Matthew Lewis, the African species expert for World Wildlife Foundation, says, "In just the past few years, we've lost the Western black rhino, the Vietnamese Javan rhino and the Northern white rhino is assumed to be extinct in the wild. At the rate rhino poaching is increasing in southern Africa, no rhino species is safe from extinction." (Green Renaissance/WWF/WWF'S Black Rhino Range Expansion Project)

Imagine the most fantastical creatures that ever lived — the wooly mammoth, the saber-tooth tiger, the Dire Wolf, Haast’s Eagle — and now imagine them brought back from extinction through a miracle of modern genetics. A groundbreaking new project from Stewart Brand (yes, that Stewart Brand) called “Revive & Restore” hopes that a process called de-extinction can bring back extinct species, such as the passenger pigeon, and restore them to their former glory. Narcissistic? Perhaps, but it’s a truly mind-blowing idea that now has support from the likes of TED, the National Geographic Society and some of the smartest scientists on the planet.

As Carl Zimmer writes in the April cover story for National Geographic, the concept of de-extinction rests on a relatively simple premise: that we can locate DNA samples from the ancient past, reassemble this DNA into a full genome, inject this genome into embryonic cells that have been emptied of their own DNA, and then find a suitable modern surrogate to give birth. In the case of the passenger pigeon, this cloning process would take place with the help of the band-tailed pigeon, its closest living relative. In cases where there are not enough DNA fragments to construct a full genome, as in the case of most species that disappeared thousands of years ago, geneticists would essentially need to “reverse engineer” the species through the manipulation of stem cells and the splicing together of DNA fragments.

So where are we now? Ten years ago, a team of French and Spanish scientists almost brought back an extinct wild goat known as the Pyrenean ibex.They used roughly the same process outlined above and after 56 attempts to impregnate a modern-day goat with the extinct goat’s DNA, they found a surrogate mother who could give birth to the extinct wild goat. Yet, the “de-extinct” goat only lived for 10 minutes before a severe genetic mutation resulted in the goat’s tragic death.

Even the strongest proponents of de-extinction admit that there are a whole host of problems to work out on the scientific side, such as how do you get a good enough sample of DNA to make the cloning possible in the first place? If you think that de-extinction could ever lead to a “Jurassic Park” scenario of cloning dinosaurs for fun, think again. There are no samples of dinosaur DNA to make this happen. (Hence, the newest bit of Twitter wisdom, "You can't clone from stone") Even then, there are all kinds of issues of how to keep alive an animal in captivity, how to re-release the extinct species into the wild, and how to build a thriving population in a new ecosystem.

A sand kitten sits at her enclosure at the Ramat Gan Safari near Tel Aviv August 14, 2012. Four sand kittens, considered extinct in Israel, were born 3 weeks ago at the safari park, an open-air zoo, a statement from the safari said. (NIR ELIAS/REUTERS)

And how do we even know that we brought back the right species? If it looks like a dodo bird, quacks like a dodo bird, but has slightly different DNA from the last living dodo bird, does it mean it’s still a dodo bird?

And that doesn’t even scratch the surface of the moral and philosophical questions that de-extinction raises. At the TEDx DeExtinction event in Washington, D.C. last week, for example, participants raised the question of whether we would even want to bring back an extinct species if we could. After all, if you view extinction through a Darwinian lens — as a process for weeding out the species that proved to be unfit and inferior over time because of a failure to adapt — then we’re essentially reversing the evolutionary process. That’s not something to be taken lightly. Reviving an extinct species and trying to re-introduce it into the wild might cause an unknown shock to a natural ecosystem, a Butterfly Effect in reverse.

At the end of the day, though, that’s what makes de-extinction such a mind-blowing concept — as well as such a fertile topic for science fiction writers (and TED speakers). The moral and ethical consequences of de-extinction are staggering, but so are the moral and ethical consequences of letting a species go extinct. If the passenger pigeon de-extinction project from Revive & Restore is ultimately successful, it would not only open a door to breathtaking advances in genetic engineering, it could also help to undo hundreds of years of ecological damage that the human species has inflicted on planet Earth.

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