Few things feel as final in the natural world as a species going extinct. But thanks to an odd set of circumstances off the Galapagos Islands involving rugged geography and whalers with hearty appetites, humanity has a chance to bring back what it once obliterated.

Upon the very islands that inspired Charles Darwin to develop the theory of natural selection, an international team of scientists and conservationists has undertaken a first-of-its-kind effort to revive two extinct tortoise species -- not using high-tech genetic engineering, but by breeding living creatures related to the ones now gone.

"This a peculiar case; I don't think you can extend this example to many other species," said Adalgisa Caccone, a senior research scientist at Yale University. "It's just a strange accident of history. This genome of the extinct species [was] locked in a place that was remote enough for humans not to go there."

Last month, park rangers and scientists removed 32 hybrid tortoises from Wolf Volcano in a complex operation that involved airlifting creatures from rugged terrain. The tortoises now reside in a Santa Cruz breeding center, as part of a project spearheaded by the Galapagos National Park Directorate and Galapagos Conservancy.

"There's not really even terminology for basically rescuing the genomes of two extinct species using surviving hybrids," said James Gibbs, a professor of conservation biology at State University of New York in Syracuse. "The whole process of population restoration is fairly common. It's been successful in many places. But we're talking about recovering the remnants of the original species."

The hybrids share genomes with two tortoise species: the Floreana tortoise, or Chelonoidis elephantopus, that went extinct about 150 years ago; and the Pinta tortoise, or Chelonoidis abingdonii. The last known living Pinta tortoise died in 2012; his name was Lonesome George.

"Darwin was practically the last person who wrote about the tortoises on Floreana," Gibbs said.

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While Galapagos tortoises are iconic figures in the realm of conservation, these particular species maintained the balance of vegetation on the islands by consuming massive quantities of plant life, Caccone said. Gibbs described the creatures as "bulldozers" and a "major ecological force."

In recent years, researchers discovered the hybrid population of tortoises living at Wolf Volcano, far from the Pinta and Floreana islands. Some of them are the offspring of purebred, extinct tortoises.

How did they end up near the remote Wolf Volcano? Likely because of the eating habits of whalers, pirates and other seamen of the 1800s, researchers said. These people used tortoises as a long-lasting fresh food source, especially since the animals could survive on ships for months without food or water. Humans would disembark and retrieve saddleback tortoises on low-elevation islands, which were smaller and more accessible than the domed variety.

"They were well known as major destinations for whalers," Gibbs said of the arid islands.

Some 250,000 tortoises were snatched from the Galapagos, Caccone said. Ships would anchor in Banks Bay, near Wolf Volcano; but when they had quickly leave, either because they were under attack or wanted to go to new whaling waters, people likely tossed living tortoises overboard to lighten ships' loads. One report from a vessel included a description of a bunch of tortoises floating in the water, Caccone said.

Some tortoises made it to shore, where they mated with the indigenous tortoises and, voilà, there appeared hybrid tortoises.

"Humans were the ones responsible for their demise because we basically ate them to extinction," Caccone said. "On the other hand, by doing this, by taking them and eventually dropping them in this other place, we sort of preserved the genetic material of this extinct species."

Many years later, researchers discovered the Wolf tortoises that had been protected from humans by the "brutal geography of the Galapagos," Gibbs said.

Caccone recalled examining the DNA sequences of the creatures in 2000. "I vividly remember looking at the computer screen and said, 'Where are these coming from, Mars?' We called them alien," she said.

Eventually, researchers were able to compare the DNA of the living Wolf tortoises to the extinct Pinta and Floreana ones by using material preserved in museum collections, Caccone said. After an expedition in 2008, they identified a group that had a high "conservation value" because of their genetic makeup.

Finally in November, the rangers and scientists transported 32 hybrids to the breeding center. In about a year, mating will begin, based on a breeding plan that selects for genes.

"It's not Jurassic Park," Caccone said. "We are just doing some artificial selection to eventually increase the genome."

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The revival won't be immediate; it will take decades of breeding generations to get the right combination of genes. But the longevity of Galapagos tortoises -- Lonesome George was thought to have lived to about 100 -- may also be their saving grace.

"The fact that they don't breed so quickly means they haven't assimilated well into this new population," Gibbs said. "It also gives us a tremendous opportunity to recover from our mistakes."

Scientists likely won't be able to breed back into existence a tortoise that is a 100 percent genetic match to the extinct Pinta or Floreana, but they could get up to 90 percent in just four generations, said Caccone. In the meantime, first generation offspring will be released onto the islands.

"Both the Pinta and Floreana need their tortoises back,” Caccone said. “They need them sooner rather than later. These islands can’t wait 200 years.”

Besides, even though the hybrids' offspring won't be identical to their extinct relatives, natural selection can take care of the rest. Just as Darwin described.

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