The author argues that humans have not evolved gradually since the split from their great ape ancestor. Instead, modern humans emerged suddenly around 120,000 years ago, with a `below the neck' physiology similar to our hominid ancestor, but with a radically altered skull, face and brain. Adult humans have essentially retained the infant proportions of our immediate ancestor's 'above the neck' morphology. A mutation that radically altered the early developmental pathway of our immediate hominid ancestor has led to the dramatic changes in both anatomy and brain architecture. Modern human cognition and language did not evolved gradually in Darwinian fashion, but emerged suddenly with this mutation. Evidence from Paleontology, Archaeology and Genetics, is garnered to support this theory for the sudden appearance of modern humans.