"If all living things strive to satisfy their innate urges, none ever forgets to go forth and multiply. They can't: wild creatures are programmed to breed for nothing, certainly not for old-age care. Homo sapiens, exceptional by its brain, broke this rule. Though sex remains one of the most powerful human instincts, intelligence, or the contraceptives it invents, allows people the fun without the function. Evolution has made us the thinking beings who know how to trade blind multiplication for the good life. This unique intelligence could also, however, make us the only species to vanish on its own, smoothly, without any ecological disruption typical of all previous extinctions. This most-evolved animal constitutes, in many ways, evolution's end of the road. The moment a wave hits its shore, it swiftly disappears."