Why do dogs have smaller brains than wolves?
29 Apr 2026

A study has revealed that dogs' brains began to shrink at least 5,000 years ago.

The research sheds light on the domestication of our furry friends, but it doesn't explain why they ended up with smaller brains than their wolf-like ancestors.

Dr. Thomas Cucchi from the French National Centre for Scientific Research, lead author of the study, said modern dog breeds are extremely clever and domestication didn't make them stupid, but made them capable of reading and communicating with us.

How did the researchers conduct the study?
Research methodology

The study, published in the journal Royal Society Open Science, examined CT scans of skulls from 22 prehistoric wolves and dogs (dating back 35,000-5,000 years ago) as well as modern ones.

This included different breeds of modern dogs, "village" or stray dogs, and dingoes.

The researchers tracked how brain size changed over the evolutionary history of dogs using these scans.

How much smaller are dogs' brains?
Size comparison

The study found that modern dog breeds, dingoes, village dogs, and Late Neolithic dogs had a brain size 32% smaller than ancient and modern wolves.

Dogs from the Late Neolithic period (5,000-4,500 years ago) had brains 46% smaller than those of their wolf counterparts.

Despite being smaller overall in body size, these ancient dogs still had significantly smaller brains than ancient wolves even when factoring in body size.

Canines from early domestication period had bigger brains
Brain growth

Interestingly, the study found no evidence that the brains of two canines that lived alongside humans 35,000 and 15,000 years ago, were smaller than those of ancient wolves.

In fact, one brain was relatively larger. This suggests that brain size may have actually increased during the early stages of domestication.

Dr. Cucchi said it's unclear why domestication led to dogs with smaller bodies and brains than their wolf-like ancestors.

Why were smaller dogs favored during domestication?
Environmental adaptation

Dr. Cucchi noted that when brain size is reduced, it reorganizes, making smaller dogs less trainable and more wary of environmental changes.

This could make them useful as "alarm systems."

He also claimed that limited food resources in the Neolithic village environment may have favored smaller dogs with smaller brains because they require less energy.