It took almost all of human history (until 1804) for the Earth's human population to reach one billion. But more recently, during just twelve years, humans increased their numbers by one billion from 1987 to the present. These and other statistics are of supreme interest to scientists and others, as we attempt to predict environmental conditions and biological responses to future population...

Taking as its focus the deceptively simple questions, How has the world’s population changed over time? and How will it change in the future?, this engaging website (designed as a companion to the television program) developed by NOVA explores both of these queries through a set of interviews, interactive features, and additional resources, such as weblinks and guides for teachers. The interviews...