GALÁPAGOS, ECUADOR — A 100-year-old giant tortoise is being credited for singlehandedly reviving his species from impending extinction. br br In 1976, Diego, a Chelonoidis hoodensis tortoise, was brought over from the San Diego Zoo to Santa Cruz Island in the Galapagos for a single purpose — repopulate his dwindling species. br br Along with six females on the island, Diego spent decades copulating, and today his genes can be traced to almost 40 of the current population in the wild. br br A study conducted by tortoise preservationists found that of the roughly 2000 tortoises on the island, Diego has fathered about 800 babies.