Defining the Anthropocene, Earth's new era

Scientists have made the case that Earth has entered a new epoch known as the Anthropocene. Unlike previous epochs, dating Earth's 4.6 billion-year history, which came about through natural changes, the Anthropocene is believed to be brought about by human action. How do we know if we've entered the Anthropocene? While the term Anthropocene has been widely used for many years now, only geologists can officially denote the start of a new epoch. Specifically, experts look for a "golden spike," whi...