Forty Signs of Rain by Kim Stanley Robinson

"We are animals, animals whose wisdon has epanded so far as to tell us we are mortal creatures. We die. For fifty thousand years we have known this. Much of our mental energy is spent avoingding this knowledge. We do not like to think of it. Then again, we know that even the cosmos is mortal. Reality is mortal. All things change ceaselessly. Nothing remains that same in time. Nothing can be held on to. The questions becomes, what do we do with this knowledge? How do we live with it? How do we make sense of it?"

[And now they hook Frank with an evolutionary idea!]

"One of the scientific terms for compassion ... you say, 'altruism.' This is a question in your animal studies. Does true altruism exist, and is it a good adaptation? Does compassion work, in other words? You have done studies that suggest altruism is the best adaptive strategy, if seen from a group context. This then becomes a kind of ... admonishment. To practice compassion in order to successfully evolve -- this coming from your science, which claims to be descriptive only! Only describing what has worked to make us what we are. But in Buddhism we have always said, if you want to help others, practice compassion; if you want to help yourself, practice compassion. Now science adds, if you want to help your species, practice compassion."

p. 243

All throughout the book, our hero, Frank, keeps thinking about the prisoner's dilemma game and its strategies. It does seem that in repeated games the best strategy is to be generous the first time. It sort of makes sense in the way of holding a group together. The Golden Rule is an evolutionary adaptation.