Beginning in Ethiopia, we discover how the universe played a key role in our ascent from apeman to spaceman by driving the expansion of our brains. But big brains alone did not get us to space. To reveal what did, we head out of Africa to the ancient city of Petra in Jordan, for the next part of our story - the birth of civilisation - and then on to Kazakhstan, where we witness the return of astronauts from space and explain what took us from civilisation...