Dogs' brains are getting bigger: Scientists didn't expect it
A dog's brain is much smaller than a wolf's, but new research suggests that modern domestication has contributed to an increase in its relative size. Namely, compared to ancient dogs, modern breeds, which have developed over the last 150 years, have larger skulls relative to body size. Scientists still don't know why.
Numerous previous studies have shown that the domestication of wild animals such as dogs, fish, pigs, cattle, sheep, rabbits and cats dramatically reduces their relative brain size. This is thought to be due to less use of the brain's furrows to come up with ways to survive.
But that doesn't seem to be the case for all pets. When experts compared the skulls of 159 dog breeds, including some wolves, they discovered something unexpected. While the wolf's brain size was 24 percent larger than that of a similarly sized dog, the more genetically different the breed was from the wolf, the larger the brain.
The results suggest that modern dog breeding over the past 150 years has caused modest cognitive development in dogs. But how and why? "Dog breeds live at different levels of social complexity and perform complex tasks, which probably require greater brain capacity," says evolutionary biologist Niklas Kolm of Stockholm University in Sweden, as reported by Science Alert.
Colm and his colleagues first hypothesized that some dogs, bred by humans for more complex tasks such as herding or hunting, developed relatively larger brains. But that was not the case. Instead, the only factor that seemed to affect the relative brain size of modern breeds was their genetic diversity with wolves.
Previous studies have shown that the absolute brain size of individual dogs plays a role in their memory and self-control, but it does not appear to be a strong enough factor to influence the relative brain size of their breed.
"Perhaps a more complex social environment, urbanization and adaptation to more rules and expectations caused this change, which affects all modern races," speculates ethnologist Eniko Kubigny of Eotvos Lorand University in Hungary. This is consistent with the social intelligence hypothesis, the idea that the brain can evolve to adapt to more complex social environments.