Richard Dawkins, talking about his new book, The Magic of Reality, explains an important fact about evolution. Namely that a chimpanzee didn't one day give birth to a human, nor a dinosaur give birth to a bird. At any point along the ancestral trail, there was never a point where the parent of one species gave birth to a different species. The creature born is always the same species as the parent. I previously wrote about this concept here. Watch the video for a great explanation.