ARIZONA: A new theory is challenging the long-held idea that Native American groups living in the Grand Canyon region 1,000 years ago relied predominantly on corn for subsistence. Instead, research suggests that prehistoric communities set controlled fires to burn off the grasses and weeds along the canyon’s forested rim. This stimulated the growth of edible plants such as amaranth and chenopodium, wild relatives of quinoa. These plants likely dominated local diets at that time, as pollen analysis of ceramic storage vessels has indicated.