The study links the sudden downing of the shutters on intermixing to the beginning of the caste system: ‘The four-class (varna) system, comprised of Brahmanas, Kshatriyas, Vaisyas, and Sudras, is mentioned only in the part of the Rigveda that was likely to have been composed later. The caste (jati) system of endogamous groups having specific social or occupational roles is not mentioned in the Rigveda at all and is referred to only in texts composed centuries after the Rigveda.’
