Will it be possible to see woolly mammoths lumbering through their natural habitat in the wilds of Siberia or getting up close to a living Tasmanian tiger? The prospect of bringing back extinct animals is looking more likely than ever, by virtue of the developments in cloning and gene-editing technology.
Ten days ago, science media outlets around the world reported that a Harvard university led team was on the verge of resurrecting the woolly mammoth. Although many articles oversold the findings, the concept of de-extinction through genetic engineering is beginning to move from the realm of science fiction to reality. Bringing us more on this topic is Perspectoverse’s Hiba Riaz.
Cloning is the most widely proposed method to carry out the process of de-extinction, (the process of generating an organism that either resembles or is an extinct species) although genome editing and selective breeding have also been considered. In How to clone a mammoth : The science of De-extinction, Beth Shapiro, evolutionary biologist and pioneer in “ancient DNA” research, walks readers through the astonishing and controversial process of de-extinction. From deciding which species should be restored, to sequencing their genomes, to anticipating how revived populations might be overseen in the wild, Shapiro vividly explores the cutting-edge science that is being used today to resurrect the past.
Journeying to far-flung Siberian locales in search of ice age bones and delving into her own research, as well as those of fellow experts such as Svante Paabo, George Church and Craig Venter- Shapiro considers de-extinction’s practical benefits and ethical challenges. Would de-extinction change the way we live? What are the costs and risks? And what is the ultimate goal?
Using DNA collected from remains as a genetic blueprint, scientists aim to engineer extinct traits-traits that evolved by natural selection over thousands of years- into living organisms. But rather than viewing de-extinction as a way to restore one particular species, Shapiro argues that the overarching goal should be revitalisation and stabilization of contemporary ecosystems. For example, elephants with genes modified to express mammoth traits could expand into the Arctic, re-establishing lost productivity to the tundra system. Looking at the very real and compelling science behind an idea once seen as science fiction, How to clone a mammoth demonstrates how de-extinction will redefine conservation’s future.
On July 30, 2003, a team of Spanish and French scientists reversed time. They brought an animal from extinction, just to watch it become extinct again. The animal they revived was a wild goat known as bucardo, or Pyrenean ibex. The bucardo was a large creature, reaching up to 220 pounds. For thousands of years it lived high in the Pyrenees, the mountain range that divides France from Spain. As the hunters drove down the bucardo population over several centuries, Spanish scientists did a survey and concluded that there were only a dozen or so individuals left. Ten years later, a single bucardo remained: a female nicknamed Celia. Nine months later, they found her dead. With her death, the bucardo became officially extinct.
But Celia’s cells lived on, preserved in labs in Zaragoza and Madrid. Over the next few years a team of reproductive physiologists led by Jose Folch, injected nuclei from those cells into goat eggs emptied of their own DNA, then implanted the eggs in surrogate mothers. After 57 implantations, only seven animals had become pregnant and six ended in miscarriages. Although one mother- a hybrid between Spanish ibex and a goat- carried a clone of Celia to term. As they delivered the 4.5 pound clone, he could see that she was struggling to take in air, her tongue jutting grotesquely out of her mouth. Despite the efforts to help her breathe, after a mere ten minutes Celia’s clone died. A necropsy later revealed that one of her lungs had grown a gigantic extra lobe which raises the question: Could it still be done ? and Should cloning still be done?
Over the past decade scientists have improved their success with cloning animals, shifting the technology from high-risk science to workaday business. Researchers have also developed the ability to induce adult animal cells to return to an embryo-like state. These can be coaxed to develop into any type of cell and can be further manipulated into full-fledged embryos.
Such technical sleights of hand make it far easier to conjure a vanished species back to life. Scientists and explorers have been talking for decades about bringing back the mammoth. Their first and only achievement so far was to find the well-preserved mammoths in the Siberian tundra. Now, armed with the new cloning technologies, researchers at the Sooam Biotech Research Foundation in Seoul have teamed with mammoth experts North-Eastern Federal university in the Siberian city, drilling tunnels into the frozen cliffs. In one of those tunnels, they found chunks of mammoth tissue, including bone marrow, hair and skin. The tissue is now in Seoul, where the Sooam scientists are examining it.
Most scientists doubt that any living cell could have survived freezing on the open tundra. But Sooam’s Insung Hwang, who organized the Yana river expedition, had a plan B: to capture an intact nucleus of a mammoth cell, which is far more likely to have been preserved than the cell itself. The Sooam researchers will need to transfer the nucleus into an elephant egg that has had its own nucleus removed.
The dodo and the great auk, the thylacine and the Chinese river dolphin and the imperial woodpecker-the bucardo is the only one in the long list of animals humans have driven extinct, sometimes deliberately. Fernandez-Arias belongs to a small but passionate group of researchers who believe that cloning can help reverse that trend.
For the first time in history a group of geneticists, wildlife biologists, conservationists and ethicists had gathered at the National Geographic society’s headquarters in Washington DC to discuss the probability of de-extinction. One by one, they stood up to present remarkable advances in manipulating stem cells, in recovering ancient DNA, in reconstructing genomes. As the meeting unfolded, a consensus was emerging: De-extinction was now within reach.
“What we really need to think about is why we would want to do this in the first place, to actually bring back species’’ says Ross Mcphee, a curator of mammalogy at the American Museum of Natural History in New York.
In Jurassic Park dinosaurs are resurrected for their entertainment value. The disastrous consequences that follow have cast a shadow over the notion of de-extinction, at least in the popular imagination. But people tend to forget that Jurassic Park was a pure fantasy. In reality, the only species we hope to revive now are those that died within the past few tens of thousands of years and left behind remains that harbor intact cells or, at the very least, enough ancient DNA to reconstruct the creature’s genome. Because of the natural rate of decay, we can never hope to retrieve the full genome of Tyrannosaurus rex, which vanished about 65 million years ago. The species theoretically capable of being revived all disappeared while humanity was rapidly climbing toward world domination.
Other scientists who favor de-extinction argue that there will be concrete benefits. Biological diversity is a storehouse of natural invention. Most pharmaceutical drugs, for example, were not invented from scratch, they were derived from natural compounds in wild plant species which are also vulnerable to extinction. Some animals also performed vital services, which might benefit from their return.
Even if de-extinction proved a complete logistical success, the questions would not end. Passenger pigeons might find the rebounding forests of the eastern United States a welcoming home. But wouldn’t that be, in effect, the introduction of a genetically engineered organism into the environment? Could passenger pigeons become a reservoir for a virus that might wipe out another species.
De-extinction advocates are pondering these questions, and most believe they need to be resolved before any major project moves forward. Hank Greely, a leading bioethicist at Stanford university, has taken a keen interest in investigating the ethical and legal implications of de-extinction. And yet, as for many others, the very fact that science has advanced to the point that such a spectacular feat is possible is a compelling reason to embrace de-extinction.
Written by Hiba Riaz
Illustrated by Anushka Doshi
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