Genes for Curiosity Separate Working German Shepherds From Show Dogs

"It's interesting that we can now see that this selective breeding has indeed led to differences between working dogs and show dogs among German shepherds — differences that can be seen at both the behavioral and genetic levels," Lindblad-Toh said.

How did the researchers find the genes?

Behavior alone wasn't enough. The team then collected blood samples and mapped the complete genomes of 373 German shepherds from the pool of DMA-tested dogs — roughly one in every 62 of the animals in the behavioral dataset.

With genomes in hand, the researchers could compare DNA against behavior scores. The divergences were stark enough to locate on the genome.

"We could then see that there were areas in the genome where differences could be seen in the dogs depending on how curious or playful they were, for example," Lindblad-Toh explained. "That meant that we were able to identify some of the genes in working dogs that are linked to curiosity and playfulness."

Why would working lines carry these variants? Breeding, basically. "Breeders of working dogs have selected and bred the ones that really enjoy working; it's a bit like a game for them," she said.

What does this have to do with humans?

Here's the part that could matter beyond dog breeding: in some cases, the same genes shaping German shepherd personalities are also tied to the same behaviors in people. That overlap suggests dogs could become a useful model for studying human psychology — a much easier population to test, measure and breed selectively than humans.

Lindblad-Toh is careful about how far this goes, though. She described the study as "just a first step" along that path. It's an association found in one breed, not a demonstrated cause, and the sample of fully sequenced dogs — 373 animals — is a fraction of the behavioral cohort. The next phase, she and her colleagues hope, is learning more about breed-specific genetic traits and how they overlap with owners.

"We now have an example of how we might also acquire more knowledge about different behaviors in people with [the] help of dogs in the longterm," she said.

Why German shepherds?

The breed has a defined starting point, which makes it a good natural experiment. Max von Stephanitz introduced the German shepherd in 1899, breeding dogs for the practical work the name implies. More than 125 years later, the breed has split into two worlds: you're as likely to see one sniffing for contraband at an airport as competing at a kennel club show.

Those two careers demand very different temperaments — and, it now appears, select for slightly different versions of the same genome.