What is the theme in Alive: The Story of the Andes Survivors by Piers Paul Read?

Cannibalism was a major theme in this book. The only way for the survivors to sustain themselves was through cannibalism. In the beginning, many of the survivals were opposed to the practice. Some overcame their revulsion when they grew weak from hunger. It is especially significant to note that the people who committed cannibalism did so with complete reverence for the departed.This was not an easy transaction; instead it involved a mixture of contemplation and desperation.