For the first time, researchers of the museum and their international team have systematically compared the neuroanatomy of dogs and wolves. A total of 243 dogs and wolves were examined, representing a wide range of breeds, populations, and different body shapes and sizes. Many of them come from the NMBE collection. Compared to wolves, dogs have smaller brain sizes, but exhibit enormous differences in shape: up to four times the brain shape variation shown by wolves. In addition, dogs also have altered proportions of various sensory regions. This is a clear example of so-called mosaic brain evolution and thus confirms one of the strongest hypotheses about brain evolution in mammals – namely, that total brain form change relies on form changes across the brain’s constituent parts.
Faster development than expected
It is also noteworthy that the frontal lobe and brain regions associated with social behavior are proportionally larger in dogs than in wolves. These areas are more pronounced in particularly “cooperative” breeds than in independent breeds. This underscores how much human selection to breed particularly social animals has influenced the brain development and brain composition in dogs. “Ancient” breeds such as the Siberian Husky have a more wolf-like neuroanatomy compared to “modern” breeds such as the German Shepherd. Although this is not a focus of the study, it suggests that genetic factors also play a role in the brain evolution among dog breeds.
Overall, the brains of dogs are significantly more “integrated” than those of wolves. An integrated brain means that the individual subregions are better coordinated with each other. These findings challenge the conventional understanding of the evolutionary capacity of the mammalian brain and contradict long-held assumptions in evolutionary theory that a highly integrated brain indicates a slow evolutionary capacity. Instead, they underscore the exceptionally rapid adaptability of the mammalian brainunder the influence of domestication and artificial selection. The example of the dog clearly shows the enormous influence humans have had – and continue to have – on the evolution of our closest animal companions.
