The research found that dogs have about 530 million cortical neurons while cats have about 250 million. These neurons are the brain cells associated with thinking, planning and complex behavior, which are all considered hallmarks of intelligence.
“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,” explained the leader of the study, Suzana Herculano-Houzel, who is an associated professor of psychology and biological sciences.
“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 added. “At the least, we now have some biology that people can factor into their discussions about who’s smarter, cats or dogs.
The study also found that brain size has little relationship tointelligence. They found that the brain of a golden retriever has more neurons than a hyena, lion or brown bear – even though the bigger predators have brains up to three times as large. The analysis also discovered that raccoons pack the same number of cortical neurons as a dog into a brain the size of a cat’s.
Also taking part in the study were graduate students and professors from the Universidade Federal do Rio de Janeiro in Brazil; the University of California’s Davis School of Medicine, King Saud University in Saudi Arabia and the University of the Witwatersrand in South Africa.
The study was funded by the James S. McDonnell Foundation; the Schapiro Undergraduate Research Fund at Randolph-Macon College; the Vice Deanship of Research Chairs at the King Saud University; the National Research Foundation of South Africa; and Brazilian crowd funding contributors.