goundamani sir, you have made a sweeping assertion,that 15% of our population eats dead cows,cleans toilets and washes mensus clothes of upper caste women. Though this was( is) done(still done) by some groups,it was(is) not even remotely close to 15%.something near 1% might be the correct figure.night soil cleaning was a practice unknown before the muslim and british period. In Tamilnadu,pallans had serious debilities,some social but more due to the fact they were agricultural landless labourers. I oppose discrimination on grounds of birth,but economic differentiation seems to the main reason for emergence of pallar castes.