What does the natural world hide from the secrets of sexual differences in our various animals? From the sparkle of the feathers of the birds of Paradise to the centuries of the complex elders, this book raises exciting questions about the reason behind the contrast of male behavior about females in the animal world. Why are sexual features often harmful to the type in some cases? Scientists reveal recent discoveries that reveal the extreme diversity of our natural world and how basic principles can help us explain this diversity. The book deals with the sexual election process and how it leads to competition between the sexes to ensure reproduction, not only to survive. It highlights the history of our understanding of sexual election, from Darwin's basic ideas to the modern era, and reviews issues such as female choice for males based on aesthetic criteria and how to settle sexual conflicts in various types.