Dogs with bigger brains relative to their body size aren’t necessarily smarter, according to a new study. How do dogs have smarter brains?
The study was published in the journal Biology Letters.
Although working dogs may have more complex abilities compared to other breeds, they are organized into a more compact space in their brains, a difference from the evolution of wild mammals, where the enlargement of the brain relative to the body is usually associated with more complex cognitive skills.
“In other groups of species, the relative size of the brain indicates superior cognitive abilities, here we observe the opposite,” explained Ana Balcarcel, lead author of the study and evolutionary biologist at the Institut des Sciences de l’Évolution de Montpellier (France).
What is the difference between more intelligent and less intelligent dogs?
The study compared the ratio of brain to body size in dogs by measuring 1,682 skulls of adult dogs from 172 breeds housed at the Natural History Museum in Bern, Switzerland. The researchers calculated the relative endocranial volume of the dogs, meaning the size of the brain in relation to the size of the body. The scientists also assessed 14 behavioral traits using the Canine Behavior Assessment Questionnaire, which measures trainability, attention-seeking, aggression and other traits, notes Live Science.
“Working” breeds such as the Siberian Husky, which specializes in complex human assistance skills, had the smallest brains relative to body size. In contrast, “companion” breeds such as the Chihuahua, bred specifically to be pets, had the largest relative brain size.
Relative brain size was smaller in more trainable dogs, typically working breeds such as the Siberian Husky, Great Pyrenees, and Rottweiler, bred for human assistance tasks such as search and rescue, guiding, and policing. Previous research has shown that these dogs have better executive function, meaning greater behavioral control and superior short-term memory than other breeds.
Larger dogs have a different composition of internal brain tissues than small dogs, Balcarcel explained. Previous studies suggested that a larger brain correlates with a greater chance of survival, better decision-making ability, and superior information-processing capacity.
So the results of this new study about smarter dogs are surprising.
The more intelligent dogs had a human-assisted evolution
“The key difference is that quadrupeds are not in natural environments. They are a product of artificial selection, a very directed selection, an evolution under the hand of man,” said Balcarcel.
The study also found that dog breeds with a relatively larger brain size, mainly toy breeds such as Chihuahuas, Pomeranians and Yorkshire Terriers, tended to show higher levels of fear, separation anxiety, aggression and attention-seeking behaviors. These breeds are bred primarily as pets, so affection and attention-seeking are favored traits in selection. Fear and aggression may not have been a disadvantage for these breeds, unlike working dogs, which were bred to be more trainable, Balcarcel speculates.
“We can say that we have indeed modified the brains and not just the body sizes and proportions of the different races, but it seems that we have also changed their brains in a significant way,” Balcarcel said.
Specialized dogs
Next, the team plans to compare brain shape and function in different dog breeds. Variations in the shape of the neocortex, the part responsible for higher brain functions, could provide information about the senses and functions important to different types of dogs, Balcarcel said.
Studying the shape of the brain in dogs could also answer questions about evolution and domestication. The brain of domestic dogs (A familiar wolf dog) are about 20% smaller than those of wild wolves (Canis lupus) relative to body size, but unlike wild wolves, domestic dogs are more specialized in complex social skills such as following human gaze and interpreting pointing gestures.
Balcarcel reminded dog owners that regardless of the brain-to-body ratio, the results don’t necessarily translate directly to the dog’s intelligence. “Dogs have been bred for different cognitive abilities, so even if your dog is on the smaller end of the brain spectrum, he’s special and specialized in his own way,” Balcarcel said.
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Source: www.descopera.ro
