According to the Guinness Book of World Records, Lonesome George, a tortoise living on the island of Pinta (a northern island of the Galápagos),, is the "rarest living creature."

By the late 1960s, it was noted that the tortoise population on this island that is visited only occasionally by scientists and fishermen, had dwindled close to extinction, and in 1972, only this single male of the species "Geochelone abingdoni" was found.

Lonesome George was immediately brought into captivity at the Charles Darwin Research Station on the island of Santa Cruz where he is housed with two female tortoises from a species found on the neighboring island of Isabela.

"Even after 35 years, Lonesome George seems uninterested passing on his unique genes and has failed to produce offspring," said lead author Michael Russello of the University of British Columbia Okanagan. 

"Although Lonesome George has yet to find a tortoise partner, upwards of 50,000 people visit him each year," said Russello.