Wednesday, 2 October 2013

Building Lazarus: How to Bring Back Extinct Animals

Humans have an uncanny ability to kill things. Going back as far as the first colonization of the Americas, people have been credited with wiping out everything from wooly mammoths, to giant ground sloths, to passenger pigeons, to the European Aurochs (the ancestor of all domestic cattle). Show us a sky that is darkened with the soaring bodies of millions of majestic birds, and pretty soon we will show you an impressive pile of meat.




Fortunately, a few more enlightened souls are at work to undo some of the steam-rolling of the past. Using any one of several ingenious methods, biologists might soon start filling in the holes in nature that our forefathers carved out with spears and shotguns. It sounds a bit like the plot to Jurassic Park, only more intensely sciencey and, to my mind, even more exciting.

A leading strategy for raising the dead is to take what we know about our target animals and use it to tweak the DNA of living species. The Passenger Pigeon is a good example. These birds didn’t die out all that long ago in the grand scheme of things. Martha, the last known passenger pigeon died on September 1, 1914. Long enough ago that she knew a world without Nazis, but near enough in time that we can still pull viable DNA from her preserved skin cells.




Using that DNA, scientists have reconstructed the Passenger Pigeon genome and are now turning to their closest living relatives, the band-tailed pigeon, for some adventures in genetic manipulation. Using methods that are a bit too advanced for me to adequately explain in a short blog, researchers plan to one day be able to take the DNA of band-tailed pigeons and change the base pairs (adding a adenine here, a guanine there) to produce what will genetically be passenger pigeons. The results won’t be perfect, but nothing in nature ever is. In the words of biologist and de-extinction advocate Stewart Brand, “the results will be close enough.”




If you’re a member of the “close enough” camp, you might also be interested in the case of the European Aurochs, an animal that the first herders used to breed every existing line of domestic cattle before tossing them into nature’s waste-basket. Since their DNA still exists, albeit spread out between a number of different cattle breeds, anyone with a mind to do so could start back-breeding modern cattle and one day (probably quite a long time from now) be herding their formerly extinct bovine brethren.

However, if like me you are more impressed by intensely freaky science experiments, you might prefer the more exact results and bizarre methods used in the cloning of extinct species. Since 1996 when Dolly the sheep first found her way into the lexicon, researchers have been working to take the DNA of extinct species and infuse it into the eggs of living animals in the hopes of producing something shocking. They have actually already succeeded in doing this once.

The Bucardo, a subspecies of Spanish Ibex went extinct in 2000, but in 2003 a baby Bucardo was born using the same methods that produced Dolly. Unfortunately the newborn only survived about ten minutes before succumbing to respiratory failure (a common problem with cloned animals), but scientists are hopeful that as their methods improve so will the lifespan of their  creations.




Similar methods have been used to play god with chickens and endangered falcons. Take some falcon skin cells, reverse engineer them into stem cells, and implant those into chicken embryos and the resulting chickens will effectively have the gonads of a falcon. If you could persuade a male and female "modified chicken" to breed, the birds would lay eggs that hatch into honest to goodness falcons, presumably to the surprise of the hapless and soon-to-be helpless parents.




Cloning extinct animals raises all kind of questions about ethics. What kind of life would these animals have as the only members of their species? How would they learn how to behave if they have no same-species parents? What impact would reintroducing these animals have on presently modified ecosystems? These are all things that need to be considered, but the overarching theme surrounding the topic is hope. If we can find a way to responsibly and successfully bring back animals and use them to restore the world to some of its former glory, it at least seems worth a shot. 



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