If one's ancestors spent 50 generations running from assorted beasts in the jungle or on the veldt, it would hardly be surprising to find that the present-day genetic pool carried an excess of whatever genes encourage sprinting. The same is clearly true in the case of whatever genes encourage mental processes.
If mental processes are stimulated and used over generations, genes will adapt and propagate and those connected to mental processes will become enhanced; if not, then the reverse occurs, and genes will adapt to enhance other things and, to one extent or another, let mental processes diminish.
I believe there was a study with wild foxes, breeding them to enhance specific traits and find out how many generations it would take to basically domesticate them.
After something like seven generations, they were able to make them lose most of their wild traits and become pretty much like house dogs.
They still looked exactly like wild foxes.
These types of speculations about how there are only slight differences in the genetics between races don’t really cut the mustard in terms of proving anything.
For instance, there is a gene in humans (and many other animals) called FoxP2. It is called the “speech gene”, and for good reason. They have discovered families where there is an inherited mutation in FoxP2 and the people literally can’t talk.
So there are some tremendously important traits and abilities in humans that are controlled by a paltry few genes. The human genome has something like 100,000 genes, and a defect in one - ONE - the FoxP2 gene can make the person unable to speak.
Personally, I’ve always been very curious to know what would happen if they took the human FoxP2 and put it into a beagle or something.