The Big Debate: Are Cats or Dogs Cleverer?

The researchers from Vanderbilt University published their study's findings in the journal Frontiers in Neuroanatomy.

By liquifying the brains of already dead animals, the team was able to count the number of neurons each animal had. The specimen animals were donated by a zoo, a forest preserve, a wildlife rehab facility, and several pet owners.

The study was not only dedicated to comparing dogs and cats. It also examined the brains of ferrets, mongooses, raccoons, hyenas, lions, and a brown bear.

Neuroscientist Suzana Herculano-Houzel, one the studies leads, helped created the technique that was originally devised to count neurons in human brains. The process involves dissolving the brain, which in turn liquefies each and every neuron. 

The resultant brain-soup is then mushed, separating out the nuclei of neurons. The team then counted these free-floating neurons to determine the total number of neurons present. 

The result? They found that dogs appeared to have almost twice the number of neurons as cats - - 530 million in their cortex to be precise. Cats, on the other hand, "only" had 250 million.

To put these values into perspective, a human being has around 16 billion neurons. By this metric, humans are about 30 times "cleverer" than dogs and about 60 times "cleverer" than cats.

If the total number of neurons in a brain equates to intelligence then there appears to be a clear winner.

“[The] logical implication is that, yes, dogs are much more capable than cats,” Herculano-Houzel said in a PBS NewsHour interview on the subject.  

Are cats smarter than dogs, yes or no?

According to the above-mentioned study, dogs appear to have a lot more neurons, and by extension, brainpower, than cats. But all might not be as it first appears. 

The study also had some other surprises in store for the neuron-counts in other carnivorous mammals. The larger predators like the hyena, lion and brown bear, all had fewer neurons than some of the smaller ones.

In fact, the brown bear had as many as the study's cat brains. Yet another surprise came from raccoons.

They found that even though their brains are about the size of cats, they had as many neurons as a dog's brain. In fact, the ratio of neurons to brain size rivaled that of some primates. 

“The very large number of neurons that we found in the raccoon cortex fits very nicely with the lore about raccoons,” Herculano-Houzel explained. “It matches with how incredibly ingenious these little creatures are and how good at problem-solving they are when it comes to finding food.”

They also studied the brains of some herbivores to test a hypothesis that they required less brainpower and thus should have fewer neurons. What was fascinating is that many of the herbivores actually had comparable neurons counts as their carnivore rivals. 

Domesticated versus wild animals also showed little variation. This suggests, almost counterintuitively, that the size of an animal's brain, and the number of neurons it packs, doesn't necessarily provide a useful "measuring stick" for intelligence. 

This doesn't come as much of a surprise for other experts in the field like Brian Hare. He is the founder and director of Duke University's Canine Cognition Center. 

“Asking which species is smarter is like asking if a hammer is a better tool than a screwdriver,” Hare, explained. “Each tool is designed for a specific problem, so of course it depends on the problem we are trying to solve.”

Each species, according to Hare, has been shaped by evolution to solve problems that have most effected its survival and reproduction throughout time. You won't find a dolphin sitting in a tree, or a chimpanzee fishing in the sea; yet both are widely considered very clever animals in their own habitats. 

This appears to be confirmed, in part, by a 2019 study investigating the correlation between neuron count and intelligent behavior. They concluded that it was very difficult to make any real correlation. 

So what's going on here? Like all good science, we now appear to have more questions than answers. 

For example, is the number of neurons and intelligence a linear scale? Or is it perhaps exponential? Perhaps the number of neurons isn't really the main factor that determines intelligence in living creatures?

Some neuroscientists believe intelligence has more to do with connections between neurons rather than the quantity of them. In a 2018 study, it was found that higher IQ people appeared to have fewer connections between neurons in the outer layer of the brain. 

If true, this could explain why some animals can "get away" with fewer neurons and still show remarkable intelligence for their brain size. As the adage goes, it might be more about "quality over quantity". 

But, we may never know for sure.

Are cats intelligent?

As we have seen above, it depends on your metrics. Many scientists now consider intelligence, especially in animals, to be on something of a spectrum. 

Kristyn Vitale Shreve, a cat cognition and behavior research fellow at Oregon State University explained to PBS that intelligence is not so "cut and dry".

For example, cats are widely considered to be excellent hunters. This requires significant mental abilities to be successful. 

Dogs are not so accomplished and humans pale in comparison. But if we test cats, dogs, and humans for, say, mathematical ability, humans would be the clear winner. 

According to scientists like Vitale Shreve, we need to stop pitting species against each other in direct comparisons as each is intelligent in their own way. She does, however, acknowledge that some comparative studies need to be developed that focus more on behavior, rather than purely physiology, that can smooth out the difference between species' brains. 

But this is notoriously difficult, especially with cats. Cats tend to be very uncooperative. It is for this reason that very few studies have been completed on them.

“There’s this perception of cats being untrainable or maybe hard to work with,” Vitale Shreve explained. “Cats display a lot of individual variation and have distinct personalities, which make it hard for researchers to understand them.”

Whether or not cats are intelligent is like determining intelligence in any other animal. It is, by definition very nuanced indeed. 

What is the smartest animal in the world?

If we remove human beings from the equation, various studies have been conducted on the relative "intelligence" of our animal cousins. 

According to various sources, the "top 8" geniuses of the animal kingdom appear to be as follows: -

• Chimpanzees
• Pigs
• Bottlenose Dolphins
• Parrots
• Whales
• Dogs
• Octopus
• Elephants