That’s a very strong claim without any evidence. Not only that, it’s the kind of claim that you could never have evidence for. It’s purely speculation on your part.
The mainstream accepted view on human population differences is so schizoid to me. On the one hand, you're supposed to believe that "race is a social construct", and indeed many aspects of race/ethnicity are arbitrary and socially constructed.
On the other hand, it's well documented and widely accepted that huge number of measurable and physical traits including skin color, eye color, hair color, hair consistency, face shape, height potential, facial hair growth, and susceptibility to both genetic and infectious diseases (see for example, Cystic Fibrosis and Northern Europeans, Sickle-Cell anemia and Sub-Saharan Africans), are strongly correlated with race and ancestry.
But you're supposed to believe that the same genetic variation that causes all of these physical differences between groups has no effect at all on behavioral differences. Personally, I don't understand how one can honestly reconcile that. I understand why it's not discussed in the current milieu, and I understand that it's potentially very dangerous to the existing social order, but as far as I'm concerned it's a pretty obvious thing to anyone who is willing to see it.
That’s all we’re talking about here isn’t it?
But my comment wasn't about saying any one group is "better" than another, I was just pointing out how incongruous it is to believe that population group genetics have a significant effect on physical features and disease susceptibility, while having zero effect on temperament and behavior.
Since we don't set goals for humanity at large, there's no definition of "best" to optimize for, just complex combinations of sub-behaviors that may or may not be beneficial to certain groups under certain conditions, nothing more.
> But you're supposed to believe that the same genetic variation that causes all of these physical differences between groups has no effect at all on behavioral differences.
Well, yes. None of those differences you mentioned are in the brain. Why should they lead to behavioural differences?
Also: culture is not nearly as conserved as genetics. Populations can change languages within a few generations, and most culture shifts come from wanting to assimilate into the culture of the perceived elites, rather than population replacement or large-level mixing. The exceptions (European settlement in the New World, the Bantu migration, and possibly some others that don't immediately come to mind) are notable because they are the exceptions to the norm.