Although wolf brains are substantially larger than dog brains, recent study
indicates that contemporary breeding practices have somewhat boosted the
relative size of dog brains.
Modern dog breeds that have emerged in the last 150 years have bigger heads
proportion to their body size than historic varieties had. But researchers
are still baffled as to why.
The proportional size of the brains of domesticated wild animals, such as
dogs, fish, pigs, cattle, sheep, rabbits, and cats, is drastically reduced.
This has been demonstrated in several studies.
According to scientists, this is a reaction to a decreased demand for
cognitive power for survival.
But when scientists compared the skulls of 159 dog breeds, including some
wolves, they made an unexpected discovery.
Even if a wolf's brain is 24% bigger than a dog of comparable size,
genetically speaking, the more a dog breed varied from a wolf, the bigger
their brain.
According to the research, while dog domestication thousands of years ago
may have originally caused some areas of the dog's brain to shrink, such as
those connected to partner selection, predators, or hunting, current
breeding has resulted in a little amount of cognitive gain during the past
150 years.
Yet how?
"Different dog breeds live in varying levels of social complexity and
perform complex tasks, which likely require a larger brain capacity,"
claims
evolutionary scientist Niclas Kolm of Stockholm University in Sweden.
Kolm and his associates therefore proposed the theory that those dogs with
human breeding for more intricate jobs, such as herding or sports, would
have larger relative brains.
That wasn't the situation. Not the purpose of the breed, its litter size,
or life expectancy, but rather how divergent their genes were from wolves
proved to have an influence on the relative brain size of current dog
breeds.
In reality, scientists were unable to detect any variation in the relative
size of the brains in the breeds listed by the American Kennel Club.
The absolute brain size of individual dogs was found to affect their memory
and self-control in
previous research, but this effect doesn't appear to be powerful enough to affect the
relative brain size of their breed as a whole.
Other recent research that reveals the behavior certain dogs are bred for
is not inherent in their genetic makeup also supports the findings of the
present study.
Enik Kubinyi, an ecologist from Hungary's Eötvös Loránd University,
hypothesizes
that "possibly the more complex social environment, urbanization, and
adaptation to more rules and expectations have caused this change, affecting
all modern breeds."
This is consistent with the
social brain theory, which holds that big brains may develop to adapt to increasingly
complicated social settings.
For instance,
prior studies
have shown that dogs that are more closely related to wolves are less adept
at connecting with people.
The team advises that future study should examine the size of various brain
areas to understand more about how ancient and contemporary canine brains
vary from wolves.
Then researchers might be able to determine what effect humans have had on
canine cognition and behavior.
The study was published in
Evolution.
