WILDLIFE ESSAY THE END OF EXTINCTION? Cutting-edge lab techniques such as IVF and DNA editing now have the potential to rescue animals from the edge of extinction – and even beyond. Helen Pilcher finds out why some species are less extinct than others. Under the vigilant gaze of their rifle-clad guards, three very special rhinos wallow in the mud at the Ol Pejeta Nature Conservancy in Kenya. Their tasselled ears flick back and forth under the hot African sun, but the animals have no idea how precious they are. For these are the last three northern white rhinos anywhere on Earth. We all know that rhinos are in danger, that poaching and habitat loss are driving them ever closer to extinction, but the northern white rhino is in an unenviable class all of its own. The surviving animals are too old, too ill and too related to be able to breed naturally, so to all intents and purposes the northern white rhino is already extinct. Grandfather, mother and daughter – Sudan, Najin and Fatu – are the walking dead; ghosts of a magnificent subspecies that once roamed Africa in the thousands. and Wildlife Research in Berlin. Traditional conservation has failed the northern white rhino, so Hildebrandt is part of an audacious mission that is working to save the subspecies by blending high-tech assisted-reproduction methods with the latest research in cell biology. The idea is to create test-tube northern white rhinos, then use southern white rhinos – the species are cousins – as surrogates to carry the embryos and then nurture the calves beyond birth. It’s a tall order, not least because no one has ever created a rhino through in vitro fertilisation (IVF) before, and it hinges on the availability of two vital ingredients: sperm and egg. With this in mind, Hildebrandt and his team have been collecting and freezing semen samples from male northern white rhinos for years. Eggs are more of a problem. They are difficult to collect and even harder to freeze, so Hildebrandt is having to make his own. His team are taking skin cells, biopsied So how can we save an animal when its future seems so hopeless? Over the past few years I’ve been following the work of Thomas Hildebrandt, a veterinarian from the Leibniz Institute for Zoo IF WE HAVE THE DNA OF A CREATURE AND THE METHODS TO RECREATE IT, TO WHAT EXTENT IS THAT ANIMAL EXTINCT? from northern white rhinos in the past, adding in genes to turn them into stem cells, and then coaxing them to become eggs. It’s cellular alchemy. I find research like this fascinating, not just because it could change the fate of the northern white rhino, but because it could be applied to other species too, living and dead. Using these and other related techniques, scientists are on the verge of being able to claw species back not just from the edge of extinction, but from beyond it too. They call it de-extinction. The stage was set a little over a decade ago, when researchers resurrected an extinct type of mountain goat called a bucardo (a subspecies of the Spanish ibex). They collected skin cells from the last living animal and then, once she died, used the DNA inside these cells for cloning. After many attempts they managed to create a kid, but though the newborn looked perfect on the outside, her lungs were grossly deformed. She lived for just seven minutes. It was a devastating blow to the scientists who created her, but for the world at large it was the beginning of something much bigger: an end to the finality of extinction. It’s a profound and dogma-challenging thought. If we have the cells or DNA of a creature and the necessary methods to recreate it, then to what extent is that animal extinct? We can’t get DNA from dinosaur bones because they’re too ancient. So these and other creatures older than a million years old are truly lost forever. But what of the bucardo? Vials of the goat’s frozen cells still exist, and the scientists who tried to bring it back tell me that the only obstacles between September 2016 Illustrations by Danny Allison BBC Wildlife 31