Slate has an expanded article based on last year’s discovery of “curry” in Farmana. It has details on the technical advances that made this discovery possible.

Archaeologists have long known how to spot some ancient leftovers. The biggest breakthrough came in the 1960s, when excavators began to drop soil from their sites—particularly from places where food likely was prepared—onto mesh screens. The scientists then washed the earth away with water, leaving behind little bits of stone, animal bones, and tiny seeds of wheat, barley, millets, and beans. This flotation method allowed scientists to piece together a rough picture of an ancient diet. “But spices are absent in macro-botanical record,” says archaeologist Arunima Kashyap at Washington State University Vancouver, who, along with Steve Weber, made the recent proto-curry discovery.*
Examining the human teeth and the residue from the cooking pots, Kashyap spotted the telltale signs of turmeric and ginger, two key ingredients, even today, of a typical curry. This marked the first time researchers had found unmistakable traces of the spices in the Indus civilization. Wanting to be sure, she and Weber took to their kitchens in Vancouver, Washington. “We got traditional recipes, cooked dishes, then examined the residues to see how the structures broke down,” Weber recalls. The results matched what they had unearthed in the field. “Then we knew we had the oldest record of ginger and turmeric.” Dated to between 2500 and 2200 B.C., the finds are the first time either spice has been identified in the Indus. They also found a carbonized clove of garlic, a plant that was used in this era by cooks from Egypt to China.[The Mystery of Curry]

As you read the article you find that our food habits (rice with curry, tandoori chicken), the ingredients used in our food (ginger, turmeric), culture of leaving food for animals and treating cows as sacred animals have not changed in the past four millennia.