The latest research from a Vanderbilt University neuroscientist has some potentially controversial findings, depending on your pet preference: Suzana Herculano-Houzel's team found that dogs have more neurons in their cerebral cortex than cats.
But does this mean dogs are smarter? Not necessarily.
First, the back story: Herculano-Houzel created a method of counting loose cells floating around in an animal's brain — "turning brains into soup," as she describes it. With this ability, she and other researchers started counting neurons across the animal kingdom — first in rats, then other rodents, then primates, now a whole slew of animals.
"If you consider that neurons are the basic information processing units of brains, then whoever has the most neurons should also have the most information processing capabilities," says Herculano-Houzel, whose team is publishing an article in the open access journal Frontiers in Neuroanatomy.
Humans, they found, are clearly superior, with about 16 billion neurons in the cerebral cortex, which is responsible for cognitive abilities. Her book, The Human Advantage: A New Understanding of How Our Brain Became Remarkable, delves into this topic.
If you go down the chain, you find dogs, with 530 million neurons — and then cats, with less than half that at 250 million.
Herculano-Houzel admits she is a dog person, but that's not why she wasn't surprised by the findings. "The ancestor was a large-brained carnivoran. It was wolves. So because of the large size of the wolf brain, so we can expect that [a dog] should have more neurons than a cat brain anyway."
It's important to remember that this number of cortical neurons is merely an indicator of cognitive ability.
So when looking at dogs versus cats, "to say that it actually is smarter, more intelligent, craftier, better at solving problems or anything like that compared to a cat would actually take measuring their behavior directly, and that is a really hard thing to do," she says.
But Herculano Houzel hopes her research at Vanderbilt will inspire some animal behavioral psychologists to take up the challenge.