Ladder to the Stars | Cosmos: Possible Worlds

I'm standing on the southern tip of Africa and imagining what it was like sometime in the last hundreds of thousands of years. Back then, Africa was home to all the world's Homo sapiens, all 10,000 of them. If you were an extraterrestrial on a survey mission, you might have thought we were an endangered species. Someday soon, there will be 10 billion of us.

What happened? How did we become the globe-girdling, space traveling species that we are today? Welcome to the first laboratory on Earth. We're in Blombos Cave, where the evolution of the mind made a great leap. Our ancestors were conducting chemistry experiments here with a mineral rich in iron, ocher.

They used it to decorate objects with bits of red color, but it may have also had other uses. To preserve animal hides, or as a medicine, or as a way to sharpen their tools. Or maybe as an insect repellent. And they engraved the ocher with symbols, something completely new on the planet Earth.

Art. Not to be eaten, not to provide shelter, but to symbolize something. Or just to be. Looks a little bit like a ladder or double helix. Whatever it was supposed to be, it's the earliest remnant we have of human culture. We had found a way to leave behind something distinctly human.

A means to communicate, however enigmatically, to you and me 100,000 years away. A great power was discovered here in Blombos Cave.