It all began with a single cell. In the course of almost four billion years, this cell evolved into the diversity of life that surrounds us today. Around 1.8 million species have been documented and given a name. But there are many more species that have never been seen. Estimates range between 10 and 100 million. But however many forms of life there are, thanks to Charles Darwin we know that every single one of them shares the same origin. Much later, Jane Goodall removed another stone from the wall that separates man from the ape. But why is one species threatened by extinction while the other continues to thrive and proliferate?