A recent study has found that modern dog breeds, which are genetically more distant from wolves, possess a relatively larger brain size compared to ancient breeds that have existed for thousands of years.
This discovery has led scientists to believe that the increase in brain size is likely influenced by urbanization and a more complex social environment, rather than breed roles or life history characteristics.
With over four hundred known dog breeds, the canine species showcases remarkable diversity, providing valuable insights for researchers studying rapid changes within a species. Investigating the factors that affect brain size is of particular interest, as the human brain is notably large in comparison to body size.
By comparing various dog breeds, researchers hope to answer questions about correlations between brain size, breed tasks, life expectancy, and offspring rearing challenges.
László Zsolt Garamszegi, an evolutionary biologist at Hungary’s Ecological Research Centre, has been examining the evolution of brain size for an extended period.
“The brains of domesticated animals can be up to twenty percent smaller than those of their wild ancestors. The likely reason for this is that 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 Garamszegi.
“Therefore, there is no need to sustain the energetically costly large brain, and the freed-up energy can be directed towards other purposes, such as producing more offspring, which is important for domesticated animals.”
Niclas Kolm, a researcher at Stockholm University, studies brain evolution and the connection between brain morphology and behavior.
“Different dog breeds live in varying levels of social complexity and perform complex tasks, which likely require a larger brain capacity,” said Kolm. “Therefore, we hypothesize that the selective pressures on the brain can vary within the dog species, and we may find differences in brain size among breeds based on the tasks they perform or their genetic distance from wolves.”
This groundbreaking study, the first of its kind to examine the brain size of different dog breeds, took several decades to prepare. Tibor Csörgő, a senior research fellow at Eötvös Loránd University (ELTE), has been collecting skulls for decades.
Medicopus Nonprofit Ltd. in Kaposvár performed CT scans of the skulls, and veterinarian Kálmán Czeibert used the scans to reconstruct the brains and determine their exact volume.
This invaluable collection was supplemented by the Canine Brain and Tissue Bank, operated by ELTE for the past seven years, allowing researchers to verify brain volumes calculated from skull images using actual brains.
Ultimately, data from 865 individuals representing 159 dog breeds and 48 wolf specimens was gathered for analysis.
The findings, published in the journal Evolution, revealed that wolves have an average brain volume of 131 cm3, associated with an average body weight of 31 kg.
Comparatively, dogs of similar weight have a brain volume of around 100 cm3, only about three-quarters of that of wolves. This confirmed that domestication has led to a decrease in brain size in dogs.
Surprisingly, however, the researchers also found that the more genetically distant a dog breed is from wolves, the larger its relative brain size becomes, regardless of the breed’s original role, average litter size, or life expectancy.
“The domestication of dogs began approximately twenty-five thousand years ago, but for ten thousand years, dogs and wolves did not differ in appearance. Many ancient breeds, such as sled dogs, still resemble wolves today. However, 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,” explained Enikő Kubinyi, a senior research fellow at the Department of Ethology at ELTE.
“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,”
“The results show that the breeding of modern dog breeds has been accompanied by an increase in brain size compared to ancient breeds. We couldn’t explain this based on the tasks or life history characteristics of the breeds, so we can only speculate about the reasons. Perhaps the more complex social environment, urbanization, and adaptation to more rules and expectations have caused this change, affecting all modern breeds.”
Research supports these findings, suggesting that ancient breeds, renowned for their independence, show reduced responsiveness to human cues and emit fewer barks, indicating distinctive variations in visual and acoustic communication when compared to contemporary breeds.
The evolution of dogs from wolves to the diverse modern breeds we see today is a fascinating journey that spans thousands of years. It is widely believed that the domestication of dogs began between 20,000 and 40,000 years ago when humans began taming and breeding wolves for specific traits. Early humans likely found these tamed wolves beneficial for hunting, protection, and companionship.
The process of domestication involved selecting and breeding wolves that exhibited desirable traits, such as tameness, smaller size, or specific coat colors. Over generations, these traits became more prominent, leading to the gradual emergence of distinct dog breeds. The genetic divergence between dogs and wolves was further driven by geographic isolation, human migration, and varying environmental conditions.
As human societies evolved, so did their needs for specific dog breeds. Agricultural societies required herding dogs to manage livestock, while hunters sought breeds with exceptional tracking and hunting abilities. Over time, the roles of dogs continued to diversify, giving rise to breeds specialized in tasks such as guarding, sledding, and even serving as companions.
In more recent history, the Victorian era marked a significant turning point in dog breeding. The 19th century saw the emergence of dog shows and breed standards, leading to a surge in the number of breeds and the refinement of their physical and behavioral characteristics. Selective breeding during this period produced many of the modern breeds we are familiar with today.
The process of selective breeding has not only led to the vast diversity in dog breeds but has also impacted their brain size and cognitive abilities.
As the recent study highlighted, modern dog breeds genetically more distant from wolves have a relatively larger brain size compared to ancient breeds. This increase in brain size is thought to be influenced by urbanization and a more complex social environment rather than breed roles or life history characteristics.
In summary, the evolution of dogs from wolves to modern breeds is a product of thousands of years of domestication, selective breeding, and adaptation to human society. This rich history has given rise to the incredible diversity in dog breeds, each with its own unique set of physical and behavioral traits.