Please note: This is a companion version & not the original book. Sample Book Insights: #1 The human penis is between 5 and 9 inches long on average, with the largest ever recorded being 13. 5 inches long by 6. 2 inches in circumference. The corkscrew-shaped penis of the Argentine duck is the largest known, relative to an animal's body size, in the entire vertebrate world. #2 The human penis is between 5 and 9 inches long on average, with the largest ever recorded being 13. 5 inches long by 6. 2 inches in circumference. The corkscrew-shaped penis of the Argentine duck is the largest known, relative to an animal's body size, in the entire vertebrate world. #3 The human penis is between 5 and 9 inches long on average, with the largest ever recorded being 13. 5 inches long by 6. 2 inches in circumference. The Muscovy duck experiment highlights one of the fundamental differences between mammal and bird penises and asks when, where, and why the practice of mating by copulation first evolved. #4 In 1983 I was studying the armor-plated placoderms, a group of fish-like animals, and I discovered a new genus of the group that I named Austrophyllolepis. In 1986, I led an expedition to the Gogo fossil sites in Western Australia, and the first big discoveries that would impact on the origin of vertebrate reproduction were made.