Centuries of selective breeding has reshaped dog’s brains, according to a study.
Dogs have been bred for tasks such as hunting, herding animals, or simply as human companions, researchers found.
The result has been changes in the shape of their brains, which can’t be explained by other evolutionary factors.
Erin Hecht and colleagues at the department of human evolutionary biology at Harvard University analysed magnetic resonance imaging (MRI) scans of 62 male and female dogs of 33 breeds.
The research team observed wide variation in brain structure that was not simply related to body size or head shape.
Scientists examined the areas of the brain with the most variation across breeds, including beagles, dachshunds, greyhounds and Labrador retrievers.
This generated maps of six brain networks, with proposed functions varying from social bonding to movement, that were each associated with at least one behavioural characteristic.
The authors write: 'These results indicate that through selective breeding, humans have significantly altered the brains of different lineages of domestic dogs in different ways.
'Finally, on a philosophical level, these results tell us something fundamental about our own place in the larger animal kingdom - we have been systematically shaping the brains of another species.'