Modern humans are one of the most biologically successful, and unique, living mammals. Through the development of extensive and elaborate technology, we have become a major influence on the modern world, modifying it for our purposes and altering the lives of other creatures. Ancestors will lead you through those aspects of modern humanity that makes us unique and successful tracing the path of evolution through the past four million years. Walking on two legs, and the use of tools, symbols, and language have their own evolutionary trajectory throughout the era of human emergence. All of these traits, along with other unique human behaviors, merged to produce that complex biological and cultural creature we know as Homo sapiens.