Humans have consciousness, while other inferior beings—like babies and robots—do not. But this wasn’t always the case. Not so long ago (say fifty thousand years, give or take a couple) we were just about as sentient as the average toaster.

But at some point in our evolutionary history, we got that pivotal leg-up. That mental edge would eventually give way to the language, the wheel, and eventually, the Snuggie. So what brought about the Great Leap Forward? Science in Seconds traveled back in time to find out.

_{Host: Brit Trogen}

_{Photo credits: Yellowstone National Park, s-tiger, Jack Versloot, G. Caselli, newscientist.com, NASA and Wikimedia user TheBrain}

References:

http://news.nationalgeographic.com/news/2003/02/0220_030220_humanorigins2.html

http://www.nytimes.com/2003/07/15/science/early-voices-the-leap-to-language.html?sec=health&spon=&pagewanted=1