direction only in our ancient ancestors. ...
Intelligence is our defining characteristic and our only real advantage over other animals.
It is now known that human evolution has been accelerating. Some population groups are taller than others.
High intelligence is not an unqualified good. Large brains consume energy and make birth painful. Many of the most intelligent Western women do not reproduce at all, while low IQ women have lots of babies. If you view life as a struggle to reproduce, as evolutionists usually do, high IQ is not necessarily a winning strategy. It is plausible that merchants would evolve higher IQ than farmers.
At any rate, there is no need to speculate. IQ is easily measured, and there is a lot of empirical data on it.