Brain size predicts problem-solving ability in mammalian carnivores

As all the critics will be quick to tell you, there is no direct correlation between intelligence and brain size, but there certainly is a general correlation.

A cat has a brain 2% as large as a human, and a dog 5%. A chimp has a brain 20% the size of yours. No cat is as intelligent as a dog and no dog is as intelligent as a chimp. No chimp can be trained to live as a human.