A new study published in the JNeurosci shows that through selective breeding, humans have significantly altered the brains of different lineages of domestic dogs in different ways.
Left: structural differences in three dog breeds. Right: composite scan from 33 breeds displaying areas that vary the most. Image credit: Hecht et al, doi: 10.1523/JNEUROSCI.0303-19.2019.
“Dog breeds are known to vary in cognition, temperament, and behavior, but the neural origins of this variation are unknown,” said Harvard University researcher Erin Hecht and colleagues.
The scientists examined whether and how selective breeding by humans has altered the gross organization of the dog brain.
They analyzed magnetic resonance imaging (MRI) scans of 62 male and female dogs across 33 breeds.
They observed wide variation in brain structure that was not simply related to body size or head shape.
The team then examined the areas of the brain with the most variation across breeds. This generated maps of six brain networks, with proposed functions varying from social bonding to movement, that were each associated with at least one behavioral characteristic.
The variation in behaviors across breeds was correlated with anatomical variation in the six brain networks.
“In an MRI-based analysis, we found that brain anatomy covaries significantly with behavioral specializations like sight hunting, scent hunting, guarding, and companionship,” the study authors said.
“Neuroanatomical variation is not simply driven by brain size, body size, or skull shape, and is focused in specific networks of regions.”
“Nearly all of the identified variation occurs in the terminal branches of the dog phylogenetic tree, indicating strong, recent selection in individual breeds.”
“Our results establish that brain anatomy varies significantly in dogs, likely due to human-applied selection for behavior.”
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Erin E. Hecht et al. Significant neuroanatomical variation among domestic dog breeds. JNeurosci, published online September 2, 2019; doi: 10.1523/JNEUROSCI.0303-19.2019
