The lost tribes of humanity.

Presented by Professor Alice Roberts, this programme explores how recent research and genetic techniques have given us insight into the four distinct groups of humans who lived on the planet at the same time as ourselves; examining the complexity of human evolution. Roberts starts with the Neanderthals, travelling to Gibraltar where Prof Clive Finlayson of the Gibraltar Museum has been studying a cave system which contains the final refuge of the Neanderthals. Finlayson explains how the stereotypes regarding Neanderthals have been proven wrong evidence shows they were not only very cultured, but even capable of abstract thought, an ability that was previously thought to be exclusive to Homo sapiens. Professor Chris Stringer of the Natural History Museum, who has spent the last 30 years investigating the similarities and differences between modern humans and Neanderthals, explains that the two groups shared much of the same behaviour. With master flint knapper John Lord, Stringer looks at the tools Neanderthals used, which were the result of an exchange of ideas between the two groups. These interactions between Neanderthals and modern humans also helped our ancestors learn how to deal with the colder temperatures outside Africa. Professor Svante Pääbo, a geneticist from the Max Planck Institute for Evolutionary Anthropology, then recounts how the excavation of a small finger bone in a cave in Siberia led to his team discovering the genome of an entirely new human group, which they called the Denisovans. So did modern humans come in contact with the Denisovans? The discovery of modern human teeth in Daoxian in China enabled archaeologist Dr Maria Martinón-Torres of UCL and her colleagues at the Chinese Academy of Sciences to date the move out of Africa at around 100,000 years ago. This means that our ancestors would have been living in Asia and Europe at the same time as Denisovans and Neanderthals. Anthropologists Dr Laura Shackelford and Dr Fabrice Demeter then recount the discovery of the third extinct human group, Homo floresiensis, in the small island of Flores in Indonesia. This species were nicknamed hobbits due to their small size, the result of island dwarfism. But since so many human groups have been discovered, Professor Roberts asks the pressing question why did Homo sapiens survive, when all these other groups died out? Professor Stringer discusses the environmental factors that led to the extinction of Neanderthals, and Dr Janet Kelso of the Max Planck Institute explains how the lack of genetic diversity would have been a major factor as well. However, genetic research has allowed us to realise that present-day human beings actually share some DNA with these extinct groups, which Dr Kelso explains was the result of interbreeding. Her team were able to analyse DNA from people all over the world and concluded that those from within Africa generally lacked Neanderthal DNA, whereas people living outside of Africa often did have it as their ancestors had come in contact with Neanderthal groups. They even found traces of Denisovan DNA, particularly among Papua New Guineans, Aboriginal Australians, and Tibetans. Most recently, a fifth Hominin group was discovered by Professor Joshua Akey, a geneticist at the University of Washington. Very little is known about this group as no fossil evidence exists, and thus far they are known simply as an Archaic African group whose DNA can only be found in some parts of central Africa. Professor Roberts explains that all of these recent discoveries have forced us to completely reimagine our linear view of human evolution, and that genetics has made a huge difference to the study of our species.