Panayiota Siskos ’23
The selective breeding of dogs by humans has led to variation in the brain across different breeds.
Selectively breeding dogs for traits and abilities has been a recent occurrence in evolution, and genetic research shows behavioral variation is heritable. Behavioral specializations depend on neural specializations, and strong selection pressure exhibits that brain differences between dog breeds correlate with differences in behavior. Selection for breeding was based on physical appearance, including the craniofacial morphology that puts limits on the brain and affects possible brain morphology. However, neuroanatomical variation may also be due to body size instead of the dog’s breed membership, with different brains having minor, random, scaled-up, or scaled down alternatives of a species-wide pattern. This study approached studying morphological differences in dog brains using data-driven, whole-brain, and agnostic (general) methods. The study focused on finding if variation in the brain is present across all dogs, and if it is, to find differences between competing and interacting explanations.
The study used T2-weighted MRI scans of 62 purebred dogs from 33 different breeds that were grouped into 10 different breed groups with each having similar behavioral specializations. There are neuromorphological differences across dog breeds spread across the brain in a nonrandom pattern. Independent components analysis exhibited that particular regional subnetworks correlate with one another. This variation is not because of brain size, body size, or skull shape, but instead due to the anatomy of networks correlating with behavioral specializations. Phylogenetic analysis showed that most change occurred in terminal branches of the phylogenetic tree which indicates recent selection in breeds. These results show that dog’s brain anatomy varies because of the selection humans performed for their behavior. This study is important, because as neural variation is introduced in dog breeds it is possible to examine the evolution of brain-behavior relationships; and the findings also show that the method of grouping different breeds together, which many fMRI studies have used, may be ineffective. The results could pave the way for future brain-assessment for various dogs in completing tasks, and outcomes show how humans have shaped the brains of another species. New directions for this research include finding more specific neuroanatomical features in relation to specialized behavior of different dog breeds, followed by selective breeding for amplified expression of such features.
 E. Hecht, et al., Significant Neuroanatomical Variation Among Domestic
Dog Breeds. Journal of Neuroscience 39, 7748-7758 (2019). doi: 10.1523/JNEUROSCI.0303-19.2019
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