How does Balram describe the history and evolution of caste system in India in "The Second Night"?

Balram describes the history, concept and practice of “caste,” which is an aspect of Indian culture that sets an identity on an individual's family for generations. He describes how the caste system was broken down after the British left India in 1947, and how the system then evolved into “just two castes: Men with Big Bellies, and Men with Small Bellies."