“Hidden Details of World’s Most Famous Sled Dog Revealed in Massive Genomics Project: Hundreds of Genomes Clarify the Life of Balto and the Fate of Free Willy’s Peers”, 2023-04-27 (; backlinks):
…Now, researchers have pieced together a fuller picture of the celebrated canine from DNA taken from the underbelly of his stuffed, faded carcass. Aided by hundreds of newly sequenced genomes and an extensive database of dog DNA, they were able to glean details about Balto’s size, appearance, and stamina not captured in historical photos of the famed canine.
“Even with the genome of a single individual, you can learn a lot”, says Nathan Upham, an evolutionary biologist at Arizona State University who was not involved with the research. The work, reported today in Science with 10 other papers about a massive sequencing effort called Zoonomia, speaks to the power of having many accurately sequenced genomes on file, says Greger Larson, an evolutionary geneticist at the University of Oxford who also was not involved in the research. He says the project will permit scientists to better assess the looks, physiology, and perhaps even the conservation status of species based on single genomes. “The predictive ability is just staggering.”
For the Zoonomia project, researchers from around the world obtained and compared complete DNA sequences of 240 placental mammals, from tiny bumble bee bats to giant whales, then matched up all the genomes to see what DNA was the same, or conserved, in all of them. This conserved DNA reveals genes critical to a mammal’s survival, as harmful deviations are less likely to have been passed down. “We can learn exciting things about how species diverged and adapted”, says Zoonomia collaborator Beth Shapiro, a paleogeneticist at the University of California, Santa Cruz.
But Shapiro and her postdoc, Katie Moon, also wanted to know what this new resource could reveal about individuals. So, they sequenced DNA from a pencil eraser-size tissue sample from the 100-year-old sun-bleached belly of the stuffed Balto, who is on display at the Cleveland Museum of Natural History.
That feat was “extraordinary”, says Elaine Ostrander, a dog geneticist at the National Human Genome Research Institute (NHGRI) not involved with the work. “It gives us a very clear picture of dogs who were selected for [sled dogs] at that point in time.”
…From Balto’s DNA, Morrill, Moon, and their colleagues determined that he was a relatively small sled dog. At 55 centimeters at the shoulders, he was smaller than most Siberian huskies and Alaska malamutes, sled dogs later recognized as American Kennel Club breeds. They also predicted that Balto would have had a double layer of black fur twinged with tan; modern sled dogs tend to have just a single layer. All of this matched up with and further clarified the dog’s actual appearance, Moon says. “It was something that I never thought would be possible.”…In the past, characterizing an individual’s traits based on DNA—say the red hair of ancient humans—“you just have to go on faith” that they are right, Larson says. With Balto, scientists actually know what he looked like, he says, so he’s “a brilliant control. You can make all these predictions that turn out to be absolutely true.”