Life on Earth started with simple protocells, which over time developed into all the organisms that have ever existed. This process, where species of organisms change over time, is called evolution. In this film we will take you through this process. You will get examples of how natural selection works, where organisms that are well adapted to their environment survive, while the less adapted ones go extinct. You also get to know that some organisms, like bacteria and archaea have existed since life began on Earth, whilst other species quickly disappear, which shows that the development of the life forms is not linear, but branches out. Finally you will get to know how to find traces of evolution by studying fossils and DNA.