Our Vanishing (and Reappearing) Wildlife Z 5
with Hornaday’s work.9 In Wild Life, Hornaday tried to convey a sense of the size of the biological stakes when a species was pushed to the brink of extinction. “Let no one think for a moment,” he warned, “that any vanishing species can at any time be brought back; for that would be a grave error. . . . The heath hen could not be brought back, neither could the passenger pigeon.”10 What a difference a century makes. In his wildest dreams Hornaday could not have envisioned that someday scientists and their allies would seriously be contemplating bringing longextinct species—including the passenger pigeon and the heath hen—back from the dead. Called “de-extinction,” the proposal taps into a range of established and still emerging techniques in cloning and genetic engineering, including the ability to rapidly sequence ancient DNA from preserved tissues of extinct animals to allow scientists to create approximations of lost species by “editing” the genomes of closely related (living) species. So, for example, the genome of a contemporary band-tailed pigeon could be altered to resemble more closely that of a passenger pigeon, and a population of the new birds could theoretically be bred and released into the wild.11 Stewart Brand, the influential writer, entrepreneur, and technoenvironmentalist, is one of the driving forces behind the idea, which has grabbed considerable media attention in recent years. Brand’s Long Now Foundation is currently supporting scientific efforts to re-create the passenger pigeon— and exploring possibilities for the heath hen— within its “Revive & Restore” project, which also has set its sights on a range of resurrection candidates, from the Tasmanian tiger (thlyacine) to the woolly mammoth.12 And the list continues to grow.