"I think probably the greatest single threat to life on the planet is the over proliferation of us." So said Doctor Brian May, the astrophysicist, campaigner and musician with legendary rock group Queen. He is quoted in this month's electronic bulletin from Population Matters, a group which campaigns for sustainable levels of humans on earth, and which has long pointed out the dangers of heterosexual political fanatics who want there to be larger and larger families. As well as features on biodiversity and the environment, the organisation takes aim at s