Conservationists and scientists have a saying, “extinction is forever.” But soon biologists will be able to clone long-gone animals, in the hopes of redefining that axiom to “DE-extinction is forever.”

TIME talked with Stewart Brand, president of Revive & Restore, about the technology that may soon allow scientists to bring back extinct species using the DNA found in museum fossils.

In the video above, researchers discuss the process of bringing extinct species like the passenger pigeons back to life.

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