Dogs’ brains are shrinking – and humans may be partly to blame, study warns

They may be man’s best friend, but humans are at least partly responsible for dogs’ shrinking brains.

Hungarian scientists report that the brain of the domestic dog is significantly smaller than that of its wild ancestor, the gray wolf.

The brains of domestic dogs have become smaller because they live in simpler environments, which require less brain power than wild dogs.

Experts say there may be other factors causing the decline in the size of domestic dogs, but they do not specify what they are.

In the wild, however, factors such as hibernation can cause a decrease in brain size in other species of the dog family, they say.

Domestic dog brains have evolved to become smaller because they live in simpler environments compared to their wild counterparts. Pictured is a 3D model of the dog brain based on high-resolution CT scans

The research was led by László Zsolt Garamszegi from the Institute of Ecology and Botany of the Centre for Ecological Research in Hungary.

“The dog is a canid that was domesticated from its ancestor, the gray wolf, at least 15,000 years ago,” the team said.

‘There are over 400 dog breeds in existence today and the general pattern is that relative brain size has decreased dramatically in dogs compared to their ancestral species, the gray wolf.’

The theory that dogs’ brains have become smaller over centuries of domestication is widely accepted by veterinarians and researchers.

Whether it’s foraging for food, avoiding predators or finding a mate, domestic dogs are subject to less cognitive strain than wild dogs.

According to the theory, the brains of domestic dogs have gradually shrunk as the need for brain capacity decreases.

The team explains: ‘This phenomenon is thought to result from the decreased need for metabolically expensive brain tissue in a domesticated environment.’

In domesticated dogs, the brain size is significantly smaller than that of their wild ancestor, the gray wolf (Canis lupus, pictured).

The researchers wanted to know whether the brains of domestic dogs are unusually small (relative to their body size) compared to those of their wild counterparts.

They analyzed the brains and body size of 25 canid species, including the domestic dog (Canis familiaris), the gray wolf (Canis lupus) and the raccoon dog (Nyctereutes procyonoides).

They found that the brains of domesticated dogs were significantly smaller than those of their wild ancestor, the gray wolf.

But overall, the domestic dog had a relatively large brain size compared to some other species studied.

Interestingly, the study found that the common raccoon dog is a “more obvious outlier” in terms of brain size reduction.

In other words, the common raccoon dog’s brain is unusually small for its body size. The researchers believe this is because it is the only dog ​​that hibernates.

The picture shows the common raccoon dog (Nyctereutes procyonoides), a wild canid that hibernates

This graph shows the brain size (y-axis) and body size (x-axis) of individual canid species, including the domestic dog (Canis familiaris). Note the “outlier,” the common raccoon dog (Nyctereutes procyonoides), which has an unusually small brain for its medium-sized body.

Hibernation involves prolonged periods of low metabolic activity and food scarcity, likely leading to a reduction in brain size, the team said.

‘Prolonged periods of food shortage, such as during hibernation, prevent the development of large brains due to the constantly high energy requirements,’ the team said.

The study finds that while domestication contributes to the decline in brain size in dogs, hibernation is also another cause, at least in wild canids.

Domestication should not be overemphasized as a “uniquely powerful evolutionary force” that is shrinking dogs’ brains, the authors say.

The research was published today in Biology Letters.