Human beings appear to be unique amongst mammals - we live in huge cities, we walk on two legs and we have language. But how far have we really come from our mammal heritage? Are we really as different as we think from other mammals? To answer these questions we journey from the urban jungle to the real jungle. This is the natural home of apes. In the forests of Borneo, David meets a remarkable orang-utan who has learnt how to row boats and wash clothes by imitating humans. You may be surprised that an ape can do something so human, but of course we are apes too. Food and how apes find it has been key to the evolution of large brains - something that all apes share with humans. But are we similar to apes in the way that we think? David communicates with Koko the gorilla in sign language and cracks nuts with chimps in the Congo who have learnt this tradition from watching humans. We visit the famous chimps of Gombe to witness another tradition common to both humans and chimps - hunting for meat. Humans are different from apes because we walk on two feet - or are we? David wades through water with a remarkable group of chimps that give us a unique window into our past. There are only four men on earth who can run a kudu antelope to its death. They are Kalahari bushmen - this `persistence hunt' is thought to link modern humans to the earliest form of human hunting. Humans hunt animals with more techniques than any other mammals and have learnt to shape wild animals to our needs with domestication. But the ultimate control is when you can grow your own foods... anywhere. Man began to reshape the earth into patterns that can be seen from space - from the hand-sculpted rice terraces in China to the vast irrigated wheat circles in the desert of Arizona. Once a surplus of food could be made and stored, humans could settle. David travels to the remote thatched granaries of the Dogon tribe of Mali, to an ancient mud city, and then to the ruins of one of the great capitals of the Mayan civilisation to trace the evolution of human settlement from villages to great cities. The temples of Tikal used to be the highest building in the Americas until the skyscrapers of New York were built. So why did the city collapse? Satellite technology reveals that over-intensive agriculture was probably to blame. Can modern day city-dwellers avoid a similar fate? NASA scientists believe that they have come up with a way of genetically modifying plants with jellyfish genes so that they can be remotely grown and monitored on Mars. David launches the latest plant experiments in a recent shuttle launch. 'Now we are looking for food not just on our planet but beyond our planet to others. Perhaps the time has now come when we should put that into reverse. Instead of controlling the environment for the benefit of the population, maybe we should control the population to ensure the survival of our environment.'