Students are rarely presented with a diversity of viewpoints about evolution and its mechanisms. The historical background to evolution normally suffices: Darwin's journey on The Beagle, his concepts of natural selection and common descent, and an outline of Mendel's experiments. With supplementary concepts such as ecological niches and the modes of speciation, we can present a classic picture of neo-Darwinian evolution. However, this picture implies that the principles of evolution have all been deduced, leaving the study of evolution appearing static and historical. In fact, evolutionary mechanisms are investigated more actively than ever, and Darwin's principles continue to be challenged, developed and expanded.