Study Suggests Dogs Today Are Experiencing a Mysterious Brain Growth

A recent European study reveals that contemporary dog breeds possess larger brains compared to their ancient counterparts. Researchers suggest that this increase is linked to the complex social environments that modern dogs now navigate.

While domesticated animals generally have smaller brains than wild species, modern dogs are showing a trend toward closing that gap. Though their brains have not yet reached the size of a wolfs, the difference is decreasing.

The study, published in Evolution, examined brain volumes in both modern and ancient dog breeds. Scientists discovered that breeds genetically farther from wolves tend to have relatively larger brains. This surprising finding challenges previous assumptions about domestication and brain size.

Our results indicate that selective breeding in modern dogs has coincided with brain enlargement compared to older breeds, said Enik Kubinyi from the Department of Ethology at ELTE Institute of Biology. We cannot attribute this solely to breed-specific tasks, so the underlying reasons remain speculative.

The research team, comprising scientists from Hungary and Sweden, analyzed CT scans of over 850 dogs from 159 breeds and compared them with 48 wolf specimens. Findings confirmed that, for a dog of similar body weight to a wolf, brain volume is about 75% of the wolfs size, supporting earlier research showing a roughly 20% reduction due to domestication.

Maintaining a large brain is energetically expensive. Energy saved can be redirected to other functions, such as reproduction, explained Lszl Zsolt Garamszegi, evolutionary biologist at the Ecological Research Centre in Hungary.

Interestingly, breeds further removed from wolves genetically displayed larger relative brain sizes, regardless of their roles or energy-intensive responsibilities. Kubinyi suggests that urban living, intricate social rules, and close human interaction may have driven this evolution across all modern breeds.

The study also found that factors such as skull shape, lifespan, litter size, and functional category did not significantly affect brain size. Ancient breeds tend to show more independence, vocalize less, and respond less to human signals, reinforcing the idea that social environment plays a key role in modern dogs brain growth.

Dogs inhabit diverse social settings and perform complex tasks, which may demand larger brain capacity, said Niclas Kolm of Stockholm University. We believe selective pressures on the brain differ among breeds, influenced by their tasks and genetic distance from wolves.

Author: Natalie Monroe