Mr. Prasad’s latest mission is sure to stir the debate. He is conducting a qualitative survey of nearly 20,000 households here in northern state of Uttar Pradesh to measure how everyday life has changed for Dalits since economic liberalization began in 1991. The preliminary findings, though far from generalizable, reveal subtle shifts.

Image Dalit women planted rice in a field flooded by monsoon. Credit... Brian Sokol/Rapport, for The New York Times

The survey, financed by the Center for the Advanced Study of India at the University of Pennsylvania, finds that Dalits are far less likely to be engaged in their traditional caste occupations  for instance, the skinning of animals, considered ritually unclean  than they used to be and more likely to enjoy social perks once denied them. In rural Azamgarh District, for instance, nearly all Dalit households said their bridegrooms now rode in cars to their weddings, compared with 27 percent in 1990. In the past, Dalits would not have been allowed to ride even horses to meet their brides; that was considered an upper-caste privilege.

Mr. Prasad credits the changes to a booming economy. “It has pulled them out of the acute poverty they were in and the day-to-day humiliation of working for a landlord,” he said.

To prove his point, Mr. Prasad recently brought journalists here to his home district. In one village, Gaddopur, his theory was borne out in the tale of a gaunt, reticent man named Mahesh Kumar, who went to work in a factory 300 miles away so his family would no longer have to live as serfs, tending the animals of the upper caste.

When he was a child, Dalits like him had to address their upper-caste landlords as “babu-saab,” close to “master.” Now it is acceptable to call them “uncle” or “brother,” just as people would members of their own castes.

Today, Mr. Kumar, 61 and uneducated, owns an airless one-room factory on the outskirts of Delhi, with a basic gas-fired machine to press bolts of fabric for garment manufacturers. With money earned there, he and his sons have built a proper brick and cement house in their village.