William Schopf, paleobiologist, John Valley, geoscientist: As humans, it’s difficult to take the long view of history because we’re the new kids on the block, having only been around 3 million years or so. Although you may feel old by the time you’re an adult, the reality is that people are a recent development. The first life forms existed long before our arrival, now confirmed as some 3.5 billion years ago.

Associated Press: Researchers in South Africa have unveiled what they call "by far the most complete skeleton of a human ancestor older than 1.5 million years ever found." The skeleton dates back 3.6 million years. Its discovery is expected to help researchers better understand the human ancestor's appearance and movement. "Not only is Africa the storehouse of the ancient fossil heritage for people the world over, it was also the wellspring of everything that makes us human, including our technological prowess, our artistic ability and our supreme intellect,"