Grains are the bedrock of civilization. They led humans from hunting and gathering to city-building. According to the Food and Agriculture Organization, the fruits of three grasses provide the world with 60 percent of its total food: corn, wheat and rice. Aside from energy-rich carbohydrates, grains feed us protein, zinc, iron and essential B vitamins. But rice as we know it is at risk. An anonymous reader shares a report: As humans expel billions of metric tons of carbon into the atmosphere and raze vast swaths of forests, the concentration of carbon dioxide in our air hurries ever higher. That has the potential to severely diminish the nutritional value of rice, according to a new study published this week in Science Advances. For people who depend heavily on rice as a staple in their diets, such a nutritional loss would be devastating, says Kristie Ebi, a professor at the University of Washington and an author on the study.