Dog people and cat people have an age-old debate about which animal makes a better pet. Dog owners brag about canine intelligence, and cat lovers reply that cats are as just smart as dogs, they simply can’t be bothered to obey. Well, new research published in the journal Frontiers in Neuroanatomy seems to support the argument that dogs might actually be smarter than cats.
Débora Jardim-Messeder and her colleagues looked at the brains of animals in the order Carnivora, a group of mammals that contains bears, seals, and raccoons, as well as our domesticated cats and dogs. The purpose of the study was to explore the link between brain size and the number of neurons (specialized cells that transmit information) in the brain. If brain size is equal in different animals, the higher the number of neurons, the more densely packed those neurons are.
The researchers were particularly interested in the cerebral cortex – the part of the brain linked with intelligence - because it controls complex thought processes such as decision-making and planning. The more densely packed the neurons are in a species’ cerebral cortex, the more intelligent that species is considered to be. For example, primates, renowned for their smarts, have brains with very dense neurons.
Eight species of Carnivora were included in the study, with one or two sample animals from each species. The one domestic cat and the two dogs (one Golden Retriever and one dog of unspecified breed) used by the researchers died of natural causes, and their bodies were donated to science. Images were made of the structure of each animal’s brain, and the brain’s weight was measured for purposes of size comparison. Then, to determine the exact number of neurons, each brain was dissolved, and the number of cells in a sample of the resulting liquid was counted under a microscope. This sample count was used to estimate the number of cells in the complete brain.
Results showed that the dogs, having larger brains to begin with, had more than twice as many neurons in their cerebral cortex as the domestic cat, with around 530 million cortical neurons to the cat’s 250 million. (For comparison, there are billions of neurons in the human brain.) Because the brain relies on neurons to process information, the more neurons an animal has in its cerebral cortex, the more information it can process, and the richer its mental capabilities likely are. This means that dogs have the potential for more complex and flexible behavior than cats.
But it wasn’t simply a case of the dog having a bigger brain than the cat. The Golden Retriever’s brain, in particular, had even more cortical neurons than the African lion and brown bear also included in the study, even though the lion and bear had far larger cerebral cortices than the dog. In other words, the dog packed more neurons into a smaller space. It seems that thousands of years of living domestically with humans hasn’t hurt our canine companion’s intelligence.
Before dog people start saying, “I told you so,” to their cat-loving friends, it’s important to keep in mind that the researchers looked at a very small sample size. There was only one cat and two dogs in the study. However, it’s almost certain that the trend would stay the same, even with more animals included. The neuron counts were too far apart to simply be a case of individual variation.
More importantly, the scientists didn’t test the intelligence of living dogs and cats with animal IQ tests or even observe the animals’ behavior. The results are based on brain cells alone. So, although dogs have greater potential than cats, we have no proof they are using their brains’ full capabilities. In truth, there is no better animal at being a cat than a cat, and nothing can be a dog quite as well as a dog. And as for which one makes the better pet? It all depends on who you ask.