Part of being human is to learn new ideas, reject them or modify them and pass them on. What we choose to do with an idea depends on who we are; our gender, ethnicity, earlier ideas, what we do for a living, etc. That is, ideas spread to our minds depending on whether they are fit for the environment or not. Descent with modification and selection is the central feature of both biological and ideological evolution. An evolutionary approach helps us to understand such issues as changes in Christianity over time, the mimicry of colonial regimes, the cycles of corruption that are followed by purges in the police and business, and much more. This approach can even shed a light on the belief that the end of the world is nigh. However, there are major differences between ideological and biological evolution. The roles played by consciousness and powerful individuals or groups cannot be ignored. The book contains examples that highlight the similarities and differences between biological and ideological evolution. We have a rich ideological flora and fauna in our minds. Hopefully, an understanding of how they got there will help us distinguish between beautiful flowers and pernicious weeds.