Rice growing wild in large fields under suitable conditions is still gathered by all savages. This grain needed no preparation except boiling, while wheat and barley must be crushed or ground between stones, probably used at first for grinding dry nuts. Peas and beans, many vetches, and other members of this family so characteristic of the dryer uplands, were gathered very early, and may have been cultivated before wheat. Melons and many of the gourds always must have been eaten. We shall notice later that the zone of Persia and Asia Minor lay on the boundary line between two great botanical provinces, a northern and a southern, and furnished a very wide range of plants for this earliest experiment station.[83] A great variety of plants were tested sooner or later, and only a few of the very best and most capable of improvement have been retained to our day. On the steppe at a later date wheat and barley were most profitable, and most widely cultivated. But even here hoe-culture was for a long time the only mode. It still exists in Africa, Asia, and Japan; and was the only mode of culture known in America at the time of its discovery. Hoe-culture was at first, and has generally remained, woman's work; ploughing with cattle was a man's job. This had far-reaching results to which we must return in a later chapter. But we must not think that the Iranian plateau, with its great zone of piedmont steppe stretching eastward and westward along its northern border across the continent of Asia, was the only place where agriculture could start and reach a high degree of development in ancient times. Its possibility lay in the habit of the woman of collecting the vegetable food and smaller animals, while the men hunted and fished. Useful food plants furnishing large amounts of food are to be found in all continents, and differ markedly in different soils and climatic zones. Hence even the beginnings of agriculture were probably not confined to any one region, but were wide-spread, manifold, and independent. The Chinese migrating eastward and southeastward down the great river valleys from eastern Turkestan may have carried with them the cultivation of wheat, or adopted it independently. The rice culture of China may have been borrowed from India or independently evolved. India and the Malay Archipelago and Africa have every one its own agriculture, of whose origin and early development we know nothing.