evidence: As the world reaches an estimated seven billion people, people like Vivek say efforts to bring down the world's population must continue if life on Earth is to be sustainable, and if poverty and even mass starvation are to be avoided. [...] Western experts and local elites in the developing world soon imposed targets for reductions in family size, and used military analogies to drive home the urgency, says Matthew Connelly, a historian of population control at Columbia University in New York.