"DNA from the legendary husky whose achievements in part inspired the Iditarod Trail Sled Dog Race is helping reveal how the intrepid canine -- named Balto -- and his contemporaries could survive and succeed in the harsh Alaskan environment a century ago.
New research led by scientists at the University of California, Santa Cruz delved deep into the genome of Balto and found he and his fellow sled dogs were genetically healthier than modern dog breeds.
"He had lower rates of inbreeding than other dogs, and fewer potentially rare and damaging genetic variations as well," said Katie Moon, a UC Santa Cruz paleogenomicist who led the work, which was published Thursday in the journal Science. "There aren't related individuals mating to create the next generation."
Balto made his paw print on history during the winter of 1925, when a diphtheria outbreak swept through Nome, Alaska. With an epidemic imminent and accessibility limited -- the remote town could be reached only by sled dog -- a group of 20 mushers worked together to transport lifesaving medicine from the nearest railway station, 674 miles south in Nenana. Balto led the last leg of the roughly six-day relay. Upon delivering the medicine, he and his musher were heralded as heroes. The sled dog's legacy spawned movies, books and a statue in New York City's Central Park.
After his death in 1933, Balto's taxidermied remains eventually were put on display in the Cleveland Museum of Natural History in Ohio. The study authors collected Balto's DNA from a skin sample taken off the well-preserved dog's underbelly. They then compared his genome to ones from hundreds of individuals encompassing more than 130 species of modern dog, wolf and coyote. The work is part of the Zoonomia project, an international effort that sequenced and compared genomes of 240 mammalian species.
Despite having belonged to a population of huskies imported to Alaska from Siberia in the early 20th century, Balto differed physically -- he and his kin were small, fit and fast -- and genetically from the Siberian husky breed recognized today.
"He was rich in genes that were associated with tissue development -- those would have been involved in things like muscle growth and metabolism and oxygen consumption," said Beth Shapiro, an evolutionary biologist at UC Santa Cruz and co-author of the study. "Exactly the kind of traits that you would need in a dog that was doing this endurance kind of work."
Modern Siberian huskies are less genetically diverse than Balto and his kin were, likely because of current breeding practices, according to Kathleen Morrill, a genomic scientist and a study co-author. "A lot of the modern breeds today are held to very strict physical standards," Dr. Morrill said, adding that not all Siberian huskies today fulfill the same function as their ancestors did.
Heather Huson, a Cornell University animal geneticist and another study co-author, said a future goal would be to try to identify what genes in, for example, modern Alaskan sled dogs make the animals so fast and possess such endurance.
"Why is a sled dog as hardy and strong as it is, physically and behaviorally?" said Dr. Huson. "What makes them do the things they do and persevere in such harsh environments, and love it?"" [1]
1. U.S. News: DNA Reveals Secret to Heroic Dog's Success
Woodward, Aylin. Wall Street Journal, Eastern edition; New York, N.Y. [New York, N.Y]. 29 Apr 2023: A.6.
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