However, it was in this same century that technology -- the material fruit of scientific research -- helped double our species' average lifespan and, in many parts of the world, made unprecedented levels of health, comfort and opportunity possible. "Technology has two faces: one that is full of promise, and one that can discourage and defeat us. We dispose of a staggering amount of physical power, but that, surely, is a challenge to be wise, not an invitation to despair," wrote Harvard University professor Emmanuel Mesthene, in 1967.