Evolution

"For good Darwinian reasons, evolution gave us a brain whose size increased to the point where it became capable of understanding its own provenance, of deploring the moral implications and of fighting against them."

-- Richard Dawkins in Rebelling Against Our Selfish Genes

"Stand tall, Bipedal Ape. The shark may out-swim you, the cheetah out-run you, the swift out-fly you, the capuchin out-climb you, the elephant out-power you, the redwood outlast you. But you have the biggest gifts of all: the gift of understanding the ruthlessly cruel process that gave us all existence; the gift of revulsion against its implications; the gift of foresight - something utterly foreign to the blundering short-term ways of natural selection - and the gift of internalizing the very cosmos."

-- Richard Dawkins in A Devil's Chaplain