Well, Darwin’s theory of natural selection is premised on self-preservation—to maximise the passing on of one’s genes and, hence, one’s genetic stake in the future.

She shifts restlessly and he waves a hand.

Sorry, you know that, of course you do. Well, the old man’s superstitions about letting the sea ‘have its prey’ can be restated in the most basic Darwinian terms: survival of the fittest. You don’t risk saving someone else at a cost to yourself. Meggie’s resolve to do the opposite is biologically anarchic. He taps his chin with two fingers and smiles. Yep, I reckon Allee would have liked that.

I never thought I’d hear a biologist rejecting Darwinism.

Not rejecting, just acknowledging its reductiveness. Evolutionary biologists will tell you it’s a whole lot more complex. Even old Darwin himself suspected that. And you know what? One of the things that stumped him most was altruism. He just couldn’t account for it. Why do certain animals sacrifice themselves for the benefit of the group? Insect workers that devote their lives to the queen. A species of monkey that warns others of the approach of predators, making itself the vulnerable one.

He pours the last of the wine into Laura’s glass.

Well, the old man toed the Darwinian line, she says grimly. No problem with pesky altruism there.

Are you going to give the pages to Avril?

Mmm, she says, frowning. I don’t want to, god knows, but I will. There’ve been too many secrets in this family. She hugs her knees, rests her chin there. And anyway, she’d never forgive me if I didn’t. Meggie’s real to her, you know? There’s a connection there … something …

Gideon’s quiet for a moment, and then he looks up at the sun. The old man—you know, I wonder whether the whole thing was rather bewildering for him.

You’re defending him?

Hardly. But imagine what it must have been like in 1905, a whole way of life sort of … collapsing. Suddenly you’re shunned for upholding beliefs your people held for generations.

Laura swirls the wine in her glass without tasting it. So you don’t think there’s a gene for it? This pointless self-destruction, I mean.

I don’t think there’s a gene ‘for’ most of the things that get trotted out as genetic these days. He counts off on his fingers. Gay gene. ADD gene. Fat gene. Huh. Forget individual variations in biochemistry; forget interactions with the environment, the social world. History. Chance. Choice. Forget the plasticity of living things. It’s about as simplistic as the fishermen’s superstitions—and look, they evolved as just a way of explaining the natural world.

He pauses. Laura says nothing.