A first of its kind study may just have answered the perennial question of: which are smarter, dogs or cats?
Humans have bickered over the animals for the longest of times.
It can be a first date deal breaker, and provoke some very strong reactions, but the rivalry has blessed humanity with at least one good thing – Cats & Dogs: The Revenge Of Kitty Galore.
Now, after counting the number of neurons in the cerebral cortex of a range of carnivores, there’s finally something in the way of conclusive evidence about which animal has more capacity for intelligence, and it’s dogs.
The research, which was led by Vanderbilt University’s Suzana Herculano-Houzel, found that cats had just 250 million cortical neurons compared to dogs’ 530 million.
The cells are associated with thinking, planning and behaviour, and Herculano-Houzel developed the method for accurately measuring their numbers.
“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,” Herculano-Houzel said.
One of the key questions the study hoped to answer was whether carnivores have more brain neurons than the herbivorous species they prey upon, with the researchers hypothesising that they should because hunting is cognitively more demanding.
Small and medium-sized carnivores were found to have a roughly similar brain size-to-neuron ratio as the animals they preyed upon, suggesting that to escape predators herbivores had to develop just as much brain power as the animals trying to catch them.
But large carnivores were actually found to have a lower neuron to brain size ratio, with golden retrievers having more neurons than hyenas, lions or brown bears, which can have cortices up to three times the size of dogs.
Ferrets, mongoose, raccoons, cats, dogs, hyenas, lions and brown bears were analysed.
It is suggested that fewer neurons in larger carnivores might be beneficial metabolically, with hunting expending a lot of energy and meals often more intermittent due to the unpredictability of hunting.
“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,” said Herculano-Houzel.
Raccoons, despite having cat-sized brains, have neuron numbers more similar to dogs, making them similar to primates in neuronal density, according to the study.
And just to make the cat lovers a little happier, our feline friends have about the same number of neurons as brown bears despite having brains 10 times smaller.
Although given the raccoon news, maybe that’s not even a consolation.
The research was published in the journal Frontiers Of Anatomy.