India, June 25 -- Since the days of Thomas Malthus, we've worried that overpopulation is about to overwhelm our planet. Those fears haven't gone away. A further two billion people will be added to the current world population of 7.7 billion by 2050, the United Nations Population Division said in a report this week. Numbers will still be rising as the total approaches 11 billion people in 2100, according to the UN's central forecast....