There are seven billion humans on Earth, spread across the whole planet. Scientific evidence suggests that most of us can trace our origins to one tiny group of people who left Africa around 70,000 years ago. In this five-part series, Dr Alice Roberts follows the archaeological and genetic footprints of our ancient ancestors to find out how their journeys transformed our species into the humans we are today, and how Homo sapiens came to dominate the planet.

Alice looks at our ancestors' seemingly impossible journey to Australia. Miraculously preserved footprints and very old human fossils buried in the outback suggest a mystery: that humans reached Australia almost before anywhere else. How could they have travelled so far from Africa, crossing the open sea on the way, and do it thousands of years before they made it to Europe?

The evidence trail is faint and difficult to pick up, but Alice takes on the challenge. In India, new discoveries among the debris of a super volcano hint that our species started the journey much earlier than previously thought, while in Malaysia, genetics points to an ancient trail still detectable in the DNA of tribes today.

Alice travels deep into the Asian rainforests in search of the first cavemen of Borneo and tests out a Stone Age raft to see whether sea travel would have been possible thousands of years ago, before coming to a powerful conclusion. Show less