by By comparing the genetic blueprints of a range of animals, scientists are gaining new insights into our own species and everything we share with other creatures.
One of the more startling revelations is that some passages in the instructions for life have persisted through evolutionary time, representing a boundary line that binds all mammals, including us.
The findings come from Project Zoonomia, an international effort offering clues about human traits and diseases, animal abilities like hibernation and even the genetics behind a sled dog named Balto that helped save lives a century ago.
The researchers shared some of their findings in 11 papers published Thursday in the journal Science.
David O’Connor, who studies primate genetics at the University of Wisconsin-Madison, said the studies address profound questions.
“It’s just the wonder of biology, how we are so similar and different from all the things around us,” said O’Connor, who was not involved in the research. “It’s the kind of thing that reminds me why it’s good to be a biologist.”
The Zoonomia team, led by Elinor Karlsson and Kerstin Lindblad-Toh of the Broad Institutes of MIT and Harvard, examined 240 species of mammals, from bats to bison. They sequenced and compared their genomes: the instructions organisms need to develop and grow.
They found that some regions of these genomes have remained the same in all mammalian species over millions of years of evolution.
One study found that at least 10% of the human genome is largely unchanged across species. Many of these regions are found outside the 1% of genes that give rise to proteins that control cell activity, the main purpose of DNA.
The researchers theorized that the long-conserved regions likely serve a purpose and are likely what they call “regulatory elements” containing instructions about where, when and how much protein is made. Scientists have identified more than 3 million in the human genome, about half of which were previously unknown.
Scientists have also focused on change within the animal kingdom. When they aligned the genetic sequences for the species and compared them to their ancestors, Karlsson said, they found that some species saw a lot of changes in relatively short periods of time. This showed how well they were adapting to their environments.
“One of the really cool things about mammals right now is that they’ve basically adapted to survive in almost every single ecosystem on Earth,” said Karlsson.
A group of scientists has been looking for genes that humans don’t have, but other mammals do.
Instead of focusing on new genes that could create uniquely human traits, “we kind of turned the tables,” said Steven Reilly, a genetics researcher at Yale University.
“The loss of pieces of DNA can actually generate new features,” Reilly said.
For example, he said, a tiny DNA deletion between chimpanzees and humans caused a cascade of changes in gene expression that could be one cause of prolonged brain development in humans.
Another study focused on the fitness of a well-known animal: Balto.
Scientists have sequenced the genome of the sled dog, which in 1925 led a team of dogs carrying a life-saving diphtheria serum to Nome, Alaska. His story was made into a 1995 animated film and a statue of the puppy stands in New York’s Central Park.
By comparing Balto’s genes to those of other dogs, the researchers found that he was more genetically diverse than modern breeds and may have carried genetic variants that helped him survive harsh conditions. One of the authors, researcher Katherine Moon of the University of California, Santa Cruz, said Balto “gives us this guide through comparative genomics,” showing how genetics can shape individuals.
O’Connor said he expects Zoonomia to provide even more insights in the future.
“Having these tools and having the kind of boldness to ask these big questions” helps scientists and others “learn more about life around us,” he said.
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