This is a carousel. Use Next and Previous buttons to navigate India will surpass China's population this month. Or maybe in July. Or, perhaps it's happened already? Demographers are unsure exactly when India will take the title as the most populous nation in the world because they're relying on estimates to make their best guess. But they know it's going to happen soon, if it hasn't occurred by now. China has had the most people in the world since at least 1950, the year United Nations population data began. Both China and India have more than 1.4 billion people, and…