Variety is more than the spice of life. It could be the key to sustaining life. A commentary in the science journal “Nature” released yesterday calls for a worldwide plan to “mine” the vast bio-diversity of plants to grow enough food to feed a world population that will reach nine billion by mid-century. A population genetics researcher at Clemson University, Amy Lawton Rauh, is among the scientists in the commentarty urging that time is running out to meet food security goals. According to the authors, food production must double in the next 25 years, yet it took 20 years and 34,000 attempts to produce one new rice variety.