If we have ever wondered who is smarter, dogs or cats, scientists have a definitive answer.
Our cerebral cortex does the thinking: collecting information, processing it and making decisions, solving problems, dealing with emotions and behavior and so on. It is literally our thinking cap and the neurons in it are our tiny processors.
It is not just the size of the brain that matters, but how many neurons it contains. If a small brain has densely packed neurons (think a crow or parrot) it could be very smart. So how do cats and dogs measure up?
For a reference point consider humans. Our cortex weighs 1232.9 grams on average, has 16.34 billion neurons for a density of 13.3 million neurons per gram. On the other hand, a brown bear weighing five times as much in body weight has a cortex of only 222 grams containing just 251 million neurons for a much, much lower density of 1.1 million neurons per gram.
To answer the dog versus cat question:
Two dogs, a small mutt, and a four times larger golden retriever were used in a study
of carnivore brains. The smaller one had a cortex weighing 46.2
grams with 429 million neurons for a density of 9.3 million neurons per
gram. The larger golden retriever was over 4 times heavier at 32 kg but
had a cortex that weighed only twice as much and just 46 percent more
neurons (623 million). However, they were smarter than all the other
carnivores in the study. A lion with 542 million neurons was second,
followed by a striped hyena with 495 million neurons.
The 4.5-kg cat came in at a cortex mass of 24.2 grams and 250 million neurons giving a density of 10.3 million neurons per gram. So dogs, on average, with twice as many neurons are smarter. Sorry, cat lovers.
The real surprise were the raccoons. They averaged a cortex weighing only 24.5 grams (about the same as a cat) but containing more neurons, 438 million, than the small dog, and more densely packed than even a human brain at 17.9 million neurons per gram. One individual raccoon boasted 512 million cortex neurons. If we have ever been frustrated in our attempts to keep them out of garbage cans, this could explain it.