We’re getting a lot better at cloning than we used to be. Just last week, in fact, Japanese scientists revealed news that they had successfully cloned 25 generations of mice from the same single mouse. It wasn’t so long ago that our clones— like Dolly, the Scottish Sheep—were effectively “born old” at best, or completely unviable. Today, it seems clear that clone perfectibility is a possibility.Indeed, it’s hard to call the results from those Japanese experiments anything less than perfect. The 581 mouse clones—and clones of clones—all lived full, healthy lives, and could reproduce normally, in that particularly virile fashion for which rodents are known. It’s raised a lot of discussion. And one of the more compelling ideas put forward by the scientists who conducted the study was the idea that cloning could be the key to saving species that are going extinct.It’s at least conceivable, given these recent advances, that species that are already extinct could be revived, Jurassic Park-style, with a suitable DNA sample. (Unfortunately, new research shows Jurassic Park is probably impossible because DNA, it seems, has a half-life—about 521 years. Harvard Genetics professor George Church thinks recreating Neanderthals, however, is distinctly possible.) But horror and sci-fi scenarios notwithstanding, is it desirable to recreate any extinct species? Surely there’s nothing wrong with recreating, say, the dodo bird, or the Pyrenean ibex, right?Wrong, says Stuart Pimm, an ecology professor at Duke, for National Geographic . His reasons are partly what we might call a moral argument: We’re misplacing our priorities to concentrate our efforts on extinct species:De-extinction intends to resurrect single, charismatic species, yet millions of species are at risk of extinction. De-extinction can only be an infinitesimal part of solving the crisis that now sees species of animals (some large but most tiny), plants, fungi, and microbes going extinct at a thousand times their natural rates.But Pimm’s argument is also practical. Keeping just one dinosaur alive would require thousands of trees throughout its lifetime, a luxury the earth can’t afford today the way it could during the Mesozoic Era. Even in less extreme scenarios, Pimm says, “practical problems abound.” To wit:A resurrected Pyrenean ibex will need a safe home, not just its food plants. Those of us who attempt to reintroduce zoo-bred species that have gone extinct in the wild have one question at the top of our list: Where do we put them? Hunters ate this wild goat to extinction. Reintroduce a resurrected ibex to the area where it belongs and it will become the most expensive cabrito ever eaten.Even the passenger pigeon’s habitat is not still sufficiently intact to merit brining them back. “The land use changes since then,” Pimm says, “have been far too extensive.”Well, that isn’t much fun, is it? No, but it’s a fair point. Pimm’s isn’t the only opinion out there, though. As Carl Zimmer notes in his wonderful breakdown of the issue for a NatGeo symposium on species de-extinction, some scientists who argue in favor of de-extinction say “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 found in wild plant species, which are also vulnerable to extinction. Some extinct animals also performed vital services in their ecosystems, which might benefit from their return. Siberia, for example, was home 12,000 years ago to mammoths and other big grazing mammals. Back then, the landscape was not moss-dominated tundra but grassy steppes. …The mammoths and numerous herbivores maintained the grassland by breaking up the soil and fertilizing it with their manure. Once they were gone, moss took over and transformed the grassland into less productive tundra.There are other potential benefits to bringing species back, as Stewart Brand notes. He points, among other things, to possibility of restoring genetic variability in certain species that are struggling. “A species with a genetic Achilles' heel,” he writes—like Tasmanian devils who have a transmissible cancer believed to be caused by a single gene—“might be totally cured with an adjustment introduced through cloning.”Those arguments are certainly compelling. But the lessons of Jurassic Park, fictional as it may have been, are instructive. It’s impossible to really conceive of what it would be like to release a mammoth back onto the tundra without the vast, vast host of other flora and fauna that constituted its original ecosystem. We might have a mini, second-time-around extinction on our hands.But, damn, it would sure be cool to see one.
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