How does the makeup of the major Indian castes compare to and contrast with the social structures of the Egyptian and Mesopotamian civilizations?

All three
civilizations were highly stratified, with low social mobility. In general, within all three
civilizations, ancestry was destiny, in the sense that most people followed fixed paths in life
determined by their birth. In general, the son of a slave would be a slave; the son of a potter,
a potter; and the daughter of an aristocrat would marry an aristocrat. However, the system of
social stratification was far more complex and rigid and more closely tied to religious belief
in India than in Egypt and Mesopotamia.

First, the Indian caste system was
based on a theology of karma, in which one's actions in previous life determined what caste one
was born into, and progression through castes could only occur by rebirth into a different caste
after death. While social mobility was limited in Egypt and Mesopotamia, there were no formal
rules forbidding it. Nor was there any equivalent to the dalit or untouchable caste. While all
three cultures had nobles, priests, scribes, artisans,...