Traditionally human racial differentiation was classified mostly in terms of pigmentation. The notion of there being more than one living subspecies (race) of homo sapiens has nevertheless been thoroughly debunked by science. Yet, it cannot be ignored that a certain divergence, the early stages towards the emergence of multiple human subspecies has been in progress throughout the evolutionary history of homo sapiens. The social effects of this incomplete process of human genetic divergence are otherwise known as racism.
Depigmentation as an evolutionary adjustment to allow for better absorption of vitamin D from the sun happens rather quickly in terms of evolutionary history as evidenced in Ashkenazi Jewry which generally looks quite European despite being of mostly Middle Eastern genetic origin although having arrived in the Rhineland in the year 800 CE. There are several geographic continuums of genetic depigmentation around the world such as India, the Nile Valley and of course Europe.
There are many aspects of human racial differentiation, most of which pertain to anatomy such as body length, size of genitalia, pigmentation, size of muscles and the existence of the epicanthic fold in some genetic groups as thoroughly shown by J. Philippe Rushton. However, those differences are mere accidents of history that resulted from historical isolation between different human genetic groups and incomplete divergence towards developing multiple subspecies. The two factors that truly matter in contemporary society are the still existing evolutionary racism and racial divergence in average intelligence.
Former US president Barack Obama once received the question whether he had ever been discriminated against for being a person of color. His answer was in the negative. Modern societies discriminate against the relatively lesser intelligent irrespective of racial identity. Who is less intelligent? In Europe are genetic South Asians (Romani people) on average significantly less intelligent than the majority population and thus low achievers. In East Africa are South Asians traditionally an economic elite and high achievers because they are on average significantly more intelligent than the surrounding population. Mizrahi Jews were traditionally high achievers because they were one average more intelligent than the historical surrounding populations, this changed however when they came to Israel since both Sephardi and particularly Ashkenazi Jews have higher average intelligence than them. The Nazis claimed that Jews were inferior to ethnic Germans when in fact Ashkenazi Jews have far higher average IQ than ethnic Germans and are higher achievers by all accounts. This shows that traditional rhetoric of racial inferiority/superiority is a product of racism and completely unfounded as a scientific concept since it really depends on who is compared to whom, by whom and on what basis or non-basis.
No one should ignore the problem of racism and its evolutionary basis. However, the real problems faced by disadvantaged genetic groups are today due to lower academic and socio-economic performance by the less intelligent, something which is to the disadvantage of human genetic groups with “relatively lower” average IQ. It should however be pointed out that high IQ members of such genetic groups are usually not disadvantaged and in contrast low IQ members of high IQ groups are usually disadvantaged. Meritocracy works to the advantage of the more intelligent because of the correlation between learning speed and IQ and thus also school grades and SAT scores. The reality is that meritocracy is nowadays mostly colorblind, yet works to the disadvantage of the less intelligent of all genetic origins. Yet, it must be recognized that the school system and meritocracy as a whole in its current form reproduces the racial wealth gap and racial inequity at large, including throughout the system of education.