New Delhi, Oct. 1 -- Every society must solve the same intimate problem: how to eat food prepared by a stranger. For most of history, people rarely had to.

Food arrived through relationships. You knew the family that owned the field and the woman who ground the flour. You knew the local halwai's hands and his temper, the ghee he swore by and the ghee he actually used, the fly he waved off the jalebi with a practised wrist. Trust was never printed on the food. It surrounded it.

That trust was neither innocent nor equally assigned. Traditional Indian eating codes decided who could cook, who could serve, who could touch a water pot and who could only look at it. These codes policed people more carefully than germs. We became a country that...