"It was once convenient to think biblically..."

Throughout the day Saturday (in Ian McEwan's 2005 novel), Henry Perowne continues to reflect on our post-Darwinian, post-9/11 world:

He turns the corner into Paddington Street and stops in front of the open-air display of fish on a steeply raked slab of white marble. He sees at a glance that everything he needs is here. Such abundance from the emptying seas. On the tiled floor by the open doorway, piled in two wooden crates like rusting industrial rejects, are the crabs and lobsters, and in the tangle of war-like body parts there is discernible movement. On their pincers they're wearing funereal black bands. It's fortunate for the fishmonger and his customers that sea creatures are not adapted to make use of sound waves and have no voice. Otherwise there'd be howling from those crates. Even the silence among the softly stirring crowd is troubling. He turns his gaze away, towards the bloodless white flesh, and eviscerated silver forms with their unaccusing stare, and the deepsea fish arranged in handy overlapping steaks of innocent pink, like cardboard pages of baby's first book. Naturally, Perowne the fly-fisherman has seen the recent literature: scores of polymodal nociceptor sites just like ours in the head and neck of rainbow trout. It was once convenient to think biblically, to believe we're surrounded for our benefit by edible automata on land and sea. Now it turns out that even fish feel pain. This is the growing complication of the modern condition, the expanding circle of moral sympathy. Not only distant peoples are our brothers and sisters, but foxes too, and laboratory mice, and now the fish. Perowne goes on catching and eating them, and though he'd never drop a live lobster into boiling water, he's prepared to order one in a restaurant. The trick, as always, the key to human success and domination, is to be selective in your mercies. For all the discerning talk, it's the close at hand, the visible that exerts the overpowering force. And what you don't see....[pp. 184-185]