They penetrated the jungle slowly; the thorned shrubs were even denser and more tangled than the species they’d seen before, with long, narrow involuted branches like coils of barbed wire. Prabir cut off a sample, tearing his thumb on a barely visible down of tiny hooks that coated the vines between the large thorns. He sucked the ragged wound. ‘Nice as it would be to solve the mystery, I’m beginning to hope we don’t stumble across a herbivore that needs this much discouragement.’
‘It’d probably be no worse than a rhinoceros or a hippo,’ Grant suggested. ‘But apparently it has no descendants here, to give birth to something similar.’
Prabir fished in his backpack for a band aid. ‘OK, I can accept that: seeds get blown about, continents drift, animal lineages die out locally. But why is it always the most extreme trait that gets resurrected? Why couldn’t these shrubs just grow something mildlyinappropriate, like flowers optimised for a long-vanished pollinating insect?’
Grant mused, ‘There’s no evidence of the São Paulo protein ever having been used for mutation repair. So maybe that was never the case; maybe I’ve been clinging to that idea too stubbornly. It could be that the protein’s role has alwaysbeen to reactivate old traits, to bring old inventions back into the gene pool from a dormant state.’
Prabir considered this. ‘A bit like a natural version of those conservation programmes where they cross endangered animals with frozen sperm from twenty years ago, to reinvigorate the species when the population becomes too inbred?’
‘Yeah. And sometimes they use a closely related species, not the thing itself. If this protein manages a kind of “frozen gene bank”, it would be even less purist about it: it wouldn’t have any qualms about creating a hybrid with a distant ancestor.’
To Prabir this sounded both simpler and far more radical than the mutation repair hypothesis: shifting the mechanism from an esoteric emergency response to a major factor in genetic change. Most of the same problems remained, though.
He said, ‘That still doesn’t explain how particular traits get frozen and thawed. Are you saying that this plant’s ancestors knewthat they’d evolved a spectacularly effective set of defences, and deliberately tucked away a copy of the genes for the next aeon when they’d come in handy?’
Grant smiled, refusing to be provoked. ‘More likely it’s just a matter of the genes that persist the longest having the greatest chance of being duplicated at some point, which then increases their chance of surviving in an inactive form.’
‘And the mimicry? The symbiosis? How does something like that get synchronised?’
‘That, I don’t know.’
They pressed on. Prabir kept waiting for a flash of recognition, for the sight of an old gnarled tree or an outcrop of rock to awaken memories more strongly than the beach. He’d explored this side of the island completely; every step he was taking here was one he must have taken before. But too much had changed. Though the trees themselves appeared unaltered, there were no ferns, there were no small flowers on the ground, just the carnivorous orchids they’d seen on the other islands, and the ubiquitous barbed-wire shrubs. Even the scent of the forest was alien to him. It was like returning to a city to find it repaved and repainted, emptied of its old inhabitants and repopulated by strangers with new customs and new cooking smells. Ambon with its nouveau-colonial refurbishment had seemed more familiar than this.
The black cockatoos were here, too. Prabir stood and watched one for half an hour, waiting for Grant to finish dissecting an orchid.
The bird was sitting in a kanari tree. Using its teeth, it chewed straight through a slender branch that sprouted twigs bearing half a dozen white blossoms swollen with fruit. The cluster of twigs and fruit fell at the bird’s feet, landing on the large, solid branch where it was perched. It proceeded to attack one of the fruits, chewing through the leathery hull, which had not quite ripened to the point where it would split open and spill the seeds, the almonds, on to the ground.
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 muchsimpler 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 somethingabout 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.