Since neurons are the brain's "information-processing units", Herculano-Houzel explained, "whatever species has the most neurons in the cerebral cortex is therefore expected to be capable of more complex and flexible behavior".
Cat and dog lovers can peacefully coexist while still believing their favorite animal is superior.
Researchers at Vanderbilt University in the US state of Tennessee recently studied the brains of several meat-eating mammals, including dogs, cats, lions, raccoons and bears.
Did you think cats were more clever and smart than dogs?
In order to reach the findings, the researchers - Suzana Herculano-Houzel, an associate professor of psychology and biological sciences at Vanderbilt University and her team - evaluated the neuronal density and brain sizes of various carnivorans, a class of mammals that includes many predators - along with some omnivores and and a few herbivores.
Dogs have about 530 million cortical neurons while cats have about 250 million.
She says the higher the number of neurons an animal has, the greater their ability to, in her words, "predict what is about to happen in their environment based on past experience".
The study examined and compared the size of their brains.
The researchers published their findings this week in the journal Frontiers in Neuroanatomy under the title "Dogs have the most neurons, though not the largest brain: Trade-off between body mass and number of neurons in the cerebral cortex of large carnivoran species".
Just because an animal is bigger and has a bigger brain size, that doesn't mean it has more neurons. Its brain is 10 times larger than a cat's, but has about the same number of neurons. And raccoons? They're scary smart - despite having a brain the size of a cat, they have the same cortical neurons as a dog or a primate.
An worldwide team of scientists studied a variety of furry critters and discovered dogs have more neurons in an important part of the brain than cats.
"Raccoons were the huge surprise", Herculano-Houzel said.