Hungarian and Swedish researchers have recently established that the brains of many modern dog breeds have actually increased in size — a surprising finding given that, overall, domestication has been thought to result in decreased canine brain size, “because the lives of domesticated species are simpler compared to those of their wild counterparts. In the safe environment provided by humans, there is no need to fear predator attacks or hunt for food,” explained evolutionary biologist László Zsolt Garamszegi in a press release.
However, a recent study published in the journal Evolution found that the more genetically removed a dog breed is from wolves, the larger its brain actually becomes.
As Nice News reports, after studying hundreds of specimens, the research team found that breeds that are increasingly distant from wolves, genetically speaking, have in fact developed larger brains “compared to ancient breeds that are thousands of years old,” per the release. And modern diversification of breeds has broadened the number of dogs that are less like wolves.
The researchers gathered data from 865 individual specimens from 159 different dog breeds, and 48 specimens from wolf breeds, controlling for body size, skull shape, and genetic relatedness. CT scans of the skulls were taken, which veterinarian Kálmán Czeibert used to reconstruct the brains and determine their exact volume.
Study co-author Tibor Csörgő, a senior research fellow at Eötvös Loránd University (ELTE), began collecting skulls decades ago. Csörgő’s collection was supplemented with samples provided by the Canine Brain and Tissue Bank, whose samples made it possible to use actual brains to verify brain volume calculated from skull images.
Before completing the study, the team predicted that dogs bred by humans to complete complex tasks like herding or hunting would have larger relative brains. “Different dog breeds live in varying levels of social complexity and perform complex tasks, which likely require a larger brain capacity,” co-author Niclas Kolm had initially theorized. And larger numbers of modern dogs have been bred to serve an expanding array of needs of their human owners.
His colleague, Enikő Kubinyi, a senior research fellow at the Department of Ethology at ELTE, explained that “the transition to settlement, agriculture, pastoralism, and the accumulation of wealth offered various tasks for dogs, requiring guard dogs, herding dogs, hunting dogs, and even lap dogs.” adding: “However, a significant portion of the distinct-looking breeds known today has only emerged since the industrial revolution, primarily in the last two centuries, as dog breeding has become a kind of hobby.”
But surprisingly, whether or not a breed had in fact been developed to complete certain complex tasks proved irrelevant, as did a number of other differentiating features, including life expectancy and litter size. The only factor that seems to impact canine brain size is its genetic distance from wolves.
“We couldn’t explain this based on the tasks or life history characteristics of the breeds, so we can only speculate about the reasons,” said Kubinyi. “Perhaps the more complex social environment, urbanization, and adaptation to more rules and expectations have caused this change, affecting all modern breeds.”
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