"Advancements in medicine and a greater understanding of the biological composition of Serra's organic population have lead to astounding genetic manipulations. They created faster, stronger, and more cunning biological creatures. However, this tampering has lead to some... minor side effects. Subjects are very quick to enrage and have developed an uncontrollable hunger, unfortunately to a point where they senselessly attacked those around them ripping flesh from bones. I should know. But, hey, all in the name of science, I guess" - a Dr. Portuud, a geneticist.