“They used to teach us that evolution of intelligent beings wasn't possible," she said. "Societies protect their weaker members. Civilizations tend to make wheel chairs and spectacles and hearing aids as soon as they have the tools for them. When a society makes war, the men generally have to pass a fitness test before they're allowed, to risk their lives. I suppose it helps win the war." She smiled. "But it leaves precious little room for the survival of the fittest.”