It's been 4500 years since herds of wooly mammoth roamed the earth, and passenger pigeons have been gone for a century. But if a group of biologists and genetic scientists is successful, they might just make a comeback. We report on a project to bring back extinct animals. Reporter: Deirdre Kennedy
Biologists and genetic scientists in California are working on a project to bring back extinct animals.
But before you start imagining T-Rex stomping through your local shopping mall, be assured that dinosaurs are off the menu. That’s because there’s no DNA in dinosaur fossils. And without DNA, as one genetic scientist says: “You Can’t Clone from Stone.”
At a recent TEDx conference, experts from all sides of the “de-extinction” issue spoke about the pros and cons of re-animating long-dead creatures.
Evolutionary biologist Beth Shapiro boiled down the complex process of cloning a woolly mammoth, starting with creating a genetic blueprint.
“First you have to sequence the genome and somewhere in there are the genes that code for the proteins that make the cells in the body and the behaviors. … Then we have to get these genes onto the chromosomes. Then we have to get the chromosomes into the nucleus and the nucleus into the cells so that they can start to divide, and then we have to get the cells and the embryo into a surrogate mother.”
Shapiro and other scientists have hauled tens of thousands of bones from a giant freezer full of mammoth DNA – otherwise known as the Arctic. Sequencing a genome from a living subject has gotten a lot faster, but Shapiro said there’s a huge challenge with extinct animals because the genetic information falls apart.
“You imagine our own DNA is like a rope or a party streamer… then the mammoth genome is going to be more like confetti that’s been run over by a herd of mammoths in the rain," she said.
So, woolly mammoths aren’t on the horizon. But Shapiro and her colleagues at UC Santa Cruz are also working on bringing back the passenger pigeon – not to be confused with carrier pigeons, which are the ones that delivered messages during wartime.
In 1800, there were billions of passenger pigeons in North America. Now you can find the bird preserved only in private collections and research institutions, such as the one at the California Academy of Sciences in San Francisco. Jack Dumbacher, chairman and curator of the department of ornithology, brought me into a special climate-controlled room that houses 110,000 specimens. He unlocked an airtight cabinet and slid open a thin drawer, where a row of taxidermied birds were laid out and tagged.
He picked up one of the passenger pigeons and stroked its feathers as he described its features in an almost reverential tone.
“They kind of look like a giant morning dove -- mostly gray above and they’re sort of buffy tan below," Dumbacher said. "And they have a long pointed tail. And on the sides of the head you see this beautiful iridescent purplish glow.”
Back in the 19th century, passenger pigeons were considered pests or cheap food. You could buy one for a dime. The telegraph was instrumental in their destruction because word spread about where the pigeons were migrating, and trainloads of people would go out and shoot them. Within 50 years, their population was halved. Within a few decades, the birds that once filled the skies were completely obliterated.
Scientists are hoping to bring back the passenger pigeon with some help from its nearest living relative -- California’s band-tailed pigeon.
The idea is to use the band-tailed pigeon to carry passenger pigeon chicks. But there’s a problem. You can’t introduce DNA into a bird egg, because the embryo is sealed inside the shell long before it is laid.
Graduate researcher Ben Novak said, “If we disrupt the process of that egg being formed, then the embryo won’t form properly and the egg won’t work.”
Novak and his colleagues want to try a different strategy: genetically alter band-tailed pigeons using passenger pigeon DNA. That technology is still being developed. But Novak already has figured out how to teach the chicks to sing and migrate to their former habitat once they are hatched.
“The plan is to use pure white homing pigeons and cosmetically color them the same color as a passenger pigeon," Novak said. "That way your baby passenger pigeon hatches and it sees a pigeon that looks like a passenger pigeon.”
That’s a step up from the hand puppets that biologists used to raise California condor chicks in captivity.
Novak’s project was created by the San Francisco-based Long Now Foundation. Co-founder Alexander Rose said the “Revive and Restore” project also aims to help save thousands of species from extinction.
“You learn very quickly, in trying to bring back an extinct species, how much easier it is to keep a species alive," Rose said. "And a lot of the techniques you use for bringing back a species can be used for revitalization.”
For now, the concept of de-extinction is closer to the realm of science fiction than the realm of possibility. But it has launched a sort of space race for biologists that could spin off other beneficial discoveries. Even if researchers don’t reach their goal, they will likely develop genetic therapies for human medicine and greatly increase our understanding of the animal world.