Final answer:
European racial hierarchies evolved from a somewhat fluid system into a rigid structure influenced by Christian enlightenment philosophers and pseudo-scientific ideas of hierarchy, used to justify European superiority and colonization.
Step-by-step explanation:
The racial classification systems that were developed during the era of European colonialism and the Enlightenment underwent a significant transformation from the last cast as of 130 racial categories of sexually mixed race. These initial systems were based on the purity of blood and had legal and social consequences but were somewhat fluid. However, with the influence of Enlightenment thinking and increasing European colonial expansion, these systems evolved into new, more rigid structures that were heavily influenced by concepts developed by Christian enlightenment philosophers. The racial hierarchies became more explicitly rooted in notions of European superiority and were used to justify the enslavement of African peoples and the colonization of lands outside of Europe.
During the Enlightenment, the concept of race became linked to the idea of social progress and evolution, with the false notion of European races being more evolved. This period saw the emergence of Social Darwinism which claimed that non-white races were inherently inferior and had stopped evolving, whereas the white race was the pinnacle of evolution.
Racial classification thus evolved from a flexible system into one that was more rigid and justified through a combination of religious beliefs and pseudo-scientific ideas of hierarchy. This transition is evident in the institutionalization of racial discrimination in colonies around the world, where social status was increasingly tied to race and Europeans dominated the highest echelons of power.