Dreaming of de-extinction

As a young boy, Michael Archer from Australia had nightmares about the trilobite, an arthropod that succumbed to extinction 200 million years ago (fossil shown above). He was fascinated by the animal, once the most abundant resident of our oceans, and in his dreams he found a living trilobite. Only he didn’t know what to feed the little orphan, and so it died, despite his frantic attempts to find it suitable sustenance.
Archer went on to study paleontology, the science that examines the fossil remains of organisms. He became director of the Australian ­Museum for natural history. There he found a glass jar containing a fetus of the extinct thylacine, also known as the Tasmanian tiger, once a common carnivorous marsupial in Australia. European colonists who settled Down Under in the 17th century began hunting the species; the last specimen died in 1936.
Over the years, the thylacine came to interest Archer at least as much as the trilobite had in his youth. But there was a significant difference between the two: DNA from the thylacine was still available. Archer began to ponder how that DNA could be used to set up a cloning experiment. “I asked myself, Is extinction really forever? I grew up in a research field that was making that assumption. But I thought, Maybe we can bring back the Tasmanian tiger.” Archer’s colleagues laughed at the idea and ridiculed him for dabbling in science fiction.
That was nearly 15 years ago, and a few pioneers are now busy reviving extinct species. “De-extinction,” you could call their work. For example, American scientist Ben Novak is working on the resurrection of the passenger pigeon. In 2009, teams of Spanish and French researchers succeeded in cloning a Pyrenean ibex, extinct since 2000. (The animal died of lung defects shortly after birth.) Scientists are convinced that restoring these species will enrich our planet’s biodiversity. “This research triggers the hope that we may be able to reverse all the harm we did to nature,” Archer says, “such as the extinction of the thylacine.”
No one has yet succeeded in creating a healthy clone, but that’s just a matter of time, Archer says. “We’re currently stepping across the threshold into an entirely new world; a whole lot of things will have to be re-thought.” De-extinction experts held their first workshop in October 2012 in Washington, D.C., at the invitation of National Geographic and the Long Now Foundation’s recently created Revive & Restore project, which was designed to create greater awareness of the de-extinction science field. That meeting was closed, but in March 2013 the group went public to call for serious global discussion on the consequences of their research. By the way, no need to panic: There’s no way to bring back Tyrannosaurus rex. Dinosaur species’ DNA has not been sufficiently preserved, and, as biologist Robert Lanza put it, “you can’t clone from stone.”

The de-extinction techniques developed by biotechnologists center primarily around cloning. Consider Dolly, for example, the sheep cloned in 1996. Dolly’s genetic material was constructed using biotechnological procedures. She was identical to her mother; no father was involved. Since then, cloning techniques have continued to develop. Rats, mice, goats, monkeys and dogs have all been cloned. Now scientists are trying to collect as much DNA as they can from specimens of extinct species that have been preserved in labs and museums. Even a tiny sample of blood or tissue is enough to go on.
Novak found a few stuffed passenger pigeons in museums, from which he was able to put several pieces of the species’ DNA puzzle into place. He’s been unable to finish the job, however, because the stuffed birds’ tissue was not complete. His current plan is to start with the DNA of the related band-tailed pigeon and add the genes that make the passenger pigeon unique. A band-tailed pigeon could then give birth to a passenger pigeon. The Revive & Restore project is helping Novak with his research and using it as an opportunity to highlight some important questions about de-extinction: What criteria should we use to determine whether we should revive a species? How ethical is it to change a species’ DNA? Who will and will not be allowed to engage in species revival? And what are the consequences?
According to Novak, it’s extremely important to revive the passenger pigeon. Once—before they were all shot—passenger pigeons were the most common bird in North America: Some 4 billion to 5 billion of them filled the skies. They fulfilled an important role in nature, Novak says. “The way that dense flocks of passenger pigeons utilize forest regions for nesting sites and roosts spurs the ­development of all kinds of trees. This increases the types of biotopes available to other plants and animals and increases the productivity of biodiversity.”

Tasmanian Tiger
This image of the Tasmanian Tiger was taken while it was in captivity in the Washington D.C. National Zoo in 1906.

Archer believes it is equally important to revive the thylacine. “This unique animal is severely missed in Australia,” he says. According to Archer, it played an important predatory role in the ecological system. Moreover, it is important to study the animal’s genes and behavior because the distantly related Tasmanian devil is now threatened with extinction through cancer. A better understanding of the Tasmanian tiger’s genes might help researchers find a cure for the disease.
In the meantime, Archer is well on the way to reviving an ­extinct species of frog. The Rheobatrachus silus died out in 1983, and the medical world is eagerly waiting to study its stomach. The frog ­reproduces by swallowing eggs and turning its stomach into a kind of uterus. If scientists can learn to understand how the animal does that, it may have a significant effect on research into human gastrointestinal diseases.
The trilobite is eternally gone, but Archer is certain that many years from now, we won’t think twice about reviving more recently extinct species. “Think back 20 years ago,” he says, “and consider how far we’ve come with technologies.”
Photo of trilobite fossil: Flickr/ cobalt123
Video courtesy of TEDx
Photo of Tasmanian Tiger: Wikicommons Via Smithsonian Institute archives

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