The findings prompted a larger 2008 expedition, in which teams sampled 1,669 individuals, drawing blood, noting the locations, and marking the tortoises so they could be monitored after analysis. The work found 84 hybrids of Floreana ancestry — of which 30 were less than 15 years old — and 17 with Pinta ancestry. A follow-up expedition is planned for next year to search the area where those populations were concentrated, hoping to find pureblood individuals and bring them to a captive breeding center on Santa Cruz Island. If all goes well, those individuals will serve as founders of a restored population.

"Human activity may have led to the preservation of lineages of species thought extinct," Russello said.