Is there an objective, scientific basis for racial egalitarianism? I have yet to encounter any kind of justification for this assumption. As far as I can tell, it just seems to be something that is taken on faith. But why would we expect various groups of humans who evolved in relative isolation from each other for tens of thousands years in completely different environments to all magically come out with identical cognitive ability? Especially when it is universally accepted that these same groups exhibit significant, measurable genetic differences at a group level in many other physical characteristics, including skin tone, eye and hair color, height, body build, lung capacity, and athletic ability, just to name some of the more obvious ones. But of course, there are countless other differences that lie below the surface as well that are especially relevant in the medical field. It's also an indisputable fact that different groups have different brain shapes and sizes.

Then you bring up the evidence of IQ research, the historical achievements of various groups of people, with some groups showing no evidence of having invented even a wheel after thousands of years, and also the modern day status of different groups, both in first-world and third-world countries. All of this points to the same conclusion, and yet it's a conclusion that runs counter to the mainstream scientific consensus, and one that, if voiced publicly, is very likely to get you fired, denounced, and ostracized.

So again, what is the scientific basis for racial egalitarianism. In light of all of the evidence that go against it, it seems that it would need even stronger evidence to support it. What is the argument?