The giant tortoises of the Galapagos Islands are large, conspicuous and slow-moving. Encased in their shells, they might seem like impregnable tanks, but they have no defences against machetes. It’s no surprise that their numbers plummeted at the hands of humans who landed on the islands – first pirates, then whales and fur-traders, then permanent settlers.

The lineage of giant tortoise from the island of Floreana was one of the first permanent casualties. It was extinct by 1835, just 15 years after a certain Charles Darwin visited the Galapagos.

Or was it? A team of scientists has found traces of the tortoises, which suggests that a lost population might still be alive on nearby Isabela Island, the largest of the Galapagos