This isn't the first time Chelonoidis abingdoni has been revived: The massive reptiles were last seen in 1906 and considered extinct until the 1972 discovery of Lonesome George, then around 60 years old, on Pinta Island. The population had been wiped out by human settlers, who overharvested the tortoises for meat and introduced goats and pigs that destroyed the tortoises' habitat and much of the island's vegetation.

Now, in an area known as Volcano Wolf—on the secluded northern tip of Isabela, another Galápagos island—the researchers have identified 17 hybrid descendants of C. abingdoni within a population of 1,667 tortoises.

Genetic testing identified three males, nine females, and five juveniles (under the age of 20) with DNA from C. abingdoni. The presence of juveniles