Over a long period of time some of these hunter-gatherers found that there were things they could do to increase their food supply. The Aborigines of Australia, for example, discovered they could use fire to burn off existing vegetation. This encouraged fresh young grass to grow, which attracted grass-eating animals and so made hunting easier. Other Aborigines discovered that they could improve the supply of yams by breaking off the top of the tuber and putting it back in the ground, where it would grow again. And so, gradually, hunter-gatherers became farmers who deliberately planted crops and stayed in the same place to wait for the harvest.