Does GM (genetic modification) increase crop yields?

The answer to this question depends on whom you ask.  If you ask the Union of Concerned Scientists, the answer is no. Just out is this group’s report, Failure to Yield: Evaluating the Performance of Genetically Engineered Crops. Its conclusion: traditional genetic crosses outperform genetically modified crops by a wide margin.  Monsanto, as you might guess, has a rather different take on this issue, one that now faces a serious challenge.