Today, there are over 7,000 languages spoken throughout the world. They may sound different, but in every case, they're drawing on the same regions of the brain. If you had told me that stone-tool-making had something to do with our ability to speak, I would have said you've got rocks in your head, but the latest studies indicate that once Homo erectus got creative with stone, our brains were on the way to inventing the most powerful tool of all: language.