I cani come specie hanno dimensioni incredibilmente diverse. Ci sono razze di cani minuscole, razze di cani gigantesche e tutto il resto. La taglia di un cane influisce sulla sua salute e di solito gioca un ruolo nel determinare la durata della vita di un cane. Ma alcune persone si sono chieste se gli effetti della taglia siano più profondi:la taglia di un cane può predire la sua intelligenza?
Come misuriamo l'intelligenza nei cani? È una domanda difficile. Nel suo libro L'intelligenza dei cani , il professore di psicologia Stanley Coren lo suddivide in tre categorie:
Coren ha inviato una serie di questionari all'American Kennel Club e ai giudici del processo di obbedienza del Kennel Club canadese, chiedendo loro di classificare le razze canine in base alle prestazioni.
Sulla base delle 199 serie complete di risposte ricevute, Coren ha creato un grafico. 
credit:Stanley Coren via Psychology Today
The chart shows medium to large dogs ranking as the most intelligent, with intelligence dropping off in both very small and very large dogs.
To be clear, The Intelligence of Dogs is not regarded as immutable truth. In Coren’s own words, the book “received a lot of media attention and scientific commentary, both pro and con” when it was first published. But, assuming he is onto something, what could account for the relationship between size and intelligence in dogs?
In his article for Psychology Today , Coren brings up Theodosius Dobzhansky, a behavior geneticist and evolutionary biologist. Dobzhansky says that evolution favors the middle of a population. In other words, individual animals at the extremes are never as well-adapted as the animals with “average” characteristics. 
We also have to take into account that humans tend to treat small dogs differently than they treat large dogs. It’s entirely possible that the way we treat our dogs has a bearing on the types of intelligence Coren tested for. For example, we have a tendency to forgive behaviors in small dogs that we reprimand in large dogs, such as jumping or barking. This phenomenon even has a name:small dog syndrome. A dog’s experiences with its owners could affect how the dog performs in such a test, especially in the area of “working and obedience intelligence.”
It’s tempting to theorize that brain size plays a part in a dog’s intelligence. Much fuss has been made about whether brain size — both overall, and relative to body size — is an accurate predictor of intelligence. Humans, historically, have wanted to believe that a large brain relative to body size equates to a more intelligent species. Come mai? Because that would mean we, as a species, are geniuses. However, it’s simply not true:brain size has very little to do with intelligence.
Alexandra Horowitz, author of the book Inside of a Dog:What Dogs See, Smell, and Know , points out that the brain of a wolf-sized dog is roughly 30 percent smaller than the brain of its ancestor, the gray wolf. Does that mean that the domesticated dog of today is less smart than its ancestor? Horowitz doesn’t think so:“When the mere gaze from the dewy eyes of a member of this species causes you to get up from the couch, repair to the refrigerator and retrieve a hunk of cheese for your charge—well, you tell me who is smarter.”
Professor Coren’s research suggests that medium to large sized dogs are the most “intelligent,” based on the three intelligence categories he used in the study. However, those categories are limited, and his research was based on questionnaires from obedience trial judges, who are human and thus subject to biases. Additionally, many factors in a dog’s life, both genetic and environmental, could contribute to its intelligence. We don’t have nearly enough evidence to definitively say that size affects intelligence one way or the other.
Want to learn more about your pup? Check out Smallest Dog Breeds, Really Big Dog Breeds, and Do Herding Dogs Need to Learn How to Herd? at Cuteness.com!
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