Alice Roberts tries to find out how Stone Age people reached North and South America for the first time. She finds out about an ancient corridor through the Canadian ice sheet that might have allowed the first humans through. Old finds in Chile though point to a whole different route for the first humans making it there.

The journey continues into Asia, the world's greatest land mass, in a quest to discover how early hunter-gatherers managed to survive in one of the most inhospitable places on earth - the Arctic region of Northern Siberia. Alice also explores what may have occurred during human migration to produce Chinese physical characteristics, and considers a controversial claim about Chinese evolution: that the Chinese do not share the same African ancestry as other peoples.

Dr Alice Roberts 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.

When our species first arrived in Europe, the peak of the Ice Age was approaching and the continent was already crawling with a rival: stronger, at home in the cold and even (contrary to their popular image) brainier than us. So how did the European pioneers survive first the Neanderthals and then the deep freeze as they pushed across the continent? Alice Roberts reconstructs the head of the 'first European' to come face to face with one of our ancestors; she discovers how art became crucial for survival in the face of Neanderthal competition; and what happened to change the skin colour of these European pioneers from black to white.

Dr. Hannah Fry takes us on a whistle-stop tour around the mathematics of success, to help us understand how to get more of what we want in our own lives. From the best way to bag a budget dinner or keep the kids quiet, to averting nuclear Armageddon and negotiating global climate change agreements.

The documentary explores the controversial use of marijuana and the evolution of mainstream society. From a dangerous narcotic, listed as a Schedule 1 Drug substance since the 1970s, to the rush to decriminalize it today. What has changed and why? What will the cannabis industry look like in five years? Will it retain its integrity as a homegrown industry or be co-opted by Big Business? Experts, growers, celebrities and politicians weigh in on the future of Cannabusiness.