"Your solution to the Mamathisk self-annihilation game was brilliant. Subtle. Effective. You redirected them to a life of productive peace. I had to go in and destroy them myself."
"You did what?"
"I reversed the effects of your meddling. The Mamathisk reverted to cannibalism when they experienced repeated crop failures. A plant parasite. Impossible for them to stop. But as you know, cannibalism is a losing adaptation. The Mamathisk are effectively extinct."
Crayak and the Ellimist[src]

The Mamathisk were a race encountered by the Ellimist in The Ellimist Chronicles. Ellimist managed to save them from themselves, though what they were doing that was leading them into extinction is unknown. He showed them how to live a productive life, were they lived in peace for sometime. However, Crayak came along and created a parasite that destroyed their crops. Without enough crops to feed the hungry Mamathisk, they quickly reverted to cannibalism. By the time the Ellimist learns this, the Mamathisk is just about extinct.