What is the theme in Ender's Shadow by Orson Scott Card?

The importance of intelligence is an important theme. The main character Bean, whose actual name is Julian Delphiki, has altered DNA that gives him superior intelligence. However, the genetic change also shortens his life. The thematic idea is that to attain higher intelligence, something else must be given up, and yet this is required to save the human race. The outcome was not been anticipated when the illegal experiment was done, thereby bringing the element of chance into play. Genetics has chance as part of the theoretical workings, where random genetic changes can bring about desirable traits. These is generally thought of as survival improvements for a species and may explain why human intelligence is limited.