Encephalization Quotient - EQ and Intelligence in Mammals

EQ and Intelligence in Mammals

Intelligence in animals is hard to establish, but the larger the brain is relative to the body, the more brain weight might be available for more complex cognitive tasks. This is based on the assumption that a larger animal will require more brain mass simply to control its larger body. The EQ formula, as opposed to the method of simply measuring raw brain weight or brain weight to body weight, makes for a ranking of animals that coincide better with observed complexity of behaviour.

Mean EQ for mammals is around 1, with carnivorans, cetaceans and primates above 1, and insectivores and herbivores below. It also puts humans at the top of the list. The relationship between brain-to-body mass ratio and complexity of behaviour is not perfect as other factors also influence intelligence, like the evolution of the recent cerebral cortex and different degrees of brain folding, which increase the surface of the cortex, which is positively correlated to intelligence in humans.