Teranesia

Grant came over to see what he was looking at. Prabir described what he’d observed so far. The bird had extracted one of the almonds from the fruit, and was performing an even more elaborate routine to penetrate the hard shell.

She said, ‘This part’s old hat: its a famous case of specialisation for a food source.’ The bird had broken away part of the shell, and was now holding the nut with one foot while it used the sharp, hooked part of its upper beak to tear out fragments of the kernel; a tongue like a long-handled pink-and-black rubber stamp darted out to pick up the pieces and take them into the bird’s mouth. ‘Going for the unripe fruit is new, though.’

‘So it doesn’t have to wait for the nuts to fall. Which means the teeth are there to help it stay off the ground?’

‘I suppose so,’ Grant conceded. ‘But there might have been any number of reasons in the past why that was a good idea. It doesn’t require co-evolution with the ants.’

Prabir turned to her. ‘If you’d come to this island knowing nothing about its history, nothing about the ordinary fauna of the region – if you’d dropped in out of the sky in a state of complete ignorance about this entire hemisphere – what would you think was going on here?’

‘That’s a stupid question.’

‘Humour me.’

‘Why? What point is there in ignoring the facts?’

Prabir shook his head earnestly. ‘I’m not asking you to do that. I just want you to look at this afresh. If you’d just arrived from the insular British Isles with an immaculate, theoretical training in evolutionary biology, but no contact for a thousand years with anyone east of Calais, what would you conclude about the plants and animals here?’

Grant folded her arms.

Prabir said, ‘I’m withdrawing my labour until you answer me. Forgetting all the history you know, what does this really look like to you?’

She replied irritably, ‘It looks to me as if the affected species originally shared territory with all the others, then became isolated on some remote island and co-evolved separately for a few million years – and now they’re being progressively reintroduced. OK? That’s what it looks like. But on what island is this meant to have happened?’ She spread her arms. ‘It didn’t happen here: you can vouch for that yourself. There’s no island in the whole archipelago sufficiently isolated, and sufficiently unexplored.’

‘Probably not.’

‘Certainly not.’

Prabir laughed. ‘OK. There’s no such island! All I’m saying is, when the account you’ve just given sounds so much simpler than a hundred separate genes in a hundred separate species marching back from the past in perfect lock-step – I have a lot of trouble seeing how it can’t be telling us something about the truth.’

Grant’s expression softened, her curiosity getting the better of her defensiveness. ‘Such as what?’

‘That, I don’t know.’

Prabir had rewritten the image-processing software to run directly on Grant’s camera. In the afternoon, she found the camouflaged fruit pigeons all around them.

Fluttering across the viewfinder between the pigeons were the butterflies. The wing patterns had changed dramatically – the dappled imitation of foliage and shadows they’d acquired was far less striking, far less symmetric, and far more variable from insect to insect than the old concentric bands of green and black – but when Grant finally captured one and Prabir saw the body, he knew they were the descendants of the insect he’d first seen pinned to a board in his father’s office at the university.

The tranquilliser darts were useless for insects, but Grant had a spray based on wasp venom that could temporarily paralyse the butterflies without killing them. Using a net to keep their victims from falling to the ants, they managed to collect half a dozen live specimens of both the pigeons and the butterflies.

Back on the boat, Grant killed and dissected one of the male pigeons, removing the testes and then working under a microscope to extract stem cells and various stages of maturing spermatocytes. She was hoping to catch the São Paulo protein in the act, though given the uniformity of the pigeons it seemed unlikely that it was still producing radical changes in their genome.

Prabir left her to it and stood out on the deck, staring back into the harmless shadows of the jungle, numb with relief as he realised how painlessly the day had passed. Between the distracting riddle of the altered species and the sheer physical effort of gathering samples, he’d had little time or reason to dwell on the significance of the place. And that was how it should be. He’d already mourned his parents, in the camp, in Toronto, and he’d recounted their triumphs a thousand times for Madhusree. There was nothing to be done here, nothing to be remembered, nothing to be learnt but the secret of the butterflies. He refused to imagine them trapped on the island. In the only sense that they survived at all, they’d left in the very same boat as he had.