"Let's suppose for the sake of argument," said Crake one evening, "that civilization as we know it gets destroyed. Want some popcorn?"
"Is that real butter?" said Jimmy.
"Nothing but the best at Watson-Crick," said Crake. "Once it's flattened, it could never be rebuilt."
"Because why? Got any salt?"
"Because all the available surface metals have already been mined," said Crake. "Without which, no iron age, no bronze age, no age of steel, and all the rest of it. There's metals farther down, but the advanced technology we need for extracting those would have been obliterated."
"It could be put back together," said Jimmy, chewing. It was so long since he'd tasted popcorn this good. "They'd still have the instructions."
"Actually not," said Crake. "It's not like the wheel, it's too complex now. Suppose the instructions survived, suppose there were any people left with the knowledge to read them. Those people would be few and far between, and they wouldn't have the tools. Remember, no electricity. Then once those people died, that would be it. They'd have no apprentices, they'd have no successors. Want a beer?"
"Is it cold?"
"All it takes," said Crake, "is the elimination of one generation. One generation of anything. Beetles, trees, microbes, scientists, speakers of French, whatever. Break the link in time between one generation and the next, and it's game over forever."
"Speaking of games," said Jimmy, "it's your move."
--Margaret Atwood, Oryx and Crake