Proving once again that foolish ideas don't die or fade away -- they walk the earth eternally, preying on the brains of the living -- scientists at a UK think tank have determined that the greatest threat to the planet is more human beings. "The effect on the planet of having one child less is an order of magnitude greater than all these other things we might do, such as switching off lights," explains Professor John Guillebaud, co-chairman of the Optimum Population Trust (OPT). "The greatest thing anyone in Britain could do to help the future of the planet would...