DNA Nation

Ian Thorpe, Ernie Dingo and Julia Zemiro are setting out on an extraordinary experiment. They're about to become some of the first people in Australia to use DNA to go on a journey tracing their ancestry back through more than 200,000 years. Guiding the trio on their journey is Dr John Mitchell. Dr Mitchell has spent more than 40 years studying genetics and what it tells us about our identity. But how can this journey of genetic time travel be plotted? The Y and Mitochondrial DNA on our fathers and mothers lines passes from generation to generation as exact copies. But every so often, a mutation occurs - a marker. These markers denote a new branch of the human family tree and the great journey of humankind. And crucially they can plot where Ian, Julia and Ernie's ancestors were and when. The trio heads towards the Serengeti plains in northern Tanzania. They're stepping back 200,000 years to the beginnings of humankind.

Around 70,000 years ago, Ian, Ernie and Julia's ancestors lived in what we now know as the Arabian Desert. But much has changed through the course of human history. This arid, unforgiving desert was once a very different place. Archaeologist Jeff Rose has been studying the region for the past decade, and reveals to the three travellers that this was once a lush green expanse. To unearth more secrets of the past, the three go deep into the desert in search of the stone tools their ancestors used for everything from hunting to cutting. Hoping to channel the skills of his ancestors, former Olympic champion Ian attempts to make his own stone tool, but soon discovers it's not quite as easy as it looks.

Ian Thorpe, Ernie Dingo and Julia Zemiro have all donated their DNA so they can retrace their ancient ancestry. Having started out together in Africa, they're now making their way across the world on separate journeys. Ian's come to the grasslands of Kyrgyzstan in the former Soviet Union to discover how his forebears, to the west in the Russian Steppes, were part of a pivotal period of history. In Sardinia, Julia is taken to an archaeological dig and helps extract the tooth of her two and a half thousand-year-old ancestor. On the other side of the world Dr Mitchell is also plotting Ernie Dingos genetic route map. Next stop is Timor Leste. Here Ernie will learn about one of humankind's greatest ever achievements, the journey to arrive on the shores of Australia for the first time.