In Sept 2001, I had the pleasure of meeting the reclusive celebrity. Conversation isn’t a giant tortoise thing and we didn’t establish an enduring relationship but I feel I owe him an obituary.
The islands of the Galapagos, a thousand kilometres off the west coast of Ecuador, are the tips of undersea volcanoes. Fourteen large and innumerable small ones are spread over a sea area the size of Munster. In the primordial past, tortoises arrived in the archipelago, probably carried on driftwood from mainland South America. These plant eaters colonised the larger islands, each of which has its own unique eco-system. Over countless millennia, the tortoises evolved into distinct sub-species.
The ‘island rule’ states that small creatures arriving on islands, where they don’t have enemies or competition, become larger. The dodo, for example, was a huge flightless pigeon. The giant rats of Tenerife and Gran Canaria were the size of rabbits. Like the dodo, they are no longer with us; the cats we brought in saw to that. The most famous living examples of ‘gigantism’ are the giant tortoises of Pacific and Indian Ocean islands.
The Galapagos were discovered by accident in 1535, when a ship carrying Tomás de Berlanga, bishop of Panama, drifted off course. Soon, ships were calling to take on water and tortoises. The reptiles were stacked, one on top of the other, in the holds of the vessels. Capable of surviving without food or water, they provided fresh meat. Exploitation rendered three of the 14 giant tortoise sub-species extinct. With George’s demise, a fourth has been added.
Pinta is the most northerly of the larger islands. It was thought that its tortoises were gone. Then, in 1972, George was discovered. He was taken to the Darwin Centre, on Santa Cruz Island, where he was been ever since. Meanwhile, a search got underway on Pinta in the hope of finding a female. It was not to be. George was the sole survivor of his race. In 1993, with hopes of finding a pure-bred partner finally abandoned, two females from other islands were introduced to George. They belonged to races closely related to the Pinta one. Offspring he might have produced with them would have a 50% complement of Pinta genes, offering a partial victory over extinction. George, however, had other plans. He had taken a vow of celibacy; eggs were produced on two occasions but they proved to be infertile. He was about 100 years old when he died, not a great age for a tortoise; one which Captain Cook is said to have presented to the Tongan royal family, died in 1977 at the age of 226.
So the Pinta sub-species of tortoise, it would seem, is gone for ever. There is, however, a tiny glimmer of hope, if the findings of a paper published by 13 scientists in the journal Current Biology earlier this year, are to be believed. In 1996, blood samples were taken from 1,600 tortoises on Isabela, the largest Galapagos island. DNA analysis of these revealed ‘genetic signatures’ of the extinct Floriana race among 11 hybrid individuals. This led the authors to speculate that pure-bred Floriana tortoises are ‘very likely still alive’ on Isabela and that ‘they could constitute core founders of a captive breeding programme directed towards resurrecting this species’.
But how did Floreana tortoises come to be on Isabela? Floreana, a relatively small island southeast of Isabela, has something which is very rare on Galapagos; a source of fresh water. Mariners, calling there to fill their ship’s tanks, helped themselves to tortoises as well. Within 10 years of Darwin’s visit to Floreana, its unique race of tortoise was gone. It’s suggested that, occasionally, captured Floreana tortoises fell from ships and swam ashore as they passed Isabella. There is little hope that members of George’s tribe have survived elsewhere, but samples of his DNA are being preserved. With advances in genetic engineering, who knows what will be possible in the future?