It's not likely to be the last word on the subject, but researchers at Vanderbilt University have come up with an answer to the age-old question of whether dogs or cats are smarter. And it's a win for dog lovers. Study author Suzana Herculano-Houzel explains neurons in the cerebral cortex of the brain are linked to complex behavior like thinking and planning. More specifically, their number "determines the richness of [an animal’s] internal mental state and their ability to predict what is about to happen in their environment based on past experience," per a release. By counting these cells in carnivoran species including cats, dogs, raccoons, hyenas, lions, and brown bears, Herculano-Houzel says she determined which of dogs and cats are mentally superior: Dogs have about 530 million cortical neurons, while cats have about 250 million.
This means "dogs have the biological capability of doing much more complex and flexible things with their lives than cats can," says Herculano-Houzel, whose research is published in Frontiers in Neuroanatomy. Interestingly, a golden retriever was actually found to have more cortical neurons than a hyena, lion, or brown bear (which has a similar number of neurons as a cat), even though the latter animals have bigger brains. Herculano-Houzel suggests this is because predator animals spend most of their time resting, saving energy for hunts, so their brains don't get as much opportunity to develop. One animal whose brain does appear well-developed: the raccoon. Raccoons, with a brain size similar to cats, have a neuronal density similar to that of a dog, reports New Atlas. Humans still reign supreme, however, with about 16 billion cortical neurons.