The South Asian love affair with yogurt can be traced back to to 3500 B.C., when it was first consumed by the Indus Valley civilization, in what is now part of western India and Pakistan. But sometime between 1500 and 500 B.C., it became a staple food among the Vedic Aryans, pastoral people who raised buffalos and cows, said Pushpesh Pant, a historian and the author of “India: The Cookbook.”
Yogurt, which was probably discovered after milk had accidentally curdled, was a highly practical dairy product: It had a long shelf life; its cooling properties helped people tolerate warm climates; it could tenderize meat when used as a marinade; and it aided digestion.
Because of this, Mr. Pant said, yogurt was considered sacred and pure. In Hindu folklore and ancient poetry, yogurt is frequently mentioned. A spoonful of sweetened yogurt is considered good luck.
To many who enjoy it, it’s a cure-all. “If anything went wrong, I was given yogurt,” said Naz Deravian, 46, the Iranian-American author of the 2018 cookbook “Bottom of the Pot.” “Burns or cuts, hair growth, skin. My boyfriend broke up with me? Have some yogurt.”
Mr. Pant theorized that the thickness and tanginess of South Asian homemade yogurt result from the types of bacteria used. The strains in many Western yogurt brands are chosen to produce milder-tasting, more homogeneous curds. South Asian yogurt is typically made with a more acidic culture, the descendant of a yogurt that was originally created by curdling milk.
More important than the yogurt itself, a long-lived starter culture can become an heirloom, the physical representation of a lineage that can be passed on to future generations.
Sumayya Usmani, 46, a food writer in Glasgow whose family is from Karachi, Pakistan, said making yogurt from scratch “is the closest way that I feel the memories associated with my mom. Now I am teaching my daughter how to do it. It is a dying skill.”