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So You're Extinct? Scientists Have Gleam In Eye

Publication Date: 
March 18, 2013
The New York Times
Gina Kolata

Professor Hank Greely spoke with The New York Times' Gina Kolata on the idea of bringing back extinct species and the consequences it could have for the Endangered Species Act. 

Until recently, the arrow of natural selection seemed to go only one way. A species could form, then it could flourish, then it could go extinct. And once it was extinct, it could not come back.

Now, though, some scientists say they see a new path.

"Maybe we can no longer delay death, but we can reverse it," said George Church, a Harvard Medical School geneticist.


Before humans killed them, the nation had three billion to five billion passenger pigeons. They would take days to cross a city, noted Hank Greely, the director of the Stanford Center for Law and the Biosciences at Stanford University. "They left cities covered in an inch of guano," he said.


In theory — a wild theory — backbreeding humans might even enable scientists to bring back Neanderthals, Mr. Greely said. About 2 to 3 percent of human DNA seems to be relics of Neanderthal DNA, he said, and different people have different Neanderthal DNA segments. Of course, he added, "a 500-generation backbreeding among humans is not feasible." And, he added, "It would be a really bad idea."


One is the consequences for the Endangered Species Act. Its premise, Mr. Greely pointed out, is that extinction is forever.

"If you take away that argument, what happens?" he asked. "Suppose developers want to build on a last bit of land where an endangered bird lives. And suppose they say, 'We will be happy to pay for freezing. Now let us build our golf course.'"

Mr. Greely cited another argument in favor of bringing back extinct species. He did not quite buy it, he said, but for him it had "a visceral appeal."

It is an argument about justice. Take the passenger pigeon. "We are the murderers," Mr. Greely said. "We killed them off. Shouldn't we bring them back?"

But that raises questions, he added. "Do we owe duties of justice to nonhuman species? If so, where do we draw the line? How much money do we have to spend? How many species do we have to bring back?"

In the end, a sense of wonder draws Mr. Greely and many others to the idea of bringing back species.

"For me, it’s just would just be so cool to see a woolly mammoth or a saber tooth tiger or a ground sloth," Mr. Greely said.

"We are not talking Jurassic Park," Mr. Greely said. "We are talking Pleistocene Park, 100,000 or 200,000 years ago." And, he added, "there are an awful lot of cool things that died within the past 200,000 years."