In 1925, a sled dog was named Palto He led the brave dog team on the final leg of a grueling 127-hour dog sled relay across Alaska to deliver life-saving medicine to the famous Nome people.Serum run. Balto was celebrated for this feat, even inspiring a 1995 animated film and two sequels. Now scientists have sequenced the dog’s genome for the first time and compared it to modern dog breeds, highlighting why Balto and similar sled dogs from the period proved so well-suited to growing in the harsh winter environment.

It turns out that Balto was just part Siberian husky and, contrary to popular myth, not part wolf. The authors even used the sequenced genome to reconstruct Balto’s physical appearance. These and other results appear in new leaf Published in the journal Science. It’s one of many featured in a special edition of results reporting from Zoonomia Projectan international collaboration to sequence and compare the genomes of 240 mammals in order to discover the genetic basis for traits essential to all animals, as well as the changes that underlie the unique traits of individual species.

“The fact that DNA from a small sample of Balto’s skin can provide new scientific insights is a powerful reminder of how advances in science continue to allow us to extract new information from museum collections.” Gavin Svenson saidChief Science Officer at Cleveland Museum of Natural History In Ohio, where Balto’s mummified remains are located. “Each of the millions of objects in our museum has the potential to reveal important clues to the world of the future, which in turn can advance our understanding of the past, present, and future of the world around us.”

Balto was born in 1919 to a breeder of sled and ski dogs Leonard Seppala. Balto was neutered at six months old because Seppala considered him a “scrub dog”, stronger and more robust than the small, fast-racing huskies that were normally bred, and therefore better suited to carrying goods. But the dog continued to prove his mettle when, in January 1925, there was a severe outbreak of diphtheria in Nome, the city’s harbor was surrounded by ice and therefore inaccessible from the sea.

The life-saving serum needed by residents was in Anchorage, about 674 miles away, and the engine of the only available plane froze and wouldn’t start. So the officials decided to organize a relay for the dog sled teams. The conditions faced by the more than 20 mushers who took part in the Serum Run were harsh, featuring strong winds and temperatures of -23 degrees Fahrenheit (-31 degrees Celsius), as well as a blizzard.

named pilot Gunnar Casson He was in charge of Balto’s sled dog team. Kaasen took charge of the serum pack on February 25 at Bluff and led the sled to Port Safety, where the last team, led by Marshal Ed Rohn, was supposed to take over on the final stretch of the race. Kassen gets there earlier than expected, and Ron is still asleep, so Kassen decides to save time and run the final match himself, with Balto in the lead. They reached Nome at 5:30 the next morning and distributed ampoules of medicine. Legend has it that after delivering the medicine, Kassen hugged Balto and declared him “a wonderful dog.”

It should be noted that there is some debate as to whether Balto actually led the sled team, given his relative lack of experience in the role, or whether he was led by another dog named Fox. Kaasen’s historic photos and videos with Balto in Nome were re-creations taken hours after they arrived. Ron and many other vagabonds believed that Kassen’s decision not to wake Ron was less altruistic than Kassen claimed – that he wanted to take all the glory for himself. Even Seppala was upset at Balto’s sudden fame. Seppala has always been disappointed in Balto and felt for his dog Togo, who drove for another team, deserved equal recognition because the Togo team had endured the longest and most dangerous part of the race. (Togo eventually got a Disney movie 2019.)

Unfortunately, fame is fickle and fleeting, even for heroic sled dogs. Balto could not be raised as a breeder because he was neuter, so he and his team ended up on the vaudeville circuit. In the end, Kaasen sold the dogs to the highest bidder to finance his trip to Alaska. Former Cleveland fighter George Kimble encountered Balto and his team in chains at a new museum in Los Angeles, where they were treated badly in cramped and unsanitary conditions. An enraged Kimble organized a successful campaign to raise money to bring the dogs to Cleveland, where they received a hero’s welcome in March 1927. Balto and the six other surviving dogs on his team lived at the Brookside Zoo (later the Cleveland Zoo Metroparks) for the rest of their lives.

Balto died of natural causes in 1933, and a taxidermist installed his remains. It has been on display at the Cleveland Museum of Natural History ever since, apart from occasional loan – most notably in 1998 for a five-month stay at the Anchorage Museum of History and Art. His physical remains prove the importance of this latest study. “Balto’s fame and the fact that he was a taxidermist gave us this wonderful opportunity 100 years later to see what this group of sled dogs would have looked like genetically and compare it to modern dogs.” said co-author Catherine MoonHe is a postdoctoral researcher in paleobiology University of California, Santa Cruz.

After sequencing Balto’s genome, Moon and his coauthors compared it to 682 extant genomes of modern dogs and wolves, as well as an alignment of 240 mammalian genomes developed by the Zoonomia Consortium. This genome alignment tool, developed at the University of California, Santa Cruz, was important to their analysis. A gene on one chromosome in us is on a completely different chromosome in another species. said co-author Beth Shapiro, an evolutionary biologist at the university. “You need a tool that can arrange them so that you can tell which parts of these genomes are similar and which are different. Without that, it’s just a collection of genomes from highly variable species.”

The results showed that Balto was only partly Siberian husky, with additional ancestry related to Alaskan sled dogs, village dogs, Greenland sled dogs, and Tibetan mastiffs. His population of working sled dogs was genetically more diverse than modern Siberian Huskies, and these genetic variants may be why Balto and his ilk were so well equipped to thrive in the harsh Alaskan environment of the 1920s. For example, Balto had genetic variants related to weight, coordination, joint formation, and skin thickness, according to Moon. And Balto would have been better able to digest starch than wolves and Greenland sled dogs, though not as well as modern dogs.

For a reconstruction of Balto’s appearance, analysis of known relevant genetic variants was consistent with Balto’s smaller stature and atypical coat characteristics, as shown in historical photographs and his taxidermy remains. His coat was double-layered and mostly black, with a bit of white on his chest and legs. While the Balto genome contains alleles for light pigmentation and blue eyes, the authors said that “both were masked by his melanistic face.”

“It’s really exciting to see the evolution of dogs like Balto, even just in the last 100 years,” Moon said. This project gives everyone an idea of ​​what is starting to become possible as more high-quality genomes become available for comparison. It’s an exciting moment because these are things we’ve never done before. I feel like an explorer, and once again Balto is leading the way.”

DOI: Science, 2023. 10.1126 / Science. abn5887 (about DOIs).