I used to work for Greenpeace. Sanest bunch of people I've ever known.

There are many ironies in the story line of the film...By wanting to free teh chimps from being forced into violent behavior, they exposed the human race to this virulent epidemic of violence (thus reducing them to "animals."

But even more interesting is what the film has to say about the nature of the killing instinct. Once someone is "infected" there is between 10 and 20 seconds before the victim goes mad and starts tearing apart everything in sight and vomiting blood thus spreading the virus...so they must be killed instantly, even if seconds before they were your best friend or father...mild-mannered bike couriers must turn into utter mercenaries. There is also a fascinating plot twist which suggests that the implementation of martial law and the rounding up of women as chattel/cattle may be an even worse development than the virus which turns everyone into killing machines...some people, in other words, don't need an excuse to behave in a depraved manner.