This photo of harvest time in a village in India shows some of the processes necessary to prepare cereal grains like wheat for use. The same techniques have been employed since ancient times. At right, a kind of sled is being pulled by oxen over the harvested grain to separate the hard, compact seeds from the unusable plant material of the hulls and stalks of the wheat. Sometimes this threshing of the grain is achieved by flailing piles of grain with a club or by treading on it. In the background at left, a man is winnowing the threshed grain by tossing it into the air with a shovel: gravity returns the heavier grains to the pile at his feet while a breeze separates the light chaff and blows it away.