Discrimination is an act of nature to create something novel and new. Evolutionist would say reproductive isolation is the root of variation in biology. The biodiversity one sees in the world arises out of selective discrimination. It is easy to practice this in an animal world but not so in human world where the natural selection invariably fails. However, nature tries its age old trick on mankind constantly. Tamil society being one of the oldest in human evolution exhibited this natural selection in the form of caste. A caste is a variation, a tribe in making, a micro evolutionary attempt. The fascinating aspect of caste is reproductive isolation. Intercaste marriage is strongly discouraged in order to isolate a caste as unique as possible.

To find the origin of caste is very difficult as it is deep hidden in the social psychology from time immemorial. The varnasrama dharma quoted in Baghavat Gita is a flexible system of societal movement based on ones human qualities. If your interests are more in learning, then you are a priest, a brahmin. In stead, if you are brave and not worried about death, you are a warrior, a sakhtria. If you are clever with money, you are a trader, the vaisya (bania). If your interests are on earth and make it flourish, then your Sutra the life giver. People were allow to move on this fabric based on their interest. A classical example is Viswamitra a warrior turned brahmin because of...