How selective breeding disrupts dog brains

The selective breeding of dogs was initiated by the British in Victorian times, while many sincerely believed in eugenics as a means of “purifying” and improving both man and animal. Beyond its ideologically horrific roots, breeding has had all kinds of unintended consequences for dogs in particular, from chronic breed-related illnesses to temperament issues to the premature death of some breeds.

For better or for worse, we live in the world of the Victorians: we always think of dogs in terms of breeds, rather than thinking of “mutts” as the normal and genetically average dog, and pure breeds as weird aberrations. and inbred. So, we are used to having stereotypes about different breeds that go beyond appearance: Golden Retrievers are affable family dogs, while Chihuahuas are neurotic.

But are these traits real, imagined, or culturally specific? Recently, researchers have attempted to determine precisely this – whether breeding has altered the physical structure of dogs’ brains, making certain regions larger or smaller in a way that fits behavioral stereotypes.

“The first question we wanted to ask was: Are the brains of different breeds of dogs different?” Erin Hecht, a neuroscientist studying canine cognition at Harvard University and lead author of the study, told the Washington Post.

In a first such study, the researchers, who published their results in the Journal of Neuroscience, found that different races have different brain organizations due to human reproduction. This means that dogs’ skills vary and are caused by their different neuroanatomy.

For example, “breeding is really in the brain of border collies”, Hecht told StatNews, “and these results give us the first window into how.”

Hecht and his colleagues analyzed MRI scans of 62 purebred dogs representing 33 breeds. Through this analysis, they identified six brain networks – the structure of the dog’s brain – that are most common between breeds, but also exhibited neuroanatomical differences. What they found was that the differences in the brain were linked to differences in behavior in different races.

For example, there is a brain network that causes the brain to respond strongly to a reward, such as a treat, that promotes social bonding. While dogs already associate the treats with the people who give them, in terriers this network is particularly developed, according to the study.

“These results establish that brain anatomy varies considerably in dogs, possibly due to behavioral selection applied by humans,” the authors wrote. “We have found that the anatomy of the brain varies considerably with behavioral specializations such as sight hunting, scent hunting, guarding, and companionship.”

The study provided insight into dogs with particularly complex looking skills, such as Border Collies, who are predisposed for herding abilities. Although Border Collies are not born knowing how to herd, their brains are pre-wired to learn. Hecht compared it to how human toddlers are pre-wired, to some extent, to learn the language.

“They [the Border Collies] must be exposed to sheep; there is some training involved. Learning plays a crucial role, but there is clearly something about breeding that is already in their brains when they are born ”, Hecht noted. “It is not an innate behavior, it is a predisposition to learn this behavior.”

Hecht told the Harvard Gazette that there had been some surprises in their research. In particular, they found that scent hunting was not associated with the anatomy of the olfactory bulb, which is a part of the brain that detects odors. “Rather, this skill was related to higher order regions involved in more complex aspects of perfume processing,” she said.

“It’s not about having a brain that can detect if the smell is there. It’s about having the neural machinery to decide what to do with that information, ”added Hecht.

Hecht noted that understanding the relationship between brain wiring and learned behavior “might tell us something about our own brain and how it happens” in humans as well.


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Jeanetta J. Stewart

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