What motivated the creation of working dog breeds?

Genetic variants associated with brain development help distinguish breeds designed for different physical tasks, new study finds.

In creating modern dog breeds, humans have sculpted canines into physical specimens perfectly suited for a wide variety of tasks. Bernese Mountain Dogs have strong, muscular bodies capable of pulling heavy loads, while Greyhounds have lean, streamlined frames that are ideal for hunting deer. The compact Jack Russell terrier can easily sneak into fox or badger dens.

Now a large study, published in Cell on Thursday, suggests behavior, not appearance alone helped qualify these dogs for their work. Breeds that were bred for similar roles - whether herding sheep or chasing birds through the air - tend to cluster into distinct genetic lines, which may be characterized by different combinations of behavioral tendencies. , the researchers found.

"Much of modern breeding has focused primarily on the appearance of dogs," said Evan MacLean, an expert in canine cognition at the University of Arizona who was not involved in the study, in an email. But, he pointed out, "long before we were breeding dogs for looks, we were breeding them for behavioral traits."

The study also revealed that many of the genetic variants that distinguish these lineages from each other appear to regulate brain development, and many appear to predate modern races. Together, the findings suggest that people may have created today's amazing assortment of breeds, in part by exploiting and preserving desirable behavioral traits that already existed in ancient dogs, the researchers said.

"Dogs basically have the same blueprint, but now you have to emphasize certain things to accomplish particular tasks," said genomics expert Elaine Ostrander canine at the National Human Genome Research Institute and lead author of the study. "You're going to change a gene, you're going to change it."

In an email, Bridgett vonHoldt, an evolutionary biologist at Princeton University who was not involved in the research, called the new paper "a major landmark in the field of canine genomics and behavior." We know it's complicated. This study not only gives us hope, it will be seen as a source of inspiration for all in the field. deliberately sought to create breeds with specific behavioral tendencies. "We don't have a ton of evidence for intentional selection," said Elinor Karlsson, a canine genomics expert at the University of Massachusetts Chan Medical School, who was not involved in the research.

But she praised the study, noting that the results were consistent with her own research, which also concluded that many genetic factors that shape the behaviors of modern dogs have their origins in canine history.

ImageResearchers analyzed behavioral surveys conducted by owners of over 46,000 purebred dogs to match behavioral traits with bloodlines.Credit...Jonno Rattman for The New York Times

"They really profit of this truly complex history of dog breeds, and these differences in com relatively subtle but real behavioral traits, to explore how genetics and genetic variation can actually shape these behavioral traits,” she said.

Behavioral breeding

Researchers studied the genomes of more than 4,000 canids, i...