In 1804, our world's population reached the one-billion mark. Since then, it has grown exponentially to 7.8 billion today. The United Nations had predicted that this number would rise to a shocking 10.8 billion people by the end of this century. However, recent studies have found that the world population estimate by 2100 would be two billion less, at 8.8 billion. Let's look at how experts estimate population growth, why it is important, and what led to the projected drop. Estimating Population Demographers (people who study populations) estimate future population sizes and makeup based on...