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Every pet parent believes their furry friend is the smartest animal ever. But everyone can’t be right—just the dog owners, it turns out.
A new study, led by Vanderbilt University professor Suzana Herculano-Houzel, suggests canines possess “significantly” more neurons in their cerebral cortex than cats.
You’d think the brains of carnivores would have more cortical neurons than the herbivores they prey on. After all, hunting is pretty demanding, cognitively speaking.
But, Herculano-Houzel and her team have debunked that theory, claiming the ratio of neurons to brain size in small-to-medium meat eaters is about the same as vegetarians.
Seems size really doesn’t matter: Researchers found the brain of a golden retriever has more neurons than a hyena, lion, or brown bear. The latter, in fact, with a brain 10 times larger than a cat’s, but boasting about as many neurons.
“Meat eating is largely considered a problem-solver in terms of energy, but, in retrospect, it is clear that carnivory must impose a delicate balance between how much brain and body a species can afford,” Herculano-Houzel said.
The study, which analyzed specimens from eight carnivoran species—ferret, mongoose, raccoon, cat, dog, hyena, lion, and brown bear—also challenges the popular view that domesticated animals have smaller brains than their wild cousins.
In terms of household smarts, though, humans take the cake. People have about 160 billion cortical neurons, compared to dogs’ 530 million, and cats’ measly 250 million.
“I believe the absolute number of neurons an animal has, especially in the cerebral cortex, determines the richness of their internal mental state and their ability to predict what is about to happen in their environment based on past experience,” according to self-described “dog person” Herculano-Houzel.
“But, with that disclaimer, our findings mean to me that dogs have the biological capability of doing much more complex and flexible things with their lives than cats can,” she continued. “At the least, we now have some biology that people can factor into their decisions about who’s smarter, cats or dogs.”
For this study, Herculano-Houzel collaborated with graduate students Débora Messeder and Fernanda Pestana from the Universidade Federal do Rio de Janeiro in Brazil; professor Kelly Lambert of University of Richmond; associate professor Stephen Noctor of the University of California, Davis School of Medicine; professors Abdulaziz Alagaili and Osama Mohammad from King Saud University in Saudi Arabia; and research professor Paul Manger at the University of the Witwatersrand in South Africa.
The results are described in a paper published this week by the journal Frontiers in Neuroanatomy.
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