Thousands of years ago one small group of our species, Homo sapiens, crossed out of Africa and into the unknown. Their descendants faced baking deserts, sweat-soaked jungles and frozen wildernesses and risked everything on the vast empty ocean. Within 60,000 years they colonised the whole world... How did they do it? Why do we, their descendants all look so different? And what did we have that meant we were the only human species to survive? Using the evidence from genetics, fossils, archaeology and climatology, Dr Alice Roberts uncovers five epic routes our ancestors took across the globe and the obstacles and brutal challenges they encountered along the way. It reveals how our family tree grew and spread out across the world, producing all the variety we see in the human species today - but despite all that diversity, Alice reveals how astonishingly closely related we all are.