George, who has stubbornly refused to mate with the female tortoises from a related subspecies placed in his pen, has been considered the last of his kind since his discovery in 1971.
His wrinkled face became a symbol of how human activity leads to extinction, and the meter-wide, 88-kilo tortoise has long held the Guinness Book of World Records title of "rarest living creature."
Three of the 14 species of Galapagos tortoises - which helped Charles Darwin develop the theory of natural selection - have become extinct because of hunting and competition for food from goats introduced in the 1950's.
The loss of George - the first tortoise found on the island of Pinta since 1906 - would have brought that number to four.
"Even after 35 years, Lonesome George seems uninterested in passing on his unique genes and has failed to produce offspring," said lead author Michael Russello of the University of British Columbia Okanagan who began working with the tortoises as a postdoctoral fellow at Yale.
"The continuing saga surrounding the search for a mate has positioned Lonesome George as a potent conservation icon, not just for Galapagos, but worldwide."
Researchers now hope that another tortoise from George's subspecies - Geochelone abingdoni - may be living the neighboring Galapagos island of Isabela.
A multinational team headed by researchers at Yale has identified a tortoise which has half his genes in common with George and is "clearly a first generation hybrid between the native tortoises from the islands of Isabela and Pinta."
They hope that with further testing they will be able to find a genetically pure Pinta tortoise among the 2,000 tortoises living on Isabela and start a breeding program.
"These findings offer the potential for transforming the legacy of Lonesome George from an enduring symbol or rarity to a conservation success story," said Yale biologist Jeffrey Powell.
It will take a team of about 20 people around two months to do an exhaustive sampling and transmitter-tagging of the tortoises on the volcano and then to find the potential Pinta tortoises and bring them in captivity.
The study was published in the May 1 edition of Current Biology.
Tue May 1, 3:09 PM ET