From The White Bone:

"There have been humans since the Descent, which took place ten thousand years ago, during the first long drought, when a starving bull and cow killed and ate a gazelle and in doing so broke the first and most sacred law: 'You shall eat no creature, living or dead.' Even before the two miscreants had finished their meal they began to shrink. As their bodies grew smaller and thinner their trunks receded to stubs, their eats contracted and they sprouted fur on top of their heads. They rose up on their hind legs to protest but only a weak howl came from their throats. Furious and defiant they declared themselves carnivorse, free to pray on any creature that did not walk upright (as they, in their careless rage, did now.)"

Interesting story of how man came to be.....from the elephants perspective.