Dogs' brains are shrinking - and humans are responsible.
Dogs' brains are small due to domestication
Boffins in Hungary have found that the domestic canine's brain is much smaller than its wild grey wolf ancestor because they live in simpler environments that require less brain power.
The theory about brain shrinkage has been widely accepted by vets and researchers as modern dogs are cared for by humans in terms of their needs for food and avoiding predators.
The team at the Institute of Evolution, Centre for Ecological Research said: "The dog is a canid species that was domesticated from its ancestral species the grey wolf at least 15,000 years ago.
"Over 400 breeds of dogs exist today, and the overall platform is that relative brain size is dramatically reduced in dogs as compared with the ancestral species, the grey wolf.
"This phenomenon is thought to be a result of the decreased necessity for metabolically costly brain tissue in a domesticated environment."