How, oh how, did an unloving and mindless universe, cough up minds who were capable of love?

"No mystery in that," you say, "it's just a matter of natural selection."

But natural selection is cruel, bloody, and bloody stupid. Even when, on the surface of things, biological organisms aren't directly fighting each other—aren't directly tearing at each other with claws—there's still a deeper competition going on between the genes. Genetic information is created when genes increase their relative frequency in the next generation—what matters for "genetic fitness" is not how many children you have, but that you have more children than others. It is quite possible for a species to evolve to extinction, if the winning genes are playing negative-sum games.

How, oh how, could such a process create beings capable of love?

"No mystery," you say, "there is never any mystery-in-the-world; mystery is a property of questions, not answers. A mother's children share her genes, so the mother loves her children."

But sometimes mothers adopt children, and still love them. And mothers love their children for themselves, not for their genes.

"No mystery," you say, "Individual organisms are adaptation-executers, not fitness-maximizers. Evolutionary psychology is not about deliberately maximizing fitness—through most of human history, we didn't know genes existed. We don't calculate our acts' effect on genetic fitness consciously, or even subconsciously."

But human beings form friendships even with non-relatives: how, oh how, can it be?

"No mystery, for hunter-gatherers often play Iterated Prisoner's Dilemmas, the solution to which is reciprocal altruism. Sometimes the most dangerous human in the tribe is not the strongest, the prettiest, or even the smartest, but the one who has the most allies."

Yet not all friends are fair-weather friends; we have a concept of true friendship—and some people have sacrificed their life for their friends. Would not such a devotion tend to remove itself from the gene pool?

"You said it yourself: we have a concept of true friendship and fair-weather friendship. We can tell, or try to tell, the difference between someone who considers us a valuable ally, and someone executing the friendship adaptation. We wouldn't be true friends with someone who we didn't thi...

Why We Fight